Gems of Ophthalmology: Cataract Surgery [1 ed.] 9789352704019, 9352704010

Table of contents :
Cover
Half Title Page
Title Page
Copyright Page
Contributors
Preface
Acknowledgments
Contents
Chapter 1
Chapter 2
Chapter 3
Chapter 4
Chapter 5
Chapter 6
Chapter 7
Chapter 8
Chapter 9
Chapter 10
Chapter 11
Chapter 12
Chapter 13
Chapter 14
Chapter 15
Chapter 16
Chapter 17
Chapter 18
Chapter 19
Chapter 20
Chapter 21
Chapter 22
Chapter 23
Chapter 24
Chapter 25
Chapter 26
Chapter 27
Index

Citation preview

Gems of Ophthalmology

CATARACT SURGERY

Gems of Ophthalmology

CATARACT SURGERY

Editors

HV Nema MS

Formerly, Professor and Head Department of Ophthalmology Institute of Medical Sciences Banaras Hindu University Varanasi, Uttar Pradesh, India

Nitin Nema MS DNB

Professor Department of Ophthalmology Sri Aurobindo Institute of Medical Sciences Indore, Madhya Pradesh, India

JAYPEE BROTHERS MEDICAL PUBLISHERS

The Health Sciences Publisher New Delhi | London | Panama

Jaypee Brothers Medical Publishers (P) Ltd Headquarters Jaypee Brothers Medical Publishers (P) Ltd 4838/24, Ansari Road, Daryaganj New Delhi 110 002, India Phone: +91-11-43574357 Fax: +91-11-43574314 Email: [email protected] Overseas Offices J.P. Medical Ltd 83 Victoria Street, London SW1H 0HW (UK) Phone: +44-20 317 08910 Fax: +44 (0)20 3008 6180 Email: [email protected]

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Website: www.jaypeebrothers.com Website: www.jaypeedigital.com © 2019, Jaypee Brothers Medical Publishers The views and opinions expressed in this book are solely those of the original contributor(s)/author(s) and do not necessarily represent those of editor(s) of the book. All rights reserved. No part of this publication may be reproduced, stored or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior permission in writing of the publishers. All brand names and product names used in this book are trade names, service marks, trademarks or registered trademarks of their respective owners. The publisher is not associated with any product or vendor mentioned in this book. Medical knowledge and practice change constantly. This book is designed to provide accurate, authoritative information about the subject matter in question. However, readers are advised to check the most current information available on procedures included and check information from the manufacturer of each product to be administered, to verify the recommended dose, formula, method and duration of administration, adverse effects and contraindications. It is the responsibility of the practitioner to take all appropriate safety precautions. Neither the publisher nor the author(s)/editor(s) assume any liability for any injury and/ or damage to persons or property arising from or related to use of material in this book. This book is sold on the understanding that the publisher is not engaged in providing professional medical services. If such advice or services are required, the services of a competent medical professional should be sought. Every effort has been made where necessary to contact holders of copyright to obtain permission to reproduce copyright material. If any have been inadvertently overlooked, the publisher will be pleased to make the necessary arrangements at the first opportunity. The CD/DVD-ROM (if any) provided in the sealed envelope with this book is complimentary and free of cost. Not meant for sale. Inquiries for bulk sales may be solicited at: [email protected] Gems of Ophthalmology—Cataract Surgery First Edition: 2019 ISBN 978-93-5270-401-9

Contributors Abhay R Vasavada  MS FRCS Director, Illadevi Cataract and Intraocular lens Research Center and Raghudeep Eye Clinic Ahmedabad, Gujarat, India

Albert Galand  MD Professor and Chairman Department of Ophthalmology University of Liege Liege, Belgium

Amrutha Padhaye  MS Rajan Eye Care Hospital (P) Ltd Chennai, Tamil Nadu, India

Anurag Badhani  MS DNB FRCS–I Fellow (Vitreoretinal Services) LV Prasad Eye Institute Bhubaneswar, Odisha, India

Arindam Chakravarti  MS Consultant Center for Sight Dwarka, New Delhi, India

Arshi Misbah  MS Senior Resident Department of Ophthalmology MLB Medical College Allahabad, Uttar Pradesh, India

Arup Chakrabarti  MS Director Chakrabarti Eye Care Center Thiruananthapuram, Kerala, India

Ashish Khodifad  DNB Fellow, Vitreoretina Aravind Eye Hospital and Postgraduate Institute of Ophthalmology Puducherry, India

Bela Kamboj  MS

Fellow, LV Prasad Eye Institute Hyderabad, Telangana, India

David J Apple  MD

Professor Ophthalmology and Pathology Director, Research on Ocular Therapeutics and Biodevices Department of Ophthalmology Storm Eye Institute Medical University of South Carolina Charleston, South Carolina, USA

Frank Joseph Goes  MD

Director, OagchirurgieOagheekunde, Antwerp, Belgium

Geetika Badhani  DNB

Senior Resident, Ophthalmology Deen Dayal Upadhyay Hospital New Delhi, India

Gitansha Sachdev  MS FICO Center for Sight Safdarjung, New Delhi, India

H Verbraeken  MD

Professor Department of Ophthalmology University of Ghent, Ghent, Belgium

Himanshu Shekhar  MD

Senior Registrar Dr RP Center for Ophthalmic Sciences All India Institute of Medical Sciences New Delhi, India

I Howard Fine  MD PC Physician and Surgeon Ophthalmology Oregon Eye Associate Eugene, Oregon, USA

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Gems of Ophthalmology—Cataract Surgery

Jagat Ram  MS

Professor, Department of Ophthalmology, Postgraduate Institute of Medical Education and Research, Chandigarh, India

Jagruti P Desai  MS

Consultant, Illadevi Cataract and Intraocular Lens Research Center and Raghudeep Eye Clinic Ahmedabad, Gujarat, India

Jaime Javaloy  MD

M Edward Wilson  MD

N Edgar Miles Center for Pediatric Ophthalmology, Department of Ophthalmology, Storm Eye Institute Medical University of South Carolina Charleston, South Carolina, USA

Manas Nath  DO FAICO

Consultant, Department of Cataract and Refractive Services, Aravind Eye Hospital and Postgraduate Institute of Ophthalmology, Puducherry, India

Consultant Miguel Hernández University School of Medicine Alicante, Spain

Mathew Kurian Kummelil  MS

Jeewan S Titiyal  MD

Senior Consultant Chakrabarti Eye Care Center Thiruananthapuram, Kerala, India

Professor, Dr RP Center for Ophthalmic Sciences All India Institute of Medical Sciences New Delhi, India

Jorge L Alió  MD PhD

Director, Department of Cornea and Refractive Surgery, VISSUM, Instituto Oftalmológico de and Miguel Hernández University School of Medicine, Alicante, Spain

Kamaljeet Singh  MS

Professor and Head Department of Ophthalmology MLB Medical College Allahabad, Uttar Pradesh, India

Lalit Verma  MD

Ophthalmologist Center for Sight Dwarka, New Delhi, India

Liliana Werner  MD PhD

Visiting Assistant Professor and Director, Lions Biomaterial Laboratory Department of Ophthalmology Storm Eye Institute Medical University of South Carolina Charleston, South Carolina, USA

Consultant, Narayan Nethralaya Bengaluru, Karnataka, India

Meena Chakrabarti  MS DO DNB

Mohan Rajan  MS

Director Rajan Eye Care Hospital (P) Ltd Chennai, Tamil Nadu, India

Moulindu Paul  MS

Consultant Rajan Eye Care Hospital (P) Ltd Chennai, Tamil Nadu, India

Mahipal S Sachdev  MD

Center for Sight Safdarganj, New Delhi, India

Murali K Aasuri  MS

Consultant, LV Prasad Eye Institute Hyderabad, Telangana, India

Naresh Babu  MS

Consultant, Aravind Eye Hospital and Postgraduate Institute of Ophthalmology Madurai, Tamil Nadu, India

Neelam Runda  MD

Resident Dr RP Center for Ophthalmic Sciences All India Institute of Medical Sciences New Delhi, India

Contributors

PD Ramamurthy  MD

Rohit Shetty  DNB FRCS

Parul Sony  MD

Vice President Consultant Narayan Nethralaya Bengaluru, Karnataka, India

Chairman The Eye Foundation Coimbatore, Tamil Nadu, India Senior Registrar Dr RP Center for Ophthalmic Sciences All India Institute of Medical Sciences New Delhi, India

Piers Percival  FRCS FCOphth

Consultant Ophthalmic Surgeon Scarborough District Hospital Scarborough, UK

Pradeep Venkatesh

Professor, Dr RP Center for Ophthalmic Sciences All India Institute of Medical Sciences New Delhi, India

Rajendra Prasad  MD

Director and Consultant RP Eye Institute New Delhi, India

Rajesh Sinha  MD FRCS

Professor Dr RP Center for Ophthalmic Sciences All India Institute of Medical Sciences New Delhi, India

Rengaraj Venkatesh  DNB

Head and Consultant Department of Glaucoma Services, Aravind Eye Hospital and Postgraduate Institute of Ophthalmology, Puducherry, India

Richard S Hoffman  MD Ophthalmic Consultant Oregon Eye Associate Eugene, Oregon, USA

Rohit Om Prakash  MS

Consultant, Cataract Surgery Dr Om Prakash Eye Institute Amritsar, Punjab, India

Sat Pal Garg  MD Professor, Dr RP Center for Ophthalmic Sciences All India Institute of Medical Sciences New Delhi, India

Shreesh Kumar  MD Consultant, The Eye Foundation Coimbatore, Tamil Nadu, India

Shruti Mahajan  MS Consultant, Refractive Surgery Dr Om Prakash Eye Institute Amritsar, Punjab, India

Sonia Rani John  DNB Chakrabarti Eye Care Center Thiruananthapuram, Kerala, India

Soumya Ganesh Nanaiah  MS Consultant, Narayan Nethralaya Bengaluru, Karnataka, India

Sudeep Das  MS Consultant, Narayan Nethralaya Bengaluru, Karnataka, India

Sujatha Mohan  MS Consultant Rajan Eye Care Hospital (P) Ltd Chennai, Tamil Nadu, India

Supreet Singh Juneja  MS Junior Consultant Aravind Eye Hospital and Postgraduate Institute of Ophthalmology Madurai, Tamil Nadu, India

vii

Suresh K Pandey  MD

Valsa Stephen  MS DO DNB

Department of Ophthalmology Storm Eye Institute Medical University of South Carolina Charleston, South Carolina, USA

Consultant Chakrabarti Eye Care Center Thiruananthapuram, Kerala, India

Tushya Om Prakash  MS

Senior Resident Dr RP Center for Ophthalmic Sciences All India Institute of Medical Sciences New Delhi, India

Consultant, Cataract Surgery Dr Om Prakash Eye Institute Amritsar, Punjab, India

Vijay Kumar Sharma  MD

Preface In spite of launching of “Vision 2020: The right to sight program”, cataract continues to remain the main cause of visual impairment and blindness. Cataract has become a serious public health problem in developing countries. According to WHO estimates, cataract is responsible for 51% of blindness. As the world population is rapidly aging, cataract cases are increasing and cataract backlog is accumulating each year. With the introduction of recent technology, the cataract surgery has completely changed. During the past 50 years, a number of innovations have transformed cataract surgery from intracapsular cataract extraction to phacoemulsification with intraocular lens (IOL) implantation and near normal recovery of vision. The cataract surgery is now considered as a refractive procedure. The most significant landmark innovation was performed by Ridley in 1949 by implanting an IOL after extraction of opaque lens. However, his innovation was fiercely criticized and not adopted by majority of eye surgeons. Later, it was accepted universally. Many formulas were introduced to calculate the power of the IOL to be implanted in order to achieve excellent refractive results. The other outstanding discovery was phacoemulsification by Charles Kelman in 1967. A small percentage of surgeons realized the value of phacoemulsification surgery and performed the surgery with implantation of rigid 5 mm IOL. Subsequently, foldable IOLs were manufactured to be used through a small 3 mm self-sealing clear corneal incision. Bifocal, toric, and accommodative IOLs are now available to suit the need of individual patients. Besides improvisation in IOL and incision, there is refinement in the phacoemulsification machine to make the operative technique more safe, simple and rewarding. Attempts are being made to make the surgery, postoperatively drop-free procedure by injecting corticosteroid and moxifloxacin intracamerally/intravitreally. The present book covers a wide range of topics on cataract surgery such as Manual small-incision cataract surgery, Dye-enhanced cataract surgery, Pediatric cataract Surgery and IOL Implantation, etc. A number of chapters on phacoemulsification in difficult situations such as Posterior polar cataract, White cataract, Hard cataract, and Cataract surgery in small pupil, Subluxated lens and Compromised cornea have also been included for the benefit of young cataract surgeons. We have given useful surgical tips on how to efficiently manage these cases without creating complications. The chapter on Dropped nucleus or nuclear fragment cautions the cataract surgeon where to stop. Femtosecond laser (FL) has made its inroads in cataract surgery also. FL clear corneal incision, capsulotomy and softening of nucleus make phacoemulsification easy and provide excellent results. Chapters contributed

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by Sachdev and Sachdev and Nanaiah, et al. reveal merits of the new procedure. Undoubtedly, after phacoemulsification, femtolaser-assisted cataract surgery is the landmark advancement in cataract surgery because it offers precision and safety. The various safe and recent options for performing capsulotomy is described by Chakrabarti in his chapter on anterior capsulotomy. We assure the readers that the major part of the work presented in this book comes from the Recent Advances in Ophthalmology series edited by us. In each chapter, the author/s has provided references for the benefit of those who want to read the topic in detail. The book is multi-authored, therefore, repetition could not be avoided. Readers can take the advantage of knowing the views of different authors. However, special effort has been put to avoid ambiguity. The book is concise and information on cataract surgery is presented in an easily readable form. It is profusely illustrated. Postgraduate students, residents, and general ophthalmologists can learn not only how to perform a safe cataract surgery but also to tackle difficult cases. HV Nema Nitin Nema

Acknowledgments We wish to record our grateful thanks to all the authors for their spontaneity, cooperation and hard work. Some of them have revised their chapters. Our special thanks go to Drs Mahipal S Sachdev, Arup Chakrabarti, Rohit Om Prakash, and Venkatesh Rengaraj for contributing their chapters on a short notice. Credit goes to Mr Jitendar P Vij (Group Chairman), and Mr Ankit Vij (Managing Director) of Jaypee Brothers Medical Publishers (P) Ltd. who have agreed to start a new series—Gems of Ophthalmology. “Cataract Surgery” is the fifth book of this series.

Contents 1. Manual Small-incision Cataract Surgery: Techniques

1

Manas Nath, Ashish Khodifad, Rengaraj Venkatesh •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• •• ••

Technique 2 Ocular Anesthesia  2 Peribulbar Anesthesia  4 Sub-Tenon’s Anesthesia  5 Bridle Suture  5 Conjunctival Flap  6 Sclerocorneal Tunnel Construction  6 Capsular Opening  11 Capsulorhexis 12 Envelope Technique  14 Can-Opener Technique  14 Hydroprocedures 15 Nucleus Management  17 Cortex Aspiration  21 Intraocular Lens Implantation  24 Wound Closure  24 Pre- and Postoperative Medications  24

2. Clear Corneal Cataract Incisions

28

I Howard Fine, Richard S Hoffman •• •• •• •• •• •• •• ••

History 28 Indications 31 Classifications 32 Controversies 33 Preoperative Evaluation  35 Techniques   35 Intraoperative/Postoperative Complications  39 Postoperative Clinical Course and Outcomes  41

3. Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation

46

Suresh K Pandey, M Edward Wilson, Jagat Ram, Liliana Werner, David J Apple

•• Diagnosis of Pediatric Cataracts  46 •• Cataract Surgery in Children  49 •• Surgical Techniques  63

4. Capsular Dye-enhanced Cataract Surgery Suresh K Pandey, Liliana Werner, David J Apple •• Dye-enhanced Anterior Capsulorhexis  112 •• Dye-enhanced Phacoemulsification  127 •• Dye-enhanced Posterior Capsulorhexis  133

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5. Posterior Polar Cataract

147

Arup Chakrabarti, Meena Chakrabarti

•• •• •• •• •• •• •• •• ••

Pathogenesis 147 Inheritance and Genetics  148 Classification 148 Clinical Features  148 Management 152 Management of the Posterior Capsule  159 Nucleus Drop in Posterior Polar Cataract  160 Intraocular Lens Implantation  160 Posterior Polar Cataract with Spontaneous Dislocation of Nucleus  161 •• Surgery for Posterior Polar Cataract in Children  162

6. Multifocal Intraocular Lenses

167

Frank Joseph Goes

•• •• •• •• •• •• ••

Tecnis Zm900  168 Selection of Patients  169 Patient Expectations  170 Preoperative Testing  171 Surgical Technique  172 Implantation Technique of Tecnis or ReZoom  172 Refractive Lens Exchange Customizing–Mixing and Matching Tecnis–ReZoom  174 •• Results 175

7. Advances in Intraocular Lenses

179

Mohan Rajan, Sujatha Mohan, Amrutha Padhaye, Moulindu Paul

•• •• •• ••

Multifocal Intraocular Lenses  180 Why Accommodative Lenses? Why Not Multifocals?  186 Newer Exciting Lenses  197 Intraocular Lenses of the Future  203

8. Present Status of Phakic Intraocular Lenses in Modern Refractive Surgery

205

Jorge L Alió, Jaime Javaloy

•• Introduction: What is the Role of Phakic Intraocular Lenses in Today’s Refractive Surgery?  205 •• Diagnostic Methods for a Modern Phakic IOL Indication as a Surgical Proposal  209 •• Phakic Intraocular Lens Types Available on the Market  216

9. Intraocular Lens Power Calculation

240

Himanshu Shekhar, Rajesh Sinha, Jeewan S Titiyal

•• Intraocular Lens Power Formulae  241 •• Optical Biometry  248 •• Intraocular Lens Power Calculation in Special Situations  250

10. Scleral Fixated Intraocular Lens Naresh Babu, Supreet Singh Juneja

•• Sutures 256

255

Contents

11. Recent Advances in Anterior Capsulotomy

265

Arup Chakrabarti

•• •• •• •• •• •• •• ••

Zepto Precision Pulse Capsulotomy 266 Equipment 267 Technique 269 Study Results  270 Advantages of Zepto Precision Pulse Capsulotomy  272 Capsulaser 273 Aperturectc™ Continuous Thermal Capsulotomy™ System 278 Verus Ophthalmic Caliper (Mile High Ophthalmics, Denver, Co, United States) 281 •• Handling of the Device  282

12. Phacoemulsification in White Cataracts

286

Rohit Om Prakash, Shruti Mahajan, Tushya Om Prakash

•• •• •• •• •• ••

Classification 286 Pathophysiology 287 Clinical Presentation of White Cataracts  288 Preoperative Workup  288 Management 289 Complications 297

13. Terminal Chop: New Technique for Full Thickness Nuclear Segmentation in Hard Cataract

301

Rajendra Prasad, Anurag Badhani, Geetika Badhani

•• •• •• ••

Mechanics of Terminal Chop  302 Technique 306 Results and Discussion  308 Advantages of Terminal Chop  310

14. Small Pupil Phacoemulsification

314

Rohit Om Prakash, Shruti Mahajan, Tushya Om Prakash

•• •• •• •• •• ••

Etiology 314 Relevant History  314 Preoperative Evaluation  315 Preoperative Dilatation of Small Pupil  315 Decision-Making for the Use of Dilating Aids  316 Intraoperative Floppy Iris Syndrome  324

15. Phacoemulsification in Uveitic Cataract

328

Pradeep Venkatesh, Parul Sony, Sat Pal Garg

•• Preoperative Examination  329 •• Investigations 329 •• Preoperative Treatment  330

16. Phacoemulsification in Eyes with Corneal Diseases Bela Kamboj, Murali K Aasuri

•• •• •• ••

Preoperative Evaluation  338 Choice of Incision Site  338 Maintenance of Anterior Chamber and Protection of Endothelium  338 Ophthalmic Viscosurgical Devices  339

337

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Gems of Ophthalmology—Cataract Surgery •• •• •• •• •• •• •• ••

Irrigating Solution  339 Capsulorhexis 340 Phacoemulsification 340 Microscope Alignment  341 Bullous Keratopathy  342 Epithelial Irregularity  343 Limbal Pathologies  343 Keratoconus and Postkeratorefractive Surgery Eyes  343

17. Phacoemulsification in Vitrectomized Eyes

345

Arup Chakrabarti, Meena Chakrabarti, Valsa Stephen, Sonia Rani John

•• •• •• •• •• •• •• ••

Risks in Vitrectomized Eyes  345 Preoperative Considerations  347 Intraocular Lens Power Considerations  348 Choice of Intraocular Lens  350 Preoperative Patient Counseling  351 Surgical Strategy for Phacoemulsification in Vitrectomized Eyes  352 Postoperative Management  355 Complications 357

18. Management of Subluxated Lenses

360

Shreesh Kumar, PD Ramamurthy

•• Etiology 360 •• Management 362 •• Discussion 371

19. Dropped Nucleus or Nuclear Fragments: Complication of Phacoemulsification

374

H Verbraeken

•• •• •• ••

Incidence of Dropped or Diving Nucleus  374 What Should the Cataract Surgeon Do?  375 Possible Complications of Dislocated Lens Fragments  375 An Unsolved Question: The Best Timing for Pars Plana Vitrectomy  377 •• Techniques of Pars Plana Vitrectomy for Dislocated Lens Fragments  378 •• Visual Prognosis  379

20. Posterior Capsular Opacification Vijay Kumar Sharma, Neelam Runda, Rajesh Sinha

•• •• •• •• •• •• •• ••

Incidence 381 Risk Factors  381 Age 382 Surgical Technique  382 Intraocular Lens Material  382 Intraocular Lens Design  383 Types of Cataract  383 Coexisting Disease  383

381

Contents •• Types and Mechanism of Posterior Capsular Opacification Development 383 •• Quantification and Grading  384 •• Management 385 •• Prevention 386 •• Surgical Technique  387 •• Intraocular Lens Design and Material  387 •• Chemotherapy 388

21. Primary Posterior Capsulorhexis in Adults

391

Albert Galand

22. Femtosecond Laser-assisted Cataract Surgery–1

396

Mahipal S Sachdev, Gitansha Sachdev

•• •• •• •• ••

Currently Available Platforms  396 Procedure 397 Advantages over Conventional Phacoemulsification  399 Techniques for Improved Outcomes  400 Femtosecond Laser in Challenging Cases  401

23. Femtosecond Laser-assisted Cataract Surgery–2

406

Soumya Ganesh Nanaiah, Sudeep Das, Mathew Kurian Kummelil, Rohit Shetty

•• •• •• •• •• •• ••

Basic Science  406 Nomenclature 407 Preoperative Evaluation  407 Planning 410 Technique 410 Contraindications 413 Complications Unique to Femtosecond Laser-assisted Cataract Surgery  413 •• Advantages 414 •• Disadvantages 415 •• Comparison of Femtosecond Laser-assisted Capsulotomy with Manual Capsulorhexis  416

24. Secondary Intraocular Lens Implantation

420

Piers Percival

•• •• •• ••

Indications 420 Contraindications 420 Preoperative Assessment  421 Operative Procedures  421

25. Malpositioned Intraocular Lenses Jagruti P Desai, Abhay R Vasavada

•• •• •• •• •• ••

Incidence 433 Symptomatology 434 Diagnosis 434 Anterior Chamber Lenses  435 Posterior Chamber Lenses  436 Management 446

433

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26. Postoperative Endophthalmitis: An Update

454

Lalit Verma, Arindam Chakravarti

•• •• •• •• •• •• •• •• •• •• •• ••

Incidence 454 Classification 455 Etiology 455 Clinical Features  456 Case Situations and Studies  457 Fungal Endophthalmitis  461 Chronic Endophthalmitis  464 Prevention and Prophylaxis  468 Newer Intravitreal Antibiotics  473 What to do in Case of Infection?  478 What to do in Cluster Infections or Outbreak  478 Legal Issues Related to Endophthalmitis  478

27. Toxic Anterior Segment Syndrome: An Update

481

Kamaljeet Singh, Arshi Misbah

•• •• •• •• •• ••

Index

Epidemiology   481 Etiology 482 Clinical Features  484 Prevention 486 Treatment 488 Clinical Outcome and Prognosis  488

491

CHAPTER

1

Manual Small-incision Cataract Surgery: Techniques Manas Nath, Ashish Khodifad, Rengaraj Venkatesh

INTRODUCTION It is very well proven that cataract surgery is one of the most satisfying and cost-effective surgeries in the medical field, with promising results.1,2 Over the years, it has remarkably evolved: starting from couching through intracapsular cataract extraction (ICCE), conventional extracapsular cataract extraction (ECCE), manual small-incision cataract surgery (MSICS), and phacoemulsification, to femtosecond laser-assisted cataract surgery (FLACS), with each of the techniques having its own advantages and drawbacks. In the current era, the main goals of cataract surgery are better uncorrected visual acuity with minimal complications and early postoperative rehabilitation. Phacoemulsification uses smaller incisions. This provides better uncorrected visual acuity due to less astigmatism and early postoperative recovery. These advantages make phacoemulsification the preferred technique in the settings where resources are available. Phacoemulsification, even with all its benefits, may not be an affordable technique in developing countries. Alternatively, MSICS has similar or sometimes even better advantages over phacoemulsification and is more affordable. However, in this era of FLACS, the relevance of MSICS is still often underquoted. To explain the point, the following advantages of MSICS can be pointed out: •• Small-incision cataract surgery can be done in all types of cataracts. Phacoemulsification may be difficult in brown cataracts, black cataracts, and hard mature cataracts. •• Small-incision cataract surgery, irrespective of the grade of cataract, requires the same time. The time duration for phacoemulsification is more in harder cataracts. •• As reported in a study,3 SICS can be done within 3.8–4.2 minutes. This makes it the preferred technique in a high-volume setup.

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Gems of Ophthalmology—Cataract Surgery

•• It is affordable. One study points out the cost to be US $17 for ECCE, US $18 for MSICS, and US $26 for phacoemulsification.4 •• It is safe and provides good outcomes in challenging cases also like brunescent and brown cataracts, 5 phacolytic, 6 and phacomorphic glaucoma.7 •• Unlike phacoemulsification, SICS does not require a costly machine. •• Small-incision cataract surgery training makes transition to phacoemulsifi­ cation easier.8 It becomes handy for conversion from phacoemulsification if the need arises. In summary, phacoemulsification, being an expensive technique, cannot be employed as the standard procedure in developing countries. MSICS offers merits similar to that of phacoemulsification along with the advantages of shorter learning curves and lower costs. Even today, MSICS is practiced by many eminent surgeons in our country as well as across the world with excellent outcomes. The immense demand for it is visible. Hence, this communication is an attempt to discuss the techniques of MSICS. The steps of the technique are described below (pertaining to the right eye):

TECHNIQUE Instruments Figure 1.1 shows the various surgical instruments used in MSICS.

OCULAR ANESTHESIA The purpose of anesthesia is to safely provide comfort to the patient while optimizing conditions for the surgeon.

Fig. 1.1: Instruments for manual small-incision cataract surgery (MSICS). (a) Lieberman eye speculum. (b) Superior rectus holding forceps. (c) Westcott’s spring scissors. (d) Corneal forceps. (e) Bard-Parker handle with number 15 disposable surgical blade. (f) Crescent knife. (g) 15° side port blade. (h) Keratome. (i) Cystotome. (j) Hydrodissection cannula. (k) Sinskey hook. (l) Cyclodialysis spatula. (m) Irrigating vectis. (n) Simcoe cannula. (o) Shepard intraocular lens (IOL) holding forceps. (p) Vannas scissors. (q) Needle holder.

Manual Small-incision Cataract Surgery: Techniques

Objectives of anesthesia in intraocular surgery are to achieve akinesia of the globe and lid, anesthesia of the globe, lids, and adnexa, control of intraocular pressure, control of systemic blood pressure, and relaxation of the patient. The various types of anesthesia available for intraocular surgery are retrobulbar, peribulbar, parabulbar, topical, topical with intracameral, facial, sedation, and general anesthesia. However, a detailed discussion of all these techniques is beyond the scope of this article. We will discuss in brief some of the commonly employed techniques of anesthesia that we follow in SICS— retrobulbar, peribulbar, and sub-Tenon’s anesthesia.

Composition of Anesthetic Solution •• Two percent lignocaine with or without adrenalin. •• Bupivacaine 0.5–0.75% solution. •• Hyaluronidase: Dose varies from 5 IU/mL to 150 IU/mL. One vial of 1,500 IU is added in 30 mL lignocaine solution making an effective concentration of 50 IU/mL.

Retrobulbar Block The retrobulbar block involves injection of local anesthetic into the muscle cone in the retrobulbar space. Its advantages include faster take-up of block, better akinesia, less quantity of anesthetic solution is required, and is not associated with chemosis as is often seen with peribulbar block (faster onset of action or faster uptake of block). All these factors facilitate high-volume, efficient cataract surgery.

Complications Possible complications include retrobulbar hemorrhage, globe perforation, retinal vascular occlusion, and subarachnoid injection. Though the literature reports the rate of complications associated with retrobulbar block to be higher than that of peribulbar blocks, our experience with retrobulbar blocks over the years has been good and associated with minimal complications.

Technique •• The patient is asked to look in the primary gaze position, which keeps the optic nerve out of the needle’s path. •• A blunt 35-mm, 22-gauge needle with a 5-mL syringe is used. •• Palpate the inferior orbital margin at its outer one-third and clean the skin in this area with an alcohol swab. •• In the lower lid, the junction of the medial two-thirds and the lateral onethird is marked. The needle is introduced at this point. It should remain parallel to the orbital floor. •• As the needle goes beyond the equator, the direction of the needle is changed. It is directed upwards and inwards.

3

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•• As the needle advances, it enters the muscle cone. The entry into the muscle cone can be felt as the change in resistance as it pierces the intermuscular septum. •• Initial rotational eye movements followed by a rebound should occur. No need to advance the needle beyond this point. •• Inject slowly 1 mL/10 seconds. •• Minimize needle movement to prevent possible laceration of the blood vessels. •• After injecting the drug, the needle is withdrawn and pressure is applied over closed lids with a “pinky ball” or with hand for 1–2 minutes, intermittently. •• Unlike peribulbar block, retrobulbar block requires a separate facial block.

Signs of a Good Block •• Ptosis •• Akinesia (or minimal movement) •• Inability to fully close the eye once opened.

PERIBULBAR ANESTHESIA In peribulbar block, the anesthetic agent is injected in the peribulbar space around the eye-ball. This drug gradually spreads inside the muscle cone.

Technique •• 25-mm, 24-guage needle •• 7–10 mL of anesthetic solution •• Two injections are given at the inferotemporal and superonasal quadrants: –– Inferotemporal injection (4–5 mL) is essentially the same as a retrobulbar block, except that the needle is not angled and is not moved centrally after passing the bulbar equator. –– The second superonasal injection is given just below the supraorbital notch which is identified by palpating the orbital rim. –– The needle is passed parallel to the orbital roof and the anesthetic solution injected in the peribulbar space.

Digital Massage after Block •• It is given with fingers of the hand, or with the application of a super pinkie. •• Intermittent massage with release of pressure every 30–45 seconds. •• It results in the following benefits: –– Decreases vitreous volume –– Decreases orbital volume –– Provides better akinesia and anesthesia –– Hemostasis within the orbit.

Manual Small-incision Cataract Surgery: Techniques

Complications are similar to retrobulbar block, but the incidence is less as compared to retrobulbar injection. The disadvantage of a peribulbar block is an inferior quality anesthetic effect when compared to retrobulbar block.

SUB-TENON’S ANESTHESIA Sub-Tenon’s block involves injection of anesthetic agent below the Tenon’s capsule around the globe.

Technique •• •• •• ••

Instruments: Westcott’s scissors, blunt cannula. 3–5 mL of anesthetic solution. The topical anesthetic drops are instilled. In the inferonasal quadrant, 7 mm from the limbus, a small conjunctival nick is made with Wescott scissors. •• The scissors is introduced in the sub-Tenon’s plane and blunt dissection is done by the opening action of the scissors. •• A blunt cannula is introduced in this plane and 2.5–3 mL of anesthetic agent is injected.

Advantages •• Less chances of globe perforation •• Less chances of injury to optic nerve or muscles.

Disadvantages •• Poor akinesia compared to retrobulbar and peribulbar block •• Conjunctival chemosis and subconjunctival hemorrhage.

BRIDLE SUTURE Bridle suture refers to a 5-0 silk suture passed beneath the insertion of superior rectus muscle. It facilitates downward rotation of the eye and increases exposure of superior surgical field. It also aids in the nucleus delivery with an irrigating wire vectis.

Technique •• Grasp the conjunctiva at 12 o’clock or 6 o’clock with fine-notched forceps and rotate the eye inferiorly. •• Grasp the superior rectus muscle at its insertion with a pair of toothed forceps and rotate the muscle toward 6 o’clock. •• Using a needle-holder, pass a 5-0 nylon suture through the conjunctiva and beneath the superior rectus muscle.

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A

B

C

D

Figs. 1.2A to D: Conjunctival flap.

•• Rotate the eye inferiorly to expose the superior limbus and clamp the suture to the eye drape.

CONJUNCTIVAL FLAP We prefer a small fornix-based conjunctival flap from 11 o’clock to 2 o’clock position. •• Pick up the conjunctiva with fine, notched forceps at the temporal limbus (Fig. 1.2A). •• Make a small conjunctival nick with conjunctival scissors at 11 o’clock (Fig. 1.2B). •• Insert the scissors into the sub-Tenon’s space with jaws closed and with the blades parallel to the limbus and bluntly dissect in the sub-Tenon’s space. •• After this, insert one blade of the scissors into the space created and position the other on the conjunctival surface at the limbus. •• Cut both the conjunctiva and Tenon’s capsule and continue until 2 o’clock is reached (Fig. 1.2C). •• Retract the conjunctival flap, exposing the sclera (Fig. 1.2D). •• Apply moderate-intensity cauterization to any bleeding vessels and vascular areas. Avoid excess cautery as it can cause shrinkage of scleral tissue and this increases the risk of postoperative astigmatism.

SCLEROCORNEAL TUNNEL CONSTRUCTION The external incision of sclerocorneal tunnel is smaller in length as compared to the internal incision. This gives the tunnel a trapezoidal configuration.

Manual Small-incision Cataract Surgery: Techniques

The scleral side-pockets allow for the accommodation of a large-sized nucleus. These features of the tunnel allow comfortable delivery of the largest sized nuclei. Instruments: Toothed forceps, 15-number Bard Parker knife, bevel-up crescent knife, 2.8 mm bevel-down keratome.

Technique The technique for the corneoscleral tunnel can be described under three main parts: 1. External incision or scleral groove 2. Construction of the tunnel 3. Entry into the anterior chamber (AC).

External Incision The various types of external incisions are: •• Smile incision: It follows the curvature of the limbus and is parallel to it. When made in superior quadrant, this induces against-the-rule astigmatism due to flattening effect on vertical meridian. •• Straight incision: It is a straight line and does not follow the curvature of the limbus. It has the advantage of inducing less astigmatism when compared to the smile incision. •• Frown/chevron incision: The major part of this incision lies in astigmatic neutral funnel. The ends of the incision are further away from the limbus than the ends of smile and straight incision. Due to these features, it induces least astigmatism. Flowchart 1.1 exhibits the essential points which should be noted while placing the external incision. Flowchart 1.1: Essential points of external incision.

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Fig. 1.3: Frown incision.

We usually perform a frown incision 6–7 mm in size as it is an astigmatically stable incision. The size of 6–7 mm allows us to deal with almost all types of cataracts comfortably. The globe is stabilized by holding the limbus with the help of a toothed forceps. A frown incision is made in the superior quadrant, using a 15-number Bard-Parker knife. The features of this incision are: •• 1.5–2 mm from limbus •• 6–7 mm in length (Fig. 1.3) •• Depth should be one-third to one-half thickness of the sclera. As frown incision is technically difficult to make, beginners can start with a straight tunnel incision first and then later shift to a frown-shaped incision.

Dissection of Sclerocorneal Pocket Tunnel Once the external incision is made, dissection is extended anteriorly by a wriggling movement with a crescent knife lifting its heel and keeping the tip down till it reaches the limbus (Fig. 1.4A). The curvature of the cornea is different from that of the sclera. At the limbus, the direction of movement of the crescent knife should be changed. The tip of the crescent is lifted up following the curvature of the cornea (Fig. 1.4B) and dissection is continued till 1.5–2 mm into the clear cornea. With sideways-sweeping movements of the crescent, the dissection is extended on either side along the length of the incision (Figs. 1.4C and E). Following points should be kept in mind during sideways dissection: •• Remain in the same plane. •• Follow the curvature of the cornea.

Manual Small-incision Cataract Surgery: Techniques

A

B

C

D

E

F

Figs. 1.4A to F: Sclerocorneal tunnel.

•• Create a larger internal incision as compared to the external incision. This will give a funnel-shaped tunnel. For this, the crescent is swept about 45° sideways at the ends of the tunnels. •• At the ends of this internal lip, carry out the dissection in the sclera in an obliquely backward manner. This will create side-pockets (Figs. 1.4D and F). These side-pockets facilitate nucleus delivery out of the anterior chamber.

Internal Incision: Entry into the Anterior Chamber Before entering into AC, one side port entry is made at the 9 o’clock position in the clear cornea just inside the limbus using a 15° blade. This 1.6-mm stab entry is done parallel to iris. Through the side port, AC is filled with viscoelastics. A 2.8-mm angled keratome is introduced in the tunnel with a slight sideways movements taking care not to cut the floor or roof of the tunnel. The keratome is advanced till it reaches the inner end of the tunnel. At this point, the tip of the keratome is

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tilted down. This creates a dimple in the cornea (Fig. 1.5A). A gentle forward push results into AC entry (Fig. 1.5B). Care should be taken so as not to have a sudden jerky entry which may result in injury to the iris or lens capsule. After AC entry, the keratome is made straight and parallel to the plane of the tunnel. The internal incision is enlarged by forward and sideways movements of the keratome, taking care to cut only while going in. The movements of the keratome should respect the curvature of the cornea and limbus. At the ends of the tunnel, keratome is turned 45° sideways to accomplish the lateral ends (Figs. 1.5C and D). The tissue should be cut only with forward movement of keratome, because cutting of tissue with backward movements creates an irregular internal wound that may cut across the limbus. To stabilize the globe during tunnel construction, the lips of the tunnel should not be held as it damages the tunnel. The globe is stabilized by holding the limbus. However, the temporal approach of the scleral tunnel is preferred in certain situations such as: •• Pre-existing against-the-rule astigmatism •• Superior filtering bleb •• Deep-seated eyes. Technique: The technique is the same as described earlier but the dissection into the cornea should be more anterior to get a better self-sealing incision as the surgical limbus width is shorter in horizontal meridian.

A

C

B

D

Figs. 1.5A to D: Anterior chamber (AC) entry.

Manual Small-incision Cataract Surgery: Techniques

Pearls and Pitfalls •• When we begin the sclerocorneal tunnel with a crescent knife, it is suggested that it should be started in the center of the groove as the depth in the center is adequate. The depth of groove may not be appropriate at its ends due to the hesitation while beginning it and haste to finish it. •• During sclerocorneal dissection, the blade should be “just visible” (Figs. 1.4A to F). The tunnel is superficial, if it is very clearly visible, and too deep, if hardly visible. •• A superficial external wound will cause buttonholing of the tunnel. In such cases, a new tunnel can be constructed at a deeper plane after deepening the incision. •• A deep external incision may cause premature entry. In such cases, dissection is done in a superficial plane. If a premature entry has happened, the wound should be sutured and the tunnel should be constructed at another site. •• A very deep external incision may cause scleral disinsertion. In this scenario, the wound should be sutured and the tunnel should be constructed at another site. •• A blunt keratome will require extra force for AC entry. This can cause Descemet’s detachment or sudden jerky entry into AC, damaging the iris and the lens. •• The bleeding during tunnel construction stains the anterior end of the tunnel. This helps to identify the anterior end of tunnel during AC entry.

CAPSULAR OPENING Instruments: A cystotome or Utrata forceps, toothed forceps. Capsular opening is an important step of SICS because a good and an adequate capsular opening makes the subsequent steps easy. Three types of capsular openings that we commonly do depending upon the cases are: (1) continuous curvilinear capsulorhexis (CCC), (2) can-opener capsulotomy, and (3) envelope capsulotomy. In absence of red reflex, as is the case with advanced cataracts, the visibility of the anterior capsule is poor. In such cases, making a good capsular opening becomes challenging. A compromised capsular opening makes the subsequent steps of the surgery difficult. To improve the visibility of capsule in such cases, the capsule is stained with the help of dyes. Various dyes that are commonly used include sodium fluorescein, indocyanin green, and trypan blue. Trypan blue is the preferred and most commonly used dye as it is cheap, does not stain the vitreous and endothelium, and is not endotheliotoxic. The lens capsule is stained under air bubble. Through the side port, air is injected in AC. Under the air bubble, 0.1 mL of dye is injected over the anterior lens capsule. After 15–30 seconds, the dye is washed out of the AC. Viscoelastic is injected and the AC is formed.

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CAPSULORHEXIS The technique of capsulorhexis was described by Gimbel and Neuhann independently. The Japanese surgeon Shimizu called it circular capsulotomy.

Technique A rhexis can be made by cystotome or Utrata forceps. A cystotome is prepared from a 26G needle by making two bends. The first one is a 90° bevel down-bend near the tip of the needle and the second one is an obtuse-angled bend near the hub of the needle, exactly opposite to the direction of the first bend. After filling the AC with viscoelastic, the sharp cutting tip of the cystotome is used to first make a radial incision over the anterior capsule starting from the center of the capsule (Fig. 1.6A). Then the cystotome is engaged under the capsule at the junction of outer one-third and inner two-thirds and pulled to raise a flap of the capsule. The tip of the cystotome is placed on the flap (Figs. 1.6B and C) and the flap is moved in an anticlockwise manner, 1–2 clock hours at a time. This way the cystotome and the flap are repositioned five to six times to create a capsular opening of the desired diameter. The point at which the capsule is grasped by the cystotome is always adjusted, so that it stays 2–3 clock hours away from the base of the flap (Figs. 1.6B and C). The size of the capsulorhexis is modified depending on the size of nucleus. Generally, a 6-mm rhexis suffices for most of the cases. At the end, the capsulorhexis should be completed by the outside-in movement of the flap.

B

A

C

Figs. 1.6A to C: Capsulorhexis with cystotome.

Manual Small-incision Cataract Surgery: Techniques

While using Utrata forceps (Fig. 1.7), the flap is grasped near its base and advanced. The advantage with Utrata forceps is that it does not require support from the cortex below the capsule for the advancement of the flap. Therefore, it is usually employed in cases of hypermature or morgagnian cataract and for posterior capsulorhexis in pediatric cataract.

Pearls and Pitfalls The flap should not be perforated and the underlying cortex should not be disturbed during capsulorhexis with cystotome. •• The anterior chamber must be maintained deep all the time because shallowing of AC may lead to run away and extension of capsulorhexis. In case of extension, it is managed by any of the following methods: –– Little’s technique:9 Anterior chamber should be deepened by injecting viscoelastics. The capsular flap is unfolded and should lie flat over the lens. Then, holding the flap near its base with the forceps, it is pulled backward. This maneuver will re-direct the flap toward the center and then can proceed in the routine manner. If the capsule is not torn easily or the entire lens is pulled centrally, this technique should be stopped immediately to prevent wrap-around capsule tear. –– Alternatively, one can cut the capsule at the escape point using Vannas scissors and direct the opening back to the initial route. –– Another option is to raise another flap at the starting point of capsulorhexis and advance the flap in the opposite direction than that of the escaped flap and join them at the point of escape.

Fig. 1.7: Capsulorhexis with Utrata forceps in a Morgagnian cataract.

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–– The escaped capsulorhexis can also be managed by completing the remaining part of the rhexis in a can-opener fashion. •• If the capsulorhexis size is too small, it can be managed by: –– Multiple radial relaxing incisions –– Double capsulorhexis: A small nick is made with Vannas scissors at any site and a small flap is raised which is advanced with a Utrata forceps or cystotome. –– The nucleus can be managed by doing hydrodelineation so as to debulk the nucleus.

Advantages of Continuous Curvilinear Capsulorhexis •• Continuous curvilinear capsulorhexis can be stretched considerably limiting the risk of radial tears. •• It eases subsequent steps like hydrodissection, cortical aspiration, and in-the-bag intraocular lens (IOL) implantation. •• Helps in stability and centration of the IOL. •• In cases of posterior capsular rupture, the IOL can be placed over the rhexis with capture of optic in the CCC margin for better IOL centration.

Disadvantages of Continuous Curvilinear Capsulorhexis •• Requires more experience to master it adequately. •• Small CCC can prevent safe prolapse of the nucleus out of the capsular bag.

ENVELOPE TECHNIQUE It was proposed by Sourdilla and Baikuff in 1979.10 A linear incision of 4–5 mm is made on the anterior capsule at the junction of the superior one-third and inferior two-thirds which is extended inferiorly on both sides by Vannas scissors and torn off with Utrata forceps.

Advantages •• Simple and efficient technique •• Can be done in cases of morgagnian cataract, intumescent cataract where CCC is difficult.

Disadvantages •• Risk of anterior capsular tear leading to PCR during forceful uncontrolled manipulation inside the AC. •• Incomplete overlap of IOL optic.

CAN-OPENER TECHNIQUE The can-opener technique, though less commonly used in MSICS, can come handy in cases like hypermature cataract or intumescent cataract where

Manual Small-incision Cataract Surgery: Techniques

making the rhexis is difficult, or in case of the extension of rhexis to complete the remaining part of the rhexis. It involves placing multiple tiny cuts in the peripheral part of the capsule so as to create a capsular opening of desired diameter. The cuts are made from uncut to cut end on the capsule and joining them.

Advantages •• Precisely easier to master than CCC •• Can be sized properly depending on the hardness of the cataract.

Disadvantages •• The opening created has got irregular margins which carry the risk of tear during succeeding steps like hydroprocedures and nucleus prolapse. •• Cortex aspiration is challenging due to the presence of anterior capsular tags. •• Restricted opportunity for optic capture with sulcus placement.

HYDROPROCEDURES Hydroprocedures were first described by Michael Blumenthal. Hydroprocedures separate different layers of the lens from the capsule (as in hydrodissection) or from each other (as in hydrodelineation) by creating a cleavage plane. This makes the nucleus and cortex management easier. It facilitates nucleus prolapse into AC and also facilitates cortex wash. Thorough hydroprocedures play an important role in MSICS. Hydroprocedures comprise hydrodissection and hydrodelineation.

Hydrodissection Hydrodissection refers to creating a cleavage plane between the anterior lens capsule and the cortical matter by a fluid wave. Conventional hydrodissection was done between the superficial cortex and the epinuclear sheet. Cortical cleaving hydrodissection refers to the separation of the cortex from the anterior lens capsule. It was first described by Howard and Fine.11 It has largely replaced conventional hydrodissection. Before performing hydroprocedures, viscoelastic is washed out of AC. This prevents rise in pressure while doing hydroprocedures. An irrigating solution (Ringer lactate/BSS) is loaded in a 2-mL syringe. The smaller syringe has the advantage of better control while injecting the fluid. The tip of the cannula is introduced under the capsulorhexis margin. The rim is tented a little with the tip of the cannula and the cannula is advanced till it is halfway between the capsulorhexis margin and the equator. Tenting ensures that there is no layer of cortex between the anterior capsule and cortex and a slow and steady stream of fluid is injected to produce a fluid wave.

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This stream of fluid traverses under the capsular bag and separates it from the corticonuclear mass, thereby facilitating nuclear rotation and manipulation out of its bag. Signs that indicate that hydrodissection has happened: •• Visual confirmation of the fluid wave •• Shallowing of the AC. Gentle taps on the central part of nucleus help to release the fluid behind the lens, complete the hydrodissection and deepen the AC. After successful hydrodissection, the nucleus is freely mobile and most of the time one pole of the nucleus will prolapse in the AC with the fluid wave (Fig. 1.8). In cases with capsulorhexis extension, hydroprocedures should be performed carefully with minimal fluid.

Hydrodelineation Hydrodelineation is also known as hydrodelamination/hydrodemarcation. In hydrodelineation, the cleavage plane is between the epinucleus and endonucleus. Hydrodissection causes separation of the lens matter from the capsule, whereas hydrodelineation results in debulking of the nucleus. The cannula tip is introduced in the lens matter and gently moved forward till the resistance of the central hard nucleus is felt. The cannula is withdrawn a little and the fluid is injected in small pulsed jerky doses. This will create a cleavage plane between the nucleus and the epinuclear sheet. The edge of the nucleus and the cleavage plane will be appreciated as a golden ring. The appearance of the golden ring indicates successful hydrodelineation. Soft cataracts may have multiple cleavage planes resulting in significant debulking of the nucleus. Hard cataracts may not have any cleavage plane.

Fig. 1.8: Hydroprolapse.

Manual Small-incision Cataract Surgery: Techniques

Hydrodissection can be routinely done in all cases except for posterior polar cataracts and mature cataracts. Hydrodissection provides the ease of removing the nucleus, the epinuclear plate, and the cortical matter at one go. After cortical cleaving hydrodissection, there is hardly any cortex left for aspiration. Hydrodelineation is performed in posterior polar cataract cases as it provides epinuclear cushion.

Pearls and Pitfalls There are certain points to remember while performing hydroprocedures. •• Any compromise in the rhexis warrants extra caution by avoiding hydroprolapse to prevent extension of the tear. •• Intermittent gentle taps at the center of the nucleus decompress the bag. Injection of excess fluid without decompression may cause PC to give away, resulting in PC rupture. In posterior polar cataracts, hydrodissection is better avoided. It may result in PC rupture. In such cases, hydrodelineation is done. The epinucleus sheet between the cleavage plane and the PC will act as a cushion, increasing the safety of this procedure. •• Hydrodissection should be performed with care in cases where PC weakness/defect is anticipated (e.g. vitrectomized eyes, traumatic cataracts, and pseudoexfoliation). •• Hydroprocedures are not required for hypermature cataracts as the cortical matter is liquefied. •• Insufficient hydrodissection makes subsequent manipulation of the nucleus difficult and provokes excess strain on the bag and zonules.

NUCLEUS MANAGEMENT Nucleus management consists of: •• Prolapse of nucleus into AC from the bag •• Delivering the nucleus out of the AC through the tunnel Nucleus handling in absence of adequate hydroprocedures leads to excess stress on the zonular apparatus, which may lead to zonular dialysis. The completion of a successful hydroprocedure can be confirmed by rotating the nucleus in the bag with the tip of the hydro cannula or with a Sinskey hook. If the nucleus is not rotating freely, hydroprocedure must be repeated. Free rotation of the nucleus indicates that the nucleus is completely free from the bag and can now be maneuvered out of the bag.

Prolapsing the Nucleus in the Anterior Chamber Hydroprolapse: At the end of hydrodissection, one of the poles of nucleus prolapses out of the capsular bag. The prerequisites for this to happen are adequate capsulorhexis size and good hydrodissection. The prolapsed pole is engaged with a Sinskey hook (Figs. 1.9A to D) and cartwheeled in a clockwise or anticlockwise manner. This will prolapse the nucleus out of the bag into

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A

B

C

D

Figs. 1.9A to D: Sinskey hook prolapse of nucleus.

the AC. If the nucleus pole does not prolapse out after hydroprocedures, it can be prolapsed using the bimanual technique.

Bimanual Technique The bimanual technique requires some degree of expertise and experience to practice. Fill the AC with viscoelastics. Introduce one Sinskey hook and a spatula into the AC through the main tunnel. Keeping the spatula near the rhexis margin at 3 o’clock or 9 o’clock, place the Sinskey hook at the center of the nucleus. Move the Sinskey hook radially (toward 3 o’clock or 9 o’clock) on the surface of the nucleus making a track on the nucleus till it goes 1 mm below the rhexis margin. The nucleus is engaged with a Sinskey hook and pulled toward the center. This brings the equator of the lens near the capsulorhexis margin. At this point, a spatula is passed under the lens equator and it is nudged out of the capsular bag. Viscoelastic is injected above and below this prolapsed tip of the nucleus. It is supported by the spatula underneath it and cartwheeled out of the bag with the help of the Sinskey hook (Fig. 1.10). The bimanual technique is useful in cases with capsulorhexis extension and can-opener capsulotomy as it puts minimal stress on zonules.

Viscoprolapse Viscoprolapse is similar to hydroprolapse. In this technique, viscoelastic is injected under the capsulorhexis margin. This creates a cleavage plane

Manual Small-incision Cataract Surgery: Techniques

Fig. 1.10: Bimanual technique.

separating the lens matter from capsule and also prolapses the pole of the nucleus on the opposite side. This technique is useful for soft cataracts. Adequate size of capsulorhexis is an important prerequisite for this procedure.

Difficult Situations •• Hard-large nucleus (brown–black cataracts)—A larger capsulorhexis should be made and a bimanual prolapse as described above should be done in such cases. If the capsulorhexis is small, it can be enlarged or multiple relaxing incisions can be made. •• Hypermature cataract—A small, free-floating nucleus in the bag and absence of counter support makes the nucleus prolapse difficult in these cases. In such cases, after filling the AC with viscoelastics, the capsulorhexis margin is pressed with the visco-cannula as the viscoelastic is injected in the capsular bag. This will bring the small, free-floating nucleus into the AC.

Delivery of Nucleus The nucleus can be delivered out of the AC by any one of the below-mentioned techniques: •• Irrigating vectis technique •• Phacosandwich technique •• Phacofracture technique •• Modified Blumenthal technique •• Fishhook technique •• Viscoexpression.

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Irrigating Vectis Technique This is the technique that we use in our hospital, the reason being that it is simple and can be done with the aid of a single instrument. Viscoelastic is injected first above the nucleus to protect the corneal endothelium and then below the nucleus to push the iris and bag down to prevent them from engaging in the vectis. An irrigating vectis mounted on a 5-cc syringe filled with BSS or RL is introduced in the AC under the nucleus to engage superior one-third to one-half part of the nucleus (Fig. 1.11). The vectis along with the nucleus is withdrawn back till the nucleus is engaged in the inner lip of the tunnel. Pull the bridle suture tight. Pressing the posterior lip of tunnel with the vectis, start injecting the fluid through the vectis and slowly bring the vectis along with nucleus out of the AC.

Pearls and Pitfalls •• If the nucleus is not engaging into the inner lip of the tunnel, reasons may be: –– Small, irregular tunnel –– Premature entry in the AC where the iris may plug the tunnel. •• In cases of a small tunnel, it must be enlarged. For this, AC is filled with viscoelastics. A 2.8-mm keratome is introduced in the tunnel and moved sideways, cutting the corneoscleral tissue following the three planar architecture of the tunnel and the curvature of the cornea. •• One should never struggle in a small tunnel and shallow AC as it causes damage to corneal endothelium. •• The size of the initial incision should be planned based on the size of the nucleus so as to facilitate the smooth passage of the nucleus through the tunnel and avoid undue struggle in nucleus delivery.

Fig. 1.11: Irrigating vectis technique.

Manual Small-incision Cataract Surgery: Techniques

•• In hard brown or mature cataracts, it is better to have a larger external incision with large side-pockets. •• The irrigating vectis should not be introduced more than half way through the nucleus as it may catch the iris or posterior capsule during delivery leading to iridodialysis or a posterior capsular rent. •• In cases of soft cataract, the vectis is visible under the nucleus while it may not be distinctly visible in harder cataracts (Fig. 1.12). Hence, adequate care should be taken during delivery of such cases.

CORTEX ASPIRATION A thorough cortex clean-up is a must to prevent the occurrence of postoperative iritis, PCO formation, and cystoid macular edema. After a good cortical cleaving hydrodissection, very minimum cortex is left which is aspirated with Simcoe’s cannula. The structure of cortical matter comprises an anterior leaf underneath the rhexis margin and a posterior leaf oriented along the posterior capsule. The body of the cortical matter lies in the fornix of the bag. The basic principle of the cortex removal is to engage the anterior leaf using the aspiration force and use it to peel the body and posterior leaf from the capsule. This is accomplished using Simcoe’s cannula. The anterior leaf is engaged in the tip of the cannula; with gentle side-to-side movements and pulling movements, the cortex is loosened and stripped off from the capsule. The cortical matter should be approached in a systemic manner.

Fig. 1.12: Irrigating vectis technique (Brown cataract).

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•• Inferior three to four clock hours of cortex is approached from the main tunnel. It is removed first. •• The area opposite to the side port (2–5 o’clock area for side port at 8–9 o’clock) should be approached through the side port. •• The cortical matter under the side port is approached through the main tunnel. •• The subincisional cortex is approached through the side port (Fig. 1.13).

Difficult Situations Subincisional Cortex •• The subincisional cortex is commonly removed through the side port. •• The other option is to use specially designed cannulas—“J” or “U” cannula. •• Minimal residual cortex can be removed after IOL implantation by rotating the lens in the bag.

Small Pupil Pupil may constrict after nucleus removal. The common reason for this is the shallowing of the AC and hypotony. Injecting the viscoelastics will reform the AC and dilate the pupil to some extent. One may inject adrenaline in the AC to dilate a very small pupil. To prevent shallowing of the AC, care should be taken so as not to press the posterior lip of the tunnel. The Simcoe cannula should slightly lift the anterior lip of the tunnel. This will keep the AC well-formed and prevent AC shallowing.

Fig. 1.13: Cortex aspiration.

Manual Small-incision Cataract Surgery: Techniques

Pseudoexfoliation Syndrome The deposition of pseudoexfoliative material weakens the zonules, making these eyes more prone to zonular dialysis. Following care should be taken in such cases: •• The anterior chamber should be well-maintained throughout the surgery. •• The nucleus should be prolapsed using the bimanual technique, exerting minimal stress on the zonules. •• The direction of stripping the cortical matter from the lens capsule should be tangential/circumferential. The radial pull will cause zonular dialysis.

Positive Pressure Positive ocular pressure during cortical aspiration increases the chances of PC rupture. In such cases, the underlying reason for positive pressure should be identified and addressed. Some of the reasons include: •• Valsalva maneuver due to pain •• Tight lid speculum •• Injection of an excessive quantity of anesthetic drug for peribulbar/ retrobulbar block •• Obese patients. In such cases, most of cortical matter should be removed through the side port. The use of the main port will cause shallowing of the AC and bulging of the PC forward, increasing the risk of PC rupture. The other option is to inject viscoelastics, which will form the AC and push the PC back. Then the cortex should be removed by dry aspiration (aspiration without switching on the irrigation).

Traumatic Cataract Traumatic cataract can often be associated with PC rupture or zonular dialysis. In cases with PC rupture, the cortex should be removed by dry aspiration after injection of viscoelastics in the AC. In cases with suspected zonular weakness or zonular dialysis, the cortex should be removed by tangential pulling. Radial pull is best avoided.

Posterior Capsular Rupture The key to good outcome in cases with PC rupture is early identification. After PC rupture is noted, the AC is filled with viscoelastics. The cortical matter is removed using dry aspiration. Automated vitrectomy is performed to remove vitreous from the AC.

Pearls and Pitfalls •• The epinuclear sheets can be loosened and removed from the bag by injecting viscoelastics between the epinuclear sheet and the capsule (viscodissection). The other option is to loosen it and remove it by

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insinuating the simcoe cannula between the epinuclear sheet and the anterior capsule. •• Cortex aspiration should be performed with utmost care in cases with rhexis extension or capsular tags. Caution should be exercised to not engage the tags in the tip of the cannula.

INTRAOCULAR LENS IMPLANTATION The commonly used IOL with MSICS is rigid PMMA IOL with 6 mm optic size. For IOL implantation, the AC is filled with viscoelastics and the bag is inflated with viscoelastics. The lens is held longitudinally, using a McPherson forceps or a lens-holding forceps. The IOL is introduced into the AC and advanced forward till the leading haptic reaches the inferior capsulorhexis margin (near the 6 o’clock position). Then, the IOL is tilted downward by lifting the trailing haptic near the tunnel and gently pushed forward. This will cause the leading haptic to pass under the capsulorhexis margin and go into the capsular bag. Once the leading haptic is inside the bag, the IOL is released and the forceps withdrawn. Then, the positioning hole is engaged with a Sinskey hook and the IOL is rotated in a clockwise direction with a simultaneous downward push till the trailing haptic slips into the bag (Figs. 1.14A to F). The correct implantation of IOL in the bag can be confirmed by the appearance of a “‘stretch line” in the posterior capsule caused by the tips of both haptics resting on posterior capsule (Fig. 1.15). The viscoelastic is washed out of the AC and capsular bag. The side port is hydrated. Due to the self-sealing nature of the tunnel, sutures are not required. The adequacy of the closure is checked by a gentle tap on the cornea to check for wound leak. The conjunctiva is closed by cautery (Fig. 1.16).

WOUND CLOSURE A well-constructed SICS tunnel of size less than 7 mm does not require sutures. The tunnel may require sutures in cases with premature entry, buttonholing, leaking tunnel, and positive pressure. High myopes and pediatric patients have thin sclera with low scleral rigidity, which may require tunnel suturing. The tunnel should be closed with either vertical interrupted sutures or infinity suture.

PRE- AND POSTOPERATIVE MEDICATIONS Preoperatively, as a routine we start topical antibiotics on the day before surgery eight times and nonsteroidal anti-inflammatory drug (NSAID) eye drops four times a day. In cases with intumescent cataract or cases with a low axial length, shallow AC, where a positive vitreous pressure is anticipated intraoperatively, we give 30 cc oral glycerol 15–20 minutes before surgery. Uveitic cataracts are done

Manual Small-incision Cataract Surgery: Techniques

A

B

C

D

E

F

Figs. 1.14A to F: Intraocular lens (IOL) implantation.

Fig. 1.15: Stretch lines on posterior capsule.

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Fig. 1.16: Well-formed anterior chamber (AC).

under the cover of corticosteroids. The cases with a history of viral keratitis or keratouveitis are done under the cover of antivirals. Postoperatively, as a routine we prescribe a topical steroid-antibiotics combination starting from five times a day, tapered every 10 days over a period of 6 weeks. Along with this combination, topical NSAIDs are also prescribed to reduce the chances of postoperative CME. The cases with PCR or vitreous disturbance are also given oral fluoroquinolones for 5 days.

REFERENCES 1. Brown GC, Brown MM, Menezes A, et al. Cataract Surgery Cost Utility Revisited in 2012. A New Economic Paradigm. Ophthalmology. 2013;120(12):2367-76. 2. Busbee BG, Brown MM, Brown GC, et al. Incremental cost-effectiveness of initial cataract surgery. Ophthalmology. 2002;109(3):606-12. 3. Balent LC, Narendran K, Patel S, et al. High volume sutureless intraocular lens surgery in a rural eye camp in India. Ophthal Surg Lasers. 2001;32(6):446-55. 4. Muralikrishnan R, Venkatesh R, Manohar B, et al. A comparison of the effectiveness and cost effectiveness of three different methods of cataract extraction in relation to the magnitude of postoperative astigmatism. Asia Pacific J Ophthalmol. 2003;15:5-12. 5. Venkatesh R, Tan CSH, Singh GP, et al. Safety and efficacy of manual small incision cataract surgery for brunescent and black cataracts. Eye. 2009;23:1155-7. 6. Venkatesh R, Tan CSH, Kumar TT, et al. Safety and efficacy of manual small incision cataract surgery for phacolytic glaucoma. Br J Ophthalmol. 2007;91(3):279-81. 7. Ramakrishanan R, Maheshwari D, Kadar MA, et al. Visual prognosis, intraocular pressure control and complications in phacomorphic glaucoma following manual small incision cataract surgery. Indian J Ophthalmol. 2010;58:303-6.

Manual Small-incision Cataract Surgery: Techniques 8. Haripriya A, Chang DF, Reena M, et al. Complication rates of phacoemulsification and manual small-incision cataract surgery at Aravind Eye Hospital. J Cataract Refract Surg. 2014;38:1360-9. 9. Little BC, Smith JH, Packer M. Little Capsulorhexis tear-out recue. J Cataract Refract Surg. 2006;32:1420-2. 10. Basti S, Vasavada A, Thomas R, et al. Extracapsular cataract surgery: Surgical techniques. Indian J Ophthalmol. 1993;41(4):195-210. 11. Fine IH. Cortical cleaving hydrodissection. J Cataract Refract Surg. 1992;18(5): 508-12.

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2

Clear Corneal Cataract Incisions*

I Howard Fine, Richard S Hoffman

INTRODUCTION The availability of foldable intraocular lenses (IOLs) which can be inserted through smaller unsutured phacoemulsification incisions1 has created an increasing trend moving away from the utilization of scleral tunnel incisions to clear corneal incisions for the removal of cataracts and insertion of IOLs.2 Among the disadvantages of scleral tunnel incisions that are of concern is the need to perform conjunctival incisions and scleral dissections, and the need for cautery to prevent operating in the presence of blood especially in patients who are on anticoagulants or have bleeding dyscrasias. In addition, there is an increased difficulty with oar-locking of the phaco tip and distortion of the cornea because of the length of scleral tunnel incisions all of which may complicate the phacoemulsification procedure.

HISTORY A historical review of sutureless clear corneal cataract surgery would not be complete without first understanding the evolution of small cataract incisions. Kratz is generally credited as the first surgeon to move from the limbus posteriorly to the sclera in order to increase appositional surfaces, thus, enhancing wound healing and reducing surgically induced astigmatism.3,4 Girard and Hoffman5 were the first to name the posterior incision a “scleral tunnel incision” and were, along with Kratz, the first to make a point of entering the anterior chamber through the cornea creating a corneal shelf. This corneal shelf was designed to prevent iris prolapse. Maloney advocated *This chapter was previously published in Ophthalmic Surgery and Lasers October 1998. Permission has been granted by SLACK, Incorporated to reprint this material for Recent Advances in Ophthalmology, Volume 5.

Clear Corneal Cataract Incisions

a corneal shelf to his incisions which he described as strong and waterproof6 (Fig. 2.1). In 1989, McFarland used this incision architecture and recognized that these incisions allowed for the phacoemulsification and implantation of lenses without the need for suturing.7 Ernest recognized that McFarland’s long scleral tunnel incision terminated in a decidedly corneal entrance. He hypothesized that the posterior lip or “corneal lip” of the incision acted as a one-way valve, thus, explaining the mechanism for self-sealability (Ernest PH. Presentation at the Department of Ophthalmology, Wayne State University School of Medicine, Detroit, MI, February 28, 1990). In April 1992, Fine presented his self-sealing temporal clear corneal incision at the annual meeting of the American Society of Cataract and Refractive Surgery.8 In May 1992, Kellan demonstrated on video a technique that he referred to as the scleral-less incision (unpublished data). It was essentially a corneal limbal stab incision through conjunctiva and the limbus, entering the anterior chamber through clear cornea, leaving a corneal shelf or lip (Figs. 2.2A and B). There have been many surgeons who have favored corneal incisions for cataract surgery prior to their recent popularization. In 1967, Kelman9 stated that the best approach for performing cataract surgery was with phacoemulsification through a clear corneal incision utilizing a triangular tear capsulotomy and a grooving and cracking technique in the posterior chamber. Also in 1967, Harms and Mackensen10 published an intracapsular technique using a corneal incision. Troutman was an early advocate of controlling surgically induced

Fig. 2.1: Cross-sectional view of corneal shelf incision. Incision begins in sclera, is beveled into clear cornea, and enters the anterior chamber producing a corneal shelf which is watertight and prevents iris prolapse.

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A

B

Figs. 2.2A and B: (A) Kellan’s corneal limbal stab incision through conjunctiva and limbus; (B) Corneal limbal incision following removal of the steel keratome.

astigmatism at the time of cataract surgery by means of the corneal incision approach.11 Arnott12 utilized clear corneal incisions and a diamond keratome for phacoemulsification although he had to enlarge the incision for introducing an IOL. Galand13 utilized clear corneal incisions for extracapsular cataract extraction (ECCE) in his envelope technique, and Stegmann has a long history of having utilized the cornea as the site for incisions for ECCE (Stegmann R;

Clear Corneal Cataract Incisions

Personal communication, December 3, 1992). Finally, perhaps the leading proponent of clear corneal incisions for modern era phacoemulsification was Shimizu of Japan.14 Fine’s personal experience with corneal incisions began in 1979 when the temporal clear cornea was utilized as the site for secondary anterior chamber IOL implantation. The temporal approach was preferred because of the vagaries and disturbed anatomy present at the superior limbus in eyes which had previous intracapsular cataract extraction (ICCE). As soon as foldable lenses were available in 1986, he utilized sutured clear corneal incisions for phacoemulsification and foldable IOL implantation in patients who had preexisting filtering blebs. After these procedures, a marked reduction in surgically induced astigmatism was noted despite the fact that these incisions were corneal rather than scleral. In 1992, Fine began routinely utilizing clear corneal cataract incisions for phacoemulsification and foldable IOL implantation with incision closure using a tangential suture modeled after Shepherd’s technique.15 Within a very short period, the suture was abandoned in favor of self-sealing corneal incisions.16

INDICATIONS Initially, the utilization of clear corneal incisions was limited to those patients with preexisting filtering blebs, patients on anticoagulants or with blood dyscrasias, or patients with cicatrizing disease such as ocular pemphigoid or Stevens-Johnson syndrome. Subsequently, because of the natural fit of clear corneal cataract incisions with topical anesthesia, the indications for clear corneal cataract surgery expanded. With the ability to avoid any injections into the orbit and utilization of intravenous medications, those patients who had cardiovascular, pulmonary, and other systemic diseases that might have contraindicated cataract surgery became surgical candidates. Subsequently, through the safety and increasing utilization of these incisions by some pioneers in the United States, including Williamson, Shepherd, Martin, and Grabow,16 these incisions became increasingly popular and utilized on an international basis. Studies utilizing topographical analyses of these incisions by Rosen demonstrated that clear corneal incisions sized 3 mm in width or less were topographically astigmatism-neutral.17This led to an increasing interest in these incisions because of an increasing utilization of techniques including T-cuts, arcuate cuts, and limbal relaxing incisions (LRIs) for managing preexisting astigmatism at the time of cataract surgery. Without astigmatism neutrality in the cataract incision, the predictability of adjunctive astigmatism reducing procedures would be decreased making it more difficult to achieve the desired result. In the initial studies and ultimate utilization of multifocal IOLs, the need for astigmatism neutrality was again a factor for stimulating interest in clear corneal incisions. Finally, the availability of phakic IOLs and the need for control of astigmatism at the time of implantation of these lenses have driven many surgeons to consider clear corneal incisions as the route for phakic IOL implantation. Other advantages of the temporal clear corneal incision include better preservation of preexisting filtering blebs,18 preservation of options for

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future filtering surgery, increased stability in the refractive results because of the neutralization of the forces from lid blink and gravity, the ease of approach to the incision site, the lack of need for bridle sutures and resultant iatrogenic ptosis, and finally, the location of the lateral canthal angle under the incision which facilitates drainage.

CLASSIFICATIONS Early on there was criticism surrounding the use of self-sealing clear corneal incisions because of a fear of a possible increased incidence of endophthalmitis secondary to poor wound healing and sealability. This potential controversy stimulated many studies into the strength and safety of clear corneal incisions compared to limbal and scleral tunnel incisions. Unfortunately, because of a lack of standardization in the definition of what constitutes a limbal versus clear corneal incision, considerable confusion has been generated in this area making it difficult for surgeons to communicate and compare the relative claims of their individual techniques. Based on Hogan’s Histology of the Human Eye,19 “The conjunctival vessels are seen with the slit lamp as fine arcades that extend into clear cornea for about 0.5 mm beyond the limbal edge” and topographical studies of incisions done by Menapace,20 Fine has categorized these incisions using the parameters of location and architecture.21 An incision is termed clear corneal when the external edge is anterior to the conjunctival insertion, limbal-corneal when the external edge is through conjunctiva and limbus, and scleral-corneal when it is posterior to the limbus (Box 2.1). In addition to the anatomic designation of the external incision, these incisions are also classified by their architecture as being either single plane when there is no groove at the external edge of the incision, shallow groove when the initial groove is less than 400 μm, and deeply grooved when it is deeper than 400 μm (Table 2.1 and Fig. 2.3). In order to reduce the confusion and facilitate communication regarding these incisions, the authors believe that these incisions should be BOX 2.1: Classification of corneal tunnel incisions by external incision location. •• Clear-corneal incision –– Entry anterior to conjunctival insertion •• Limbal-corneal incision –– Entry through conjunctival and limbus •• Scleral-corneal incision –– Entry posterior to the limbus TABLE 2.1: Classification of corneal tunnel incisions by wound architecture. Architecture

Depth

Single plane

No groove

Shallow groove

400 μm

Clear Corneal Cataract Incisions

Fig. 2.3: Cross-section view of single plane, shallow groove and deep groove (hinged) clear corneal incisions.

classified as either clear-corneal, limbal-corneal, or scleral-corneal incisions and either single-planed, shallow grooved, or deep grooved.

CONTROVERSIES One of the most controversial criticisms of clear corneal incisions has been their relative strength compared to limbal or scleral incisions. Ernest demonstrated that rectangular clear corneal incisions in cadaver eye models were less resistant to external deformation utilizing pin-point pressure than square limbal or scleral tunnel incisions.22,23 Subsequently, Mackool demonstrated that once the incision width was 3.5 mm or less and the length 2 mm or greater, there was an equal resistance of external deformation in clear corneal incisions as compared to scleral tunnel incisions.24 In Ernest’s work as well, as incision sizes got increasingly small, the force required to cause failure of these incisions became very similar for limbal and clear corneal incisions, and thus this could be used to further document the safety of incisions sized 3 mm or less. A major criticism of these cadaver studies is that there is a lack of functioning endothelium contributing to wound sealing. Others have also indicated that cadaver eye incision strength cannot be compared to incisions in vivo.17 Ernest has compared in vivo posterior limbal incisions with clear corneal incisions and found that deep-grooved incisions performed better than shallow-grooved or single-plane incisions in addition to finding that posterior limbal incisions performed better than clear corneal incisions when challenged by pin-point pressure.25 Many surgeons have called into question the validity of pin-point pressure as a clinically relevant test for cataract wound

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Fig. 2.4: Demonstration of self-sealability of clear-corneal incision to the challenge of blunt knuckle.

strength since the likelihood that anyone would challenge their own incision by pressing on it with something as fine as the instruments utilized to apply pin-point pressure in these studies is highly unlikely. Regardless of whether more posteriorly placed incisions demonstrate increased strength compared to clear corneal incisions, the real question is whether that added strength is clinically significant or relevant. Fine et al.26 have demonstrated the stability of clear corneal incisions when a knuckle or a fingertip, the most likely way patients would challenge these incisions, was utilized (Fig. 2.4). In addition, it is a well-known fact that a 1 mm “hypersquare” paracentesis will leak the day after surgery if pin-point pressure is applied to its posterior lip; however, the likelihood of any paracentesis incision leaking spontaneously or with blunt pressure the day following surgery is extremely unlikely. One final point of controversy regards the studies in cat eyes performed by Tipperman and Ernest.27 These studies revealed a fibrovascular response in incisions placed in the limbus with extensive wound healing in 6 days compared to a lack of fibrovascular healing in clear corneal incisions. This study has been used to propose an increased safety for limbal incisions as compared to clear corneal incisions. Unfortunately, the real issue for these various incisions is sealing, not healing. The authors feel that as long as an incision is sealed at the conclusion of surgery and remains sealed, the time before complete healing of the incision is accomplished is almost irrelevant especially since there is still a 6-day period in which limbal incisions are not truly “healed.” An analogy can be drawn to the sealing which takes place during laser-assisted in situ keratomileusis (LASIK). There is no fibrovascular healing of the clear corneal interface in LASIK which has little effect on the strength, effectiveness, or safety of the wound, and in fact

Clear Corneal Cataract Incisions

is an advantage by limiting scarring and an inflammatory healing response. Ultimately, the relative safety of one incision over another in the clinical setting will only be determined with the findings of a difference in the rate of incisionrelated complications which to date have not been demonstrated. One of the clear disadvantages of limbal corneal incisions is the greater likelihood of ballooning of conjunctiva which can make visualization of anterior chamber structures during the surgical procedure more difficult. In addition, studies by Park et al.18 demonstrated that violation of the conjunctiva threatens the integrity not only of preexisting filtering blebs but of the conjunctiva which would participate in filtering surgery at some future date. Finally, the presence of subconjunctival hemorrhage, although not important with respect to the ultimate function of the eye, may be of importance from a cosmetic perspective to the patient as well as to the survival of filtering blebs. Contraindications for clear corneal incisions include the presence of radial keratotomy incisions that extend to the limbus that might be challenged by clear corneal incisions,28 marginal degenerations associated with thinning of the peripheral cornea, and perhaps advanced corneal endothelial dystrophy.

PREOPERATIVE EVALUATION Certain studies that may be of value as part of a preoperative workup include endothelial cell counts in patients with endothelial dystrophies, and perhaps computerized corneal topography when refractive surgical procedures are going to be combined with the cataract surgery in the management of preexisting astigmatism, especially when refractive and keratometric measurements do not coincide.

TECHNIQUES Single plane incisions, as first described by Fine,29 utilized a 3.0-mm diamond knife. After pressurization of the eye with the placement of viscoelastic through a paracentesis, the blade is placed on the eye in such a way that it completely applanated the eye with the point placed at the leading edge of the anterior vascular arcade. The knife is moved in the plane of the cornea until the shoulders, which are 2 mm posterior to the point of the knife, touch the external edge of the incision, and then a dimple down technique is utilized to initiate the cut through Descemet’s membrane. After the tip enters the anterior chamber, the initial plane of the knife is re-established to cut through Descemet’s membrane in a straight line configuration (Fig. 2.5). Williamson30 was the first to utilize a shallow 300–400 μm grooved clear corneal incision (Figs. 2.6A and B). The rationale for the Williamson incision was that it led to a thicker external edge to the roof of the tunnel and less likelihood of tearing. Langerman31 later described the single hinge incision in which requirements for the initial groove were 90%of the depth of the cornea anterior to the edge of the conjunctiva. Initially he utilized a depth of 600 μm and subsequently made the tunnel itself superficially in that groove, believing that this led to enhanced resistance of the incision to external deformation. Adjunctive

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Fig. 2.5: Diamond keratome enters the anterior chamber after dimpling down to incise Descemet’s membrane. After the tip enters the anterior chamber, the initial plane of the knife is re-established to cut to Descemet’s membrane in a straight line configuration.

techniques were utilized to combine refractive surgery incisions with clear corneal cataract incisions. Fine continued to utilize the temporal location for the cataract incisions and added one or two T-cuts made by the Feaster knife (Rhein Medical Inc., Tampa, FL) with a 7-mm ocular zone for the management of preexisting astigmatism. Others, including Lindstrom and Rosen, rotated the location of the incision to the steep axis in order to achieve some increased flattening at the steepest axis to address preexisting astigmatism. Kershner32 utilized the corneal incision in the temporal half of the eye by starting with a nearly full-thickness T-cut through which he then made his corneal tunnel incision. For large amounts of astigmatism, he used a paired T-cut in the opposite side of the same meridian. Finally, the popularization of LRIs by Gills and Gayton33 and Nichamin34 adds an additional means of reducing preexisting astigmatism by utilizing the groove for the LRI as the site of entry for the clear corneal cataract incision. Blades have been developed which help perfect incision architecture. The Fine Triamond knife (Mastel Instruments, Rapid City, SD) was designed so that the incision could be made with an extremely sharp, thin, and narrow knife without a necessity for dimpling down which resulted in some tendency for tearing of tissue or scrolling of Descemet’s membrane. Subsequently, the 3-D blade (Rhein Medical Inc.) was developed which had differential slope angles to the bevels on the anterior versus the posterior surface (Figs. 2.7A to C), resulting in an ability to just touch the eye at the site of the external incision location and advance the blade in the plane of the cornea. The differential slopes on the anterior versus posterior aspects of the blade allowed the forces of

Clear Corneal Cataract Incisions

A

B

Figs. 2.6A and B: (A) Guarded diamond knife produces grooved incision in temporal clear cornea; and (B) Tip of the diamond keratome is placed in grooved incision as the posterior lip of the incision is depressed in order to produce shallow and deep grooved incisions.

tissue resistance to create an incision that was characterized by a linear external incision, a 2-mm tunnel, and a linear internal incision without the need to dimple down or distort tissues to create the proper incision architecture.35 The trapezoidal 3-D blade also allows enlargement of the incision to 3.5 mm for IOL insertion without altering incision architecture (Fig. 2.8). Although the authors prefer the Fine/Thornton fixation device which has been developed by

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A

B

C

Figs. 2.7A to C: Schematic representation of (A) top view and (B) bottom view of the 3.0-mm Rhein 3-D diamond keratome. (C) The front profile of the keratome demonstrates the differential slopes on the anterior versus posterior aspects of the blade which allow the forces of tissue resistance to create the proper incision architecture.

Fig. 2.8: The Rhein 3-D trapezoidal blade with 2.5–3.5 mm blade dimensions.

Clear Corneal Cataract Incisions

Fig. 2.9: The Fine-Thornton fixation ring is ideal for globe fixation during paracentesis placement, clear-corneal incision and lens insertion.

taking 8 mm of arc length out of the Thornton refractive surgery fixation ring (Fig. 2.9), others have utilized the side port incision for fixation to stabilize the eye during incision construction. Recently, Maloney and Wallace have collaborated on the design of a paracentesis knife which provides for fixation and stabilization of the globe for cataract incision construction through clear cornea. The disadvantage of this knife resides in the fact that one must place the paracentesis at least one quadrant away from the clear corneal incision location in order to maximize stabilization of the globe. Following phacoemulsification, lens implantation, and removal of residual viscoelastic, stromal hydration of the clear corneal incision can be performed in order to seal the incision.16 This is performed by placing the tip of a 26- or 27-gauge cannula in the side walls of the incision and gently irrigating balanced salt solution into the stroma (Fig. 2.10). This is performed at both edges of the incision in order to help appose the roof and the floor of the incision. Once apposition takes place, the hydrostatic forces of the endothelial pump will seal the incision. In those rare instances of questionable wound integrity, a single 10-0 nylon suture is placed to ensure a tight seal.

INTRAOPERATIVE/POSTOPERATIVE COMPLICATIONS Although clear corneal and scleral incisions for cataract surgery share many of the same intraoperative and postoperative complications, clear corneal incisions by nature of their architecture and location have some unique complications associated with them. If one incidentally incises the conjunctiva at the time of the clear corneal incision, ballooning of the

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Fig. 2.10: Stromal hydration of incision is created by placing the tip of 26-gauge cannula in the side walls of incision and gently irrigating balanced salt solution (BSS) into the stroma. This is performed at both edges of the incision in order to help appose the roof and floor of the incision.

conjunctiva can develop which may compromise visualization of anterior structures. When this develops, a suction catheter is usually required by the assistant to aid visualization. Early entry into the cornea might result in an incision of insufficient length to be self-sealing and, thus, a single suture may be required to assure a secure wound at the conclusion of the procedure. A late entry may result in a corneal tunnel incision sufficiently long that the phacoemulsification tip would create striae in the cornea and compromise visualization of the anterior chamber. In addition, incisions that are too short or improperly constructed can result in an increased tendency for iris prolapse. Manipulation of the phacoemulsification handpiece intraoperatively may result in tearing of the roof of the tunnel, especially at the edges, resulting in potential compromising of the ability for the incision to self-seal. Tearing of the internal lip can also occur, resulting in compromised self-sealability or in rare instances, small detachments or scrolling of Descemet’s membrane in the anterior edge of the incision. Of greater concern has been the potential for incisional burns.36 When incisional burns develop in clear corneal incisions, there may be a loss of self-sealability and closure of the wound may induce excessive amounts of astigmatism. In addition, manipulation of the incision can result in an epithelial abrasion which can compromise self-sealability because of the lack of a fluid barrier by an intact epithelium. Without an intact epithelial layer, the corneal endothelium does not have the ability to help appose the roof and the floor of the incision through hydrostatic forces. Postoperatively, hypotony might result in some compromising the ability for

Clear Corneal Cataract Incisions

these incisions to seal. Wound leaks and iris prolapse have been very infrequent postoperative complications37 and are usually present in incisions greater than 3.5 mm in width. In a large survey performed for the American Society of Cataract and Refractive Surgery (ASCRS) by Masket,38 there was a slightly increased incidence of endophthalmitis in clear corneal cataract surgery compared to scleral tunnel surgery. However, the survey failed to note the incision sizes in those cases where endophthalmitis in clear corneal incisions had occurred, and thus it is possible that any increase in the incidence of endophthalmitis is associated with unsutured clear corneal incisions greater than 4.0 mm in width.

POSTOPERATIVE CLINICAL COURSE AND OUTCOMES The usual postoperative regime involves examination on the first postoperative day and a second examination at 10–14 days at which time spectacle correction is prescribed. Utilization of drops postoperatively includes two to three times a day instillation of a fluoroquinolone, prednisolone acetate, and Voltaren ophthalmic solution. The antibiotic and steroid are discontinued at 10–14 days and the Voltaren is continued for an additional 10 weeks due to its theoretical benefit in suppressing lens epithelial cell division and biosynthesis of collagen precursors.39 Numerous studies have been performed documenting the safety and low magnitudes of astigmatism induced by these incisions depending on their size. Masket has documented by vector analysis 0.50 D of induced cylinder and less than 0.25 D of cylinder change in the surgical meridian using 3.0 mm × 2.5 mm self-sealing temporal clear corneal incisions. He was also able to demonstrate the refractive stability of these incisions 2 weeks following surgery.40 Kohnen et al.41 compared the surgically induced astigmatism of 3.5 mm, 4.0 mm, and 5.0 mm grooved temporal clear corneal incisions and found a mean induced astigmatism of 0.37 D, 0.56 D, and 0.70 D respectively after 6 months. A similar study by Pfleger et al.42 revealed even smaller amounts of induced astigmatism from 3.2 mm, 4.0 mm, and 5.2 mm temporal clear corneal incisions with the 3.2 mm incision demonstrating astigmatic neutrality with only 0.09 D of induced cylinder. In addition to comparing the effects of different sized temporal clear corneal incisions on induced astigmatism, numerous studies have evaluated the relative astigmatic effects of incision location in regards to clear corneal incisions versus corneoscleral incisions, and the temporal versus superior meridian. Nielsen43 evaluated surgically induced astigmatism from 3.5 mm and 5.2 mm temporal and superior clear corneal incisions and compared them with 3.5 mm and 5.2 mm corneoscleral incisions at the superior location. The 3.5 mm clear corneal incisions induced roughly 0.5 D of with-the-rule (WTR) or against-the-rule (ATR) drift, depending on temporal or superior location. Larger amounts of astigmatism were induced with the larger clear corneal incisions. He found that the refractive effect of clear corneal incisions was stable between postoperative day 1 and postoperative week 6, making their astigmatic keratotomy effect more useful and predictable if one wished to consider preoperative cylinder when selecting incision type

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or location. Cillino et al.44 compared the astigmatic effects of unsutured 5.2 mm temporal clear corneal incisions with 5.2-mm superior corneoscleral incisions and found comparable amounts of induced astigmatism. Although the use of unsutured 5.2 mm incisions is considered controversial because of a possible increase in rates of wound complications and endophthalmitis, Holweger et al.45 have demonstrated that absorbable sutured 5.0 mm clear corneal incisions were topographically comparable to 3.5 mm sutureless clear corneal incisions, 6–8 months postoperatively, making this incision and closure technique a viable option for surgeons. When temporal clear corneal incisions of 3.2 mm or less have been compared with superiorly placed scleral tunnel incisions of the same size, similar amounts of low induced astigmatism have been documented for the two incision locations.46,47 In contrast, similarly sized incisions when compared in regards to temporal versus superior clear corneal location have demonstrated more meridional flattening in the superior axis than the temporal axis48 confirming the bias for the temporal location for clear corneal incisions when astigmatic neutrality is desired. Although small clear corneal incisions appear to have similar astigmatic effects as superior corneoscleral incisions, recent concern has surrounded the possibility of increased endothelial cell loss with these incisions. Grabow 49 reported an increased incidence of endothelial cell loss for superior clear corneal incisions which increased linearly with increasing ultrasound times. Amon et al.50 discovered a significant increase in endothelial cell loss in 3.5 mm temporal clear corneal incisions when compared to 3.5 mm superior scleral tunnel incisions. However, a recent study by Dick et al.51 found that the total endothelial cell loss at 1 year with clear corneal incisions compared favorably with endothelial cell loss rates of other cataract extraction techniques, as ultrasound times decrease in the future with advancing technologies, and techniques such as lens chopping, endothelial cell loss rates should become insignificant.

SUMMARY Clear corneal cataract incisions are becoming a more popular option for cataract extraction and IOL implantation throughout the world. Through the use of clear corneal incisions and topical and intracameral anesthesia, the authors have achieved surgery that is the least invasive of any time in the history of cataract surgery with visual rehabilitation that is almost immediate. Clear corneal incisions have had a proven record of safety with relative astigmatic neutrality utilizing the smaller incision sizes. In addition, corneal incisions result in an excellent cosmetic outcome and should increase in popularity especially as newer modalities such as phakic IOLs increase in popularity.

REFERENCES 1. Fine IH. Architecture and construction of a self-sealing incision for cataract surgery. J Cataract Refract Surg. 1991;17:672-6.

Clear Corneal Cataract Incisions 2. Leaming DV. Practice styles and preferences of ASCRS members—1996 survey. J Cataract Refract Surg. 1997;23:527-35. 3. Colvard DM, Kratz RP, Mazzocco TR, et al. Clinical evaluation of the Terry surgical keratometer. Am Intraocular Implant Soc J. 1980;6:249-51. 4. Masket S. Origin of scleral tunnel methods (letter to the Editor). J Cataract Refract Surg. 1993;19:812-3. 5. Girard LJ, Hoffman RF. Scleral tunnel to prevent induced astigmatism. Am J Ophthalmol. 1984;97:450-6. 6. Maloney WF, Grindle L. Textbook of Phacoemulsification. California: Lasenda Publishers; 1988. pp. 31-9. 7. McFarland MS. Surgeon undertakes phaco, foldable IOL series sans sutures. Ocular Surg News. 1990;8. 8. Brown DC, Fine IH, Gills JP, et al. The future of foldables. Panel discussion held at the 1992 annual meeting of the American Society of Cataract and Refractive Surgery. Ocular Surg News. 1992 (Suppl). 9. Kelman CD. Phacoemulsification and aspiration—a new technique of cataract removal: a preliminary report. Am J Ophthalmol. 1967;64:23. 10. Harms H, Mackensen G. Intracapsular extraction with a corneal incision using the Graefe knife. In: Harms H, Mackensen G (Eds). Ocular Surgery under the Microscope. Stuttgart: Georg Thieme Verlag; 1967. pp. 144-53. 11. Paton D, Troutman R, Ryan S. Present trends in incision and closure of the cataract wound. Highlights Ophthalmol. 1973;14(3):176. 12. Arnott EJ. Intraocular implants. Trans Opthalmol Soc UK. 1981;101:58-60. 13. Galand A. La technique de I’enveloppe. Liege, Belgium: Pierre Mardaga publisher; 1988. 14. Shimizu K. Pure corneal incision. Phaco Foldables. 1992;5(5):6-8. 15. Shepherd JR. Induced astigmatism in small incision cataract surgery. J Cataract Refract Surg. 1989;15:85-8. 16. Fine IH, Fichman RA, Grabow HB. Clear-corneal Cataract Surgery and Topical Anesthesia. Thorofare, NJ: Slack, Inc.; 1993. 17. Rosen ES. Clear corneal incisions—a good option for cataract patients: a round table discussion. Ocular Surg News; 1998. 18. Park HJ, Kwon YH, Weitzman M, et al. Temporal corneal phacoemulsification in patients with filtered glaucoma. Arch Ophthalmol. 1997;115:1375-80. 19. Hogan MJ, Alvarado JA, Weddell JE (Eds). Histology of the Human Eye: An Atlas and Textbook. Philadelphia: WB Saunders; 1971. pp. 118-9. 20. Menapace RM. Preferred incisions for current foldable lenses and their impact on corneal topography (Abstract). Cataract Workshop on the Nile. Egypt: LuxorAswan; 1996. 21. Fine IH. Descriptions can improve communication. Ophthalmology Times. 1996;21:30-4. 22. Ernest PH, Lavery KT, Kiessling LA. Relative strength of scleral corneal and clear corneal incisions constructed in cadaver eyes. J Cataract Refract Surg. 1994;20:6269. 23. Ernest PH, Fenzl R, LaveryKT, et al. Relative stability of clear corneal incisions in a cadaver eye model. J Cataract Refract Surg. 1995;21:39-42. 24. Mackool RJ, Russell RS. Strength of clear corneal incisions in cadaver eyes. J Cataract Refract Surg. 1996;22:721-5. 25. Ernest PH, Neuhann TH. Posterior limbal incision. J Cataract Refract Surg. 1996;22:78-84.

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Gems of Ophthalmology—Cataract Surgery 26. Fine IH. New thoughts on self-sealing clear-corneal cataract incisions. Presented at Hawaii. Maui, Hawaii; January 22, 1996. 27. Ernest PH, Tipperman R, Eagle R, et al. Is there a difference in incision healing based on location? J Cataract Refract Surg. 1998;24:482-6. 28. Budak K, Friedman NJ, Koch DD. Dehiscence of a radial keratotomy incision during clear corneal cataract surgery. J Cataract Refract Surg. 1998;24:278-80. 29. Fine IH. Self-sealing corneal tunnel incision for small-incision cataract surgery. Ocular Surg News; 1992. 30. Williamson CH. Cataract keratotomy surgery. In: Fine IH, Fichman RA, Grabow HB (Eds). Clear-corneal Cataract Surgery and Topical Anesthesia. Thorofare: Slack, Inc.; 1993. pp. 87-93. 31. Langerman DW. Architectural design of a self-sealing corneal tunnel, single hinge incision. J Cataract Refract Surg. 1994;20:84-8. 32. Kershner RM. Clear corneal cataract surgery and the correction of myopia, hyperopia, and astigmatism. Ophthalmology. 1997;104:381-9. 33. Gills JP, Gayton JL. Reducing pre-existing astigmatism. In: Gills JP (Ed). Cataract Surgery: The State of the Art. Thorofare: Slack, Inc.; 1988. pp. 53-66. 34. Nichamin L. Refining astigmatic keratotomy during cataract surgery. Ocular Surgery News; 1993. 35. Fine IH. New blade enhances cataract surgery—techniques spotlight. Ophthalmology Times; 1996. 36. Fine IH. Special report of ASCRS members: phacoemulsification incision burns. Letter to American Society of Cataract and Refractive Surgery members; 1997. 37. Menapace R. Delayed iris prolapse with unsutured 5.1 mm clear corneal incisions. J Cataract Refract Surg. 1995;21:353-7. 38. Endophthalmitis: state of the prophylactic art. Eyeworld News; 1997. pp. 42-3. 39. Nishi O, Nishi K, Fujiwara T, et al. Effects of diclofenac sodium and indomethacin on proliferation and collagen synthesis of lens epithelial cells in vitro. J Cataract Refract Surg. 1995;21:461-5. 40. Masket S, Tennen DG. Astigmatic stabilization of 3.0 mm temporal clear corneal cataract incisions. J Cataract Refract Surg. 1996;22:1451-5. 41. Kohnen T, Dick B, Jacobi KW. Comparison of the induced astigmatism after temporal clear corneal tunnel incisions of different sizes. J Cataract Refract Surg. 1995;21:417-24. 42. Pfleger T, Skorpik C, Menapace R, et al. Long-term course of induced astigmatism after clear corneal incision cataract surgery. J Cataract Refract Surg. 1996;22:72-7. 43. Nielsen PJ. Prospective evaluation of surgically induced astigmatism and astigmatic keratotomy effects of various self-sealing small incisions. J Cataract Refract Surg. 1995;21:43-8. 44. Cillino S, Morreale D, Maurceri A, et al. Temporal versus superior approach phacoemulsification—short-term postoperative astigmatism. J Cataract Refract Surg. 1997;23:267-71. 45. Holweger R, Marefat B. Corneal changes after cataract surgery with 5.0 mm sutured and 3.5 mm sutureless clear corneal incisions. J Cataract Refract Surg. 1997;23:342-6. 46. Oshima Y, Tsujikawa K, Oh A, et al. Comparative study of intraocular lens implantation through 3.0 mm temporal clear corneal and superior scleral tunnel self-sealing incisions. J Cataract Refract Surg. 1997;23:347-53. 47. Poort-van Nouhuijs HM, Hendrickx KH, van Marle WF, et al. Corneal astigmatism after clear corneal and corneo-scleral incisions for cataract surgery. J Cataract Refract Surg. 1997;23:758-60.

Clear Corneal Cataract Incisions 48. Long DA, Monica ML. A prospective evaluation of corneal curvature changes with 3.0 to 3.5 mm corneal tunnel phacoemulsification. Ophthalmology. 1996;103: 226-32. 49. Grabow HB. The clear-corneal incision. In: Fine IH, Fichman RA, Grabow HB (Eds). Clear-corneal Cataract Surgery and Topical Anesthesia. Thorofare: Slack, Inc.; 1993. pp. 29-62. 50. Amon M, Menapace R, Vass C, et al. Endothelial cell loss after 3.5 mm temporal clear corneal incision and 3.5 mm superior scleral tunnel incision. Eur J Implant Refract Surg. 1995;7:229-32. 51. Dick HB, Kohnen T, Jacobi FK et al. Long-term endothelial cell loss following phacoemulsification through a temporal clear corneal incision. J Cataract Refract Surg. 1996;22:63-71.

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Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation Suresh K Pandey, M Edward Wilson, Jagat Ram, Liliana Werner, David J Apple

INTRODUCTION Congenital, early developmental and traumatic cataracts are common ocular ailments and represent an important cause of visual impairment in childhood.1 Managing cataracts in children remains a challenge; treatment is often difficult, tedious, and requires a dedicated team effort by the parents, pediatrician, surgeon, anesthesiologist, orthoptist, and community health workers. The surgeon plays a significant role in achieving a good visual outcome following the treatment of childhood cataracts.2 This chapter will focus on the management of pediatric cataracts with an emphasis on the various surgical techniques, intraocular lens (IOL) implantation, and postoperative complications.

DIAGNOSIS OF PEDIATRIC CATARACTS Congenital, developmental, and traumatic cataracts can have different morphological characteristics (Box 3.1 and Figs. 3.1 to 3.5). These have extensively been reviewed by several authors.3-5 A thorough ocular and systemic examination is mandatory in every child for the accurate diagnosis of the type of cataract. Ocular examination should include the visual acuity assessment, ocular motility, pupillary response, and posterior segment evaluation. When feasible, biomicroscopic examination of the anterior segment should be performed to evaluate the size, density, and location of cataract in order to plan the surgical procedure and to determine the visual outcome. Fundus examination should be carried out after pupillary dilatation. A-scan ultrasound helps to measure the axial length for calculating the IOL power and monitoring the globe elongation postoperatively. For an eye with total

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation BOX 3.1: Characteristics of pediatric cataracts. Congenital/Developmental Total/Diffuse •• Uncommon; Rubella cataracts, bilateral, variable visual prognosis Anterior Polar •• Unilateral or bilateral, sporadic, opacity 11 years) children, the wounds remained self-sealing. The authors attributed this to low scleral rigidity resulting in fish mouthing of the wound leading to poor approximation of the internal corneal valve to the overlying stroma. Closure is recommended using a synthetic absorbable suture such as 10-0 Biosorb or Vicryl. When a foldable IOL is being implanted, a corneal tunnel is preferred since it leaves the conjunctiva undisturbed. The corneal tunnel should begin near the limbus (so-called “near clear” incision) for maximum healing and should be sutured with a synthetic absorbable suture. While the temporal wound presents the same advantages in children as it does in adults, the location is more easily traumatized by children. The superior approach allows the wound to be protected by the brow and the Bell’s phenomenon in the trauma prone childhood years. Both scleral tunnels and corneal tunnels can be easily made from a superior approach since children rarely have deep set orbits or overhanging brows. Locating the site of tunnel

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according to the pre-existing astigmatism (e.g. temporally in against-therule astigmatism) can help in reducing the astigmatic component in the postoperative treatment of amblyopia.

Viscoelastic Substances A high molecular weight viscoelastic substance such as sodium hyaluronate 14 mg/mL (Healon GV®, Pharmacia Corp., Peapack, NJ, United States) is most commonly used in pediatric cataract surgery to effectively resist the increased tendency for anterior chamber collapse due to decreased scleral rigidity and a positive vitreous pressure. This viscoelastic helps maintain a deep anterior chamber and a lax anterior capsule, facilitating attempts at manual anterior capsulorhexis. Also, the initially convex posterior capsule is effectively held back during IOL insertion. We have also recently evaluated the use of viscoelastic with even higher viscosity, sodium hyaluronate 23 mg/ mL (Healon 5®, Pharmacia Corp., Peapack, NJ, United States) during pediatric cataract surgery. This viscoadaptive appears to be useful during various steps of pediatric cataract surgery.170 Without a high molecular weight viscoelastic, an IOL inserted in a manner acceptable for an adult eye will result in inadvertent sulcus placement secondary to the posterior vitreous pressure and posterior capsule convexity. The trabecular meshwork of children clears viscoelastic substances more easily, on average, than in adults. However, efforts should still be made to remove all of the viscoelastic material since postoperative intraocular pressure spikes have been documented when Healon GV is inadequately removed.171

Anterior Capsule Management Manual Continuous Curvilinear Capsulorhexis Gimbel and Neuhann172 advocated continuous tear anterior capsulotomy or continuous curvilinear capsulorhexis (CCC) technique for small-incision adult cataract surgery in the mid-1990s. During the same time, capsular bag fixation of a PCIOL placed at the time of cataract surgery became common place for children beyond age 2. Because manual CCC had become the standard anterior capsulotomy technique in adults, it was naturally also applied to the pediatric age group, but with mixed success. Clinically, it became evident that the pediatric lens capsule is more elastic than the adult and requires increased force before tearing begins. Laboratory investigations have now verified a markedly higher fracture toughness and extensibility in pediatric anterior capsule as compared to elderly adults. In addition, reduced scleral rigidity results in posterior vitreous upthrust when the eye is entered. This vitreous “pressure” pushes the lens anteriorly and keeps the anterior lens capsule taut. Surgeons found more difficulty completing an intact circular capsulotomy. The so-called “run-away rhexis” became all too common. In addition, a capsulotomy that started out small would end up much larger than intended. This result was also due to the marked elasticity of the child’s

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation

anterior capsule. Performing an intact CCC is challenging in young children even for an experienced surgeon as reported by Vasavada and Chauhan,104 in a series of 21 eyes of 13 infants, where the authors failed to create an intact CCC using manual techniques in as high as 80% of the cases.

Modified Continuous Curvilinear Capsulorhexis Technique in a Rabbit Model Auffarth et al.173 developed a modified CCC technique for use in experiments on eyes of young albino rabbits. These animals have very elastic lens capsules reminiscent of the pediatric human lens capsule. The technique begins with a puncture of the lens capsule at the superior border of the intended capsulotomy using a 27-gauge needle. Capsulorhexis forceps are then used to grasp the anterior capsule centrally. The capsular flap is torn toward the 6 o’clock position until a half circle is completed. The force is then reversed toward 12 o’clock, pulling with equal force to both tearing edges. Surgical steps of this technique of CCC in the rabbit eye are shown in Figures 3.9A to H. This technique was used in an experimental study with 16 rabbits (32 eyes). The authors reported radial tear in only two of 32 eyes. Although this technique has become the standard

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Figs. 3.9A to H: Showing the push–pull technique of CCC in the rabbit eye as a model for pediatric capsulectomy. (A) The anterior capsule is punctured with the cystotome to create a horizontal oval opening; (B to D) The anterior capsule is grasped centrally with the capsulorhexis forceps and the capsular flap torn toward 6 o’clock until a half circle is completed; (E to H) After a half circle is completed, the capsular flap is torn back toward 12 o’clock. The capsule will automatically tear to complete a full circle according to its elastic properties. (CCC: Continuous curvilinear capsulorhexis)

Source: Auffarth GU, Wesendahl TA, Newland TJ, et al. Capsulorhexis in the rabbit eye as a model for pediatric capsulectomy. J Cataract Refract Surg. 1994;20:188-91.

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for rabbit capsulotomies in studies performed at the Storm Eye Institute and elsewhere, it has not been adequately studied in human clinical cases.

Small Peripheral Anterior Continuous Curvilinear Capsulorhexis in Rabbit Model Researchers from Bascom Palmer Eye Institute have recently reported a manual surgical technique described for performing a small (less than 1.5 mm diameter) anterior CCC. This technique’s applications extend from PhacoErsatz, a cataract surgical technique designed to restore accommodation to pediatric cataract surgery. They have conducted an experimental rabbit study to determine the feasibility of the technique. A 30-gauge needle and Utrata capsulorhexis forceps were used to construct the CCC. These authors could able to make up to nine small peripheral anterior CCCs in the same lens capsule without the capsule tearing. The mean diameter of the CCCs was 1.1 mm ± 0.3 (SD). This technique, according to these researchers, shows promise for the successful performance of small CCCs in Phaco-Ersatz procedures and pediatric cataract surgery.

How to Create an Intact Manual Continuous Curvilinear Capsulorhexis in Pediatric Eyes? Figures 3.10A to F present illustrations, photographs, and ultrastructural appearance of the manual CCC technique, based on clinical and laboratory studies done at the Storm Eye Institute. To maximize successful completion of a CCC in a child’s eye, the following caveats are offered. Use a high molecular weight OVDs (Healon GV® or Healon® 5, Phramacia, Inc., PeaPack, NJ, United States) to push the anterior capsule back and deepen the anterior chamber. This will create laxity in the anterior capsule and combat the effects of vitreous upthrust caused by scleral collapse and aim to make a slightly smaller CCC in children than in adults. With the stretch in the anterior capsule, the opening is nearly always larger at completion than it appears during the active tearing. When creating the CCC, frequently release the capsular flap, and inspect the size, shape, and direction of the tear. Regrasp near the site of the continuous tear and readjust the direction of pull if needed to keep the capsulotomy on the planned course. Often, more pull is needed toward the center of the pupil (centripetally) to avoid an extension of the CCC out to the lens equator. Additional OVD should be added as needed to keep the capsule lax during the tearing.174 Lenticular contents may escape into the anterior chamber during the CCC as a result of increased intralenticular pressure from vitreous upthrust. If this happens, aspiration of a portion of the lens contents (cortical “milk”) may be needed before completing the CCC.

Can-opener Anterior Capsulotomy To avoid the difficulties with CCC in children, some surgeons have returned to the can-opener style capsulotomy when operating on children (Fig. 3.11A). Wood and Schelonka compared the strength and safety of a CCC with a

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation

can-opener capsulotomy in a porcine model that closely resembles the high elasticity of the human pediatric lens capsule. A CCC and can-opener capsulotomy were performed inside the anterior chamber of fresh pig eyes (47 and 102, respectively). Any uncontrolled tears were noted. According to these authors, the porcine capsule is more reliably opened with fewer uncontrolled tears by a can-opener capsulotomy than by a CCC. Based on their study, the authors predict that pediatric capsules can be opened safely (i.e. few radial

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Figs. 3.10A to D: Manual continuous curvilinear capsulorhexis (CCC) is gold standard when it can be successfully achieved. (A) Technique of manual CCC is illustrated. A bent needle cystotome usually is used to begin the capsulotomy by making a linear cut near the center of the capsule. Capsulorhexis forceps are then used to tear the capsule in a circular fashion; (B) A manual CCC is shown 4 years postoperatively. This child was 10 years old at the time of surgery. A manual tear capsulorhexis was easily accomplished. The posterior capsule was left intact but has now received a YAG laser application; (C) Anterior (Surgeon’s view) of crystalline lens in a human eye obtained postmortem, aged 5- month. The cornea and iris are excised for better visualization. Experimental surgery performed by the authors at Dr. David Apple’s Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, MUSC, Charleston, SC; (D) Creation of successful manual CCC in the same eye using capsulorhexis forceps. Note the smooth, intact edges after a manual CCC (arrows). Experimental surgery performed by the authors at Dr. David Apple’s Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, MUSC, Charleston, SC.

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Figs. 3.10E and F: Manual continuous curvilinear capsulorhexis (CCC) is gold standard when it can be successfully achieved. (E and F) Scanning electron micrograph of the capsule edge after a manual CCC and implantation of a posterior chamber IOL in the capsular bag. Note the smooth edge of the anterior capsule edge following manual CCC (E-F: original magnification X5, X100, and X500, respectively). (CCC: Continuous curvilinear capsulorhexis)

tears) with a can-opener capsulotomy. However, a clinical trial comparing the CCC and can-opener capsulotomy in pediatric eyes appears warranted before reaching any definite conclusion. In a preliminary study performed on postmortem pediatric human eyes at the Storm Eye Institute, we were able to successfully perform the lens aspiration, and IOL implantation without radial tear formation after opening the anterior capsule in a can-opener fashion (unpublished data) (Fig. 3.11B). Scanning electron microscopy revealed anterior capsule tags after these can-opener anterior capsulotomies (Fig. 3.11C). It is difficult to draw a firm conclusion about can-opener anterior capsulotomy in pediatric eyes, especially with regard to performance and radial tear formation. However, radial tears have been documented in nearly 100% of adult eyes when the can-opener capsulotomy is used. The radial tear rate may be less with the highly elastic capsules of children but it has not been adequately studied. Based on the work of Krag et al.,175 can-opener cuts at the edge of a capsulotomy would be expected to tear easily. These authors used the finite element method to document areas of high stress accumulation at each puncture made by the cystotome when performing a can-opener style capsulotomy. In contrast, a CCC demonstrated low and uniform stress distribution with a reduced risk of radial tears. It is well known that radial tears extending outward from the anterior capsulotomy margin can promote IOL decentration by allowing one of the haptics to exit the capsular bag and become fixated in the ciliary sulcus. Decentration has been documented pathologically in up to 50% of adult eyes implanted after a can-opener style anterior capsulotomy. Since children have much greater tissue reactivity and more intense equatorial capsular fibrosis, asymmetric loop fixation would be expected to cause decentration at a higher rate in children than in adults.

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Figs. 3.11A to C: A can-opener anterior capsulotomy has also been proposed by some investigators as an alternative to manual CCC technique. (A) A can-opener capsulotomy is illustrated. A bent needle cystotome is used to make jagged punctures in the capsule. As these punctures are connected, they form a circular opening. Capsular tags are created that can promote radial tears. The sharp apex of each capsular tag that points outward away from the center of the circle has been shown to be an area of high-stress accumulation, making radial tear formation likely; (B) Can-opener anterior capsulotomy in the human eye obtained postmortem. Note the presence of capsular tags (arrow), which can lead to radial tear formation, jeopardizing successful in-the-bag fixation. The capsular bag was stained using 0.1% trypan blue dye to enhance visualization of the anterior capsular flap. Experimental surgery performed by the authors at Dr David Apple’s Center for Research on Ocular Therapeutics and Biodevices, Storm Eye Institute, MUSC, Charleston, SC; (C) Scanning electron microscopy of the anterior capsulotomy margin showing the presence of capsular tag (original magnification X100).

Vitrector-cut Anterior Capsulectomy (Vitrectorhexis) An ideal anterior capsulotomy for children would need to be easy to perform and yet have a low rate of radial tear formation even as it is stretched and deformed during cataract aspiration and IOL placement. The manual CCC remains the gold standard for resistance to tearing and should be accomplished when possible. However, its completion difficulty in children has prompted the development and investigation of alternative techniques.

Laboratory and Clinical Studies in Human Pediatric Eyes Wilson et al.176,177 have tested a mechanized circular anterior capsulectomy in both laboratory and clinical settings.176,177 It had proven to be a very good alternative to CCC for young children where the CCC may be difficult to control. This technique, known as vitrectorhexis, is best performed using a vitrector tip attached to a Venturi pump irrigation and aspiration system. The capsulectomy need not be started with a bent needle cystotome. Rather, the vitrector tip is placed through a tight fit stab incision at the limbus or through a scleral tunnel. Irrigation is provided with a sleeve surrounding the vitrector or through a separate stab incision. A cut rate of 150 cycles/min is recommended. With the cutting port oriented posteriorly, the center of the anterior capsule is aspirated into the cutting port to create an initial opening. Any nuclear or cortical material that spontaneously exits the capsular bag anteriorly is easily aspirated without interrupting the capsulectomy technique. The capsular

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opening is enlarged using the cutter in a gentle circular fashion. The cutter is kept just anterior to the capsular edge, aspirating the capsule up into the cutting port rather than engaging the capsular edge directly. Visualization of the capsular edge during enlargement of the capsulectomy is excellent because the aspirating capability of the vitrector continuously removes lens cortex as it enters. Vitrectorhexis or a mechanized, vitrector-cut anterior capsulotomy (Fig. 3.12A) has compared favorably to manual CCC in a direct comparison using fresh pediatric autopsy eyes (Fig. 3.12B). It was easier to perform and resisted tearing during IOL placement. A prospective clinical series was subsequently published containing data on 20 eyes of 17 patients.173 Two patients, both aged 11, were noted to have radial tears in the anterior capsule after IOL insertion. None of the children younger than age 11 developed radial tears. One of the authors (MEW) has performed more than 200 successful anterior capsulectomies in children using this technique and it has become capsulotomy technique of choice below age 6 years (Fig. 3.12C). After an initial learning curve, radial tears are very rare when using this technique. Manual CCC, while still difficult, begins to resemble the adult technique when operating on older children.

How to Create a Successful Vitrectorhexis in Pediatric Eyes? When creating a vitrectorhexis, the following surgical caveats are offered. Use a vitrector supported by a venturi pump. Peristaltic pump systems will not cut anterior capsule easily. Use an infusion sleeve or a separate infusion port, but with either approach, maintain a snug fit of the instruments in the incisions through which they are placed. The anterior chamber of these soft eyes will collapse readily if leakage occurs around the instruments, making the vitrectorhexis more difficult to complete. An microvitreoretinal (MVR) blade can be used to enter the eye. The vitrector and the blunt-tip irrigating cannula (Nichamin cannula, Storz) fit snugly into the MVR openings. Do not begin the capsulotomy with a bentneedle cystotome. Merely place the vitrector, with its cutting port positioned posteriorly, in contact with the center of the intact anterior capsule. Turn the cutter on and increase the suction using the foot pedal until the capsule is engaged and opened. A cutting rate of 150–300 cuts/min and an aspiration maximum of 150–250 (these settings are for the Alcon Accurus and the Stortz Premier—adjustments may be needed for other machines) are recommended. With the cutting port facing down against the capsule, the authors then enlarge the round capsular opening to the desired shape and size. Any lens cortex that escapes into the anterior chamber during the vitrectorhexis is aspirated easily without interrupting the capsulotomy technique. Care should be taken to avoid leaving any right-angle edges, which could predispose to radial tear formation. The completed vitrectorhexis should be slightly smaller than the size of the IOL optic being implanted. The vitrector creates a slightly scalloped edge but inspection by both the dissecting microscope and the scanning electron microscope has revealed that the scallops roll outward to leave a smooth edge (Figs. 3.12D to F).24 Any capsular tags or points created at the apex of a scalloped

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Figs. 3.12A to F: The use of vitrector for anterior and posterior capsulorhexis (termed as “vitrectorhexis”) has been extensively studied in both clinical and laboratory setting. (A) A vitrectorhexis is illustrated. The side port cutting vitrector hovers over the intact capsule. The capsule is aspirated up into the cutting port and a circular opening is fashioned. Although a scalloped edge is created (left background), this edge folds back as viscoelastic is placed within the capsular bag (right foreground) to create a smooth edge. Capsular tags made with the vitrector usually have an apex pointing toward the center of the capsular opening. As opposed to can-opener capsulotomy tags, these do not represent areas of high-stress accumulation. The mechanical vitrector-cut capsulectomy works best on the elastic capsule of young children; (B) A vitrector-cut anterior capsulectomy is shown in this pediatric autopsy eye from the Miyake-Apple posterior view; (C) The postoperative appearance of this vitrector-cut anterior capsulectomy is smooth and round. The intraocular lens is well centered and placed completely within the capsular bag; (D to F) Scanning electron micrograph of vitrectorhexis capsule edge. Note the scalloped edges, grooves, and irregularity but smooth internal surface (D to F: original magnification X5, X100, and X500, respectively).

cut from the vitrector are located in an area of low biomechanical stress much like an irregular outside-in completion of a CCC. These tags do not predispose to radial tear formation as demonstrated by finite element method computer modeling.

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Bipolar Radiofrequency Capsulotomy Radiofrequency diathermy capsulotomy, developed by Kloti et al.,179 has been used as an alternative to CCC for intumescent adult cataracts and for cataract surgery in children. The Kloti device cuts the anterior capsule with a platinum-alloy-tipped probe (Figs. 3.13A and B) using a high frequency current of 500 kHz. The probe tip is heated to about 160°C and produces a thermal capsulotomy as it is moved in a circular path across the anterior capsule. Small gas bubbles are formed while the tip is active, but these do not usually interfere with visibility during the capsulotomy. Gentle pressure must be maintained on the capsule with the tip as it moves either clockwise or counterclockwise. If contact is too light or movement too fast, skipped areas will result. If contact is too firm or movement too slow, the tip will burn through the capsule and enter the lens cortex. Subsequent tip movement drags the capsulotomy edge rather than cutting it, which may cause radial tearing. However, the preferred rate of movement and firmness of capsule contact is quickly learned after a few cases. Even when performed perfectly, a diathermy-cut capsulotomy can be seen to have coagulated capsular debris along the circular edge. In addition, this edge has been shown experimentally to be less elastic than a comparable CCC edge. Since the stretching force needed to break the edge of a diathermy-cut capsulotomy is much reduced compared to a CCC edge, surgical manipulations needed to remove a cataract and place an IOL may result in more radial tears when the diathermy is used. However, the experimental measurements were all made on adult autopsy globes. It is well-known that the pediatric capsule responds differently. In fact, Comer et al.180 reported no radial tears when using the diathermy-cut capsulotomy in 14 eyes of seven children whose mean age was 23 months. Clinically, the diathermy device is useful in children for both the anterior and posterior capsules. However, the diathermy edge tears more easily than when vitrector or manual CCC techniques are used.

Fugo Plasma Blade™ Anterior Capsulotomy The Fugo plasma blade™ has also been recently introduced as a radiofrequency unit that can be used to perform an anterior capsulectomy (Figs. 3.14A to D). The Fugo blade capsulotomy unit is a portable electronic system that operates on rechargeable batteries and provides an alternative to capsulorhexis. This unit is user friendly and may be clipped to the surgeon’s belt or may rest on a countertop. The Fugo blade provides an anterior capsulotomy that requires no red reflex and usually requires less than 10 seconds to perform. The unit also allows the surgeon to easily revise the size of the capsulotomy openings. The instrument developer reports that the Fugo blade is easy to use and does not have a steep learning curve.181 (Fugo RJ, Coccio D, McGrann D, Becht L, DelCampo D. The Fugo Blade…the next step after capsulorhexis. Presented at the American Society of Cataract and Refractive Surgery Symposium on Cataract, IOL and Refractive surgery, Congress on Ophthalmic Practice Management, Boston, Massachusetts, May 23, 2001). The Fugo blade may be particularly suited for the highly elastic capsule of children. Because it cuts the capsule with a “plasma blade”, it may not

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation

suffer from the tendency for skip areas seen with Kloti radiofrequency device. However, the edge of a Fugo blade capsulotomy will not perform better than the Kloti diathermy edge when stretched.

A

B

Figs. 3.13A and B: The Kloti radiofrequency diathermy. The platinum-alloy-tipped probe directs a high frequency current of 500 kHz. Under viscoelastic, the probe tip is placed in contact with the intact anterior capsule and moved in a circular path to create a round opening. (A) Kloti radiofrequency diathermy needle handpiece; (B) Kloti radiofrequency diathermy needle.

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Lens Substance Removal Pediatric cataracts are soft. Phacoemulsification is rarely if ever needed. Lens cortex and nucleus are usually easily aspirated with an irrigation/aspiration or vitrectomy handpiece. When using the vitrector, bursts of cutting can be used intermittently to facilitate the aspiration of the more “gummy” cortex of young children. The phacoemulsification handpiece can also be very useful when aspirating pediatric lens material. Hydrodissection78,80 has been thought to be less useful in children than in adults. However, a recent study has shown

A

B

Figs. 3.14A and B

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation

C

D

Figs. 3.14C and D Figs. 3.14A to D: Anterior capsulotomy using the Fugo Plasma Blade. (A to D) Show various steps of anterior capsulotomy in a porcine eye model. (Source: Roy H, Course for Fugo blade is enlightening, surgeon says. Ocular Surgery News, September 1, 2001).

the intraoperative benefits of performing multiquadrant hydrodissection. The benefits are overall reduction in the operative time, and the amount of irrigating solution used, and facilitation of lens substance removal (Trivedi R, Vasavada AR,

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Apple DJ, et al. “Cortical cleaving hydrodissection in congenital cataract surgery”, Presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery, San Diego, CA, USA, May 2001).182 A fluid wave can sometimes be generated in older children but not reliably in infants and toddlers. Cortical material strips easily from the pediatric capsule even in the absence of hydrodissection.183 Attempts at hydrodelineation should be discouraged in children since it does not aid in lens removal and may lead to capsular rupture.

Primary Intraocular Lens Implantation Capsular fixation of the IOL is strongly recommended for children.79,149,176 Care should be taken to avoid asymmetric fixation with one haptic in the capsular bag and the other in the ciliary sulcus. In contrast to adults, dialing of an IOL into the capsular bag can be difficult in children. An oversized IOL (adult IOL 12–12.5 mm) along with the vitreous upthrust often causes the IOL to vault forwards which results in its dialing out of the capsular bag. On the other hand, sulcus fixation of an IOL in a child appears to be easy but the long-term consequences of contact with vascularized uveal tissue are a cause for concern. To minimize the iris-optic contact, lens decentration, and to reduce the possibility of erosion into the ciliary body, prolapse of the optic through an intact anterior or posterior capsulotomy are suggested when sulcus fixation of an IOL in a child is necessary.

Secondary Intraocular Lens Implantation The vast majority of children undergoing secondary IOL implantation have had a primary posterior capsulectomy and anterior vitrectomy. If adequate peripheral capsular support is present, the implant is placed into the ciliary sulcus.25 Since the sulcus is only 0.5–1.0 mm larger than the evacuated capsular bag, most IOLs designed for capsular fixation can also be placed in the ciliary sulcus. Viscodissection is often all that is needed to break synechia between the iris and residual capsule. Both the AcrySof™ acrylic lens and the all-PMMA lens have been used by the authors for sulcus fixation in the child (Wilson ME, Holland DR, “In-the-bag Secondary Intraocular Lens Implantation in Children”, presented at the symposium on Cataract, IOL and Refractive Surgery, San Diego, California, USA, April 1998).118 Our current recommendations are to place an all-PMMA heparin-surface-modified IOL rather than an acrylic lens when sulcus placement is required. Prolapsing the IOL optic through the fused anterior and posterior capsule remnants is useful in preventing pupillary capture and assuring lens centration. In some cases, the anterior and posterior capsular remnants can be dissected apart allowing the IOL to be placed in the capsular bag.89 An exuberant Soemmering’s ring formation will often separate the anterior and posterior capsule leaflets and maintain the peripheral capsular bag. This material can be aspirated cleanly after the anterior capsule edge is lifted off of the posterior capsular edge to which it is usually fused. When inadequate capsular support is present for sulcus fixation in a child, implantation of an IOL is not recommended unless every contact lens and spectacle option has been fully explored. Although their long-term safety is unknown, modern flexible open loop anterior chamber lenses seem to be well

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation

tolerated in children when their anterior segment is developmentally normal. Scleral fixation of PCIOLs in children has been well tolerated according to some recent studies, but complications such as pupillary capture, suture erosion, and refractive error from lens tilt or anterior/posterior displacement have been reported.73,90,115 The ab externo approach is recommended for transscleral suture placement in children.

Management of the Posterior Capsule Management of the pediatric posterior capsule, especially when implanting an IOL at the time of the primary surgery, remains controversial.184 Several surgical techniques have been used by various surgeons to maintain the longterm clear visual axis.

Primary Posterior Capsulotomy and Anterior Vitrectomy Primary posterior capsulectomy and anterior vitrectomy during pediatric lensectomy were popularized by Parks in the early 1980s.83 This led to a dramatic decrease in the need for secondary surgery for congenital cataracts. Pediatric ophthalmologists are accustomed to removing a portion of the posterior capsule and the anterior vitreous at the time of lensectomy. An increase in late complications from primary capsulectomy and vitrectomy has not been reported. Adult cataract surgeons are often more reluctant to perform a primary capsulectomy and vitrectomy for fear that the risk of retinal detachment or cystoid macular edema (CME) will be increased. In point of fact, these complications are exceedingly rare after pediatric cataract surgery with or without a primary capsulectomy and vitrectomy. Neodymium (Nd):YAG laser posterior capsulotomy is usually necessary in children when the posterior capsule is left intact. This procedure also carries a risk of retinal detachment and CME. In addition, larger amounts of laser energy are often needed when compared to adults and the posterior capsule opening may close requiring repeated laser treatments or a secondary pars plana membranectomy. Dahan and Salmenson55 have recommended posterior capsulotomy and anterior vitrectomy in every pediatric cataract patient younger than 8 years. Vasavada and Desai105 also advise anterior vitrectomy along with primary posterior continuous circular capsulorhexis (PCCC) in children younger than 5 years of age. Metge et al.77 have shown that a posterior capsulectomy without a central vitrectomy did not prevent the development of a secondary membrane. The opacification rate was not significantly decreased by a posterior capsulectomy alone. Only when an anterior vitrectomy was added did the opacification rate fall. Vasavada and Trivedi,106 in a prospective and randomized study, have also shown that visual axis obscuration by reticular fibrosis of the anterior vitreous face occurred in 70% of those eyes in which vitrectomy was not done following PCCC. As opposed to this, no eye developed visual axis obscuration when a PCCC was combined with anterior vitrectomy (Figs. 3.15A and B). Also, these eyes performed better for low contrast sensitivity testing. All these results suggest that anterior vitrectomy is not only beneficial but also necessary in children aged 5–12 years.107

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A

B

Figs. 3.15A and B: Two different cases of in-the-bag IOL fixation in combination with primary posterior capsulotomy and anterior vitrectomy. This procedure is helpful to maintain a clear visual axis in younger children. (A) Clinical photograph postimplantation of an all PMMA IOL in which a primary posterior capsulotomy with anterior vitrectomy were performed at the time of primary surgery. The posterior capsule within the visual axis remained clear 1-year postoperatively. Note, however, the presence of some cell deposits on the IOL surfaces; (B) Acrylic (AcrySofTM) IOL implanted in the capsular bag of a 4-year-old child. A primary posterior capsulorhexis and anterior vitrectomy were performed. This photograph was taken 1-year postoperatively. There are several Elschnig pearls outside the IOL optic, but the visual axis is clear. (Courtesy: AR Vasavada, Ahmedabad, India)

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation

Posterior Capsulorhexis with Intraocular Lens Optic Capture Gimbel and DeBrof62,185,186 recommend performing a posterior capsulorhexis with IOL optic capture. This technique is designed to help prevent secondary membrane formation without necessitating a vitrectomy.187 It also  ensures centration of the PCIOL because the haptics remain in the capsular bag and the optic is captured in the posterior capsular opening (Fig. 3.16). Vasavada and Trivedi106 also reported a better centration of the IOL following optic capture. However, they have also expressed concern regarding the resultant increased predisposition to uveal inflammatory sequelae. The same authors,106 along with other surgeons,67,68 have reported opacification of the visual axis despite optic capture. Thus, they recommend performing an anterior vitrectomy even when optic capture is utilized through the posterior capsulorhexis.

Options for Primary Posterior Capsulotomy When a decision is made to perform a primary posterior capsulotomy, several options are available.186,188,189 The posterior capsular opening can be made using a manual PCCC technique or using an automated vitrector or the Kloti radiofrequency bipolar unit. The manual technique and the mechanized vitrector technique can each be performed either before or after the IOL has been placed in the eye. When the vitrector is used after the IOL has been placed, it is usually done via the pars plana. The radiofrequency bipolar unit

Fig. 3.16: Photograph of an eye implanted with an acrylic (AcrySofTM) IOL in the capsular bag. IOL optic capture through a posterior capsulorhexis was performed during the primary procedure. This photograph was taken at 1 month postoperatively and shows well-centered IOL and anterior and posterior capsulorhexis edges. (Courtesy: AR Vasavada, Ahmedabad, India).

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is not easily manipulated beneath an IOL and is therefore usually performed on the posterior capsule from an anterior approach prior to IOL insertion. In most instances, an anterior vitrectomy is performed simultaneously with the posterior capsulectomy.

Neodymium:YAG Laser Posterior Capsulotomy Atkinson and Hiles, 190 on the other hand, recommended leaving the posterior capsule intact even in very young children and performing Nd:YAG capsulotomy under a second general anesthesia in the early postoperative period. Subsequently, however, the same group reported a 41% need for repeating laser capsulotomy when this protocol was followed. Interestingly, Plager et al.128 reported that in their patients, the incidence of PCO began to increase markedly at approximately 18 months after surgery, independent of the age at the time of cataract extraction. They recommended a primary posterior capsulectomy and anterior vitrectomy at the time of primary lens implantation in children who are not expected to be suitable candidates for awake Nd:YAG capsulotomy within 18 months of surgery. IOL exchange, if needed later, will be more difficult if optic capture has been used.

Dye-enhanced Pediatric Cataract Surgery The use of capsular dyes such as 2% fluorescein sodium, 0.5% indocyanine green, and 0.1% trypan blue for staining the anterior capsule, while performing CCC, in white/advanced adult cataract cases is well-known. We recently reported our experience of anterior capsule staining for performing CCC in postmortem human eyes with advanced/white cataracts.80 We also reported the use of capsular dyes to enhance visualization to learn and perform other critical steps of the phacoemulsification procedure and posterior capsulorhexis, respectively.81,191-193 (Pandey SK, Werner L, Apple DJ, et al. “Anterior Capsule Staining in Advanced Cataracts: A Laboratory Study using Postmortem Human eyes,” presented at the annual meeting of the American Academy of Ophthalmology, Orlando, Florida, October 1999; Pandey SK, Werner L, Apple DJ, et al. “Dye-Enhanced Cataract Surgery in Human Eyes Obtained Post-mortem: A Laboratory Study to Learn and Perform Critical Steps of Phacoemulsification”, video presented at the ESCRS Symposium on Cataract, IOL and Refractive Surgery, Vienna, Austria, September 1999). Learning the PCCC procedure (and achieving a consistent size of posterior capsule opening for performing the optic capture) can be difficult for the beginning surgeon due to the thin and transparent nature of the posterior capsule. According to our experimental studies, posterior capsulorhexis (with or without the optic capture) is relatively easy to perform after staining of the otherwise transparent posterior capsule (Figs. 3.17A and B). The procedure of optic capture with or without anterior vitrectomy can also be accomplished easily after staining the posterior capsule.81 It is easier to localize an inadvertent tear of the posterior capsule when staining of the posterior capsule has been utilized (Fig. 3.17C).

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation

Pediatric Traumatic Cataracts and Their Management Epidemiology and Etiology Traumatic cataract in children is a common cause of unilateral loss of vision.194 Incidence of traumatic cataract in children is reported as high as 29% of all childhood cataracts.195 Penetrating injuries are usually more common than blunt injuries. About 80% of traumatic cataract cases occur in children while

A

B

Figs. 3.17A and B

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Fig. 3.17C Figs. 3.17A to C: Photographs of a pediatric eye obtained postmortem, taken from anterior (Surgeon’s view) illustrating the use of the capsular dye to enhance visualization during various steps of the pediatric cataract surgery. (A) Posterior capsulorhexis after staining of the capsular bag with trypan blue; (B) Posterior capsulorhexis and optic capture of a foldable IOL after staining of the capsular bag with trypan blue; (C) Visualization of a posterior capsule tear after staining of the capsular bag with indocyanine green.

playing or when they are involved in sport-related activities. Injuries are also caused by thorns, firecrackers, sticks, bow, and arrows.196

Surgical Management At the time of presentation after the trauma to the eye, primary repair of the corneal or scleral wound is usually preferred. Cataract surgery with IOL implantation is performed later following complete evaluation of damage to the intraocular structures (e.g. posterior capsule rupture, vitreous hemorrhage, and retinal detachment) by ancillary methods such as B-scan ultrasonography.197 Some authors report PCIOL implantation at the same time as primary repair of corneal lacerations and removal of traumatic cataract.174 We think repair of corneal or scleral wounds combined with primary IOL implantation should be considered in younger children at the risk of developing amblyopia. Implantation of IOL is preferred in the cases of traumatic cataracts with corneal injuries, because contact lenses may be difficult to fit.198

Visual Results and Postoperative Complications In sharp contrast to congenital and developmental cataracts, traumatic cataracts are mostly unilateral and often associated with good visual

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation

prognosis.199-201 We recently reported our experience on the implantation of PCIOLs in 20 children (20 eyes) with traumatic cataracts.78,79,202 Capsular bag fixation of a PCIOL was performed in 10 eyes (group A) and in other 10 eyes (group B) ciliary sulcus fixation was performed (Figs. 3.18A and B). Traumatic cataracts associated with large corneal lacerations (10 mm or more),

A

B

Figs. 3.18A and B: Cataract surgery and in-the-bag fixation of posterior chamber IOLs in pediatric traumatic cataracts. (A) Preoperative photograph of the anterior segment of a 6-year-old male child showing traumatic cataract and formation of posterior synechia at 2.30 o’clock position. The visual acuity on presentation was 20/60; (B) Same eye 4 weeks postoperatively, showing the clear visual axis after cataract extraction and capsular bag fixation of a posterior chamber intraocular lens. The best-corrected visual acuity was 20/20.

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hyphema, angle recession, or posterior segment involvement were excluded. A best-corrected visual acuity (BCVA) of 20/40 or better was achieved in 9 of 10 eyes (90%) in group A and in 8 of 10 eyes (80%) in group B at the end of the mean follow-up period (24.6 ± 10.6 months). The residual refractive error did not exceed 3.50 diopters in either group. In this prospective, randomized study, capsular bag fixation of PCIOLs provided similar visual results as was noted with ciliary sulcus fixation but was associated with fewer postoperative complications, particularly uveitis and pupillary capture. In a comparable series of eight cases of traumatic cataracts in children, Koenig et al.69,70 reported 20/40 or greater visual acuity in 87% (seven out of eight) eyes undergoing PCIOL implantation for pediatric traumatic cataracts. The average follow-up in their series was 10 months. Gupta et al.64 reported that 9 (50%) of 18 children with unilateral traumatic cataract achieved 20/40 (or greater) visual acuity after IOL implantation, with an average follow-up of 12 months. In many cases, corneal leukomata contributed for decreased postoperative visual acuity. Similarly, Anwar et al., 174 Bustos et al., 53 BenEzra,163 and Eckstein et al.57 reported visual acuity of 20/40 or better in 73.3%, 79.0%, 65.2%, and 67.0% of cases after traumatic cataract surgery with PCIOL implantation in children, respectively. Table 3.2 summarizes the visual results and postoperative complications concerning recent studies of PCIOL implantation in pediatric traumatic cataracts. TABLE 3.2: Studies of posterior chamber intraocular lens implantation in children with traumatic cataracts. Complications (%)

Study

Number of patients

Age range (years)

Mean followup (years)

Bienfait et al.199

23

0.4–11

6.5

70.1

0

9

83

Gupta et al.64*

22

3–11

0.9

45

81.8

9

27

Koenig et al.69,70

8

4–17

0.8

87

NR

NR

37

Anwar et al.

15

3–8

3.2

73.3

NR

NR

40

Bustos et al.53

19

3–15

0.7

79

26

10.5

21

BenEzra et al.163-167

23

2–13

6.2

65.2

NR

26

100

Eckstein et al.57,195

52

2–10

2.9

67

19

41

92

Pandey et al.79

20

4–10

2.5

85

45

20

60

174

BCVA (≥6/12) (%)

Fibrinous anterior uveitis

Pupillary capture

(BCVA: Best-corrected visual acuity; PCO: Posterior capsule opacification) *Four patients had an anterior chamber IOL. ****NR = Not reported

PCO

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation

Perioperative and Postoperative Treatment The perioperative routine includes a drop of 5% povidone iodine at the beginning and at the end of the surgical procedure. It is better to avoid using a miotic at the completion of surgery since this can create increased anterior segment inflammation. Topical steroid/antibiotic and atropine ointment are put in the eye, and a light patch and fox shield placed over the eye. Beginning the next morning, topical steroid drops six times a day and atropine 1% eye drop once per day for 4 weeks are recommended. A topical antibiotic is added for the first several days. The atropine eye drop regimen is stopped at 4 weeks and the topical steroid tapered and discontinued. The atropine is sometimes avoided when an IOL is placed in the ciliary sulcus to reduce the chances of pupillary capture. Glasses or an eye shield is worn over the eye continuously for the first week.

Postoperative Complications and Management Complications associated with pediatric cataract surgery continue to be a major concern for the ophthalmic surgeon. The risk of postoperative complication is higher due to greater inflammatory response after pediatric intraocular surgery.150 In many cases, these complications may be the primary reason for a poor visual outcome.203 In some cases, the complications appear to be intrinsically related to associated ocular anomalies that coexist with the developmental cataract. Close follow-up, early detection, and management of the complications are mandatory.

Early Onset Uveitis Postoperative anterior uveitis (fibrinous or exudative) is a common complication due to increased tissue reactivity in children. In a series of 40 eyes with congenital or developmental cataracts, incidence of fibrinous uveitis was seen in as high as 57.5% eyes (Pandey SK, Ram J, Werner L, Apple DJ. “Intraocular lens implantation in pediatric cataracts,” Presented at the symposium on Cataract, IOL and Refractive Surgery, Boston, MA, USA, May 2000).204 In comparative studies, the reported incidence of postoperative fibrinous anterior uveitis was 81.8%, 26.0%, and 19.0%.39,64 Uveitis results in fibrinous membrane formation, pigment deposits on the IOL, and posterior synechia formation 23,205 (Fig. 3.19). Frequent topical steroids and even systemic steroids may be needed in selected cases to reduce uveitis-related complications. Brady et al.49 recommend five units of intravenous heparin in 500 mL of irrigating solution. According to recent studies, implantation of heparin-surface-modified PMMA IOLs in children reduces postoperative inflammation. Mullaney et al.206 reported dissolution of pseudophakic fibrinous exudates with the use of intraocular streptokinase (500–1000 IU) without any adverse effect. Similarly, Klais et al.207 performed fibrinolysis in 11 eyes of 10 children who developed severe fibrin formation despite intensive

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Fig. 3.19: Slit-lamp photograph of a young child after ciliary sulcus fixation of a PMMA IOL. Note the formation of a membrane and multiple posterior synechiae.

topical steroid therapy. A complete resolution of fibrin formation was seen in 90% of children after using 10 μg of recombinant tissue plasminogen activator (rt-PA).208 Besides incomplete resolution and recurrence of membranes, other complications of rt-PA use include hyphema, dysfunction of corneal endothelial cells, and corneal band keratopathy. Other possibilities to treat fibrin formation after pediatric IOL surgery are Nd:YAG laser discission, simple mechanical discission, and intraocular steroid (e.g. dexamethasone) delivery system (Surodex®).208 However, modern surgical techniques that limit iris manipulation and ensure capsular bag fixation of the IOL have resulted in less postoperative inflammation even in small children.

Corneal Edema Transient corneal edema may occur in pediatric cataract surgery but bullous keratopathy is a rare complication. 209 Cataract surgery does not cause significant endothelial cell loss in children. Reports on corneal endothelial cell count in pediatric aphakia and IOL implantation have shown no significant loss of endothelial cells.20,104,210 Corneal decompensation may occur if detergents (e.g. glutaraldehyde) are used for sterilization of cannulas or instruments and are not rinsed thoroughly before use in the anterior chamber. Indeed, cannulas or tubing should not be sterilized in glutaraldehyde solution as, even after thorough rinsing, residual chemicals may remain.

Endophthalmitis Endophthalmitis does occur after cataract extraction in children. It is a rare complication and appears to occur with the same frequency as in adult

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation

cataract patients. The prevalence of endophthalmitis reported by Wheeler et al.211 was 7/10,000 cases, after pediatric cataract surgery. Common organisms are Staphylococcus aureus, Staphylococcus epidermidis, and Staphylococcus viridans. Nasolacrimal duct obstruction, periorbital eczema, and upper respiratory tract infections are important risk factors.212 Techniques to avoid the complication of endophthalmitis remain controversial in all cataract procedures. Authorities advise the use of topical antibiotic ophthalmic solutions applied to the cataractous eye for 24 hours preoperatively. Other authorities emphasize the need to use an undiluted povidone–iodine (Betadine™) solution not only applied to the skin but also instilled in the eye at the time of the operation to reduce the bacterial flora in the operative field. Identifying endophthalmitis in the young child is often much more difficult than in the adult aphakic patient. Careful slit-lamp examination may not be possible, even with a hand-held device. It should be recalled that the most likely time for endophthalmitis to become clinically apparent in the postoperative period is between 48 hours and 96 hours postoperatively. Postoperative schedules for evaluating these patients should be drafted keeping in mind in the era of ambulatory surgical therapy. The risk of endophthalmitis may be lower than the risks associated with general anesthesia in some neonates. Therefore, some ophthalmologists have opted to perform bilateral cataract surgery under one general anesthesia in medically unstable infants. This point remains controversial.

Noninfectious Inflammation Jameson et al.213 have described a benign syndrome of excessive noninfectious postoperative inflammatory response in young aphakic children. This syndrome presents with excessive photophobia, tearing, and even the inability to open the eyes postoperatively. It may persist for days or even weeks and may preclude the early contact lens fitting that initiates amblyopic therapy. It is not clear whether steroids applied topically or injected into the sub-Tenon’s space are efficacious in shortening this benign inflammatory process.

Intermediate/Late Onset Capsular Bag Opacification Opacification of the capsular bag universally occurs following pediatric cataract surgery. It includes opacification of the anterior, equatorial, and posterior capsules. Excessive anterior capsule fibrosis and shrinkage of the CCC opening can lead to difficulty in examining the retinal periphery and occasionally the decentration of the IOL.214 Figures 3.20A to C show examples of capsular bag opacification in three different pediatric cases. Posterior capsule opacification is the most common complication after pediatric cataract surgery with or without IOL implantation.71,215 A recent report has indicated an age independent dramatic rise in the incidence of PCO beginning at 18 months after surgery and reaching nearly 100% over time.128

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Posterior capsule opacification is amblyogenic if it occurs during the critical period of visual development in the younger children. In cases of dense, thick PCO, surgical posterior capsulotomy combined with anterior vitrectomy may be required to prevent amblyopia. Nd:YAG laser can also be used to perform posterior capsulotomy when PCO is not dense (Fig. 3.21).190 The use of newer surgical techniques such as primary posterior capsulotomy and anterior vitrectomy, posterior capsulorhexis with optic capture, or posterior

A

B

Figs. 3.20A and B

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation

Fig. 3.20C Figs. 3.20A to C: Clinical photographs showing examples of delayed postoperative capsular bag opacification (and its sequelae) after pediatric cataract surgery. (A) Anterior capsule opacification after phacoemulsification and implantation of an AcrySofTM IOL in a 7-year-old child. Both eyes had a best-corrected visual acuity of 20/40; (B) Dense anterior capsule opacification after phacoemulsification and in-thebag implantation of a PMMA IOL in an 8-year-old child; (C) Superior decentration of in-the-bag fixated posterior chamber IOL 5 months following cataract surgery secondary to asymetrical capsular bag fibrosis in a 5-year-old child.

capsulotomy performed with endodiathermy of the capsule has shown encouraging results in maintaining a clear visual axis.6,166,188

Secondary Membrane Formation Formation of secondary membranes is a common complication of pediatric cataract surgery, particularly after infantile cataract surgery.82,216-218 Nd:YAG laser capsulotomy may be sufficient to open them in the early stage. More dense secondary membranes usually need membranectomy and anterior vitrectomy.219 Pupillary membranes can occur postoperatively in children whether an IOL has been implanted or not. Microphthalmic eyes with microcoria operated in early infancy are at greatest risk, especially when mydriatic/cycloplegic agents have not been used postoperatively. When an IOL is in place, secondary membranes may form over the anterior and/or posterior surface of the implant. The incidence of secondary membranes after neonatal or infantile cataract surgery has been reduced dramatically by the “no-iris-touch” aspect of the closed chamber surgery, by applying topical corticosteroids and cycloplegic agents at frequent intervals postoperatively and by performing posterior capsulectomy and an adequate anterior vitrectomy.

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Fig. 3.21: Slit-lamp photograph of the anterior segment of a 7-year-old male child 18 months following capsular bag fixation of a posterior chamber intraocular lens. This patient required Nd:YAG laser posterior capsulotomy for posterior capsule opacification. There was also an opacification of the anterior capsule including the capsulorhexis margin.

Pupillary Capture Placing the IOL in the capsular bag helps to prevent pupillary capture, a complication that is much more common in children. It is associated with posterior synechia formation and PCO. Incidence of pupillary capture after pediatric cataract surgery varies from 8.5% to 41%. This was reported by several authors: Vasavada and Chouhan104 in 33% (7 of 21 eyes), Basti et al.188 in 8.5% (7 of 82 eyes), Brady et al.49 in 14.2% (3 of 20 eyes), and Bustos et al.53 in 10.5% (2 of 19 eyes). Pupillary capture occurs most often in children younger than 2 years of age, when an optic size less than 6 mm is used and the lens is placed in the ciliary sulcus. In a series of 20 cases of traumatic cataracts with PCIOL implantation in children, Pandey et al.79 reported an incidence of pupillary capture as high as 40% in ciliary-sulcus fixated IOLs while none of the eyes with in-the-bag fixation of the PCIOL had this complication (Figs. 3.22A and B). Pupillary capture can be left untreated if it is not associated with decreased visual acuity, IOL malposition, or glaucoma. However, surgical repair recreates a round pupil shape and IOL centration. Fixation of PCIOLs in the capsular bag (whenever possible) is recommended to decrease the incidence of this complication. Prolapsing the optic of a secondary sulcus fixated IOL through the anterior capsulorhexis opening can also prevent pupillary capture.

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation

A

B

Figs. 3.22A and B: Pupillary capture and posterior capsule opacification after pediatric cataract surgery and IOL implantation. (A) Slit-lamp photograph of the anterior segment of a 12- year-old-female child 13 months after ciliary sulcus fixation of a posterior chamber intraocular lens. Note the marked pupillary capture of the IOL optic, extending from 12 o’clock to 5 o’clock associated with pupillo-capsular synechia and marked posterior capsule opacification. Best-corrected visual acuity was 6/24 in this eye due to posterior capsule opacification. It required Nd: YAG laser posterior capsulotomy; (B) Clinical photograph of the eye of a 10-year-old girl, post PMMA posterior chamber intraocular lens implantation. There is a marked pupillary capture. This is associated with marked posterior capsule opacification. Attempt to perform Nd: YAG laser failed, resulting in multiple pits on the IOL optic. This type of dense PCO is an indication for surgical posterior capsulotomy with anterior vitrectomy.

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Deposits on Intraocular Lens Surface Precipitates composed of pigments, inflammatory cells, fibrin, blood break­ down products, and other elements are often seen during the immediate postoperative period on the surface of an IOL optic implanted in a child (Figs. 3.23A and B). The deposits can be pigmented or nonpigmented but are usually

A

B

Figs. 3.23A and B: Slit-lamp photographs showing pigment deposition on the surface of 2 different IOLs. This complication is not uncommon after the pediatric cataract surgery and usually does not cause a decrease in visual acuity. (Courtesy: AR Vasavada, Ahmedabad, India)

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation

not visually significant. They occur much more commonly in children with a dark iris, and when compliance with postoperative medications has been poor. Heparin-surface-modified IOLs have been reported to decrease the incidence of these deposits. The site of IOL implantation can also influence the formation of deposits. Vasavada and Trivedi106 have found that the incidence of deposits was higher in eyes with the IOL optic captured through the PCCC in comparison with the bag fixated IOLs.

Intraocular Lens Decentration Decentration of an IOL can occur because of traumatic zonular loss and/or inadequate capsular support. Capsular bag placement of the IOL is the most successful way to reduce this complication. Posterior capture of the IOL optic also resulted in better centration of the implanted IOL. Incidence of lens malposition in pediatric eyes following PCIOL implantation was reported as high as 40%.31 Asymmetric IOL fixation with one haptic in the capsular bag and the other in the ciliary sulcus can also lead to decentration and should therefore be avoided. Complete IOL dislocation can occur after trauma. Explantation or repositioning of the IOL may be necessary in some cases presenting with significant decentration/dislocation.

Glaucoma Pediatric aphakic/pseudophakic glaucoma remains a challenge. Its etiology, pathogenesis, incidence, onset, diagnosis, and successful treatment often confuse the surgeon. The incidence of glaucoma varies from 3% to 32%.220-225 Although microphthalmic eyes appear to be at the highest risk, cataract surgery before 1 year of age, congenital rubella, and poorly dilated pupils are other important risk factors and should alert the treating ophthalmologist. Glaucoma occurring soon after surgery is usually due to pupillary block or peripheral anterior synechia formation. This form of glaucoma is rare in children. Vajpayee et al.226 reported the development of pseudophakic pupillary block glaucoma in 16 children after PCIOL implantation leading to irreversible visual loss in two of their patients. These authors emphasized the necessity of stringent and frequent follow-up for pseudophakic children. Peripheral iridectomy may prevent pupillary block pseudophakic glaucoma. For this reason, some authors recommend that all children having PCIOLs undergo peripheral iridectomy when there is a rupture of the posterior capsule or zonular dehiscence, which may predispose to vitreous plugging. The majority of pediatric cataract surgeons, however, do not routinely perform peripheral iridectomy at the time of cataract surgery. The most common type of glaucoma to develop after pediatric cataract surgery is open-angle glaucoma. Unlike angle-closure glaucoma, which usually develops soon after surgery, open angle glaucoma is usually seen later, emphasizing the need for a life-long follow-up of these children. The reported mean interval from the time of cataract surgery until the detection of glaucoma ranged from 6 years to as long as 56 years.227 A deep anterior

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chamber, increased pigmentation of the trabecular meshwork, and the iris inserting into the posterior aspect of the trabecular meshwork are generally seen during the gonioscopic examination. Cataract surgery may accelerate the development of glaucoma in certain eyes that are predisposed to develop open angle glaucoma. The diagnosis of glaucoma may be difficult to establish in children after cataract surgery.228 Intraocular pressure should be periodically recorded to detect and treat this vision threatening complication. This may be difficult to measure with the child awake, and view of the optic disk may be compromised by lens remnants, miosis, and nystagmus. Further, it is difficult to assess the visual field until later in childhood. An excessive loss of hyperopia may be the sign of glaucoma in children following cataract surgery as noted by Egbert and Kushner.223 Asrani and Wilensky220 have recommended a screening examination for glaucoma after pediatric cataract surgery every 3 months during the first postoperative year, twice yearly until the 10th year, and annually thereafter. Medical treatment should be tried first to lower the intraocular pressure, but a glaucoma filtering surgery with antimetabolites or a drainage implant is often required to control the intraocular pressure.

Retinal Detachment The incidence of retinal detachment following pediatric cataract surgery has been reported between 1% and 1.5%. The interval from infantile cataract surgery to retinal detachment ranged from 23 years to 34 years according to some authors.229-231 The significant risk factors for occurrence of retinal detachment are high myopia and repeated surgeries. Retinal detachments following infantile cataract surgery are usually secondary to oval or round holes along the posterior vitreous base. These are difficult to repair in children due to poor visualization and retinal degeneration. Most reported cases have a history of multiple reoperations performed in the years prior to the introduction of automated lensectomy and vitrectomy. The incidence appears to be decreasing as surgical techniques advance and evolve.

Cystoid Macular Edema Cystoid macular edema (CME) is a rare complication following pediatric cataract surgery probably due to healthy retinal vasculature.232,233 Because of the difficulty of performing fluorescein angiography during infancy, surgeons seldom evaluate children for this complication. Hoyt and Nickel234 in 1982 reported that the development of CME was common in infantile eyes after lensectomy and anterior vitrectomy, but the appearance of the lesions was atypical and they were not documented photographically. The following year, Gilbard et al.235 reported no CME in 25 eyes after pars plicata removal of congenital cataracts. No subsequent paper has documented clinically significant CME after pediatric cataract surgery even when an anterior vitrectomy is performed.

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation

Hemorrhagic Retinopathy This complication may occur following infantile cataract surgery in up to one-third of eyes as reported by Mets and Del Monte.236 It presents with flameshaped retinal hemorrhages and may be associated with concurrent vitreous hemorrhage.237 The hemorrhages develop during the first 24 hours following surgery, are nonprogressive, and resolve within few weeks.

Residual Refractive Error Uncorrected aphakia after pediatric cataract surgery can cause or worsen amblyopia. When a child is left aphakic, every effort should be made to minimize time intervals when the prescribed aphakic glasses or aphakic contact lenses are not worn. Even short intervals of uncorrected aphakia are potentially very damaging to the prognosis.238-242 When an IOL is implanted, a smaller amount of residual hyperopia may be present. Correction of residual hyperopia and any significant astigmatic error is necessary to optimize visual development and recovery from amblyopia. Some surgeons prefer to correct children to emmetropia with an IOL even at young ages to minimize the amblyogenic effects of residual hyperopia. Since young children’s eyes continue to grow axially after cataract surgery and IOL implantation, significant late myopia will be more and more common as the years pass, especially if emmetropia is achieved early in life with an IOL.242-245 Glasses or contact lenses will be used for correction of secondary myopia in most cases. However, the development of new corneal and intraocular refractive procedures will provide new options for correcting significant late myopia.

Piggy-back Foldable Intraocular Lenses in Infants Polypseudophakia (piggy-back IOLs) has been used as a means to provide appropriate optical correction for patients requiring high IOL power or for secondary correction of an undesirable postoperative refraction after cataract surgery. It has been successfully used in adult patients since it was first reported by Gayton and Sanders, and Gills.246 One of us (MEW) implanted piggy-back AcrySofTM lenses in infantile eyes to manage the changing refractive status of these patients. This procedure, called “temporary polypseudophakia,” may help in the prevention and treatment of amblyopia by avoiding residual hyperopia.247 The posterior lens is implanted in the capsular bag and the anterior lens is placed in the ciliary sulcus. Within 12–24 months after the primary surgical procedure, the lens implanted in the ciliary sulcus is explanted/exchanged. To date, 15 infantile eyes have had this procedure successfully. (Wilson ME. “Pseudophakia and polypseudophakia in first year of life,” Presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery, May 2000, Boston, MA, USA).248 Long-term results would help us to further evaluate this modality of refractive correction after pediatric cataract surgery.

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Management of Amblyopia The postoperative compliant occlusion therapy of the normal eye in cases of unilateral congenital, developmental or traumatic cataract may be needed to reverse or prevent amblyopia in visually immature children.140,249-255 Pharmacological penalization may be useful in children with amblyopia secondary to unilateral aphakia. Wheeler et al.110 found poor compliance of amblyopia therapy in one-third of the children having PCIOLs. A BCVA of 20/40 or better was achieved only in 33% of eyes in their series. Noncompliance of occlusion therapy appears to be a major barrier in achieving satisfactory visual outcome during the treatment of amblyopia.

SUMMARY AND CONCLUSION Pediatric cataracts are common and represent one of the most treatable causes of visual impairment in this population. Management of cataract in children is different from the adult because of increased intraoperative difficulties, propensity of postoperative inflammation, changing refractive state of the eye, difficulty in documenting anatomic and refractive changes due to poor compliance, and a tendency to develop amblyopia. Adoption of different techniques for cataract surgery in children is a must due to a low scleral rigidity, increased elasticity of the anterior capsule, and positive vitreous pressure. Early surgical intervention and adequate visual rehabilitation are necessary to avoid irreversible visual damage secondary to amblyopia. Aphakic glasses are not desirable for the long-term correction of pediatric aphakia because of many disadvantages associated with their use. Although contact lenses offer many advantages over aphakic spectacles, there are problems of infection, lens loss, and low compliance. Current practice for providing full-time correction of pediatric aphakia is shifting toward implantation of IOLs due to refined and perfected microsurgical techniques, as well as the availability of suitable rigid and foldable implant designs. Main postoperative complications noted following pediatric cataract surgery include fibrinous uveitis, pupillary capture, aphakic glaucoma, pigment and cellular deposits on the implants, PCO or secondary membrane formation, and residual refractory error. These side effects may develop after many years. Therefore, it is crucial to follow children closely on a long-term basis after pediatric cataract surgery.

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Gems of Ophthalmology—Cataract Surgery 75. Malukiewicz-Wisniewska G, Kaluzny J, Lesiewska-Junk H, et al. Intraocular lens implantation in children and youth. J Pediatr Ophthalmol Strabismus. 1999;36: 129-33. 76. Markham RHS, Bloom PA, Chandna A, et al. Results of intraocular lens implantation in pediatric aphakia. Eye. 1992;6:493-7. 77. Metge P, Cohen H, Chemila JF. Intercapsular implantation in children. Eur J Cataract Refract Surg. 1990;2:319-23. 78. Pandey SK, Ram J, Jain AK, et al. Visual results and postoperative complications of capsular bag versus sulcus fixation of PCIOL implantation in traumatic cataracts in children. In: Pasricha JK (Ed). Indian Ophthalmology. Year Book, New Delhi, India: Aravali Publishers; 1998. pp. 135-8. 79. Pandey SK, Ram J, Werner L, et al. Visual results and postoperative complications of capsular bag versus ciliary sulcus fixation of posterior chamber intraocular lenses for traumatic cataract in children. J Cataract Refract Surg. 1999;25:1576-84. 80. Pandey SK, Werner L, Escobar-Gomez M, et al. Dye-enhanced cataract surgery. Part I: Anterior capsule staining for capsulorhexis in advanced/white cataracts. J Cataract Refract Surg. 2000;26:1052-9. 81. Pandey SK, Werner L, Escobar-Gomez M, et al. Dye-enhanced cataract surgery. Part III: Staining of the posterior capsule to learn and perform posterior continuous curvilinear capsulorhexis. Part III. J Cataract Refract Surg. 2000;26:1066-71. 82. Parks MM, Johnson DA, Reed GW. Long-term visual results and complications in children with aphakia: a function of cataract type. Ophthalmology. 1993;100: 826-41. 83. Parks MM. Posterior lens capsulectomy during primary cataract surgery in children. Ophthalmology. 1983;90:344-5. 84. Parks MM. Visual results in aphakic children. Am J Ophthalmol. 1982;94:441-9. 85. Pavlovic S, Jacobi FK, Graef M, et al. Silicone intraocular lens implantation in children: preliminary results. J Cataract Refract Surg. 2000;26:88-95. 86. Peterseim MW, Wilson ME. Bilateral intraocular lens implantation in pediatric population. Ophthalmology. 2000;107:1261-6. 87. Rosenbaum AL, Masket S. Intraocular lens implantation in children. Am J Ophthalmol. 1995;120:105-7. 88. Rosenbaum AL, Masket S. Cataract surgery and intraocular lens implantation in children, intraocular lens. Am J Ophthalmol. 1996;121:225-6. 89. Sharma A, Basti S, Gupta S. Secondary capsule-supported intraocular lens implantation in children. J Cataract Refract Surg. 1997;23:675-80. 90. Sharpe MR, Biglan AW, Gerontis CC. Scleral fixation of posterior chamber intraocular lenses in children. Ophthal Surg Lasers. 1996;27:337-41. 91. Simons BD, Siatkowski RM, Schiffman JC, et al. Surgical technique, visual outcome, and complications of pediatric intraocular lens implantation. J Pediatr Ophthalmol Strabismus. 1999;36:118-24. 92. Singh D. Intraocular lenses in children. Ind J Ophthalmol. 1984;32:499-500. 93. Singh D. Intraocular lenses in children. Ind J Ophthalmol. 1987;35:249-50. 94. Sinskey RM, Amin PA, Stoppel J. Intraocular lens implantation in microphthal patients. J Cataract Refract Surg. 1992;18:480-4. 95. Sinskey RM, Karel F, Dal Ri E. Management of cataracts in children. J Cataract Refract Surg. 1989;15:196-200. 96. Sinskey RM, Patel J. Posterior chamber intraocular lens implants in children: report of a series. J Am Intra-Ocular Implant Soc. 1983;9:157-60. 97. Sinskey RM, Stoppel JO, Amin PA. Long-term results of intraocular lens implantation in pediatric patients. J Cataract Refract Surg. 1993;19:405-08.

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation 98. Sinskey RM, Stoppel JO, Amin PA. Ocular axial length changes in a pediatric patient with aphakia and pseudophakia. J Cataract Refract Surg. 1993;19:787-8. 99. Spierer A, Desantik H. Refractive status in children after long-term follow-up of cataract surgery with intraocular lens implantation. J Pediatr Ophthalmol Strabismus. 1999;36:25-9. 100. Swinger CA. Comparison of results obtained with keratophakia, hypermetropic keratomileusis, intraocular lens implantation and extended wear contact lenses. Int Ophthalmol Clin. 1983;23:59-74. 101. Tablante RT, Cruz EDG, Lapus JV, et al. A new technique of congenital cataract surgery with primary posterior chamber intraocular lens implantation. J Cataract Refract Surg. 1988;14:149-57. 102. Thouvenin D, Arne JL, Lesueur L. Comparison of fluorine-surface-modified and unmodified lenses for implantation in pediatric aphakia. J Cataract Refract Surg. 1996;22:1226-31. 103. van der Pol BA, Worst JG. Iris-claw intraocular lenses in children. Doc Ophthalmol. 1996;92:29-35. 104. Vasavada A, Chauhan H. Intraocular lens implantation in infants with congenital cataracts. J Cataract Refract Surg. 1994;20:592-7. 105. Vasavada A, Desai J. Primary posterior capsulorhexis with and without anterior vitrectomy in congenital cataracts. J Cataract Refract Surg. 1997;23(Suppl):647-51. 106. Vasavada A, Trivedi R. Evaluation of optic capture along with anterior vitrectomy in congenital cataracts. J Cataracts Refract Surg. 2000. 107. Vasavada A, Trivedi R. Is vitrectomy necessary along with optic capture in children older than 5 years? J Cataract Refract Surg. 2000;27:1185-93. 108. Vasavada A. Posterior capsule management in congenital cataract surgery. In: Crandall A, Masket S (Eds). Atlas of Cataract Surgery. London: Martin Dunitz; 1999. pp. 281-90. 109. Wagners RS, Nelson LB. Problems in pediatric cataract-intraocular lens implantation. J Pediatr Ophthalmol Strabismus. 1997;34:332. 110. Wheeler DT, Mullaney PB, Awad A, et al. Pediatric IOL implantation. The KKESH experience. J Pediatr Ophthalmol Strabismus. 1997;34:341-6. 111. Wilson ME, Englert JA, Greenwald MJ. In-the-bag secondary intraocular lens implantation in children. J AAPOS. 1999;3:350-5. 112. Wilson ME. Intraocular lens implantation: Has it become the standard of care for children? (Editorial) Ophthalmology. 1996;103:1719-20. 113. Wisniewska GM, Kaluzny J, Junk HL, et al. Intraocular lens implantation in children and youth. J Pediatr Ophthalmol Strabismus. 1999;36:129-33. 114. Zetterstrom C, Kugelberg U, Oscarson C. Cataract surgery in children with capsulorhexis of anterior and posterior capsules and heparin-surface-modifled intraocular lenses. J Cataract Refract Surg. 1994;20:599-601. 115. Zetterstrom C, Lundvall A, Weeber H Jr, et al. Sulcus fixation without capsular support in children. J Cataract Refract Surg. 1999;25:776-81. 116. Zwaan J. Simultaneous surgery for bilateral pediatric cataracts. Ophthal Surg Lasers. 1996;27:15-20. 117. Stager D. Foldable acrylic intraocular lenses in children. In: Paper Presented at the Annual Meeting of the American Academy of Ophthalmology. San Francisco; 1997. 118. Wilson ME, Holland DR. In-the-bag secondary intraocular lens implantation in children. In: Paper Presented at the symposium on Cataract, IOL and Refractive Surgery. San Diego; 1998. 119. Shastri L, Trivedi R, Vasavada AR. AcrySofTM implantation in congenital cataract surgery—an update. In: Paper Presented at the symposium on Cataract, IOL and Refractive Surgery. Boston; 2000.

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Gems of Ophthalmology—Cataract Surgery 120. Buckley E, Lambert SR, Wilson ME. IOLs in the first year of life. J Pediatr Ophthalmol Strabismus. 1999;36:281-6.e 121. Rush DP, Bazarian RA. Intraocular lenses in children. Adv Clinical Ophthalmol. 1994;1:263-74. 122. Oliver M, Milstein A, Pollack A. Posterior chamber lens implantation in infants and juveniles. Eur J Implant Ref Surg. 1990;2:309-14. 123. Dahan E, Drusedau MUH. Choice of lens and dioptric power in pediatric pseudophakia. J Cataract Refract Surg. 1997;23:618-23. 124. Gordon RA, Donzis PB. Refractive development of the human eye. Arch Ophthalmol. 1985;103:785-9. 125. McClatchey SK, Dahan E, Maselli E, et al. A comparison of the rate of refractive growth in pediatric aphakic and pseudophakic eyes. Ophthalmology. 2000;107:118-22. 126. McClatchey SK, Parks MM. Myopic shift after cataract removal in childhood. J Pediatr Ophthalmol Strabismus. 1997;34:88-95. 127. McClatchey SK, Parks MM. Theoretic refractive changes after lens implantation in childhood. Ophthalmology. 1997;104:1744-51. 128. Plager DA, Lipsky SN, Snyder SK, et al. Capsular management and refractive error in pediatric intraocular lenses. Ophthalmology. 1997;104:600-7. 129. Wilson ME. Clinician’s Corner in Ruttum MS. Childhood cataracts. American Academy of Ophthalmology, Focal Points, Clinical Modules for Ophthalmologists. 1996;14(1):10. 130. Awner S, Buckley EG, DeVaro JM, et al. Unilateral pseudophakia in children under 4 years. J Pediatr Ophthalmol Strabismus. 1996;33:230-6. 131. Andreo LK, Wilson ME, Saunders RA. Predictive value of regression and theoretical IOL formulas in pediatric intraocular lens implantation. J Pediatr Ophthalmol Strabismus. 1997;34:240-3. 132. Bluestein EC, Wilson ME, Wang XH, et al. Dimensions of the pediatric crystalline lens: implications for intraocular lenses in children. J Pediatr Ophthalmol Strabismus. 1996;33:18-20. 133. Ram J, Pandey SK, Hutchinson A, et al. Infantile cataract surgery: How important is IOL sizing? In: Video Presented at the ASCRS Symposium of Cataract, IOL and Refractive Surgery. Seattle; 1999. 134. Apple DJ, Lim ES, Morgan RC, et al. Preparation and study of human eyes obtained postmortem with the Miyake posterior photographic technique. Ophthalmology. 1990;97:810-6. 135. Miyake K, Miyake C. Intraoperative posterior chamber lens haptic fixation in the human cadaver eye. Ophtal Surg. 1985;16:230-6. 136. Wilson ME, Apple DJ, Bluestein EC, et al. Intraocular lenses for pediatric implantation: biomaterials, designs and sizing. J Cataract Refract Surg. 1994;20:584-91. 137. Gerding H. Does the refractive shift in pseudophakic eyes of children develop slower than expected? Invest Ophthalmol Vis Sci. 1996;37:1935-6. 138. Griener ED, Dahan E, Lambert SR. Effect of age at time of cataract surgery on subsequent axial length growth in infant eyes: 3 Cataract Refract Surg. 1999;25:1209-13. 139. Lambert SR, Fernandes A, Drewa-Botsch C, et al. Pseudophakia retards axial elongation in neonatal monkeys. Invest Ophthalmol Vis Sci. 1996;37:451-8. 140. Lambert SR, Fernandas A, Grossniklaus H, et al. Neonatal lensectomy and intraocular lens implantation: effects in rhesus monkeys. Invest Ophthalmol Vis Sci. 1995;36:300-10.

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation 141. Lambert SR, Grossniklaus HE. Intraocular lens implantation in monkeys: clinical and histopathological finding. J Cataract Refract Surg. 1997;23:605-11. 142. Lorenz B, Worle J, Friedl N, et al. Ocular growth in infant aphakia. Bilateral versus unilateral congenital cataracts. Ophthal Paediatr Genet. 1993;14:177-88. 143. Rasooly R, BenEzra D. Congenital and traumatic cataract. The effect on ocular axial length. Arch Ophthalmol. 1988;106:1066-8. 144. Weisel TN, Raviola E. Myopia and eye enlargement after neonatal lid fusion in monkeys. Nature. 1977;266:66-8. 145. Wilson JR, Fernandes A, Chandler CV, et al. Abnormal development of the axial length of aphakic monkey eyes. Invest Ophthalmol Vis Sci. 1987;28:2096-9. 146. Kugelberg U, Zetterström C, Lundgren B, et al. After-cataract and ocular growth in newborn rabbit eyes implanted with a capsule tension ring. J Cataract Refract Surg. 1997;23:635-40. 147. Kugelberg U, Zetterström C, Lundgren B, et al. Eye growth in aphakic newborn rabbit. J Cataract Refract Surg. 1996;22:337-41. 148. Kugelberg U, Zetterström C, Lundgren B, et al. Ocular growth in newborn rabbit eyes implanted with a poly methyl methacrylate or silicone intraocular lens. J Cataract Refract Surg. 1997;23:629-34. 149. Kugelberg U, Zetterström C, Syren-Nordqvist S. Ocular axial length in children with unilateral congenital cataract. Acta Ophthalmol Scand. 1996;74:220-3. 150. Lambert SR, Buckley EG, Plager DA, et al. Unilateral intraocular lens implantation during the first six months of life. J AAPOS. 1999;3:344-9. 151. Hiles DA, Hered RW. Modern intraocular lens implants in children with new age limitations. J Cataract Refract Surg. 1987;13:493-7. 152. Hiles DA, Wallar PH. Visual results following infantile cataract surgery. Int Ophthalmol Clin. 1977;17:265-82. 153. Wilson ME, Pandey SK, Werner L, et al. Pediatric cataract surgery: current techniques, complication and management. In: Agarwal A, Agarwal S, Apple DJ, Burato L, Agarwal A (Eds). Textbook of Ophthalmology. NJ, Thorofare: Slack Inc; 2000. pp. 370-8. 154. Scheie HG. Aspiration of congenital or soft cataracts: a new technique. Am J Ophthalmol. 1960;50:1048-56. 155. Ridley H. Artificial intraocular lenses after cataract extraction. St. Thomas’ Hospital Reports 7 (Series). 1952. pp. 12-4. 156. Choyce DP. Correction of uniocular aphakia by means of anterior chamber acrylic implants. Trans Ophthalmol Soc UK. 1958;78:459-70. 157. Binkhorst CD, Gobin MH, Leonard PA. Post-traumatic artificial lens implants (pseudophakoi) in children. Br J Ophthalmol. 1969;53:518-29. 158. Binkhorst CD, Gobin MH, Leonard PA. Post-traumatic pseudophakia in children. Ophthalmol. 1969;158(Suppl):284-91. 159. Binkhorst CD, Gobin MH. Injuries to the eye with lens opacity in young children. Ophthalmol. 1964;148:169-83. 160. Binkhorst CD, Greaves B, Kats A, et al. Lens injury in children treated with iridocapsular supported intra-ocular lenses. J Am Intraocular Implant Soc. 1978;4: 34-49. 161. Binkhorst CD, Greaves B, Kats A, et al. Lens injury in children treated with iridocapsular supported intra-ocular lenses. Doc Ophthalmol. 1979;46:241-77. 162. Binkhorst CD. Iris-clip and irido-capsular implants (pseudophakoi); personal techniques of pseudophakia. Br J Ophthalmol. 1967;51:767-1. 163. BenEzra D. Cataract surgery and intraocular lens implantation in children. Am J Ophthalmol. 1996;121:224-6.

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Gems of Ophthalmology—Cataract Surgery 164. BenEzra D, Cohen E, Rose L. Traumatic cataract in children: correction of aphakia by contact lens or intraocular lens. Am J Ophthalmol. 1997;123:773-82. 165. BenEzra D, Cohen E. Cataract surgery in children with chronic uveitis. Ophthalmology. 2000;107:1255-60. 166. BenEzra D, Cohen E. Posterior capsulectomy in pediatric cataract surgery: the necessity of a choice. Ophthalmology. 1997;104:2168-74. 167. BenEzra D, Paez JH. Congenital cataract and intraocular lenses. Am J Ophthalmol. 1983;96:311-4. 168. Gimbel HV, Sun R, DeBrouff BM. Recognition and management of internal wound gape. J Cataract Refract Surg. 1995;21:121-4. 169. Basti S, Krishnamachary M, Gupta S. Results of sutureless wound construction in children undergoing cataract extraction. J Pediatr Ophthalmol Strabismus. 1996;33:52-4. 170. Trivedi R, Vasavada AR, Apple DJ, et al. Healon 5: helping hand to congenital cataract surgeon? In: Video Presented at the ASCRS Symposium of Cataract, IOL and Refractive Surgery. San Diego; 2001. 171. Englert JA, Wilson ME. Postoperative intraocular pressure elevation after the use of Healon GV in pediatric cataract surgery. J AAPOS. 2000;4:60-1. 172. Gimbel HV, Neuhann T. Development, advantages, methods of the continuous circular capsulorhexis technique. J Cataract Refract Surg. 1990;16:31-7. 173. Auffarth GU, Wesendahl TA, Newland TJ, et al. Capsulorhexis in the rabbit eye as a model for pediatric capsulectomy. J Cataract Refract Surg. 1994;20:188-91. 174. Anwar M, Bleik JH, von Noorden GK, et al. Posterior chamber lens implantation for primary repair of corneal lacerations and traumatic cataracts in children. J Pediatr Ophthalmol Strabismus. 1994;31:157-61. 175. Krag S, Thim K, Corybon L, et al. Biomechanical aspects of the anterior capsulotomy. J Cataract Refract Surg. 1994;20:410-6. 176. Wilson ME, Bluestein EC, Wang XH, et al. Comparison of mechanized anterior capsulectomy and manual continuous capsulorhexis in pediatric eyes. J Cataract Refract Surg. 1994;20:602-6. 177. Wilson ME. Anterior capsule management for pediatric intraocular lens implantation. J Pediatr Ophthalmol Strabismus. 1999;36:1-6. 178. Wilson ME, Saunders RA, Robert EL, et al. Mechanized anterior capsulectomy as an alternative to manual capsulorhexis in children undergoing intraocular lens implantation. J Pediatr Ophthalmol Strabismus. 1996;33:237-40. 179. Kloti R. Anterior high frequency capsulotomy. Part I: experimental study. Klin Monatsbl Augenheilkd. 1992;200:507-10. 180. Comer RM, Abdulla N, O’Keefe M. Radiofrequency diathermy capsulorhexis of the anterior and posterior capsules in pediatric cataract surgery: preliminary results. J Cataract Refract Surg. 1997;23(Suppl 1):641-4. 181. Fugo RJ, Coccio D, McGrann D, et al. The Fugo Blade…the next step after capsulorhexis. In: Presented at the American Society of Cataract and Refractive Surgery Symposium on Cataract, IOL and Refractive Surgery, Congress on Ophthalmic Practice Management. Boston; 2001. 182. Trivedi R, Vasavada AR, Apple DJ, et al. Cortical cleaving hydrodissection in congenital cataract surgery. In: Presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery. San Diego; 2001. 183. Faust KJ. Hydrodissection of soft nuclei. J Am Intraocular Implant Soc. 1984;10:75-7. 184. Mackool RJ. Management of posterior capsule during intraocular lens implantation. Am J Ophthalmol. 1994;117:121-3.

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation 185. Gimbel HV, DeBroff DM. Posterior capsulorhexis with optic capture: maintaining a clear visual axis after pediatric cataract surgery. J Cataract Refract Surg. 1994;20:658-64. 186. Gimbel HV. Posterior capsulorhexis with optic capture in pediatric cataract and intraocular lens surgery. Ophthalmology. 1996;103:1871-5. 187. Fenton S, O’Keefe M. Primary posterior capsulorhexis without anterior vitrectomy in pediatric cataract. J Cataract Refract Surg. 1999;25:763-7. 188. Basti S, Ravishankar V, Gupta S. Results of a prospective evaluation of three methods of management of pediatric cataracts. Ophthalmology. 1996;103:713-20. 189. Wang XH, Wilson ME, Bluestein EC, et al. Pediatric cataract surgery and IOL implantation techniques. a laboratory study. J Cataract Refract Surg. 1994;20:607-9. 190. Atkinson CS, Hiles DA. Treatment of secondary posterior capsular membrane Nd:YAG laser in a pediatric population. Am J Ophthalmol. 1994;118:496-501. 191. Werner L, Pandey SK, Escobar-Gomez M, et al. Dye-enhanced cataract surgery. Part II: An experimental study to learn and perform critical steps of phacoemulsification in human eyes obtained postmortem. J Cataract Refract Surg. 2000;26:1060-5. 192. Pandey SK, Werner L, Apple DJ, et al. Anterior capsule staining in advanced cataracts: a laboratory study using postmortem human eyes. In: Pandey SK, Werner L, Apple DJ (Eds). Presented at the Annual Meeting of the American Academy of Ophthalmology. Orlando; 1999. 193. Pandey SK, Werner L, Apple DJ, et al. Dye-enhanced cataract surgery in human eyes obtained post-mortem: a laboratory study to learn and perform critical steps of phacoemulsification. In: Video Presented at the ESCRS Symposium on Cataract, IOL and Refractive Surgery. Vienna; 1999. 194. Churchill AJ, Noble BA, Etchells DE, et al. Factors affecting visual outcome in children following uniocular traumatic cataract. Eye. 1995;9:285-91. 195. Eckstein M, Vijayalakshmi P, Killedar M, et al. Aetiology of childhood cataract in south India. Br J Ophthalmol. 1996;80:628-32. 196. Krishnamachary M, Rathi V, Gupta S. Management of traumatic cataract in children. J Cataract Refract Surg. 1997;23:681-7. 197. Hemo Y, BenEzra D. Traumatic cataracts in young children: correction of aphakia by intraocular lens implantation. Ophthal Paediatr Genet. 1987;8:203-7. 198. Jain IS, Mohan K, Gupta A. Unilateral traumatic aphakia in children: role of corneal contact lenses. J Pediatr Ophthalmol Strabismus. 1985;224:137-9. 199. Bienfait MF, Pameijer JH, Wildervanck de Blecourt-Devilee M. Intraocular lens implantation in children with unilateral traumatic cataract. Int Ophthalmol. 1990;14:271-6. 200. Hiles DA, Wallar PH, Biglan AW. The surgery and results following traumatic cataracts in children. J Pediatr Ophthalmol. 1976;13:319-25. 201. Jain IS, Bansal SL, Dhir SP, et al. Prognosis in traumatic cataract surgery. J Pediatr Ophthalmol Strabismus. 1979;16:301-5. 202. Pandey SK, Wilson ME, Trivedi RH, et al. Pediatric cataract surgery and intraocular lens implantation: current techniques, complications and management. Int Ophthalmol Clin. 2001;41:175-96. 203. Sharma N, Pushker N, Dada T, et al. Complications of pediatric cataract surgery and intraocular lens implantation. J Cataract Refract Surg. 1999;25:1585-8. 204. Pandey SK, Ram J, Werner L, et al. Intraocular lens implantation in pediatric cataracts. In: Presented at the symposium on Cataract, IOL and Refractive Surgery. Boston; 2000.

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Gems of Ophthalmology—Cataract Surgery 205. Ram J, Pandey SK, Jain AK, Gupta A. Visual results and postoperative complications of PC IOL implantation in children. In: Pasricha JK (Ed). Indian Ophthalmology. Year Book, New Delhi, India: Aravali Publishers; 1998. pp. 132-4. 206. Mullaney PB, Wheeler DT, al-Nahdi T. Dissolution of pseudophakic fibrinous exudate with intraocular streptokinase. Eye. 1996;10:362-6. 207. Klais CM, Hattenbach LO, Steinkamp GW, et al. Intraocular recombinant tissueplasminogen activator fibrinolysis of fibrin formation after cataract surgery in children. J Cataract Refract Surg. 1999;25:357-62. 208. Leung TSA, Lam DSC, Rao SK. Fibrinolysis of postcataract fibrin membranes in children. J Cataract Refract Surg. 2000;26:4-5. 209. Rozenman Y, Folberg R, Nelson LB, et al. Painful bullous keratopathy following pediatric cataract surgery with intraocular lens implantation. Ophthal Surg. 1985;16:372-4. 210. Hiles DA, Biglan AW, Fetherolf EC. Central corneal endothelial cell counts in children. J Am Intra-Ocular Implant Soc. 1979;5:292-300. 211. Wheeler DT, Stagger DR, Weakley DR, Jr. Endophthalmitis following pediatric intraocular surgery for congenital cataracts and congenital glaucoma. J Pediatr Ophthalmol Strabismus. 1992;29:139-41. 212. Good WV, Hing S, Irvine AR, et al. Postoperative endophthalmitis in children following cataract surgery. J Pediatr Ophthalmol Strabismus. 1990;27:283-5. 213. Jameson NA, Good WV, Hoyt CS. Inflammation after cataract surgery in children. Ophthal Surg. 1992;23:99-102. 214. Werner L, Pandey SK, Escobar-Gomez M, et al. Anterior capsule opacification: a histopathological study comparing different IOL styles. Ophthalmology. 2000;107:463-71. 215. Apple DJ, Solomon KD, Tetz MR, et al. Posterior capsule opacification. Surv Ophthalmol. 1992;37:73-116. 216. Kugelberg U. Visual acuity following treatment of bilateral congenital cataracts. Doc Ophthalmol. 1992;82:211-5. 217. Morgan KS, Karcioglu ZA. Secondary cataracts in infants after lensectomies. J Pediatr Ophthalmol Strabismus. 1987;24:45-8. 218. Zetterström C, Kugelberg. Bilateral blinding uveitis in a child after secondary U, Lundgren B, Syren-Nordqvist S. After cataract formation in the newborn rabbits implanted with intraocular lenses. J Cataract Refract Surg. 1996;22:85-8. 219. Menezo JL, Taboada JF, Ferrer E. Managing dense retro-pseudosphakos membranes with a pars plana vitrectomy. J Am Intra-Ocular Implant Soc. 1985;11:24-7. 220. Asrani SG, Wilensky JT. Glaucoma after congenital cataract surgery. Ophthalmology. 1995;102:863-7. 221. Brady KM, Atkinson CS, Kilty LA, et al. Glaucoma after cataract extraction and posterior chamber lens implantation in children. J Cataract Refract Surg. 1997;23(Suppl):669-74. 222. Chrousos GA, Parks MM, O’Neill JF. Incidence of chronic glaucoma, retinal detachment and secondary membrane surgery in pediatric aphakic patients. Ophthalmology. 1984;91:1238-41. 223. Egbert JE, Kushner BJ. Excessive lodd of hyperopia: presenting sign of juvenile aphakic glaucoma. Arch Ophthalmol. 1990;108:1257-9. 224. Simon JW, Metge P, Simmons ST, et al. Glaucoma after pediatric lensectomy/ vitrectomy. Ophthalmology. 1991;98:670-4. 225. Walton DS. Pediatric aphakic glaucoma: a study of 65 patient. Trans Am Ophthalmol Soc. 1995;93:403-20.

Principles and Paradigms of Pediatric Cataract Surgery and Intraocular Lens Implantation 226. Vajpayee RB, Angra SK, Titiyal JS, et al. Pseudophakic pupillary block glaucoma in children. Am J Ophthalmol. 1991;11:715-8. 227. Phelps CD, Arafat NI. Open-angle glaucoma following surgery for congenital cataracts. Arch Ophthalmol. 1977;95:1985-7. 228. Wallace DK, Plager DA. Corneal diameter in childhood aphakic glaucoma. J Pediatr Ophthalmol Strabismus. 1996;33:230-4. 229. Jagger JD, Cooling RJ, Fison LG, et al. Management of retinal detachment following congenital cataract surgery. Trans Ophthalmol Soc UK. 1983;103:103-7. 230. Kanski JJ, Elkington AR, Daniel R. Retinal detachment after congenital cataract surgery. Br J Ophthalmol. 1974;58:92-5. 231. Toyofuku H, Hirose T, Schepens CL. Retinal detachment following congenital cataract surgery. Arch Ophthalmol. 1980;98:669-75. 232. Morgan KS, Franklin RM. Oral fluorescein angioscopy in aphakic children. J Pediatr Ophthalmol Strabismus. 1984;21:33-6. 233. Pinchoff BS, Ellis FD, Helveston EM, et al. Cystoid macular edema in pediatric aphakia. J Pediatr Ophthalmol Strabismus. 1988;25:240-3. 234. Hoyt CS, Nickel B. Aphakic cystoid macular edema: occurrence in infants and children after transpupillary lensectomy and anterior vitrectomy. Arch Ophthalmol. 1982;100:746-9. 235. Gilbard SM, Peyman GA, Goldberg MF. Evaluation for cystoid maculopathy after pars plicata lensectomy-vitrectomy for congenital cataracts. Ophthalmology. 1983;90:1201-6. 236. Mets MB, Del Monte M. Hemorrhagic retinopathy following uncomplicated pediatric cataract extraction. Arch Ophthalmol. 1986;104:975-9. 237. Christiansen SP, Munoz M, Capo H. Retinal hemorrhage following lensectomy and anterior vitrectomy in children. J Pediatr Ophthalmol Strabismus. 1993;30:24-7. 238. Birch EE, Stager DR. Prevalence of good visual acuity following surgery for congenital unilateral cataract. Arch Ophthalmol. 1988;106:40-2. 239. Birch EE, Stager DR. The critical period for surgical treatment of dense, congenital, unilateral cataracts. Invest Ophthalmol Vis Sci. 1996;37:1532-8. 240. Birch EE, Swanson WH, Stager DR, et al. Outcome after very early treatment of dense congenital unilateral cataract. Invest Ophthalmol Vis Sci. 1993;34:3687-99. 241. Bradford GM, Keech RV, Scott WE. Factors affecting visual outcome after surgery for bilateral congenital cataracts. Am J Ophthalmol. 1994;117:58-64. 242. Catalano RA, Simon JW, Jenkins PL, et al. Preferential looking as a guide for amblyopia therapy in monocular infantile cataracts. J Pediatr Ophthalmol Strabismus. 1987;24:56-63. 243. Enyedi LB, Peterseim MW, Freedman SF, et al. Refractive changes after pediatric intraocular lens implantation. Am J Ophthalmol. 1998;126:772-81. 244. Huber C. Increasing myopia in children with intraocular lenses. An experiment in form deprivation myopia? Eur J Implant Ref Surg. 1993;5:154-8. 245. Hutchinson AK, Drews-Botsch C, Lambert SR. Myopic shift after intraocular lens implantation during childhood. Ophthalmology. 1997;104:1752-7. 246. Gayton JL, Apple DJ, Peng Q, et al. Interlenticular opacification: a clinicopathological correlation of a new complication of piggyback posterior chamber intraocular lenses. J Cataract Refract Surg. 2000;20:330-6. 247. Wilson ME, Peterseim MW, Englert JA, et al. Pseudophakia and polypseudophakia in the first year of life. J Am Ass Pediatr Ophthalmol Strabismus. 2001;5:238-45. 248. Wilson ME. Pseudophakia and polypseudophakia in first year of life. In: Presented at the ASCRS Symposium on Cataract, IOL and Refractive Surgery. Boston; 2000.

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Gems of Ophthalmology—Cataract Surgery 249. Gregg FM, Parks MM. Stereopsis after congenital monocular cataract extraction. Am J Ophthalmol. 1992;114:314-7. 250. Keech RV, Mutschke PJ. Upper age limit for the development of amblyopia. J Pediatr Ophthalmol Strabismus. 1995;32:89-95. 251. Lloyd IC, Dowler JG, Kriss A, et al. Modulation of amblyopia therapy following early surgery for unilateral congenital cataracts. Br J Ophthalmol. 1995;79:802-6. 252. Taylor D. Monocular infantile cataract, intraocular lenses and amblyopia (Editorial). Br J Ophthalmol. 1989;73:857-8. 253. Taylor D. The Doyne lecture congenital cataract: the history, the nature, and the practice. Eye. 1998;12:9-36. 254. Tytla ME, Lewis TL, Maurer D, et al. Stereopsis after congenital cataract:Invest Ophthalmol Vis Sci. 1993;34:1767-3. 255. Verma A, Singh D. Active vision therapy for pseudophakic amblyopia. J Cataract Refract Surg. 1997;23:1089-94.

CHAPTER

4

Capsular Dye-enhanced Cataract Surgery Suresh K Pandey, Liliana Werner, David J Apple

INTRODUCTION Various nontoxic ophthalmic dyes have been extensively used as diagnostic agents for the detection and management of different ocular disorders. Table 4.1 summarizes the use of various dyes in ophthalmology. Dyes such as fluorescein sodium and indocyanine green (ICG) have a long history of safety TABLE 4.1: Use of dyes in ophthalmology. Segment

Structure stained

Use

Dye

Cornea

Epithelial defects

FS

Contact lens fitting

FS

Seidel’s test

FS

Dry eye

FS, RB

Diagnosis of keratitis

FS, RB

Endothelial cell count

TB

Iris

Neovascularization

FS, ICG

Lens

Capsulorhexis (poor or no red reflex)

FS, ICG, TB

Dye-enhanced cataract surgery

ICG, TB

Retina

Angiography

FS, ICG

Vitreous

Vitrectomy

FS, ICG

Vitreoretinal surgery

IRM peeling

ICG

Anterior

Posterior

(FS: Fluorescein sodium; RB: Rose bengal; TB: Trypan blue; ICG: Indocyanine green; IRM: Internal limiting membrane)

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in humans.1 There have been an increasing number of reports for staining of the intraocular tissues for enhancing visualization during cataract surgery and vitreoretinal surgery.2-19 Staining of the ocular tissue by using the ophthalmic dyes makes the differentiation and manipulation of tissues easier. Enhanced viewing of the ocular tissues can promote a surgeon’s ability to evaluate clinical structural relationships and may help attain surgical objectives with fewer complications.2-19 Small incision cataract surgery using phacoemulsification (PE) has currently evolved into one of the most successful surgical techniques in ophthalmology. Many modifications such as continuous curvilinear capsulorhexis (CCC),20,21 hydrodissection,22-25 hydrodelineation,26 and various maneuvers for nuclear emulsification and cortical cleanup have been added to it, increasing its safety and efficacy. Posterior capsulorhexis, a technically challenging procedure, has been recommended for delaying opacification of posterior capsule in pediatric cataracts for managing the posterior capsule tears.27-31 We have extensively studied the use of nontoxic capsular dyes (fluorescein sodium, ICG, and trypan blue) to enhance visualization of the intraocular tissues while performing various critical steps of modern PE procedure.7-9,12-14,32,33 In this chapter, we address the use of nontoxic capsular dyes to successfully stain the intraocular tissues during the various steps of modern PE procedure. For convenience of readers, we have divided this chapter into three sections: Section 1 discusses the use of capsular dyes to stain the anterior capsule for performing CCC in advanced/white cataracts. Section 2 focuses on the use of capsular dyes to help enhance visualization to learn the critical steps of PE surgery which include: CCC, hydrodissection/ hydrodelineation, nuclear emulsification, and cortical cleanup. Section 3 addresses the use of capsular dyes for posterior capsule staining to learn and perform the technically challenging procedure of posterior capsulorhexis.

DYE-ENHANCED ANTERIOR CAPSULORHEXIS Cataract surgeons agree that an anterior CCC should be the goal of every opening of the anterior capsule. CCC has gained widespread popularity because it offers unquestionable advantages over other capsulotomy techniques.20,21 On account of complications such as intraocular lens (IOL) asymmetrical fixation, decentration, or pea podding of the IOL haptics associated with the envelope or the can-opener capsulotomy techniques, CCC is preferred in planned extracapsular cataract extraction.20,21,34

Capsulorhexis in Absence of Red Reflex In clinical practice, white, mature, and hypermature cataracts are commonly seen, especially in the developing world (Figs. 4.1A to C).35 It is difficult to perform a CCC in the presence of mature cataracts because the red reflex,

Capsular Dye-enhanced Cataract Surgery

which is necessary to observe the actual tearing process, is absent. With poor visibility, errant capsular tearing is very common and difficult to control, thus jeopardizing in-the-bag IOL implantation. The accepted recommendations to aid CCC in such cases are: dimming the operating room lights, increasing the operating microscope magnification and coaxial illumination, and using highdensity viscoelastic. The sue of air,36 diathermy,37 endoilluminator,2 vitrectome, scissors,38 and the two-stage CCC approach35,39 have also been suggested.

A

B

Figs. 4.1A and B

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Fig. 4.1C Figs. 4.1A to C: Slit-lamp photographs taken from three different patients showing examples of advanced white cataracts. (Courtesy: Abhay R. Vasavada, Ahmedabad, India).

Capsular Dyes for Anterior Capsulorhexis Capsular dyes such as 2% fluorescein sodium, 0.5% ICG,5,7,10 and 0.1% trypan blue6,7,11,15 have been successfully used for staining the anterior capsule, for performing CCC. Two main surgical techniques have been used for fluorescein sodium viz., (1) staining from above, under an air bubble, and (2) intracameral subcapsular injection.3,4 The use of 0.01% and 0.001% gentian violet solution and 0.25–0.05% crystal violet solution has recently been reported for staining the anterior capsule in animal models (albino rats and rabbits).16,17 Gentian violet and crystal violet dyes are not preferred in human eyes due to corneal adverse effects and possible endothelial cell toxicity.

Study Comparing Three Capsular Dyes and Two Surgical Techniques We have evaluated in an experimental closed-system surgery anterior capsule staining for performing CCC in postmortem human eyes with advanced/white cataracts, using three dyes. These are fluorescein sodium, ICG, and trypan blue that have been clinically advocated for use with this procedure.7 We also compared the two commonly used methods: (1) staining under an air bubble and (2) intracameral subcapsular injection.40

Preparation of the Capsular Dyes A 2% fluorescein sodium solution was prepared by mixing 1 mL of 10% fluorescein for intravenous use (Alcon Ophthalmic, Fort Worth, TX, United

Capsular Dye-enhanced Cataract Surgery

States) with 4 mL of balanced salt solution (BSS®). The ICG solution (Akorn, Inc., Buffalo Grove, IL, United States) was prepared by dissolving 25 mg of ICG in 0.5 mL of an aqueous solvent (provided with the ICG), which was mixed in 4.5 mL of an irrigating solution (BSS puls®, Alcon Ophthalmic, Fort Worth, TX, United States).5 To obtain 0.1% trypan blue, we mixed 1 mL of a 0.4% solution (Life Technologies, Grand Island, NY, United States) in 3 mL of BSS®.

Surgical Technique Randomly accessioned postmortem human eyes (n = 12) received within 4 days of death in the Center for Research on Ocular Therapeutics and Biodevices from eye banks nationwide were used in this study. Eyes presenting advanced/ white cataracts were used (Figs. 4.2A and B). They were immersed in dextran solution for 30 minutes and prepared according to the technique of Auffarth et al.41 After the eye was fixed in the training head, a self-sealing corneoscleral tunnel incision approximately 3.2 mm wide was made. The iris was pulled out from its attachment to allow better visualization of the anterior capsule. Two different techniques were used for the capsular staining. Initially in six globes, air was injected carefully using a 27-gauge cannula and a 2.0 cc syringe. Then, the dye was injected over the anterior capsule (0.10 mL) within the air bubble (2 globes/dye). After a few seconds, the air bubble was replaced with sodium hyaluronate (Healon®, Pharmacia Inc., Peapack, NJ, United States) and CCC was performed (Figs. 4.3A to E). Alternatively, in the other six globes, we used the technique of intracameral subcapsular injection (Figs. 4.4A to D and Figs. 4.5A and B). After the aqueous was replaced with Healon®, we carefully injected 0.05–0.10 mL of the dye beneath the anterior capsule (2 globes/dye) using a 30-gauge needle. A small leakage of dye from the subcapsular space was observed during this step. After the stained viscoelastic was replaced by clear Healon®, the point of injection was used for beginning the CCC with Utrata forceps. Blue light enhancement was used during CCC for fluorescein sodium. To compare the two techniques and the three dyes, the following two parameters were evaluated by two independent surgeons [Suresh K Pandey (SKP) and Lilian Werner (LW)]: (1) ability to perform the staining technique (+ = difficult; ++ = intermediate; +++ = easy) and (2) staining of the anterior capsule (+ = faint; ++ = intermediate; +++ = good). Photographs were taken using a Topcon camera fitted to the operating microscope with and without a blue filter. The Miyake-Apple posterior video/photographic technique42,43 was also used in another three globes to document any dye leakage into the vitreous cavity (1 globe/dye).

Results The results of our study about the evaluation of the two techniques of staining (under an air bubble and intracameral subcapsular injection) and the three dyes (fluorescein sodium, ICG, and trypan blue) used by two independent surgeons are shown in Table 4.2. In all globes, CCC was completed uneventfully.

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A

B

Figs. 4.2A and B: Gross photographs of human eyes obtained postmortem showing the presence of white cataract: (A) Anterior (surgeon’s) view; (B) Miyake-Apple posterior view.

The intracameral subcapsular injection provided a slightly better staining of the anterior capsule. The dye remained trapped in the subcapsular space after the injection, in contact with the posterior surface of the anterior capsule, allowing enough time to perform any maneuver. The staining provided by

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ICG, with the concentration used, was found to be slightly superior than the other two dyes. It was particularly easier to localize the ICG-stained posterior surface of the inverse anterior capsular flap while performing CCC, after the subcapsular injection (Figs. 4.4C and D). The Miyake-Apple posterior video/ photographic technique demonstrated a leakage of fluorescein sodium into the vitreous after using both methods of dye administration. The intensity of this leakage increased progressively with time. Figures 4.6A to C illustrate the

A

B

Figs. 4.3A and B

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C

D

Figs. 4.3C and D

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Fig. 4.3E Figs. 4.3A to E: Anterior (surgeon’s) view of a human eye obtained postmortem with advanced white cataracts showing the staining of the anterior capsule under an air bubble using fluorescein sodium, ICG and trypan blue. (A) Fluorescein sodium; (B) ICG; (C) Trypan blue; (D) Visualization of the anterior capsule is enhanced after staining with ICG; (E) Visualization of the anterior capsule is enhanced after staining with trypan blue.

progressive leakage of the fluorescein sodium into the vitreous cavity after intracameral subcapsular injection. No vitreous leakage was observed with ICG or trypan blue after using any of the two aforementioned techniques of anterior capsular staining. The advantages and disadvantages associated with the dyes and the techniques of staining used are summarized in Tables 4.3 and 4.4, respectively.

Clinical Application and Guidelines for Surgeons Staining of the anterior capsule with capsular dyes is a useful alternative for performing CCC in cases of advanced/white cataract. Fluorescein sodium was the first dye advocated for this use.2-4 ICG and trypan blue were further recommended for this purpose.5-7,10,11,15,18 ICG and trypan blue selectively stain dead corneal endothelial cells. Because the endothelial cells are alive in human cataract surgery, ICG and trypan blue neither stain them nor obstruct the surgeon’s view. Because of its smaller molecular weight (376 d), fluorescein sodium can stain the cornea and also migrate to the vitreous cavity. In the study of Horiguchi et al.,5 fluorescein sodium could not be removed from the vitreous cavity by an irrigation-aspiration system. The reconstituted ICG dye is only good for 10 hours; because the bottle of ICG is expensive (approximately US $ 90.00 for 25 mg ICG), it is better to group several cases, where no red reflex is

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present, on the same day. Intraocular solutions of trypan blue is not yet FDAapproved and, therefore, currently not available in the United States. Trypan blue 0.1% solution ready to be used for capsular staining is commercialized by DORC International BV (VN Zuidland, Holland) under the name of Vision Blue®. Recently 0.1% solution of trypan blue dye has been commercialized by Dr Agarwal’s Pharma Ltd. (Chennai, India) under the name of Blurhex®. Trypan blue is less expensive than ICG. The cost of 1 mL ampoule of trypan

A

B

Figs. 4.4A and B

Capsular Dye-enhanced Cataract Surgery

C

D

Figs. 4.4C and D Figs. 4.4A to D: Anterior (surgeon’s) view of a human eye obtained postmortem with white cataract showing the staining of the anterior capsule using intracameral subcapsular injection of ICG. Cornea and iris were excised to allow better visualization of the anterior capsule. (A) Note the entrapment of the dye into the subcapsular space (arrows); (B) The capsulorhexis can be initiated by grasping the injection hole; (C and D) The visualization of the anterior capsule is enhanced by the staining of its posterior surface with the dye.

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A

B

Figs. 4.5A and B: Anterior (surgeon’s) view of a human eye obtained postmortem showing the better contrast against the white cataract provided by the staining of the posterior surface of the anterior capsule with trypan blue.

blue (Blurhex®) is approximately US $3 when compared to the US $90 cost of 1 ampoule of 25 mg ICG powder.18 The surgeon should avoid using the trypan blue dye in fertile women, pregnant women, or children. In some animal studies, this dye, given intravenously or intraperitoneally at much higher concentrations, induced

Capsular Dye-enhanced Cataract Surgery

neoplasms.6 The surgeon should also be careful when using any capsular dyes in cataract surgery combined with the implantation of hydrophilic acrylic lenses with high water content (73.5%), as this can lead to permanent staining (discoloration) of the IOL by capsular dyes. This may be associated with a decrease or alteration in the best-corrected visual acuity requiring IOL TABLE 4.2: Evaluation of dyes and techniques used for staining the anterior capsule. Eye

_

Dye

Ability to perform the technique

Staining of the anterior capsule

1

FS

+++

+

2

ICG

+++

++

3

TB

+++

++

4

FS

+++

++

5

ICG

+++

+++

6

TB

+++

++

7

FS

+++

+

8

ICG

+++

++

9

TB

+++

+

10

FS

+++

++

11

ICG

+++

+++

12

TB

+++

++

(FS: Fluorescein sodium; TB: Trypan blue; ICG: Indocyanine green) + Difficult, ++ Moderately difficult, +++ Easy

A

Fig. 4.6A

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B

C

Figs. 4.6B and C Figs. 4.6A to C: Miyake-Apple posterior view of a human eye obtained postmortem showing the progressive leakage of fluorescein sodium into the vitreous cavity after intracameral subcapsular injection. Note that the intensity of the leakage increases as time progresses. (A) Five minutes after intracameral subcapsular injection; (B) Same globe, fifteen minutes after intracameral subcapsular injection; (C) Same globe, two hours after intracameral subcapsular injection.

Capsular Dye-enhanced Cataract Surgery TABLE 4.3: Characteristics of three dyes used for anterior capsule staining. Dye

Concentration

Advantages

Disadvantages

Fluorescein sodium

2%

Blue light enhancement can be used

Low molecular weight, vitreous leakage staining of the cornea

Indocyanine green

0.5%

High molecular weight No vitreous leakage

Cost may be prohibitive

Trypan blue

0.1%

High molecular weight No vitreous leakage

Not indicated in pregnant/ fertile females and children

TABLE 4.4: Characteristics of two techniques used for anterior capsule staining. Staining under an air bubble

Intracameral subcapsular injection

Advantages

Disadvantages

Advantages

Disadvantages

Technically less invasive

Air-filled anterior chamber is unsteady

Dye remains trapped in the subcapsular space

Technically more invasive

Staining of the peripheral anterior capsular rim, providing good visibility while performing phacoemulsification

Progressive dilution of the dye by aqueous

Good staining of the posterior surface of the capsular flap

Tear of the anterior capsule if excessive injection of dye

Injection hole can be used for initiating CCC

Anterior capsule tear in intumescent cataracts

Safer in intumescent and hypermature cataracts

explantation/exchange. We have recently analyzed 2 Acqua® hydrophilic acrylic lenses explanted secondary to bluish discoloration after the use of trypan blue dye.44 The techniques originally reported for staining the anterior capsule using fluorescein sodium are: staining from above under an air bubble, as proposed by Nahra and Castilla45 and intracameral subcapsular injection of fluorescein sodium (staining from below) with blue light enhancement.3,4 The first technique (staining under air bubble) is currently used by most of the surgeons. One benefit is the staining of the peripheral anterior rim, which is otherwise difficult to visualize during the PE procedure.6 However, air in the anterior chamber makes it unsteady. Any instrument entering the eye will cause some air to escape, with a rise of the lens-iris plane. A small amount of high-density viscoelastic placed near the incision prevents the air bubble form escaping the anterior chamber, minimizing the risk of sudden collapse. Also, with this technique, there is a progressive dilution of the dye by the aqueous humor. It may be a possible explanation for the fainter staining observed with the technique in recent clinical reports without compromising

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its usefulness.46 Most of the drawbacks of this technique can be avoided by the careful use of viscoelastic solution to seal the incision site. Alternatively the dye solution can be mixed with viscoelastic agents. Kayikicioglu et al.15 proposed a technique for limiting the contact of trypan blue by mixing the dye with viscoelastic solution. These researchers mixed 0.4% trypan blue with 1% sodium hyaluronate in a 2 mL syringe. The mixed-in viscoelastic solution is injected onto the anterior lens capsule, which covers the anterior capsule without coming into contact with the corneal endothelium. The trypan blue mixed in sodium hyaluronate greatly increases the visibility of the anterior lens capsule without significantly touching the adjacent tissues. There is a potential risk of corneal decompensation after the intraocular use of self-mixed solution; however, these authors used this technique without significant surgical and postoperative adverse effects. Intracameral subcapsular injection is the another but less commonly used technique of anterior capsule staining. It has the advantage of trapping the dye in the subcapsular space, mostly in the center and in the midperipheral part. It gives sufficient time for the surgeon to perform any maneuver until the CCC releases it. Meanwhile, the dye remains in contact with the posterior surface of the anterior capsule. This may be a possible explanation for the better staining provided in our laboratory study on postmortem human eyes.7 The capsule and cortex are both stained by the dye used, but they can be clearly distinguished from the feathery appearance of the cortex and the smooth staining of the capsule. The CCC is fairly easy to perform by grasping the injection hole. This technique was originally proposed for fluorescein with blue light enhancement, but we also used it with ICG and trypan blue. When the capsular flap is inverted, the stained posterior surface of the anterior capsule enhances visualization and thus facilitates tearing during CCC. In our study, this was more obvious with the intracameral subcapsular injection of ICG. Further, this can be performed without the need for any special type of illumination, such as a cobalt blue filter. It may be emphasized that there is a risk of anterior capsule tear after subcapsular injection of dye. However, we did not observe this complication in any postmortem human eyes during our laboratory study.7 The intracameral subcapsular injection technique is not recommended for performing CCC in intumescent and hypermature cataracts owing to high intralenticular pressure and a fragile anterior lens capsule that may result in radial tear. Horiguchi et al.5 reported the technique of staining the anterior capsule using a 2% solution of ICG in patients with mature cataracts. They compared the results of PE and IOL implantation in two groups of 10 eyes. In the first group, the anterior capsule was stained with ICG before CCC and in the second, no dye was used. There was no statistically significant difference reported between two groups regarding endothelial cell count and laser flare cell photometry. Therefore, the staining was considered a safe procedure. Indocyanine green and trypan blue are currently preferred over fluorescein sodium dye due to better staining of the anterior capsule and the absence of vitreous leakage (due to high molecular weight). Both these dyes provide excellent visualization of the anterior capsule flap during CCC, without causing

Capsular Dye-enhanced Cataract Surgery

any toxic effects on corneal endothelium. The trypan blue has the advantage of being less costly when compared to the ICG. However, trypan blue should be avoided in fertile/pregnant females and in children due to possible teratogenic and/or mutagenic effect. ICG remains a valuable alternative for these special patients. Staining under the air bubble technique is safer and, therefore, recommended for intumescent and hypermature cataracts. Viscoelastic solution can be used to viscoseal the incision site in order to avoid the escape of air bubbles and to minimize the anterior chamber fluctuation. Alternatively, mixing the dye with viscoelastic solution may also be used for better anterior capsule staining results and limiting the contact with adjacent ocular tissues.

DYE-ENHANCED PHACOEMULSIFICATION It is important to practice the PE procedure in a wet laboratory setting in order to reduce the learning curve and enhance the safety margin before operating on the patient.47-51 Human eye bank or animal eyes are commonly used for this purpose. The surgeon must be familiar with the critical steps of the PE procedure. Each step is, therefore, to be learned independently and carefully in order to achieve a successful outcome and reduce complications. This is even more important when dealing with white cataracts in a clinical setting. The absence of a red reflex in such cases renders CCC as well as nucleus sculpting maneuvers difficult, if not impossible.52 We have already discussed a detailed evaluation of the staining of the anterior capsule for CCC in advanced cataracts, comparing three dyes namely fluorescein sodium, ICG, and trypan blue and two injection techniques, in human eyes obtained postmortem. In this section, we report our experience with the application of 0.5% ICG and 0.1% trypan blue to obtain complete hydrodissection/delineation, to stain the nuclear substance during nuclear emulsification, and to stain capsular bag during the cortical cleanup. Application of capsular dye for performing PE is termed as Dye-enhanced phacoemulsification as it enhances visualization and helps in learning and performing critical steps of the PE procedure.

Study on Dye-enhanced Phacoemulsification Surgical Technique Randomly accessioned postmortem human eyes (n = 16) obtained within 4 days of death from Eye Banks nationwide were used in this study. They were prepared according to the Miyake-Apple posterior video technique.42,43 Two independent surgeons (LW and SKP) evaluated the use of 0.5% ICG and 0.1% trypan blue to perform the critical steps of PE in eight eyes (2 eyes/dye/ surgeon). Dye solutions were prepared as described earlier. The PE procedure was performed without the use of dye in eight other eyes served as controls. After the cornea and iris were removed, a CCC (4.5–5.5 mm in diameter) was initiated using a 26-gauge needle cystitome and completed using Utrata forceps. A hydrodissection was performed by injecting 2–3 cc of the dye solution

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(0.5% ICG or 0.1% trypan blue) between the lens capsule and the cortex with a 27-gauge cannula. This was followed by hydrodelineation; the placement of a 27-gauge cannula deep into the nucleus and injection of the dye solution created the colored fluid wave marking the separation of the nucleus and the epinucleus. BSS® was used for performing hydrodissection/delineation in the control group. Nuclear emulsification (Alcon Legacy 20000, Alcon Surgical, Fort Worth, TX, United States) was performed using the divide-and-conquer nucleofractis technique.52 One to two microdrops of the dye solution were instilled into the capsular bag, and cortical cleanup was performed using the irrigation and aspiration system. The enhancement of visualization while performing each step of the surgery using the dyes was evaluated by the two independent surgeons. They particularly noted: •• Whether the use of a colored solution helps in visualizing the fluid waves and the plane of cleavage during hydrodissection/delineation •• Whether the staining of the nucleus substance helps in appreciating the depth of the phaco tip and its position in relation to the posterior capsule during the nuclear emulsification •• Whether the staining of the inner surface of the capsular bag helps in identifying residual cortical material during the cortical cleanup procedure using the irrigation-aspiration system.

Results Our experimental study suggested that both dyes (0.5% ICG and 0.1% trypan blue) successfully enhanced visualization while performing critical steps of the PE procedure, when compared to the control group.8 During hydrodissection/ hydrodelineation, the use of dye helped in visualizing the formation of a complete cleavage between the capsule and cortex as well as between the nucleus and epinucleus complex (Figs. 4.7A and B). Incomplete cleavage could be easily identified by using a colored solution and promptly completed by reinjection in the appropriate quadrant. During the nuclear emulsification procedure, the use of dye helped in appreciating the position of the phaco tip and its relation with the posterior capsule, thus increasing the safety of the procedure (Figs. 4.8A and B). For the complete cleaning of the capsular bag, the use of dye provided better visualization of the residual cortical material during the irrigation-aspiration procedure (Figs. 4.9A and B). It was easy to differentiate the feathery, irregular staining of the cortex from the smooth staining of the capsule.

Learning Critical Steps of Phacoemulsification It is important to learn the critical steps of the PE procedure, which include CCC, hydrodissection, hydrodelineation, nuclear emulsification maneuvers, and cortical cleanup. In a series of 7,169 patients undergoing PE, Gimbel reported 36 per-operative posterior capsule tears.27 Of these, 19 (53%) occurred during the irrigation/aspiration step and 13 (36%) occurred during the PE itself.

Capsular Dye-enhanced Cataract Surgery

A

B

Figs. 4.7A and B: Gross photographs of a human eye obtained postmortem. Cornea and iris were excised to allow better visualization. (A) Anterior (surgeon’s) view showing hydrodissection/hydrodelineation enhanced by trypan blue. Notice the complete (360 degrees) blue colored fluid wave indicating separation of the nucleus/ epinucleus complex; (B) Sagittal section of the same crystalline lens, showing the demarcation zone between the nucleus/epinucleus complex (arrows).

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A

B

Figs. 4.8A and B: Gross photographs of a human eye obtained postmortem taken from an anterior (surgeon’s) view while performing nucleus sculpting. Cornea and iris were excised to allow better visualization (A and B) Gimbel’s divide-and-conquer nucleofractis technique. Notice that trypan blue dye enhance visualization of the groove. This is helpful to judge the position of the phacotip and its relation with the posterior capsule.

Capsular Dye-enhanced Cataract Surgery

A

B

Figs. 4.9A and B: Gross photographs of human eyes obtained postmortem taken from an anterior (surgeon’s) view after the completion of irrigation/aspiration. Cornea and iris were excised to allow better visualization. Note the cleaned capsular bags, stained green and blue after the use of ICG and trypan blue dyes. (A) ICG; (B) Trypan blue.

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Five and six percent of the posterior capsule tears occurred during the IOL implantation and the hydrodissection, respectively. The visualization while performing each step can be enhanced by the use of a dye, increasing their safety margin.

Continuous Curvilinear Capsulorhexis We have already addressed the techniques of anterior capsule staining for anterior capsulorhexis using fluorescein sodium, ICG, and trypan blue dyes. However, the drawback of in leakage vitreous is associated with fluorescein sodium.

Hydrodissection/Hydrodelineation Hydrodissection is an important step of small incision cataract surgery using PE. The use of this procedure was reported by Faust.22 Fine24 added the concept of cortical cleavage hydrodissection to separate the superficial cortex from the lens capsule. The use of dye (instead of BSS®) helps in the localization of the complete (360°) cortical cleavage plane, separating the equatorial and posterior capsule from the cortex. It is much easier to visualize a dyecolored fluid wave hydrodissection. Therefore, it helps in achieving complete separation between capsule and cortex. Hydrodelineation,26 associated with the formation of a golden ring, is sometimes difficult to notice. With the injection of a dye solution, however, the surgeon can successfully visualize the demarcation between the nucleus and the epinucleus (Fig. 4.7A). In this situation, an incomplete hydrodissection/delineation can be easily identified and completed by injecting more stained fluid in that particular quadrant, if needed. After achieving complete hydrodissection and hydrodelineation, it is easier to perform nuclear emulsification with less ultrasound power and time, decreasing the need for cortical cleanup and the risk of posterior capsule tear. Recent studies from our laboratory suggest that hydrodissection-enhanced cortical cleanup is an unidentified but important factor for delaying the onset of posterior capsule opacification (PCO).53

Nuclear Emulsification A number of different techniques have been used by phaco surgeons for the nuclear emulsification of hard and soft cataracts. While performing nuclear emulsification maneuvers, visualization of the depth at which the phaco tip is sculpting is crucial. Its significance cannot be overemphasized for preventing complications like unnoticed posterior capsular tears, vitreous loss, and dislocation of the nucleus into the vitreous cavity. When a good red reflex is present, the surgeon can rely on an increasingly brighter red reflex to gauge proximity to the posterior capsule while performing the nucleus sculpting. However, the absence of a red reflex (e.g. in white mature or hypermature cataracts) complicates nucleus emulsification because it is difficult to judge the depth of the phaco tip during sculpting.54 The staining of the nucleus (lens substance) helps in visualizing the position of the phaco tip and its relation with the posterior capsule, thus enhancing the safety margin of the procedure.

Capsular Dye-enhanced Cataract Surgery

Cortical Cleanup Studies have shown that at least half of the cases of capsular tear and vitreous loss occur at the time of cortical cleanup.27 Staining of the capsular bag enhances its visualization and the surgeon can distinguish the feathery, irregular staining of residual cortex from the smooth staining of the anterior, equatorial, and posterior capsule. The staining facilitates cleaning of residual cortical matter from the capsular bag.

Possible Clinical Application and Future Trials Our laboratory study provides evidence that both dyes (ICG and trypan blue) can be used in the clinical setting of living human eye operations to achieve a complete hydrodissection/delineation.8 They can also be used to visualize the depth of the phaco tip during the sculpting and its relation with the posterior capsule, especially in patients with poor or absent red reflex. It is easier to differentiate the cortical matter from the anterior or posterior capsules after the staining of the capsular bag. This may be helpful in achieving a complete and safe cortical cleanup during the irrigation/aspiration and in lowering the incidence of posterior capsule tear.

DYE-ENHANCED POSTERIOR CAPSULORHEXIS Posterior continuous curvilinear capsulorhexis (PCCC) is a posterior continuous central capsulotomy technique described by Gimbel, and Blumenthal and coworkers in 1990.27,28 PCCC is recommended for converting an irregular tear of the posterior capsule into a circumscribed cut not extending to the equator.27,29 It can also be used for the removal of posterior capsular plaques in posterior subcapsular or polar cataracts.55 Recently, the use of PCCC combined with the optic capture of an IOL30,31 and/or anterior vitrectomy56-59 successfully evolved for delaying the development of PCO or secondary membrane formation in pediatric cases. Primary posterior capsulotomy, in the form of PCCC, is especially important in younger children for maintaining long-term clear visual axis in order to prevent the development of amblyopia.60 Besides children, some surgeons also recommend to perform PCCC during extracapsular cataract extraction or PE procedure in adults, because this is more effective and safer procedure than the neodymium-doped yttrium aluminum garnet (Nd:YAG) laser capsulotomy for the management of PCO.61,62 However, to learn and perform PCCC is technically challenging due to the thin and transparent nature of the posterior capsule. Further, it should not be attempted if visibility is mediocre and vitreous pressure is assessed to be high.

Study on Dye-enhanced Posterior Capsulorhexis9 Considering the wide clinical implications of PCCC and keeping the difficulty to learn and perform this important procedure in mind, a study was carried out in human eyes obtained postmortem. We evaluated if the staining of

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the posterior capsule with different dyes could be useful to facilitate PCCC, similar to the anterior capsule staining for performing anterior capsulorhexis in cataracts with poor or no red glow.

Surgical Technique Randomly accessioned postmortem human eyes (n = 12) obtained within 4 days of death from eye banks nationwide were used in this study. The eyes were prepared according to the Miyake-Apple posterior video technique.42,43 They were sectioned at the equator and the anterior segment was mounted on a glass slide to provide a posterior perspective of this portion of the eye. After the cornea and iris were removed, a capsulorhexis 5.0–5.5 mm in diameter was initiated using a 26-gauge needle and completed using an Utrata forceps. A complete cortical-cleavage hydrodissection was performed by injecting balanced salt solution (BSS®, Alcon Ophthalmic, Fort Worth, TX, United States) between the lens capsule and the cortex with a 27-gauge cannula. This was followed by careful hydroexpression of the nucleus, avoiding damage to the posterior capsule. Cortical cleanup was performed using an irrigation/ aspiration system. Two independent surgeons (SKP and LW) evaluated the use of dye to enhance visualization of the posterior capsule during PCCC (4 eyes/surgeon). Both surgeons were inexperienced with the PCCC procedure and performed it for the first time in their professional career. PCCC was also performed in four other eyes (2 eyes/surgeon) without the use of dye. The posterior capsule was stained by instilling 1 microdrop of the dye solution into the capsular bag. We used 0.5% ICG and 0.1% trypan blue solutions (4 eyes/dye). After waiting for 1–2 minutes, the excessive dye was washed out. The capsular bag was filled with viscoelastic (Healon®, Pharmacia Inc., Peapack, NJ, United States) and PCCC was initiated by using a 26-gauge needle cystitome and completed using an Utrata forceps. Optic capture of a posterior chamber intraocular lens (PCIOL), as well as anterior vitrectomy, were also practiced.

Results Our laboratory study in eight postmortem human eyes confirmed that the posterior capsule can be successfully stained using ICG and trypan blue (Figs. 4.10A to E and Figs. 4.11A to E). It was much easier to initiate and complete PCCC successfully after staining of the posterior capsule when compared to the control (nonstained) eyes. The PCCC was completed in all globes, due to better visualization of the stained posterior capsule flap (PCF) against the transparent (nonstained) anterior hyaloid face of the vitreous (Figs. 4.10A to C and Figs. 4.11A to C). It was not difficult to perform optic capture of PCIOLs after staining the posterior capsule (Figs. 4.10D and E, and Figs. 4.11D and E). Both dyes used in this study provided satisfactory visualization for performing the PCCC.

Capsular Dye-enhanced Cataract Surgery

Clinical Application and Future Trials The PCCC is currently getting more and more attention due to its clinical implication of the prevention of the development of PCO primarily in children and to some extent in adults. Additionally, this procedure is also important for the management of posterior capsule tears of congenital, traumatic or surgical

A

B

Figs. 4.10A and B

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C

D

Figs. 4.10C and D

Capsular Dye-enhanced Cataract Surgery

Fig. 4.10E Figs. 4.10A to E: Gross photographs of a human eye obtained postmortem showing posterior continous curvilinear capsulorhexis (PCCC) after staining of the capsular bag with indocyanine green (ICG). Cornea and iris were excised to allow better visualization. (A) Anterior (surgeon’s) view of the cleaned and stained capsular bag showing initiation of the PCCC. Note that it is easier to visualize the stained posterior capsule flap (PCF) against transparent (non-stained) anterior hyaloid phase (AHP) of the vitreous; (B) PCCC is in progress; (C) PCCC is completed. Note the stained PCCC margin; PCF: posterior capsule flap; (D and E) Higher magnification of the optic-haptic junctions after intraocular lens (IOL) optic capture. Both haptics are present in the capsular bag and the IOL optic is captured behind the posterior capsule.

origin, and the peeling of plaques associated with posterior polar and posterior subcapsular cataracts.55 As mentioned before, learning the PCCC is technically difficult due to the thin, transparent, and elastic nature of the posterior capsule. Attempting the PCCC in the presence of the poor visibility associated with positive vitreous pressure is difficult and may cause an inadvertent radial tear extending towards the equator. Cauwenberge et al.63 recently reported the etiology, management and outcome of complicated posterior capsulorhexis. In a 1-year retrospective analysis of 650 patients, they identified 32 (5%) cases of complicated PCCC. According to them, the most frequent problem was to perform a central capsulorhexis with the optimum size (A,17 bp insertion, and 650 del G

Addison21 Semina et al.24 Berry et al.25 Burdon et al.26

CTTP 5

14 q22 and 16 q23

Berry et al.22 Liu et al.23 Pras et al.27

CLASSIFICATION Because of the low incidence of PPC, most of the study samples have been small making it difficult to evolve a grading system for PPC. Singh et al. classified PPC into four groups.2,28 Type 2 has been reported to progress to Type 3 with the passage of time (Table 5.2). Schroeder graded PPC in his pediatric patients according to its effect on pupillary obstruction in the red reflex testing (Table 5.3).29

CLINICAL FEATURES Symptoms Progressive PPC usually presents symptoms; the stationary PPC may occasionally become symptomatic. The lens may have evidence of a small opacity at birth and may develop cataractous changes later in life usually by 30–50 years of age.30 Visual acuity appears to worsen once nuclear cataract sets in. Increasing glare while driving at night, difficulty in reading fine print

Posterior Polar Cataract TABLE 5.2: Singh’s classification of posterior polar cataract. Type 1

Posterior polar opacity is associated with posterior subcapsular cataract

Type 2

Sharply defined round or oval opacity with ringed appearance like an onion with or without grayish spots at the edge

Type 3

Sharply defined round or oval white opacity with dense white spots at the edge often associated with thin or absent PC. These dense white spots are a diagnostic sign (Daljit Singh sign) of posterior capsule leakage with or without repair and extreme fragility

Type 4

Combination of the above three types with nuclear sclerosis

TABLE 5.3: Schroeder’s classification of posterior polar cataract. Grade 1

A small opacity without any effect on the optical quality of the clear part of the lens

Grade 2

A two-third obstruction without other effect

Grade 3

The disk-like opacity in the posterior capsule is surrounded by an area of further optical distortion. Only the dilated pupil shows a clear red reflex surrounding this zone

Grade 4

The opacity is totally occlusive; no sufficient red reflex is obtained by the dilation of the pupil

at close range, intolerance to light, reduced contrast sensitivity, and reduction in vision are the common symptoms.4,5

Signs Posterior polar cataract presents as a dense white circular opacity in the central posterior capsule, located near the nodal point of the eye, surrounded by concentric whorls like bull’s eye appearance4 (Fig. 5.1). The posterior polar opacity extends anteriorly into the posterior cortex appearing pyramidal which differentiates a PPC from the more common posterior subcapsular cataract. PPCs can be either stationary or progressive. The stationary type is more common and demonstrates the characteristic bull’s eye appearance. A small satellite lesion adjacent to the central opacity may also be seen. In the static form of PPC, patient may be symptom free with a good visual function. In the progressive type (Fig. 5.2), whitish opacification in the form of radiating rider opacity takes place. It has feathery and scalloped edges. It does not involve the nucleus or extend anteriorly as far as the original opacity. Visual symptoms and glare worsen during the progression of PPC. The diagnosis of a PPC is self-evident on slit-lamp examination and retroillumination. Examination of the anterior vitreous may reveal oil-like droplets or particles. The presence of such a finding should raise the possibility of preexisting capsular opening. Sometimes a posterior capsular plaque is found (Fig. 5.3). Occasionally, PPC is camouflaged by nuclear sclerosis. As normal age-related opacification occurs, nuclear sclerosis can mask the presence of a PPC, unless it is carefully

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Fig. 5.1: Slit-lamp photograph of a classical posterior polar cataract.

Fig. 5.2: Progressive posterior polar cataract with a spindle-shaped defect of the central posterior capsule.

sought. This can lead to unexpected surgical problems.4,5 Mean lens thickness in PPC was found to be lower than that found in eyes with senile cataract.5 Patients with PPC demand surgery when there is decreased vision due to increased density of lens opacity, increased glare due to forward scattering of

Posterior Polar Cataract

Fig. 5.3: Posterior capsular plaque in a case of posterior polar cataract.

light, age-related pupillary miosis, or due to increased functional needs and visual expectations.4,5 PPC may be associated with other ocular features like microphthalmia, microcornia, anterior polar cataract, and psychosomatic disorders.31-35 In addition, it can also be associated with ectodermal dysplasia, Rothmund disease, scleroderma, incontinentia pigmenti, congenital dyskeratoses, and congenital atrophy of the skin.30 There have been reports of spontaneous posterior lens dislocation though a weakened posterior capsule in PPC.36,37

Differential Diagnosis Posterior lenticonus: PPC and posterior lenticonus share certain common features. Both are posterior polar abnormalities,38 which are progressive39and are predisposed to traumatic lens rupture.40 The differentiating features include the following:38-40 Posterior polar cataract is predominantly inherited as an autosomal dominant condition whereas posterior lenticonus typically occurs sporadically. The posterior polar opacity is usually dense and compact whereas posterior lenticonus has a porous opacity. Posterior lenticonus is usually unilateral, exhibiting a female preponderance and has a central posterior protuberance which is absent in PPC.31,39 Posterior subcapsular cataract: It is important to differentiate between the two conditions since the surgical implications and management strategies

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are different. Posterior subcapsular cataract is an acquired condition, more commonly seen, occurring at any age, plate like lacking in depth, and may extend peripherally even up to the equator in some cases. It is thinner without characteristic concentric rings and not adherent to the posterior capsule. It may be associated with diabetes mellitus, steroid use, and exposure to radiation. It does not predispose to the occurrence of PCR. Once a correct preoperative diagnosis of posterior subcapsular cataract is made, the patient is spared of the rigorous techniques adopted for PPC surgery.

MANAGEMENT Risk Considerations The predominant problem in surgery for PPC is a high probability of posterior capsule rent (PCR).41 Early reports showed a very high incidence (36%).4,5 In an effort to reduce the high incidence of PCR, surgeons have developed a number of different techniques which have evolved from the understanding of the anatomical abnormality of the posterior capsule and surgical factors that increase the risk of intraoperative PCR. The more recent reports in the literature cite a lower incidence of PCR varying from 6% to 7%.18,42 Studies have suggested that the size of the polar opacity has a bearing on the risk of intraoperative PCR.18,43 In Hayashi’s series where only routine phacoemulsification was performed for polar opacity less than 4 mm, the incidence of PCR was reported as 7%.18 A posterior approach was employed for larger opacities. In the series reported by Kumar et al., PCR was noticed in 30.43% of eyes with polar opacity more than 4 mm whereas only 5.71% with posterior polar opacities of less than 4 mm.43 The incidence of PCR was higher in patients more than 40 years of age and in eyes that underwent extracapsular cataract incision when compared to phacoemulsification.44

Indications for Surgery In view of the fact that eyes with PPC are prone for PCR, it may be prudent to delay the cataract surgery till the patient becomes visually symptomatic. However, undue delay with advancing nuclear sclerosis may render the surgery more difficult and complication prone. Hence, the patient should be periodically monitored for progression indicated by visual deterioration, signs of increase of the posterior polar component, and advancing age-related lens sclerosis. In the presence of any of the above events, surgical intervention should be considered after appropriate counseling and an informed consent.

Evaluation A careful slit-lamp biomicroscopy should be performed to confirm the diagnosis of PPC particularly looking for signs of congenital dehiscence. Nuclear brunescence may camouflage an underlying PPC which can be mistaken for posterior subcapsular cataract. A meticulous evaluation will be of

Posterior Polar Cataract

great value in choosing the appropriate line of management and prognosticate the eventual postoperative outcome.

Counseling Counseling is a key component in the management of PPC. The patient should be informed about the unusual nature of the cataract and the possibility of a relatively longer surgical time. He/she should be counseled about the possibility of intraoperative PCR, dropped nucleus, and potential need for a posterior segment intervention as a primary or a secondary procedure. He should be apprised of the potential postoperative complications and possibility of delayed visual recovery. It is also prudent to counsel about the requirement for Nd:YAG laser capsulotomy for residual capsular plaque (Fig. 5.3).4,5,18 The potential for preexisting amblyopia in unilateral PPC should also be taken into consideration.18 Though these patients present early for cataract surgery, multifocal intraocular lenses (IOLs) constitute a relative contraindication since these eyes are predisposed to intraoperative PCR. After surgery, majority of patients regain 20/20 vision. Visual acuity is reported to be greater than or equal to 20/20 in 49 out of 58 eyes (84%)5,18,19 and greater than or equal to 20/40 in 88% of a total of 111 eyes.1,4

Surgery Though various surgical approaches have been proposed for managing PPC, there is no surgical technique to completely eliminate the occurrence of PCR. An appropriate technique may be selected depending on the stage of PPC at the time of presentation. Intracapsular cataract extraction (ICCE): Hayashi K et al. reported a series of 28 eyes of 20 consecutive patients with PPC who underwent cataract surgery.18 ICCE was performed only for a single case with a large opacity and hard nucleus. The posterior approach: Ghosh et al. investigated this approach in an interventional case series of 11 eyes of eight patients with PPC undergoing pars plana vitrectomy, lensectomy, and sulcus placed intraocular lens (IOL).19 The rationale behind this approach is that a controlled pars plana procedure will eliminate unpredictable capsular rupture and its attendant posterior segment complications encountered with an anterior approach. However, this technique was not without complications and during a mean follow-up of 13 months, three of 11 eyes developed posterior segment complications including one case of retinal detachment. The posterior approach was also used in two of 28 eyes undergoing cataract surgery for PPC since the opacity was large and the lens soft.18 In view of the presence of complications with the posterior approach, it may be unwise to consider this as a routine approach to manage PPC since recent reports show a much lower incidence of PCR during phacoemulsification than earlier reports. It is always desirable to be able to maintain the capsular barrier using an anterior approach wherever

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possible and not to employ a pars plana approach since it limits the options for visual rehabilitation to scleral-fixated, iris-fixated, or anterior chamber angle supported IOLs. A posterior approach to the PPC may be considered for patients with polar plaque greater than 4 mm provided the cataract surgeon has access to an experienced posterior segment surgeon or service. The anterior approach—phacoemulsification: Patients with PPC should be operated upon by experienced surgeons. The primary goal of phacoemulsification for PPC is to maintain an intact capsulozonular barrier between the anterior and posterior segments and to implant an IOL within the capsular bag. Various modifications of phacoemulsification techniques have been proposed to minimize the occurrence of intraoperative PCR and provide a closed chamber environment maintaining the contours of the globe. There are several publications in the literature describing subtle variations of techniques. The salient features of surgery are described below:

Anesthesia There is no universal anesthetic technique for PPC. However, surgeons prefer to employ an injection anesthesia since the surgical time may be prolonged in some of these situations where a PCR occurs and there is the need for anterior vitrectomy. Topical anesthesia may be employed in a suitable patient. It is preferable to perform these cases under monitored anesthetic care.

Incision The surgeon may construct an incision that is his standard for routine cases. This author creates two paracentesis incisions and the aqueous is exchanged with a cohesive OVD. Then a definitive valvular corneal incision is created for phacoemulsification. Currently, phacoemulsification is performed through temporal clear corneal approach. An incision of the right dimensions (neither too long nor too wide) is desirable. A leaky incision results in a shallow anterior chamber and a long incision causes oar-locking and intraoperative visibility issues especially while dealing with the subincisional lens matter. However, in the presence of co-existing morbidity like suprahard cataract, some surgeons may opt for the scleral tunnel incision. This may facilitate the surgery in case the surgeon has to convert from phaco to manual nonphaco technique of nucleus removal. It is important to maintain the eye at a physiological pressure level throughout the case. Once the capsule is opened, an over-pressurized anterior chamber, by increased pressure on the nucleus, may cause the weakened posterior capsule to tear. Likewise, periods of intraoperative hypotony may cause extension of any posterior capsular tear. Just the right amount of a cohesive OVD should be injected into the anterior chamber to stabilize the environment.

Capsulorhexis The eye should not be over pressurized with OVD before initiating the capsulorhexis (CCC). The CCC should be between 5 mm and 5.5 mm. A larger CCC may not provide adequate capsular support for optic capture of a sulcus-

Posterior Polar Cataract

fixated PC IOL in case the posterior capsule is significantly compromised ruling out the possibility of placing the IOL in the capsular bag.5,45 A small CCC less than 4.0 mm on the other hand may complicate the nucleus management by making the nucleus manipulations more difficult thereby putting undue stress on the posterior capsule. A small CCC will also make it difficult to prolapse the nucleus into the anterior chamber if the need arises at a later stage. Some surgeons have also attempted to modify the CCC by displacing it slightly toward the incision or by altering the contour by imparting a smooth notch to render subincisional nucleus management easier. Singh et al. have recommended making an oval CCC of approximately 8.0 mm by 4.5 mm.46 The axis of the oval CCC is the same as the meridian of the corneal incision, irrespective of the meridian of the preexisting posterior capsule rupture. The rationale is that the long axis of the CCC allows easy and atraumatic manipulation of the nucleus, instruments, and IOL insertion within the capsular bag. The shorter axis of the CCC leaves sufficient anterior capsule to allow safe and secure optic capture should it be required.

Hydroprocedure Cortical cleaving hydrodissection is a critical step in most of the popular techniques of nuclear disassembly.47 However, this should be avoided in patients with PPC since it can lead to hydraulic rupture of the posterior capsule.4,5 Hydrodelineation has been advocated by many to afford safety to the procedure by creating a mechanical cushion of the epinucleus.1,2,5,18,48-50 Fine et al. also recommended performing hydrodissection (in addition to hydrodelineation) by injecting small quantities of BSS gently in multiple quadrants, so that the fluid wave is not allowed to spread across the posterior capsule.20 Hydrodelineation may be difficult to achieve in the presence of a firm nucleus without causing undue trauma to capsular bag and zonules. At times fluid may inadvertently get injected subcapsularly resulting in unplanned hydrodissection. Inside-out delineation has been proposed as an alternative technique for hydrodelineation42 (Figs. 5.4A and B). In conventional hydrodelineation, there is a possibility of the fluid being injected inadvertently in the immediate subcapsular plane resulting in unplanned cortical cleaving hydrodissection. In inside-out delineation, after sculpting a central trench in the nucleus, the fluid is injected through one of the walls of the trench, and it traverses inside-out thereby providing the delineation. The author prefers to avoid all hydrosteps and uses a technique of hydro-free-dissection. A bluntedged cyclodialysis spatula is passed in the subcapsular plane almost up to the equatorial fornix and swept in a side-to-side motion thereby separating the anterior capsule from the underlying cortex. This process is performed through both the paracentesis sites and the main incision. This technique renders subsequent removal of lens matter much easier.

Nucleus Disassembly The techniques for nucleus disassembly in a PPC must take cognizance of the fact that no effort should be made to rotate the nucleus since cortical cleaving

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A

B

Figs. 5.4A and B: Inside-out hydrodelineation. The fluid is injected after placing the hydrodissection cannula at a proper depth after sculpting an initial trench. (B) “Golden ring” created after inside-out hydrodelineation. Source: Dr Abhay Vasavada, Ahmedabad, India

hydrodissection has not been performed. Any such attempt may lead to zonular dialysis and/or posterior capsular rent.5 Aggressive fluidics settings should be avoided in order to reduce turbulence within the capsular space and slow motion phaco as described by Osher ensures that the cataract is removed in

Posterior Polar Cataract

a gentle and controlled way.51 Many techniques for nucleus removal in PPC have been described. The technique for nucleus dismantling depends on the degree of nucleus sclerosis. Soft nucleus: The authors preferred to progressively debulk the nucleus layer by layer by sculpting adjacent grooves centrally and in the nasal quadrants, using low phaco parameters till a deep central bowl is created. During this process, most of the epinucleus would have been removed from the nasal quadrants of the capsular bag. The subincisional lens matter is viscodisplaced toward the center, by injecting OVD in a gentle and incremental manner (limited viscodissection) into the capsular fornix from a side port incision. Then the cyclodialysis spatula is maneuvered from a paracentesis site to gently nudge the subincisional lens matter so that it just presents at the capsulorhexis margin and becomes accessible to the phaco tip. This maneuver is greatly facilitated by the first step when space was created in the capsular bag for the displacement of this relatively inaccessible lens matter. The lens matter is held at the phaco tip with low aspiration and drawn toward the center before being consumed. If properly performed, the nucleus–epinucleus complex can be removed leaving behind the cortical elements. The anterior chamber must never be allowed to become shallow at any stage and a cohesive OVD must be injected into the anterior chamber before retracting the hand piece. Hard nucleus: The authors’ technique for dismantling a hard nucleus (unpublished) is based on the same philosophy as the soft nucleus. Space is created in the central and nasal quadrants of the capsular bag by removing a big chunk of the nucleus from these zones. The phaco power may have to be proportionately raised to reduce trauma to the zonules during sculpting or chopping maneuvers. Phaco chop is initiated at the right side of the bowl after engaging the nucleus at a deep plane. A Chang chopper facilitates this maneuver. The chopping maneuver is initiated after elevating the nucleus a bit anteriorly from the PC to avoid the force of lateral separation not to be transmitted to the PC. As a departure from a routine case, no attempt is made to rotate the nucleus after creating the first chop. Instead, the phaco tip is rotated facing left and buried into the nucleus. A large section of the nucleus is now chopped so that a large pie-shaped portion is chiseled out. Consumption of this fragment creates space in the central and nasal capsular bag. The phaco tip is now tilted to impale into the left portion of the residual subincisional nucleus which is then pulled toward the center into the freshly created space in the capsular bag and chopped. The rest of the nucleus is sequentially chopped in the supracapsular plane. Corneal protection is mandatory with frequent injections of a dispersive OVD. The anterior chamber should not be allowed to get shallow at any stage of the surgery by injecting an OVD before the instrument is withdrawn. Many other techniques of nuclear disassembly have been described. Vasavada et al. have reported good results with the “step-by-step chop in situ and lateral separation” using a slow motion technique in nuclear sclerosis greater than grade 2.52-54 This technique is a combination of vertical and

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horizontal chopping. The nucleus is impaled with the phaco tip and a crack is initiated by placing the chopper adjacent to the tip and depressing it down. The chopper is then repositioned distally and deep into the crack, and gentle lateral separation is performed. The chopper is then sequentially repositioned more and more proximally while continuing with the lateral separation until the whole nucleus is cracked. This approach reduces intraoperative traction of the posterior lens fibers and the polar opacity as well as the turbulence within the capsular bag and anterior chamber. In the lambda technique described by Lee and Lee,1 two trenches are sculpted into the nucleus in the shape of a Y (or the inverted Greek letter lambda) which are then split and the central (distal) segment is removed. The two remaining segments are subsequently consumed after mobilizing them. Bimanual microincision cataract surgery (B-MICS) in PPC has been advocated by Fine et al.55 and Haripriya et al.56 They have found the controlled intraocular environment for slow motion phaco to be an advantage. Additionally, in the bimanual approach since the phaco probe can be switched between the two hands, it may be easier to remove all nuclear quadrants with minimal manipulations. However, in recent times, B-MICS seems to have waned in popularity.

Epinucleus Removal If the technique of hydro-free-dissection is employed (authors’ techniqueunpublished), there will not be much epinucleus to deal with in the periphery of the capsular bag since most of it would have been removed concurrently with the nucleus removal. However, there will be epinucleus–cortex complex layered on the PC centrally including the polar region. This is carefully aspirated using bimanual I/A taking care to strip the lens matter from the periphery to the center, the polar area being the final area to be dealt with. An aspiration cannula with an aspiration port diameter of 0.5 mm comes in handy while dealing with epinucleus which is unusually thick and sticky. If there remains residual epinucleus in the periphery of the bag (which is usually present subincisionally), it can be displaced centrally by limited viscodissection injecting increasing aliquots of OVD into the capsular fornix from the sideport incisions. In the technique where hydrodelineation has been employed, endonucleus removal leaves behind a shell of epinucleus and cortex needing mobilization and removal. This is an extremely critical step of the procedure. Viscodissection of the epinucleus has been suggested to be a safe and effective method for its removal since it is easier to control the amount and speed of injection.45,49 Fine et al. reported the use of a dispersive OVD whereas Allen et al. favored a high-viscosity cohesive OVD. After inserting the visco cannula under the capsulorhexis rim, OVD is gently injected to cleave the epinucleus from the anterior capsule. Further injection of OVD closer to the capsular fornix creates a fold of peeled away epinucleus which should stop short of reaching the posterior pole. The same process is repeated after inserting the visco cannula

Posterior Polar Cataract

under the capsulorhexis edge 180° away from the first. Allen et al. reported the use of a phaco probe to gradually aspirate the epinucleus removing it piecemeal until the most posterior undisturbed portion remains. The final polar opacity can then be gently dissected away either with more OVD or with gentle hydrodissection which is then safe to remove.54 It is safe to hydrodissect at this stage as the capsular bag is not fully occupied, and hence there is no danger of pressure build-up. Occasionally, a punched out, “cookie cutter” appearance suggesting a capsular defect is noticed in the central posterior capsule after the epinucleus removal. The dilemma is to decide whether this is just a zone of absent cortex where the polar plaque had been attached or an actual hole in the posterior capsule. It is advisable not to attempt to check if the capsule is intact by touching since it may induce a rupture. This is just a “pseudohole” if the shiny reflex of the posterior capsule is visible. On the other hand, a spindle-shaped clearance, also referred to as “fish mouthing” by Nagappa et al. with vitreous presenting through the PPC, is a clear sign of posterior capsular rent.57

Cortex Removal Bimanual cortex aspiration is preferred since it ensures the stability of the anterior chamber and allows efficient removal of the cortex even from the subincisional areas. Cortex should be stripped toward the area of maximal weakness instead of away from it in order to reduce stress on the weak area that otherwise may lead to a PCR. Therefore, cortex stripping should begin under the anterior capsule, round the equator, and onto the posterior capsule. Fine et al. recommended the use of coaxial I/A while protecting the posterior capsule with OVD during cortex removal.45 Posterior capsule polishing, the next step after the cortex removal is dicey in this situation and should not be performed even at the cost of leaving behind traces of unaspirated cortex or even a thin plaque since this can be managed by Nd:YAG laser capsulotomy in the postoperative period if needed. An intact capsule can be ruptured as a consequence of a gentle attempt to aspirate a tiny strand of cortex from the central plaque area.58

MANAGEMENT OF THE POSTERIOR CAPSULE Polishing of the Posterior Capsule There is higher incidence of posterior capsular plaques in PPC. Polishing or vacuuming of the opacity is avoided due to the increased fragility of the underlying posterior capsule.2,4,5,18,45 Surprisingly, despite the plaques, many patients regain good vision postoperatively. Since posterior capsule polishing is avoided in these situations, there is a higher chance of visually significant postoperative opacification of the posterior capsule. When necessary neodymium–yttrium– aluminium–garnet (Nd:YAG) laser posterior capsulotomy may be performed postoperatively. A YAG capsulotomy rate of 18.4% was reported by Siatiri and Moghimi with a follow-up between 2 months and 20 months.48

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Management of Posterior Capsular Dehiscence It is prudent to treat every case of PPC as if each case is harboring a posterior capsular dehiscence and strategize accordingly. The same prophylactic precautions as mentioned earlier should be followed to avoid or postpone a PCR. The surgeon should be ever alert to this possibility and familiarity with the early diagnostic signs of PC rent help in limiting damage. When the tear is detected intraoperatively, the management is essentially the same as with any PCR. The goal is to prevent further extension of the capsular opening and preserve the integrity of the anterior vitreous face. A dispersive OVD is injected on the zone of the capsular defect to tamponade the vitreous face prior to withdrawing the phaco or I/A handpiece from the eye.59 It is advisable to convert a small PCR with visible margins into a posterior continuous curvilinear capsulorhexis (PCCC) to stabilize it and prevent further tear out. However, if the vitreous face is broken, a proper anterior vitrectomy should be done after staining the prolapsed vitreous with triamcinolone acetonide (4%). The prolapsed vitreous may be removed by two-port limbal anterior vitrectomy or pars plana anterior vitrectomy. After freeing the anterior chamber of the vitreous, the residual cortex may be removed by the dry aspiration technique or by bimanual I/A.

NUCLEUS DROP IN POSTERIOR POLAR CATARACT Nucleus descent may occur if the diagnosis of PPC is missed and a routine cortical cleaving hydrodissection is performed. In the presence of a brunescent nucleus and liquefied vitreous, it may even sink abruptly and rapidly without apparent antecedent vitreous loss soon after hydrodissection or as soon as nucleus emulsification is initiated. In the presence of formed vitreous, the nucleus descent may be partial and if still occupies the pupillary area, rescue maneuvers may be undertaken by the cataract surgeon after appropriate management of the prolapsing vitreous. Under no circumstance, a sinking nucleus should be chased with the phaco probe because this will exacerbate the vitreous loss and enlarge the PC rupture. Injudicious attempt at phacoemulsification of a descending nucleus will aggravate vitreous traction which in turn may result in retinal breaks or retinal detachment. A dislocated nucleus is best retrieved by posterior segment intervention at the same sitting or as a two-stage procedure. Nucleus drop may also occur in patients where cortical cleaving hydrodissection has been avoided if the PC rent goes unrecognized and the intraocular manipulations (like nucleus rotation or anterior chamber depth fluctuation) continue so that the rent enlarges. Hence, the importance of suspicion and early detection of a PC rent cannot be overemphasized. Early detection enables the surgeon to adopt an appropriate strategy for managing the residual nucleus thereby minimizing the potential for complications.

INTRAOCULAR LENS IMPLANTATION Implantation of a PC IOL in-the-bag should be as atraumatic as possible. Even a slight stretch or stress on the posterior capsule during IOL implantation may

Posterior Polar Cataract

tear the compromised posterior capsule. The author has experienced PC tearing in a PPC case while trying to dial the trailing haptic of a multipiece foldable IOL. A cohesive OVD should be injected into the capsular bag without overpressurizing it to open up the bag sufficiently for safe entry of the IOL. A single piece hydrophobic acrylic IOL is preferred due to its controlled release from the injector. The IOL is gently implanted taking care that the leading haptic is placed just under the anterior capsule without touching the posterior capsule.

Choice of Intraocular Lens in Patients with Compromised Posterior Capsule In case a definitive PCCC has been achieved in an eye with a PCR, an in-the-bag fixated posterior chamber IOL can be safely considered, but in the presence of a large PCR, the posterior chamber IOL should be implanted in the ciliary sulcus if there is adequate capsulo-zonular support. A multipiece PC IOL is the ideal IOL for the ciliary sulcus and a single piece hydrophobic acrylic PC IOL is a strict contraindication for sulcus placement.60 A posterior “optic capture” is performed by capturing the optic through the anterior capsulorhexis if the anterior rhexis is stable and reasonably well centered.61,62 Optic capture helps in long-term centration and stability of a sulcus fixed PC IOL. In preparation for sulcus placement and optic capture of the PC IOL, OVD is injected between the anterior capsule and the iris to flatten the peripheral capsular bag opposite to the incision to guide the leading haptic to the ciliary sulcus. A small amount of OVD is also placed in the capsular bag to facilitate the subsequent optic capture. The multipiece IOL is then injected into the eye with the leading haptic directed to the opposite ciliary sulcus and the trailing haptic in turn is dialed into the sulcus. Optic capture is achieved by gently guiding the optic edge (engaging it centrally midway between the two haptics) behind the rhexis rim by tilting and pushing it posteriorly using a Sinskey type hook. The opposite optic edge is also subjected to a similar maneuver so that the total optic capture is obtained. Once a perfect capture is achieved, the rhexis edge will appear oval anterior to the optic except at the optic–haptic junctions. The residual OVD should be removed as completely as possible and it is better to employ the bimanual anterior vitrectomy system which allows piecemeal and gradual removal of the OVD. The residual OVD in the bag stays sequestered and it may be left there for gradual spontaneous absorption by natural processes. A patient with a PCR should be followed-up to detect retinal breaks cystoid macular edema, etc. over a period of time.

POSTERIOR POLAR CATARACT WITH SPONTANEOUS DISLOCATION OF NUCLEUS Delaying cataract surgery in an eye with PPC may result in spontaneous rupture of the PC and dislocation of the lens matter in the vitreous.36,37 Progressive nuclear sclerosis may exert pressure on the PC, which may give way due to its inherent anatomical weakness leading to spontaneous dislocation.36

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Such eyes are preferably managed through the posterior approach by pars plana vitrectomy and lensectomy. The options for visual rehabilitation for such eyes include Kelman design Multiflex ACIOL, iris sutured PC IOL, or sclerally fixated (sutured/unsutured) PCIOL.63-65

SURGERY FOR POSTERIOR POLAR CATARACT IN CHILDREN Posterior polar cataract is present in 7–9% of children undergoing congenital cataract surgery.66,67 In majority of these eyes, unlike in adult eyes, PPC occurs as unilateral cataract (93%).66 The preexisting PC defect in these pediatric eyes with congenital cataract does not seem to be a manifestation of an associated anomaly with PPC. Vasavada et al. reported a case series of 400 eyes undergoing surgery for congenital cataract where a PC defect was present in 7% of eyes. The defect appears to be a distinct entity characterized by well-demarcated thick margins, chalky white spots in a cluster or a rough circle on the posterior capsule, and white dots in the anterior vitreous that move with a degenerated vitreous.34,68-71 The surgical principles in the management of PPC in these eyes are essentially the same as those for adults.68 The basic difference lies in the manner of dealing with the posterior capsule rent, where a posterior capsulectomy and anterior vitrectomy are performed with a vitrector. Surgical and other details being beyond the scope of this chapter, the reader is referred to standard textbooks on pediatric cataract surgery. Improvement of visual acuity (20/40 or better) has been reported in 84% of children after surgery for PPC.66

CONCLUSION Posterior polar cataract can be challenging for the novice and experienced surgeon alike. The incidence of PCR during phacoemulsification for PPC has dropped over a period of two decades. It climes down from 26–30%4,5 to 0–15%.43,48 This has happened due to an improved understanding of the pathoanatomy of PPC combined with incorporation of appropriate surgical paradigm and evolving technology in the management of this challenging situation. A plethora of techniques has been reported in the literature which include avoiding cortical cleaving hydrodissection, employing hydrodelineation or hydro-free-dissection, and application of innovative slow-motion phacoemulsification techniques for various grades of nucleus within a stable closed chamber. In spite of all precautions, PCR may still be encountered which when managed properly will result in an outcome not different from a routine case.

REFERENCES 1. Lee MW, Lee YC. Phacoemulsification of posterior polar cataracts a surgical challenge. Br J Ophthalmol. 2003;87:1426-7. 2. Masket S. Consultation section: cataract surgical problem. J Cataract Refract Surg. 1997;23:819-24.

Posterior Polar Cataract 3. Vogt G, Horvath-Puho E, Czeizel E. A population-based case control study of isolated congenital cataract. OrvHetiz. 2006;147(23):1077-84. 4. Osher RH, Yu BC-Y, Koch DD. Posterior polar cataracts—a predisposition to intraoperative posterior capsular rupture. J Cataract Refract Surg. 1990;16:157-62. 5. Vasavada A, Singh R. Phacoemulsification in eyes with posterior polar cataracts. J Cataract Refract Surg. 1999;16:38-45. 6. Vogt A. Weitere Ergebnisse der Spaltlampenmikroskopie des vorderen Bulbusabschniltes III. Abschnitt. Angeborene und friiherworbene­ Linsenveränderungen. Albrecht von graefe Arch Ophthalmol. 1922;107:196-240. 7. Cordes FC. Types of congenital and juvenile cataracts. In: Haik GM (Ed). Symposium in diseases and surgery of the lens. St Louis: CV Mosby; 1957. pp. 43-50. 8. Gifford SR. Congenital anomalies of the lens as seen with a slit lamp. Am J Ophthalmol. 1924;7:678-85. 9. Nettleship E, Ogilvie FM. A peculiar form of hereditary congenital cataract. Trans Ophthalmol Soc UK. 1906;26:191-207. 10. Szily AV. The Doyne Memorial Lecture. The contribution of pathological examination to the elucidation of the problems of cataract. Trans Ophthalmol Soc UK. 1938;58(II):595-660. 11. Eshagian J. Human posterior subcapsular cataract. Trans Ophthalmol Soc UK. 1982;102:364-8. 12. Bernheimer S. Zurkentis des angeborenen Linteren Polstares des Minschen. Arch Augenheilkd. 1913;74:8-12. 13. Hiles DA, Chotiner B. Vitreous loss following infantile cataract surgery. J Pediatr Ophthalmol. 1977;14:193-9. 14. Yamada K, Tomita HA, Kanazawa S, et al. Genetically distinct autosomal dominant posterior polar cataract in four generation of a Japanese family. Am J Ophthalmol. 2000;129:159-65. 15. Ionides ACW Berry V, Mackay DS, et al. A locus for autosomal dominant posterior polar cataract on Chromosome IP. Hum Mol Genet. 1997;6:47-51. 16. Primrose DA. A slowly progressive degenerative condition characterised by mental deficiency, wasting of limb musculature, bone abnormalities including ossification of pinnae. J Ment Defic Res. 1982;26:101-6. 17. Sacbφ J. An investigation into the mode of hereditary of congenital and juvenile cataracts. Br J Ophthalmol. 1949;33:601-29. 18. Hayashi K, Hayashi H, Nakao F, et al. Outcome of surgery for posterior polar cataracts. J Cataract Refract Surg. 2003;29:45-9. 19. Ghosh YK, Kirkby GR. Posterior polar cataract surgery—a posterior segment approach. Eye. 2008;22:844-8. 20. Hejtmanick JF, Piatigorsky J. Lens proteins and their molecular biology. In: Albert DM, Jakobiec (Eds). Principles & Practice of Ophthalmology, 3rd edition. Philadelphia: Saunders. 2008;1(105) 21. Addison PK, Berry V, Ionedes AC, et al. Posterior polar cataract is the predominant consequence of a recurrent mutation in the PITX3 gene. Br J Ophthalmol. 2005;89:138-41. 22. Berry V, Francis P, Reddy MA, et al. Alpha B crystalline gene (CRY AB) mutation causes dominant congenital posterior polar cataracts in humans. Am J Hum Genet. 2001;69:1141-5. 23. Liu M, Ke T, Wang Z, et al. Identification of a CRYAB mutation with an autosomal dominant posterior polar cataract in a Chinese family. Invest Ophthalmol Vis Sci. 2006;47:3461-6.

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Gems of Ophthalmology—Cataract Surgery 24. Semina EV, Ferrell RV, Mintz-Hittner HA, et al. A novel homeo box gene PITX3 is mutated in families with autosomal dominant cataract and ASMD. Nat genet. 1998;19:167-70. 25. Berry V, Yang Z, Addison PF, et al. Recurrent 17 bp duplication in PITX3 gene is primarily associated with posterior polar cataracts (CPP4). J Med Genet. 2004;41:e109. 26. Burdon KP, Mc Kay JD, Wirth MG, et al. The PITX3 gene in posterior polar congenital cataract in Australia. Mol Vis. 2006;12:367-71. 27. Pras E, Mahler O, Kumar V, et al. A new locus for autosomal dominant posterior polar cataract in Moroccan jews map to chromosome 14q22-23. J Med Genet. 2006;43:e50. 28. Singh D, Worst J, Singh IR, et al. Cataract and IOL. New Delhi, India: Jaypee Brothers Medical Publishers (P) Ltd.; 1993. pp. 163-5. 29. Shroeder HW. The management of posterior polar cataract: the role of patching and grading. Strabismus. 2005;13(4):153-6. 30. Francois J, Lambrecht’s J. Cataractepolaireposte’rieurecongenitaleet èvolutive á hèrèditèdominante. Boll Socbelge Ophthalmol. 1950;96:684-94. 31. Maumeene IH. Classification of hereditary cataracts in children by linkage analysis. Ophthalmology. 1979;86:1554-8. 32. Harman NB. New pedigree of cataract—posterior polar, anterior polar and microphthalmos. Trans Ophthalmol Soc UK. 1909;29:296-306. 33. Greeves RA. Two cases of Microphthalmia. Trans Ophthalmol Soc UK. 1914;34:289-300. 34. Bateman JB, Phillipart M. Ocular features of Hagberg-Santavuori syndrome. Am J Ophthalmol. 1950;96:684-94. 35. Duke-Elder S. Congenital deformities. Part 2. Normal and Abnormal Development. Syst Ophthalmol. Vol III. St Louis: CV Mosby; 1964. pp 723-6. 36. Ho SF, Ahmed S, Zaman AG. Spontaneous dislocation of posterior polar cataract. J Cataract Refract Surg. 2007;33:1471-3. 37. Ashraf H, Khalili MR, Salouti R. Bilateral spontaneous rupture of posterior capsule in posterior polar cataracts. Clin Exp Ophthalmol. 2008;36:798-800. 38. Crouch ER Jr, Parks MM. Management of posterior lenticonus complicated by unilateral cataract. Am J Ophthalmol. 1978;85:503-8. 39. Khalil M, Saheb N. Posterior lenticonus. Ophthalmology. 1984;91:1429-30. 40. Skalka HW. Ultrasonic diagnosis of posterior lens rupture. Ophthal Surg. 1977;8(6):72-6. 41. Hejtmanicik JF, Datilles M. Congenital and inherited cataracts. In: Tasman W, Jaeger EA (Eds). Duane’s Clin Ophthalmol. CD ROM edition. Vol 1. Baltimore, MD: Lippincott Williams & Wilkins; 2001. 42. Vasavada AR, Raj SM. Inside-out delineation. J Cataract Refract Surg. 2004;30:1167-9. 43. Kumar S, Ram J, Sukhija J, et al. Phacoemulsification in posterior polar cataract: does size of lens opacity affect surgical outcome? Clin Experiment Ophthalmol. 2010;38:857-61. 44. Das S, Khanna R, Mohiuddin SM, et al. Surgical and visual outcomes for posterior polar cataract. Br J Ophthalmol. 2008;92:1476-8. 45. Fine IH, Packer M, Hoffman RS. Management of posterior polar cataract. J Cataract Refract Surg. 2003;29:16-9. 46. Singh K, Mittal V, Harmit K. Oval capsulorhexis in phacoemulsification for posterior polar cataract. J Cataract Refract Surg. 2011;37:1183-8.

Posterior Polar Cataract 47. Fine IH. Cortico-cleaving hydrodissection. J Cataract Refract Surg. 1992;18:508-12. 48. Siatiri H, Moghimi S. Posterior polar cataract: minimizing risk of posterior capsule rupture. Eye. 2006;20:814-6. 49. Allen D, Wood C. Minimizing risk to the capsule during surgery for posterior polar cataract. J Cataract Refract Surg. 2002;28:742-4. 50. Aziz YA. Understanding hydrodelineation: The term and procedure. Doc Ophthalmol. 1994;87:123-37. 51. Osher RH. Slow motion phacoemulsification approach. (Letter) J Cataract Refract Surg. 1993;19:667. 52. Vasavada AR, Singh R. Step-by-step chop in situ and separation of very dense cataracts. J Cataract Refract Surg. 1998;24:156-9. 53. Osher RH, Cionni R, Burk S. Intraoperative complications of phacoemulsification surgery. In: Steinert RF (Ed). Cataract Surgery, Technique, Complications, Management, 2nd edition. Philadelphia: Saunders; 2004. pp. 469-86. 54. Vasavada AR, Raj SM, Vasavada V, et al. Surgical approaches to posterior polar cataract: a review. Eye. 2012;26:761-70. 55. Howard Fine. Bimanual microphaco advantages in posterior polar cataract. Eyeworld, 2006. 56. Haripriya A, Aravind S, Vadi K, et al. Bimanual microphaco for posterior polar cataracts. J Cataract Refract Surg. 2006;32:914-7. 57. Nagappa S, Das S, Kurian M, et al. Modified technique for epinucleus removal in posterior polar cataract. Ophthalmic Surg Lasers Imag. 2011;42:78-80. 58. Allen D. Cataract surgery in eyes with posterior polar cataracts. In: Chakrabarti A (Ed). Cataract Surgery in Diseased Eyes. New Delhi, India: Jaypee Brothers Medical Publishers (P) Ltd.; 2014. pp. 107-13. 59. Gimbel HV. Posterior capsule tears using phacoemulsification: causes, prevention and management. Eur J Implant Refract Surg. 1990;2:63-9. 60. Chang DF, Masket S, Miller KM, et al. Complications of sulcus placement of single-piece acrylic intraocular lenses: Recommendations for backup IOL implantation following posterior capsule rupture. J Cataract Refract Surg. 2009;35:1445-58. 61. Neuhann T, Neuhann Th. ‘The Rhexis-Fixated Lens,’ film presented at the Symposium on Cataract IOL and Refractive Surgery, Boston, MA, USA, 1991. 62. Gimbel HV, DeBroff BM. Posterior capsulorhexis with optic capture: maintaining a clear visual axis after pediatric cataract surgery. J Cataract Refract Surg. 1994;20:658-64. 63. Wagoner MD, Cox TA, Ariyasu RG, et al. American Academy of Ophthalmology. Intraocular lens implantation in the absence of capsular support: a report by the American Academy of Ophthalmology. Ophthalmology. 2003;110:840-59. 64. Monteiro M, Marinho A, Borges S, et al. Scleral fixation in eyes with loss of capsule or zonule support. J Cataract Refract Surg. 2007;33:573-6. 65. Hara T, Hara T. Ten-year results of anterior chamber fixation of the posterior chamber intraocular lens. Arch Ophthalmol. 2004;122:1112-6. 66. Mistr SK, Trivedi RH, Wilson ME. Preoperative considerations and outcomes of primary intraocular lens implantation in children with posterior polar and posterior lentiglobus cataract. J AAPOS. 2008;12:58-61. 67. Forster JE, Abadi RV, Muldoon M, et al. Grading infantile cataracts. Ophthal Physiol. 2006;26:372-9.

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Gems of Ophthalmology—Cataract Surgery 68. Vasavada AR, Praveen MR, Nath V, et al. Diagnosis and management of congenital cataract with pre-existing posterior capsule defect. J Cataract Refract Surg. 2004;30:403-8. 69. Vajpayee RB, Angra SK, Honavar SG, et al. Pre-existing posterior capsule breaks from perforating ocular injuries. J Cataract Refract Surg. 1994;20:291-4. 70. Vasavada AR, Praveen MR, Dholakia SA, et al. Preexisting posterior capsule defect progressing to white mature cataract. J AAPOS. 2007;11:192-4. 71. Vasavada AR, Praveen MR, Tassignon MJ, et al. Posterior capsule management in congenital cataract surgery. J Cataract Refract Surg. 2011;37:173-93.

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6

Multifocal Intraocular Lenses

Frank Joseph Goes

INTRODUCTION The second generation of multifocal intraocular lenses (IOLs) has led to renewed interest in their use to correct refractive errors, particularly in those patients who require higher levels of refractive correction and are not good candidates for corneal refractive surgery.1-7 The need for optimal refractive results in younger presbyopic patients has also opened the door to a new concept with multifocal IOLs—that of mixing and matching different designs—refractive and diffractive based on the needs of the individual patient, in order to provide a full range of vision—near, distant, and intermediate. In particular, the use of the Tecnis ZM900 and the ReZoom lens often provides the younger patients with reasonable functional vision without the need for spectacles. Our interest in multifocal IOLs is not new; we have gathered experience with several types of multifocal lenses over many years. It was started in 1985 with the use of the three-piece, 6-mm, polymethylmethacrylate (PMMA) 3M multifocal IOL. This technology was bought by Alcon in later years and we were involved in the one-piece refractive PMMA Storz True Vista study from 1992. Later, we began to implant the Alcon ReStor lens and the Crystalens. Interestingly, we have in 2004, we switched to the Tecnis ZM900 multifocal IOL in 2004; and in 2006, started combining Tecnis with the ReZoom IOL (Figs. 6.1 and 6.2). This chapter is based on our experience in implanting 400 Tecnis lenses bilaterally and additionally, 90 Tecnis combined with the ReZoom. All these eyes have a follow-up of at least 6 months.

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Fig. 6.1: Characteristics of the diffractive Tecnis multifocal IOL.

Fig. 6.2: Characteristics of the refractive ReZoom multifocal IOL.

TECNIS ZM900 The Tecnis ZM900 IOL is a three-piece foldable diffractive IOL of high-quality silicone with a near/far-light distribution of 50/50. The diffractive component consists of 32 concentric rings on the back surface of the lens and provides an optical power add of 4D corresponding with 3.2 D at the corneal plane. The lens comes in a power range of +5 to +34 D in 0.5 D steps. The −0.27-prolate

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anterior surface compensates for the positive spherical aberrations of the typical cornea, hence resulting in improved functional vision as reported for the monofocal model (8-9-10-11-12-13-). This technical feature is particularly relevant under low luminance condition because the amount of spherical aberration increases as the pupil size becomes larger. The light coming into the eye is distributed between the near and far focus, allowing a full range of vision independent of pupil size. The lens has the Z-SHARP optic edge technology, delaying early posterior capsular opacification (PCO) while minimizing edge glare. The overall diameter of the lens is 13 mm, with a 6.0 mm optic. The lens is available in hydrophobic acrylic material in Europe from 2008.

Rezoom Multifocal Intraocular Lens The ReZoom is a three-piece acrylic multifocal IOL with UV blocking and an OptiEdge design that is said to minimize edge glare while reducing the potential for PCO. The IOL is designed to provide for 100% light transmission in order to provide the full range of vision. The ReZoom multifocal, with its refractive design, has five focusing zones. From the outer edge of the lens toward the center, these are a low light/distance-dominant zone, a near-dominant zone, a distance zone, an additional near-dominant zone, and a bright light/distance dominant zone. Transitions between these zones are designed to provide intermediate vision with a design the company calls “Balance View Optics.” Patients implanted with a ReZoom multifocal are intended to have 100% light transmission over all five optical zones.1

SELECTION OF PATIENTS There are two groups of candidates or interested patients who seek implantation of multifocal IOLs. The first group consists of cataract patients. Some have heard about the possibility of multifocal lenses that correct both far and near vision; some have friends or relatives who had the procedure done with successful outcomes. These people, specifically if they are in the 60–75-year-old age group, are very interested in discussing this option. Some cataract patients have never heard about this refractive lens concept. If we do not mention the option of a multifocal concept, some of our patients will be upset later on when they find out that they have missed the opportunity to have one. The second group consists of refractive patients who specifically come in for refractive surgery: high hyperopes (greater than +4 D), moderate to low hyperopes with incipient reading problems at the age of 45 years or above, and presbyopic patients who have good distance vision but want to eliminate their reading glasses. We would not advise refractive surgery in presbyopic myopes with a clear lens since sooner or later a yttrium aluminum garnet (YAG) laser capsulotomy will have to be done, and we feel that the risk of complications (e.g. retinal detachment) is higher in myopes. It can be advised for myopes when there is some cataract. We have experience in performing at least 700 YAG laser

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capsulotomies in moderate to high hyperopes and have never seen a retinal detachment following a YAG capsulotomy. Rarely, RD occurs following laser capsulotomy in hyperopic patients. Generally speaking, the cataract patient group is less demanding than the refractive group. The ideal candidate to start with is a moderate hyperope (2–5 D) between 50 years old and 60 years old. One should be cautious about presbyopic individuals with good distance vision because they are usually very demanding.

PATIENT EXPECTATIONS General advices such as “underpromise and overdeliver” and “more chair time before surgery means less chair time after surgery” are well known, but what do these statements actually mean? It is a fact that our patients will always remember the very first things we say during our discussion. They should feel that we are confident but that we do not want to “oversell” the product; otherwise, it will backfire and discredit the technology. It is better to present your result on the basis of surgeries conducted in the past 1 year or 2 years and discuss the percentage of the spectacle-free patients after the procedure for all distances—far, intermediate, and near. It is always better to tell them that some will need time (1–3 months) to adjust to seeing at all distances. Some will have to get used to working closer to their desktop and/or laptop computer and only a minority will need to wear glasses for intermediate distances such as specific hobby tasks (Fig. 6.3). Of course, patients should be motivated and interested in becoming spectacle free or less spectacle dependent. Motivation is the key point; they should be willing to be patient with the process, recognize that it may take time to adapt to the new visual system, and have the means to pay for the added cost of Pr-C IOL surgery.

Fig. 6.3: Results of near vision with Tecnis MF.

Multifocal Intraocular Lenses

We are working together with AMO and my International Colleagues on a project to filter out those patients who will be unhappy at the end of the journey. This may have more to do with the patient’s personality than with the type of accommodative or multifocal lens implanted or the specific anatomical conditions of the eye. Much has been said regarding the adaptation of the brain but, at this point, we do not have a total understanding or a way to measure this function before implanting a lens. Some patients may experience problems like halos and glare, one cannot predict who will experience them, and that most patients often get used to them and may not be bothered after 1–3 months. We also tell our patients that the lens can later be exchanged, if necessary. Of course, one should also discuss the patient’s hobbies and activities, such as driving and computer work. Patients should enter the process with a firm understanding of possible side effects, and the final decision must come from the patient himself. Two bus drivers were recently operated with custom mixing of ReZoom–Tecnis multifocal and they experienced no problem with night driving because they were advised to be seated high and look down at the upcoming car headlights and not right into it. Also, the disturbing subjective complaints may decrease in many patients after a touch-up for residual refractive errors, after implantation of an IOL in the second eye, or with time due to neuroadaptation. Halos and unwanted images will remain significant in approximately 5% of patients and this is the same for all types of multifocal IOLs. This group of patients can still drive at night although they may not like to do so.

PREOPERATIVE TESTING It is logical that prospective candidates for a multifocal lens should have normal and healthy eyes. Diabetes (under medical control) and other systematic general conditions are not exclusion criteria. Accurate biometry (preferentially with the IOL Master) and IOL power calculation is a “conditio sine qua non”, especially for long myopic eyes where there is a staphyloma; and, in short eyes where differences of 0.1 mm have an enormous impact on the IOL power calculation. At least 2, and preferentially 3, formulae are used for multifocal IOL calculation: the Haigis formula, combined with Holladay II formula, both formulae are excellent for all axial length calculations. The SRK T is excellent for long myopic eyes and the Hoffer Q formula is outstanding for short hyperopic eyes. The constants are constantly updated on his website byHaigis and are 119.8 for the Tecnis ZM900 and 118.8 for the ReZoom lens (Fig. 6.4). With the Tecnis IOL, the target should be +0.25 D to plano since a myopic outcome will bring the reading distance too close. The refractive target should be plano with the ReZoom IOL. Preoperative astigmatism of more than 1.5 D should be a relative exclusion criterion for novices since the immediate effect of the multifocal lens would be diminished. Laser-assisted in situ keratomileusis (LASIK)

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Fig. 6.4: Distance VA with the Tecnis MIOL uncorrected and best corrected.

enhancement or limbal relaxing incisions (LRIs) can solve this problem, but the patient should be informed about it beforehand.

SURGICAL TECHNIQUE The surgery is performed under topical anesthesia. The patient is examined the day 1, day 14, and day 30 postoperatively. The site of incision is given according to the preexisting astigmatism; superiorly when the astigmatism is 0.75 D or more with-the-rule, and temporally for all other cases. The corneal incision is more anteriorly when astigmatism is 2D. Since LRIs are not predictable enough, we perform them only when the preexisting astigmatism is significant (more than 4 D). Generally, a 3.0 mm clear corneal incision is made with a diamond knife. The anterior chamber is filled with Healon GV or Healon 5 (AMO). The capsulorhexis should be 5.5–6.0 mm in diameter and preferably central and circular. Routine phacoemulsification was sometimes limited to aspiration only because of the soft structure of the patient’s natural lens.

IMPLANTATION TECHNIQUE OF TECNIS OR REZOOM Intraocular lens loading of these multifocal IOLs should be done by the surgeon under the microscope using the Silver Series unfolder. The different steps are nicely highlighted in the company brochure—that comes with the lens. Always have a back-up lens available; a novice surgeon will have to discard, because of damage during the loading procedure some lenses (around 5–10%Tecnis MF in the first 20, this will drop to 1% with experience). Carefully ensure that the lens presents itself nicely with the leading haptic protruding toward the tip when you advance the knob. Use sufficient viscoelastic material such as Healon GV or Healon 5 to fill the capsular bag. Slowly release the IOL as you would turn a pancake around.

Multifocal Intraocular Lenses

Once the optic becomes visible, proceed very slowly and the lens will unfold itself. Once the optic is in the capsular bag, retract the plunger of the unfolder and use a Sinskey hook to deliver the trailing haptic into the capsular bag. Since viscoelastic is used in a large amount, take care to thoroughly aspirate it out and go beneath the IOL with the irrigation–aspiration tip as well. The corneal wound is hydrated at the end of surgery and one drop of prednisolone acetate 5 mg/mL and polymyxin B sulfate/3500 IE-Predmycin P is administered. Afterward, these drops are continued for three times a day for 4 weeks. The Tecnis ZM centers remarkably well by itself due to the broad C-haptics, even with an oval or asymmetric capsulorhexis. We never suture the wound unless we have had to enlarge it.

Enhancement and Lens Exchange When a touch-up for residual refractive error (spherical or astigmatic) may be advisable, we prefer to use LASIK or Epi-LASIK (in case of a thin or irregular cornea) and wait until at least 3 months after the surgery. Our present enhancement rate is 10%, going down from 20% for the initial cases.

Intraocular Lens Exchange We have never been forced to explant either the Tecnis or the ReZoom. When faced with an extremely unhappy patient, one should exclude all other possibilities before considering an IOL exchange.A subjectively unsatisfactory outcome for the patient may be the result of residual refractive error, posterior capsule opacification that can be cured with YAG laser capsulotomy, or a retinal abnormality that can be demonstrated with optical coherence tomography. Even when you are convinced that the multifocal optic is the cause of persistent complaints, try to postpone doing an IOL exchange for as long as possible, at least 6 months.

Staged Implantation and Custom Mixing of IOLs Diffractive lens—Tecnis—ZM900 provides good distance vision and excellent near vision and a refractive lens—ReZoom—provides an excellent distance and intermediate vision but performs weaker for near vision. We should select the multifocal lens by considering hobbies and professions of patients. Therefore, we prefer a staged implantation of the two eyes (Fig. 6.5). Considering the profession of the patients, it is found that: •• A frequent computer user may be better off with bilateral ReZoom to provide good intermediate range. •• A professional car or truck driver who must also drive at night will be best off with a Tecnis aspheric monofocal IOL in both eyes. •• An avid reader, such as a librarian, will be better off with a Tecnis multifocal in each eye.

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Fig. 6.5: Mean near, intermediate and distance binocular visual results.

•• An outdoor enthusiast or golfer might feel better with a ReZoom in each eye. •• A person with strong motivation for complete spectacle dependence will be a candidate for a mix and match. Surgery is done first in the dominant eye, with the plan of operating on the second eye within 1–2 weeks.

Which Lens in Which Eye? •• If the major activities are distance dominant, ReZoom is implanted in the dominant eye. •• If the major activities are near dominant, Tecnis multifocal is implanted in the dominant eye. •• We evaluate the first eye outcome after 7–10 days and query the patient about his or her satisfaction. If he or she is completely happy, we choose the same lens for the other eye. •• If a ReZoom patient complains of inadequate near vision, we implant a Tecnis multifocal in his or her second eye. •• Finally, if a Tecnis multifocal patient complains of inadequate intermediate vision, we may implant a ReZoom in his or her second eye.

REFRACTIVE LENS EXCHANGE CUSTOMIZING–MIXING AND MATCHING TECNIS–REZOOM The concept behind “Mix and Match” is to provide patients with the best possible range of vision without significant visual tradeoff. The most appropriate patients for the “Mix and Match” approach are those who are motivated to become spectacle free. The best candidates will also be able to understand the concept of the “Mix and Match” approach and that it may take a number of months to adapt to this new visual system. We report on the initial visual outcomes in 140 eyes of 70 patients implanted with a ReZoom multifocal in their dominant eye and a Tecnis ZM900 in their non-dominant eye 1–2 weeks later. One hundred and twenty eyes were hyperopic (Range: +0.50 to 6.75 D, Mean SE = 2.62 D, SD ± 1.085 D), 12 eyes had a myopic spherical equivalent (−0.25 to −2.50 D), and eight eyes were 0.00 D. For all eyes, the preoperative SE was 2.17 D (SD ± 1.417 D). The mean

Multifocal Intraocular Lenses

preoperative best corrected visual acuity (BCVA) was 0.84, while the mean preoperative binocular BCVA was 0.94. All patients except 10 underwent refractive lens exchange (RLE) with the remaining patients undergoing cataract surgery with lens replacement. Exclusion criteria included corneal or retinal pathology and history of glaucoma or retinal detachment.

Intraocular Lens Power Calculation and Surgery All IOL power calculations and surgeries were carried out by the same surgeon (FG). Biometry was done with the IOL Master (Carl Zeiss, Carl Zeiss-Meditec, Jena, Germany). The targeted refraction was emmetropia to 0.25 D in the Tecnis eye and emmetropia in the ReZoom eye. Patients underwent either RLE or cataract surgery on an outpatient basis using a standardized procedure under topical anesthesia. Both eyes were operated with a 1–2 weeks interval. After surgery, patients were sent a subjective lifestyle questionnaire. Binocular acuities were recorded at distance, intermediate, and near using appropriate test cards. Six months after surgery results were analyzed using the LogMAR acuities.

Measurements and Analysis Clinical data were collected preoperatively, at 1 week and 1–2 months and, again, at 6 months following surgery. The testing carried out included refraction, binocular uncorrected near, intermediate (60 cm = 24²), and distance vision, as well, preferential reading distance. Patients were asked to report any visual complaints or difficulties they experienced, as well as their level of spectacle independence.

RESULTS In terms of visual symptoms reported by patients, 40 out of 70 patients reported no subjective disturbance by glare or halos in both eyes, and 28 reported some glare and halos in both eyes. The halos and glare were severe and important in eight patients and present but easily accepted in the other 20 patients. Three patients required slightly tinted sunglasses in order to reduce glare. The second most frequently reported visual symptom was day glare. Three patients reported with night glare in both eyes. The majority of patients reporting visual side effects indicated that visual disturbances were more apparent at night but, in general, were not a significant problem and improved over time. The majority of patients reporting visual side effects indicated that visual disturbances were more apparent at night but, in general, were not a significant problem and improved over time. The mean binocular distance vision was 1.06 (±0.6 SD), the mean intermediate was 0.5 (±0.9 SD), and the mean binocular near vision was 1.1 (±0.4 SD) (Table 6.1 and Fig. 6.6). Only one patient required spectacle correction for reading. One patient did undergo a Lasik enhancement procedure in both eyes to correct a residual cylinder of −1.5 D and one needed YAG in two eyes.

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Fig. 6.6: Preferred reading distance with Tecnis eye (red) and ReZoom eye (blue).

A follow-up questionnaire was sent to all patients following surgery to gather subjective information regarding lifestyle after “Mix and Match” multifocal implantation. Of the 70 patients enrolled in the study, 46 completed and returned the questionnaire. Topics on the questionnaire included reading, television viewing, computer, and driving habits, as well as questions about the amount of time needed for adapting to multifocal vision, preferred eye (if any), and overall degree of satisfaction. Analysis showed that the majority of patients with some complaints of glare and halo are adapted very fast (1–3 months). They did see the rings but it did not disturb them as such. Only six patients could comment on a difference of subjective complaints between both eyes –4/6 were more disturbed by ReZoom 2/6 more by the Tecnis eye. Interim analysis showed that the average amount of time needed to adapt to their new vision was 33 ±7 days). Twenty-six patients reported that they had no preference of one eye over the other, while six based their preference on the UCVA results. Ten patients preferred the vision in their ReZoom eye, while the remaining four preferred the vision in their Tecnis ZM900 eye. There did

Multifocal Intraocular Lenses

Fig. 6.7: Results intermediate distance monocular 60 cm = 42 inches: Tecnis (reading).

not appear to be a correlation between patient preference and any residual refractive error. In terms of degree of satisfaction, 38 of the 46 respondents rated their satisfaction very good, while six rated it good and two rated it fair. When asked if they would recommend a “Mix and Match” approach to friends or relatives, 40 said yes, while five said yes, with some restrictions regarding expectations, and one no. In the meantime, this patient is improving since he needed reading glasses. One patient had still problems with intermediate vision. The differences between ReZoom eye and Tecnis eye were analyzed. The preferred reading distance in the ReZoom eye was 34.2 cm (13.7²) while it was 32 cm (12.8²) for the Tecnis eye. This is understandable since the effective reading add for ReZoom is lower (2,8 D) compared to Tecnis (3.2 D) (Fig. 6.7). Considering the reading at intermediate distances, 83% of ReZoom eyes could read Jaeger 5 at 60 cm (24²) but only 41% of Tecnis eyes could do the same at that this distance. Also the mean reading capability at 60 cm was different between both eyes; the mean was Jaeger 4.5 for Tecnis and Jaeger 6.7 for ReZoom. It is because of the design, the ReZoom which allows better reading at intermediate distances. To date, only one patient in this series required Nd:YAG capsulotomy.

REFERENCES 1. Lane SS, Morris M, Nordan L, et al. Multifocal intraocular lenses. Ophthalmol Clin North Am. 2006;19:89-105. 2. Hütz WW, Eckhardt HB, Rohrig B, et al. Reading ability with 3 multifocal intraocular lens models. J Cataract Refract Surg. 2006;32:2015-21.

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Gems of Ophthalmology—Cataract Surgery 3. Kohnen T, Allen D, Boureau C, et al. European multicenter study of the AcryS of ReSTORapodized diffractive intraocular lens. Ophthalmology. 2006;113:584.e1. 4. Blaylock JF, Si Z, Vickers C. Visual and refractive status at different focal distances after implantation of the ReSTOR multifocal intraocular lens. J Cataract Refract Surg. 2006;32:1464-73. 5. Chiam PJ, Chan JH, Aggarwal RK, et al. ReSTOR intraocular lens implantation in cataract surgery: quality of vision. J Cataract Refract Surg. 2006;32:1459-63. Erratum in: J Cataract Refract Surg. 2006;32:1987. 6. Sallet G. Refractive outcome after bilateral implantation of an apodized diffractive intraocular lens. Bull Soc Belge Ophtalmol. 2006;299:67-73. 7. Souza CE, Muccioli C, Soriano ES, et al. Visual performance of AcryS of ReSTORapodized diffractive IOL : a prospective comparative trial. Am J Ophthalmol. 2006;141:827-32.

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Advances in Intraocular Lenses

Mohan Rajan, Sujatha Mohan, Amrutha Padhaye, Moulindu Paul

INTRODUCTION Cataract surgery has come a long way. It has been a long journey, starting from intracapsular cataract extraction with aphakic glasses to large-incision extracapsular cataract removal with implantation of rigid posterior chamber lens, to coaxial microincision phacoemulsification with implantation of foldable posterior chamber lens implantation through a 1.8 mm incision. In the modern era of information technology and electronics, patients want quick visual recovery in order to resume their job/work on very next day of surgery. Expectations following cataract surgery today are not limited to just restoration of vision alone but wanting vision close to what a young normal patient has, in other words, qualitative emmetropia. Monofocal intraocular lens (IOL) provides either correction for distant or for near vision; the other part being corrected by spectacles. This may be cumbersome for someone who has never used glasses before but is still employed in a visually demanding profession. Though bifocal glasses achieve pseudoaccommodation, the user must learn to cope with loss of distance vision with down gaze and poor near vision except in down gaze. Monovision that is when one eye is made emmetropic and the second eye purposely made myopic by 2.5–3.0 D for near vision has also been accepted to restore multifocality but has the inherent limitation of loss of stereopsis, which is not well accepted in most patients. Multifocal IOLs and accommodative IOLs were introduced with the intention of overcoming this hurdle.

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MULTIFOCAL INTRAOCULAR LENSES History of Multifocal Intraocular Lenses Hoffer in 1982 was the first to hit upon the idea of a multifocal IOL after observing a patient who had 6/6 vision in spite of an IOL that was decentered by more than 50% of the pupillary area. Logistic problems prevented him from being the first surgeon to implant bifocal IOL. The credit goes to John Pierce in 1986 who designed the bull’s-eye style (Fig. 7.1) of the multifocal IOL. Dedicated research into optical designs along with the development of new surgical techniques has resulted in more effective multifocal implants.

Types of Multifocals 1. Refractive 2. Diffractive 3. Combination of diffractive and refractive. Multifocal IOLs can provide the ability to focus at different distances and can thus be used to provide better quality of life postcataract surgery.

Refractive Lens It is a bifocal IOL with central add surrounded by distance optical power (Fig. 7.1). The rays of light get refracted through it and form two foci—one for near and one for distance. However, the zone principle has the shortcoming of being dependent on the pupil size for full effect. There is a sudden loss of

Fig. 7.1: Bull’s-eye lens (2-zone).

Advances in Intraocular Lenses

vision in bright sunlight since constricted pupil blocks the distance segment of lens. It is poorly tolerated by persons who enjoy outdoor sports in which clear vision is required and by those with a small pupil.

Diffractive Lens The basic refractive power is provided by the anterior aspheric surface and the diffractive power comes from the multiple grooves on its posterior surface (Fig. 7.2). Forty-one percent of light is focused for distance vision and another 41% is focused for near vision. The remaining portion of light is distributed to higher orders of diffraction. Since this lens has a diffractive optical effect present at all points of the lens, even if the lens is decentered or the pupil is eccentric or deformed, lens will always supply power for distance and near vision. Thus diffractive IOLs are pupil-independent. However, there is still loss of contrast sensitivity due to light division. Glare and halos may also disturb the vision due to the concentric annular zones. Wallace et al.1 and Simpson noticed loss of contrast sensitivity and glare and halos with the implantation of this lens.

Foldable Multifocal Lenses 1. 2. 3. 4. 5. 6.

Allergan medical optics (AMO) array Allergan medical optics ReZoom Acritec twin set multifocal (MF) Tecnis MF AcrySof ReSTOR MF4-IOL Tech.

Fig. 7.2: 3M diffractive multifocal intraocular lens.

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Allergan Medical Optics ReZoom •• Foldable acrylic (Fig. 7.3) •• Three zones similar to array: Zones 1, 3, and 5 are distant dominant, and zones 2 and 4 are near dominant •• Triple-edged design (Fig. 7.4) with: 1. Rounded internal edge to reduce internal reflection. 2. Sloping side-edge which minimizes edge glare 3. Square posterior edge to facilitate 360°capsule contact •• Aspheric transition between the 5 zones provides a better intermediate vision and reduces glare and haloes. •• Less pupil dependent.

Fig. 7.3: Allergan medical optics (AMO) ReZoom.

Fig. 7.4: Triple-edged design.

Advances in Intraocular Lenses

Acritec Twin Set Diffractive Multifocal •• Foldable silicone, •• Bifocal diffraction IOL. •• There are two models: 1. Near dominant: 70% of light for near and 30% of light for distance focus (733 D) 2. Distant dominant: 70% of light for distance focus and 30% for near focus. With the implantation there is nearly 100% of light for near and distance bilaterally therefore a considerable improvement in contrast sensitivity. •• This lens gives a very good distance/near correction with promising results and spectacle independence. •• Due to the specific edge design of the lens with Fresnel structure contributing to the total refractive power, the lens is extra thin. The anterior surface of the multifocal lens contains the diffractive optic providing the lens with a near addition of +4.0 diopters (Figs. 7.5A and B). •• Provides good near vision and at the same time giving functionally useful distance vision. Due to asymmetrical distribution of IOL there is not much loss of contrast sensitivity as compared to other bifocal IOLs.

Tecnis (AMO) Multifocal It represents the first IOL that has a wavefront designed, modified prolate, anterior-surface optic that neutralizes the positive spherical aberration of the human cornea.2

Fig. 7.5A

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Fig. 7.5B Figs. 7.5A and B: Acri-tec twin.

Its design is based on the average corneal-surface wavefront-derived spherical aberration in a group of patients, and the optic neutralizes this aberration.3 Tecnis IOL can significantly reduce spherical aberration in postoperative cataract patients.2,4 Most of the undesirable optical side effects of any single optic bifocal IOL are due to spherical aberration. Using the highly successful and stable Tecnis platform, optical engineers added a diffractive multifocal optic to the posterior surface of the lens. The result is the modified prolate Tecnis Multifocal (Figs. 7.6A and B).

ReSTOR •• It is an apodized diffractive IOL (Figs. 7.7A and B). •• Has two separate optical regions to provide quality vision at various distances •• A central apodized diffractive region is 3.6 mm wide and the peripheral refractive region contributes to distance focal point for a larger pupil diameter and is thus dedicated to distance vision. •• The central apodized diffractive region consists of 12 concentric steps of gradually decreasing (1.3–0.2 µ) steps heights provide a good range of vision for different distances. •• This lens incorporates +3.0D of additional power in lenticular plane for near vision, resulting in +2.5D at the spectacle plane. •• Apodization, which is a gradual reduction or blending of the diffractive step heights, is a special feature of AcrySof ReSTOR IOL. This technology

Advances in Intraocular Lenses

A

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Figs. 7.6A and B: (A) Tecnis multifocal lens; (B) Tecnis multifocal.

B

A

Figs. 7.7A and B: ReSTOR.

optimally manages light energy delivered to the retina, because it distributes the appropriate amount of light to near and distant focal points, regard less of the lighting situation resulting a better quality of vision. Features •• Central concentric diffractive steps—largest at center, smallest at refractive/ diffractive junction •• The pupil constricts to a greater proportion of light—near focus •• Pupil dilates to greater proportion of light—distance focus •• Distance dominance in night driving •• Near dominance in reading •• No reduction in contrast sensitivity.

MF4-intraocular Lens Tech •• •• •• •• ••

Hydrophilic foldable acrylic Four annular zones (Fig. 7.8) Two zones for distance, 2 zones for additional 4 D for near SRK II formula used for IOL power calculation 4.5–5 mm capsulorhexis required.

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Fig. 7.8: MF-4 intraocular lens.

WHY ACCOMMODATIVE LENSES? WHY NOT MULTIFOCALS? Multifocal IOLs can result in undesirable photic phenomena like glare and haloes caused by a simultaneous projection of multiple focal points on the retina. Additionally, intermediate visual acuity with multifocal IOLs is significantly worse than that obtained with accommodative IOLs. However, an accommodating IOL not only restores functional near vision, but also gives high-quality intermediate and distance vision without distortion in images because only one image at a time is formed on the retina.

Road to Accommodation in the 21st Century Intraocular Lens The loss of accommodation is multifactorial and involves age-related changes in most elements of the lenticular system. There are many possible approaches to the development of an optical system which would change its refractive power, such as a lens filled with a solution that can change its refractive index in response to application of a local electric field5-9 or a set of lenses capable of changing the distance between them when an external force is applied.10 There have been numerous attempts at lens refilling using injectable semi-fluidic materials11,12 and inflating intracapsular balloons with fluidic substances.13 However, the results have been controversial and inconclusive. The anterior movement of the IOL during the effort for accommodation has been reported. The forward movement occurs due to increased vitreous pressure which arises following ciliary muscle contraction which redistributes

Advances in Intraocular Lenses

the mass posteriorly impinging on the anterior vitreous.14 An increased vitreous pressure is associated with a reduction in anterior chamber pressure which causes a pressure differential which induces an anterior movement of the pseudophakos. Near function is ascribed to the anterior displacement of lens and the accommodative change varies with the power of the implanted lens. Roughly, the IOL movement of 0.6 mm causes 1D of accommodation at the spectacle plane.15

Available Options 1. 2. 3. 4.

C and C vision at 45 Crystalens Human optics ICU Hinged/forced transducing haptics Anterior movement of optic in response to ciliary muscle contraction.

Features •• Excellent distance vision •• Good intermediate vision •• Excellent near vision.

Crystalens HD The Crystalens HD is a modified plate-haptic high-refractive index silicone IOL. It was approved by the FDA in 2003. It has a hinge at the junction of its haptic and optic, and T-shaped polyamide haptics at the end of the plates. At the two tips of each of the polyimide loops are two small disks, round on the right and oval on the left. When the round disk is on the right, the lens is oriented with the hinge on its anterior surface.

Optic Characteristics •• •• •• •• •• ••

Diameter 4.5 mm Shape: Biconvex Material: Biosil® A constant 119.00 Refractive index 1.427 Theoretical AC depth 5.55 mm.

Haptic Characteristics •• Overall length 11.5 mm (17–33.0 D) •• 12.0 mm (4–16.75 D) •• Material polyamide.

Mechanism of Action It is thought that under ciliary muscle contraction, increased vitreous pressure forces the Crystalens IOL optic forward (Fig. 7.9). An axial optic movement

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Fig. 7.9: Crystalens implanted in the bag.

of approximately 0.720 mm for a 20 D IOL is expected to correspond to a 1 D change in refraction. A forward movement of the corresponding anterior rotation of the ciliary body during near vision effort was found to be proportional to the accommodating capacity of the IOL. This lens was reported to result in excellent uncorrected distance and near visual acuity.16 Using laser interferometry with identical measurement protocol, pilocarpine caused a small backward movement of the Crystalens.15 Such backward movement should result in slight disaccommodation and therefore, should be counterproductive for an accommodative IOL.17

Disadvantages Even though Crystalens has a sharp optic edge, there is a junction phenomenon with PCO ingrowth behind the IOL optic along the haptic plates. Therefore, the incidence of PCO is predicted to be higher than the current conventional open loop IOLs. •• Ultrasound biomicroscopy (UBM) studies showed that during accommo­ dation, the mean reduction in anterior chamber depth (ACD) was 0.32 mm at 1 month (Figs. 7.10A and B). The mean narrowing of the sclera–ciliary process angle was 4.32° at 1 month. •• Anterior displacement of the Crystalens IOL and corresponding anterior rotation of the ciliary body occurred during near vision. The IOL displacement and rotation were proportional to the accommodation capacity.

Advances in Intraocular Lenses

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B

Figs. 7.10A and B: (A and B) Ultrasound biomicroscopy showing the change in anterior chamber depth with accommodation in an eye implanted with Crystalens suggesting definite movement of the intraocular lens with accommodative effort.

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Figs. 7.11A and B: Human optics accommodative lens.

Human Optics Accommodative Intraocular Lens •• Human optics accommodative lens (Model 1CU) is a one piece, threedimensional, foldable, and acrylic IOL. •• The optic is 5.5 mm and the IOL has a diameter of 9.8 mm (Figs. 7.11A and B). •• The modified haptics are intended to allow anterior movement of the lens optic on contraction of the ciliary muscle. •• 1CU is a deformable three-dimensional IOL that mimics the properties of human crystalline lens to some extent (Figs. 7.12A and B). •• Using laser interferometry, pilocarpine-induced ciliary muscle contraction caused a forward movement of 1CU IOL of 0.314 mm compared to randomized control group, which showed no IOL movement.18 •• The estimated accommodative effect, calculated from IOL movement data with ray tracing was less than 0.5 D in more than half the eyes examined.

Mechanism of Action Forward movement of the optic during contraction of the ciliary muscles was studied by Spalton and Marshal et al.19,20 and concluded, “Small forward movement of the 1CU IOL was seen with accommodation and the amount of the IOL shift was not sufficient to provide useful near vision.”

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Figs. 7.12A and B: (A) Relaxed ciliary muscle: Distant objects being focused on retina; (B) Contacted ciliary muscle: Near objects being focused on retina.

Disadvantages There have been a number of reported cases of “infolding” of 1CU haptics in front of the optic underneath the capsulorhexis and such photodocumented cases of haptic subluxation had to undergo explanation because of hyperopic PCO as compared to current sharp edge open IOLs.11

C and C Accommodative Intraocular Lens Characteristics •• 10.5 mm length, polyamide loops—11.5 mm •• Standard plate silicone lens—optic 4.5 mm •• Increase in vitreous cavity pressure → optic forward →1 mm movement = 2 D change.

Visiogen Dual Optic Accommodating Intraocular Lenses Characteristics •• Made by Visiogen, Irvine, CA, USA. •• The Synchrony IOL is a silicone lens that has two optics joined by spring mechanism. The anterior high-powered plus optic, 5.5 mm in diameter, and a complementary minus-power optic work together to produce an accommodative effort of more than +2.75D. The optics diverge or compress together according to movements of the capsular bag. •• On accommodation, the distance between the lenses expands resulting in a more plus powered lens. •• The lens has two components, (i) anterior and (ii) posterior, each having a plate haptic design. •• Two haptics connected by bridge and work in concert with the capsular bag. •• The distance between two optics dictates the power adjustment.

Advances in Intraocular Lenses

Advantages •• Allows more accommodation than single optic IOLs, with less lens movement. •• Contrast or glare problems do not develop, unlike the multifocal IOLs.

Disadvantages •• Possibility of interlenticular opacification in between the two optics. •• Not as predictable as the multifocals in terms of visual outcome.

BioComFold •• •• •• •• ••

Manufactured by Morcher, Germany Hydrophilic copolymer of PMMA and polyHEMA Overall length 10 mm, Optic Biconvex 5.8 mm. Circular haptic ring with designed to prevent PCO formation. Peripheral bulging ring is connected to optics via intermediate forward angled 100 perforated ring section. •• Accommodative effort leads to central area moving forward. •• Elastic properties of the bulging ring permit the lens to return to initial position.

Newer Models (Animal Trials) •• Elliptical IOL designed by Baush and Lomb (Rochester, NY) is the Sarfarazi Elliptical IOL (Figs. 7.13A and B). •• Nulens (Herzliya, Israel) is based on the principle of compressible polymer between fixed plates so that on accommodative effort, there is bulge in the polymer through an aperture in the anterior fixed plate (Fig. 7.14). •• The power vision IOL redistributes peripheral fluid centrally on accommodation increasing the plus power of the optic (Fig. 7.15) The unpredictability in terms of amplitude of accommodation, incidence rates of PCO, and long-term centration are issues which need to be settled

A

B

Figs. 7.13A and B: Elliptical intraocular lens.

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Fig. 7.14: Nulens.

Fig. 7.15: Power vision intraocular lens.

before the accommodative IOLs gain widespread popularity. Thus a truly complete and ideal IOL is still amiss.

Microincision Lens •• Akreos MI60 •• Micriol •• Thin Optx.

Advances in Intraocular Lenses

Akreos MI60 Intraocular Lenses •• Material: –– 26% hydrophilic acrylic –– UV blocker –– Refractive index 1.458 (hydrated) •• Optic: –– Biconvex (Fig. 7.16) –– Aspheric anterior and posterior •• Optic body: –– 6.2 mm, from 10.0 dpt to 15.0 dpt –– 6.0 mm, from 15.5 dpt to 22.0 dpt –– 5.6 mm, from 22.5 dpt to 30.0 dpt •• Haptics: –– One piece –– 10° average angulation

Innovative Haptic Shape 1. Foundation zone: –– Formed by the optic and the haptic base (Fig. 7.17A). –– Stable portion of the lens. 2. Absorption zone: It bends under the contraction forces of the capsular bag (Figs. 7.17A to C).

Advantages •• Easy to inject (disposable injector)

Fig. 7.16: Akreos intraocular lens.

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•• •• •• •• ••

Small incision Aspheric optics Better contrast sensitivity Square edge (prevention of PCO) Antiglare technology.

A

B

Figs. 7.17A and B

Advances in Intraocular Lenses

Fig. 7.17C Figs. 7.17A to C: Haptic shapes.

Micriol Characteristics •• •• •• •• •• •• •• •• ••

Optic designed on a ray tracing program (Figs. 7.18A and B) Thinner lens design—Fresnel geometry + aspheric nature Acrylic material Rollable one-piece IOL Hydrophilic acrylic with polymerizable UV blocker Diameter: 11.00 mm A-constant: 118.2 Water content: 28% High refractive index.

Advantages •• •• •• •• •• ••

Aspheric surface eliminates spherical aberration Micriol reduces third order aberrations COMA relatively uniform thickness of optics Lowers astigmatic aberration—specialized submicron accuracy lathes Decreases curvature of field Sharper vision and reduction in distortion.

Thin Optx The lens has following characteristics: •• 100 µ thick •• 5.5 mm diameter, overall 11.2 mm •• Hydrophilic acrylic 18%.

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Figs. 7.18A and B: Micriol.

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E

Figs. 7.19A to E: Implantation of thin Optx lens.

•• 50–400 µ optic •• 50 µ plate haptic. The lens can be implanted through a less than 1.5 mm incision (Figs. 7.19A to E). The escalated perimeter of the lens allows it to be ultrathin without compromising extreme lenticular powers on the plus and minus side. The thickest part of the lens is 350 µm, and the haptic part of the lens is as thin as 50 µm.

Advances in Intraocular Lenses

NEWER EXCITING LENSES •• Smart lenses •• Light adjustable lens (LAL, Calhoun vision) •• Blue-filtering IOLs.

Smart Lens •• Made of thermodynamic hydrophobic acrylic material. •• Smart lens (Figs. 7.20A to D) fills the capsular bag on implantation (Figs. 7.21A to C), it cannot de-center, nor will it produce glare from any edge effect. •• Smart lens is reducible only to a 2.0 mm rod.

Light Adjustable Lens (Calhoun Vision) Characteristics •• Light adjustable lens (Fig. 7.22) is made of photosensitive macromers that respond to UV light to polymerize. •• Different intensities change toric as well as spherical powers. •• They reshape lens to correct higher order of aberration of cornea. •• It is a customized MG IOL.

A

C

B

D

Figs. 7.20A to D: Smart lens.

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A

B

C

Figs. 7.21A to C: Smart lens fills the capsular bag on implantation. (A) Rigid rod (at room temperature); (B) Changing to lens (at body temperature); (C) Soft gel lens (at body temperature).

Fig. 7.22: Light adjustable lens.

Blue Light-filtering Intraocular Lens There is a need for a blue light-filtering IOL because: •• We remove natural protection during ocular surgery •• Unnatural vision •• Concerns about overall health of retina •• Patients are living longer.

AcrySof® Single-Piece Design •• 0.04% covalently bonded, patented chromophore •• Light filtration designed to approximate the natural human crystalline lens

Advances in Intraocular Lenses

Fig. 7.23: AcrySof intraocular lens.

•• 6 mm, 13 mm, AcrySof hydrophobic acrylic. •• 1.55 refractive index •• Biconvex, unique modified L-shaped AcrySof haptic •• Material, unangulated 6–34 D (Fig. 7.23). The unique AcrySof single-piece design provides excellent flexibility, adaptable to different sized capsular bags.

Toric Intraocular Lenses For the past decade, ophthalmic surgeons have tried several methods to correct preexisting astigmatism during cataract eye surgery, including making incisions into the cornea to alter the shape of the eye. Now due to the introduction of the STAAR toric IOL, ND AcrySof Toric IOL, astigmatism can be reduced or corrected without further surgical intervention.

STAAR Toric Intraocular Lens STAAR Toric IOL restores focus to the eye when the natural lens or cataract is removed, but it is also designed to correct preexisting astigmatism using the same technology that has been successfully used in contact lenses. The STAAR toric IOL (Fig. 7.24) is designed for those cataract patients with 1.5–3.5 diopters of regular preexisting astigmatism. The lens has following characteristics: •• Single-piece foldable lens •• Specially designed to correct astigmatism, and help regain quality vision.

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Fig. 7.24: STAAR toric intraocular lens.

•• Only toric lens made from silicone, studies show this silicone lens provides greater optical performance and higher quality vision than acrylic lenses, with fewer “aberrations,” distortions in vision that lead to blurring, glare or halos.

AcrySof IQ Toric Intraocular Lens The AcrySof® IQ Toric IOL (Fig. 7.25) reduces astigmatism, for increased spectacle-independent distance vision and high patient satisfaction. It has following advantages: Unparalleled rotational stability: Proven biomechanics and biomaterial ensure minimal rotation—less than 4° average rotation 6 months after implantation. •• Stable force: Haptics keep AcrySof® IQ Toric highly stable and centered in the capsular bag. •• Flexible haptic design provides optimal placement in capsular bag, regardless of size. •• AcrySof® lens material binds to fibronectin, ensuring adhesion to the anterior/posterior capsule.21

Reduced Spherical Aberration •• AcrySof ® IQ toric is designed with negative spherical aberration to compensate for the positive aberration of the average cornea, which reduces both spherical and total higher order aberrations, for enhanced visual performance.22

Advances in Intraocular Lenses

Fig. 7.25: AcrySof® IQ toric intraocular lens.

•• Increased contrast sensitivity: Engineered to improve contrast sensitivity in low-light conditions, the aspheric design of AcrySof® IQ toric plays a vital role in image quality. •• Improved functional vision: Especially during night driving.

Aspheric Intraocular Lens Tecnis intraocular lens: Tecnis IOL has following features: •• Reduced spherical aberration (Figs. 7.26A and B). •• Improved functional vision. •• Improved night driving simulator performance. •• The TECNIS™ IOL corrects for −0.27 µ of spherical aberration, just like the average crystalline lens did between the ages of 19 years and 25 years (Fig. 7.27).

Effects of Aging •• With age, spherical aberration increases, reducing functional vision.22,23 •• The aging crystalline lens loses its ability to compensate for positive corneal spherical aberration. •• Spherical aberration causes diffusion of light resulting in blurred vision, reduced contrast sensitivity, and decreased functional vision. •• Patients with decreased functional vision may lack confidence in low-light situations or have difficulty with night driving or glare. •• Wavefront aberration analysis confirms that the average cornea of a cataract patient has +0.27 µ of spherical aberration throughout life.24

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A

B

Figs. 7.26A and B: Tecnis intraocular lens.

Best Possible Vision Targets Zero Spherical Aberration To rejuvenate vision to youthful levels, it is necessary to reduce or eliminate spherical aberration. IOLs provide excellent visual acuity but fail to properly address the increase in spherical aberration that occurs with age, leaving vision like that of an eye of a healthy older person. Tecnis is designed to reduce spherical aberration to zero.25,26

Advances in Intraocular Lenses

Fig. 7.27: Advantages with Tecnis intraocular lens.

INTRAOCULAR LENSES OF THE FUTURE The IOLs of future may be manufactured with hybrid polymers and improved design to minimize PCO and spherical aberrations. •• Hybrid polymers → Elastic Acrylics (higher refractive index of acrylics and elasticity of silicone) •• Squared posterior edge •• Completely fill the bag •• Filters protecting macula (current filters—380–450 nm) •• Biconvex IOL/meniscus IOL •• Customized wavefront adjustable IOLs.

REFERENCES 1. Lane SS, Morris M, Nordan L, et al. Multifocal intraocular lenses, Ophthalmol Clin North Am. 2006;19:89-105. 2. Artal P, Berrio E, Guirao A, et al. Contribution of the cornea and internal surfaces to the change of ocular aberrations with age. J Opt Soc Am A Opt Image Sci Vis. 2002;19:137-43. 3. Arens B, Freudenthaler N, Quentin CD. Binocular function after bilateral implantation of monofocal and refractive multifocal intraocular lenses. J Cataract Refract Surg. 1999;25:399-404. 4. Kershner RM. Retinal image contrast and functional visual performance with aspheric, silicone and acrylic intraocular lenses. J Cataract Refract Surg. 2003;29:1684-94. 5. Steinert RF, Post CT Jr. Brint SF. A prospective, randomized, double-masked comparison of a zonal-progressive multifocal intraocular lens and monofocal intraocular lens. Ophthalmology. 1992;99:853-60. 6. Vaquero-Ruano M, Encinas JL, Millan I, et al. AMO array multifocal versus monofocal intraocular lenses: long-term follow-up. J Cataract Refract Surg. 1998;24:118-23. 7. Bleckman H, Schmidt O, Sunde T, et al. Visual results of progressive multifocal posterior chamber intraocular implant. J Cataract Refract Surg. 1996;22:1102-7. 8. Gimbel HV, Sanders DR, Raanan MG. Visual and refractive results of multifocal intraocular lenses. Ophthalmology. 1991;98:881-8. 9. Weale R. Presbyopia towards the end of 20th century. Surv Ophthalmol. 1989;34:15-30.

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Gems in Ophthalmology—Cataract Surgery 10. Hara T, Hara T, Yesuda, et al. Accommodative intraocular lens with spring action: fixation in the living rabbit. Ophthalmic Surg. 1992;23:632-5. 11. Kessler J. Experiments in refilling of the lens. Arch Ophthalmol. 1964;71:412-7. 12. Haeflinger E, Parel JM, Fantes F, et al. Accommodation of an endocapsular silicone lens (Phaco-Ersatz) in the nonhuman primate. Ophthalmology. 1987;94:471-7. 13. Nishi O, Naka Y, Yamada Y, et al. Amplitude of accommodation of primate lenses refilled with two types of inflatable endocapsular balloons. Arch Ophthalmol. 1993;111:1677-84. 14. Strenk SA, Semmlow JK, Strenk LM, et al. Age-related changes in human ciliary muscle and lens. A magnetic resonance imaging study. Invest Ophthalmol Vis Sci. 1999;40:1162-9. 15. Holladay JT. Refractive power calculation for intraocular lenses in the phakic eye. Am J Ophthalmol. 1993;116:63-6. 16. Cumming JS, Slate SG, Chayet A. Clinical Evaluation of the model AT-45 silicone accommodating intraocular lens: results of feasibility and initial phase of FDA Clinical trial. Ophthalmology. 2001;108:2005-9. 17. Kohnen T, Koch DD. Clinical experience with available IOLs in cataract and refractive surgery. In: Krieglstein GK, Weinreb RN (Eds). Essentials in Ophthalmology Series. Berlin Heidelberg: Springer-Verlag; 2005. 18. Findl O, Kriechbaum K, Koeppl C, et al. Laser interferometric measurement of IOL movement with ‘accomodative’ IOLs. In: Guthoff R, Ludwig K (Eds). Current Aspects of Human Accommodation II. Heidelberg: Kaden; 2003. pp. 211-21. 19.   Catherine H, David S, Jo H, et al. Fellow eye comparison between the 1CU accommodative intraocular lens and the acrys of MA30 monofocal intraocular lens. Am J Ophthalmol. 2005;140:207-13. 20. Joanne H, David S, Catherine H, et al. Objective measurement of intraocular lens movement and dioptric change with a focus shift accommodating intraocular lens. J Cataract Refract Surg. 2006;32:1098-103. 21. Linnola RJ, Sund M, Ylonen R, et al. Adhesion of soluble fibronectin, laminin, and collagen type IV to intraocular lens materials. J Cataract Refract Surg. 1999;25:1486-91. 22. Guirao A, Tejedor J, Artal P. Corneal aberrations before and after small-incision cataract surgery. Invest Ophthalmol Vis Sci. 2004;45:4312-9. 23. Oshika T, Klyce SD, Applegate RA, et al. Changes in corneal wavefront aberrations with aging. Invest Ophthalmol Vis Sci. 1999;40:1351-5. 24. Scilley K, Jackson GR, Owsley C, et al. Early age-related maculopathy and selfreported visual difficulty in daily life. Ophthalmology. 2002;109:1235-42. 25. Artal P, Alcón E, Villegas E. Spherical aberration in young subjects with high visual acuity. Presented at: XXIV Congress of the European Society of Cataract and Refractive Surgeons. September 9–13, London, England; 2006. 26. Packer M, Fine IH, Hoffman RS. Functional vision, wavefront sensing, and cataract surgery. Int Ophthalmol Clin. 2003;43:79-91.

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Present Status of Phakic Intraocular Lenses in Modern Refractive Surgery Jorge L Alió, Jaime Javaloy

INTRODUCTION: WHAT IS THE ROLE OF PHAKIC INTRAOCULAR LENSES IN TODAY’S REFRACTIVE SURGERY? The correction of high refractive defects in young patients with phakic intraocular lenses (PIOLs) is widely accepted due to their good results in terms of refractive safety, efficacy, predictability and long-term stability, the maintenance of accommodation, the reversibility of the procedure, and the lack of need for investment in expensive surgical equipment such as the excimer laser units. Furthermore, the implantation technique is usually easy for ophthalmologists with experience in anterior segment surgery.1-4 In general terms, it can be said that phakic IOLs are indicated in cases where the refractive defects cannot be safely and effectively corrected by excimer or femtosecond laser in young patients who preserve reasonable amounts of accommodation. Potentially severe threats after using phakic IOLs have been described and include cataracts, corneal decompensation, uveitis or subclinical inflammation, pupil ovalization, glaucoma, angle closure, traumatic dislocation, and intraocular infections.1-3,5-8 The three types of PIOLs available—angle-supported anterior chamber lenses, iris-fixated lenses, and posterior chamber lenses—have different advantages and disadvantages, their most common indication being the correction of ametropia which exceeds the range of refractive defects that laser corneal surgery can safely or effectively correct in young people with preserved accommodation.9 Although there is some debate about the exact limits for laser surgery, it is normally accepted that other alternatives must be chosen when myopic defects are over 8–10 diopters (D) or hyperopia is over 5–6 D. In such circumstances,

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Gems in Ophthalmology—Cataract Surgery TABLE 8.1: Anterior and posterior chamber IOLs available in market. Model

Material

Power (D) Angle-supported IOLs

Kelman Duet

PMMA haptic, silicone optic

–6 to –16.5

Iris-fixated IOLs Artisan/Verisyse

PMMA, 1 piece

Myopia –1 to –23.5 Hyperopia +1 to +12 Toric +6 to –23, torus +1 to +7

Artiflex/Veriflex

PMMA haptics, polysiloxane optic

Myopia –2 to –14.5 Toric –1 to –13.5, torus –1 to –5

Posterior chamber IOLs ICL

Collamer

Myopia –3 to –23 Toric –6 to –23, torus +1 to + 6 Hyperopia +3 to +21

PRL

Silicone

Myopia –3 to –20 Hyperopia +3 to +15

the implant of a PIOL becomes an excellent option if the patient conserves a reasonable amount of accommodation. The range of dioptrical powers available on the market for CE or Food and Drug Administration (FDA) approved PIOLs is shown in Table 8.1. In this sense and taking into account the instability in young people, a higher retinal risk may lead to refractive lens exchange (RLE) in highly myopic eyes—the age range in which PIOLs are used varies from 25 years to 45 years for myopia and from 20 years to 40 years for hyperopia. The correction of astigmatism with PIOLs is usually indicated for the same reasons, but their use for treating refractive cylinders associated with corneal disorders (such as stable keratoconus with good corrected visual acuity) which counter-indicate corneal refractive surgery is increasingly accepted. Ophthalmic surgeons around the world divide their preferences for the three types of PIOLs basing their choice on personal experiences. The major advantages of angle-supported phakic IOLs (AS-PIOLs) are that they are very easy to insert and are simple to remove, and they are also completely visible in the anterior chamber in such a way that any complications may be detected easily. As the most frequently used AS-PIOLs (Fig. 8.1) are fully or partially foldable, induced astigmatism during the surgery is not a concern. However, the lack of models able to correct a preexisting refractive cylinder can be considered a limitation in the use of this kind of PIOLs. Some additional disadvantages of these lenses are related to the difficulty of ensuring an adequate centering in the pupil.10 Significant preoperative kappa or alpha angles can provoke haloes or dysphotopsia during the night. The pupils, however, are not always centered. Although larger optics in new models can compensate for this limitation, if pupillary ovalization happens the problem can be difficult to avoid.

Present Status of Phakic Intraocular Lenses in Modern Refractive Surgery

Fig. 8.1: Angle supported foldable PIOL AcrySof Cachet Alcon™ (Fort Worth, Texas).

Fig. 8.2: The iris claw Artisan® (Ophtec, Groningen, the Netherlands).

On the contrary, iris-fixated lenses (Fig. 8.2) can be centered over the pupil, but with the disadvantage that greater surgical skills are required for their insertion than for other kinds of lenses. In this way, a significant amount of the complications related to the use of these PIOLs are related to a deficient

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implantation technique. So, misalignments at the center of the pupil or insufficient iris enclavation depend on the dexterity of the surgeon. There is some controversy about the safety of these PIOLs regarding the endothelial cell survival. While some authors suggest that the absence of contact with the cornea guarantees a good maintenance of the corneal endothelium, other investigators assume that some degree of subclinical inflammation could play a role in deteriorating such delicate structure.2,11,12 Posterior chamber PIOLs (PC-PIOLs) represent perhaps the most frequently used alternative for the correction of high refractive defects today due to the simplicity of the surgical technique for the implantation and for their well proven safety, stability and predictability. Two different models of PC-PIOLs (Fig. 8.3) are available on the market today: The implantable collamer lens (ICL) and the phakic refractive lens (PRL) which is a silicone lens. The difficulty in the exact sizing of both (derived from the complexity in measuring the exact maximum diameter of the ciliary sulcus) can lead to complications related to an underestimation of the ideal size of the lens (mainly rotations, misalignments and cataract formation in the case of ICLs) or with the choice of an excessively large implant (pigmentary dispersion syndrome and glaucoma). Furthermore, lens decentration, and zonular dehiscence with IOL luxation into the vitreous cavity have been reported after implanting PRLs.13,14 The main technical features of the cited models will be detailed in next sections of this chapter. In spite of the fact that there are still no definitive reasons for choosing some particular models as especially advantageous for all preoperative conditions, we have made a table showing the strong and weak points for the main preoperative circumstances which will guide the surgeon to decide the best option in each situation (Table 8.2).

Fig. 8.3: The posterior chamber “Phakic Refractive Lens” PRL® Medennium Inc. (Irvine, CA, USA).

Present Status of Phakic Intraocular Lenses in Modern Refractive Surgery TABLE 8.2: Positive (blue) and negative aspects of the main marketed PIOLs. Anglesupported IOLs

Iris-fixated IOLs

Posterior chamber IOLs

Artisan/ Verisyse

Artiflex/ Veriflex

ICL

PRL

Model

Kelman Duet

Biocompatibility (material)*

+

+++

+

+++

+

High refractive defects (Range Power)**

+

+++

++

++/+++

+

Small incision (foldable)

+++

–

+++

+++

+++

Night vision (Optic diameter)

++

+++

+++

++/+++

++

Accuray for sizing adequately

++

+++

+++

+

+/++

Visibility of the implant

+++

+++

+++

+

+

Easy to implant

+/++

+

+

+++

+++

Cataract formation

++

++

++

+++

+++

Endothelial damage risk

+++

++

++

+

+

Risk for misalignment/ decentration

+++

+

+

++

++/+++

Pupil ovalization

+++

+

+

–

–

Glaucoma

++

+

+

++/+++

++/+++

Luxation to anterior chamber

+++

+++

+++

–

–

Luxation to vitreous chamber

–

–

–

+

+++

*Silicone is +, Hydrophilic materials are +++ **If toric models are not available, scoring is + Other complications as retinal risk or endophthalmitis are not considered as the risk when using different models should be the same

DIAGNOSTIC METHODS FOR A MODERN PHAKIC IOL INDICATION AS A SURGICAL PROPOSAL Although several pros and cons have been pointed out for the different models of phakic IOLs available on the market, the key to success when choosing laser refractive surgery or PIOLs or even different models of intraocular lenses, is obviously a correct indication. For achieving this goal, the ophthalmologist must combine knowledge, surgical skills, and the possibility to use the adequate technology for a correct assessment of each patient. The estimation of the power of a PIOL is not only based on biometrical records as occurs when calculating IOLs for pseudophakia. In 1988, Van der Heijde proposed a formula for such calculation taking into account the subjective refraction of the eye, the dioptrical power of the cornea and the anterior chamber depth (ACD).2,15 Most of the PIOL models base their software for calculations on this formula. Other morphological aspects have to be considered to avoid postoperative complications as detailed in the selection criteria section.

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The main parameters which must be measured before implanting PIOLs are: 1. The visual acuity and refraction 2. The dioptrical power of the cornea 3. Corneal thickness 4. Anterior chamber depth 5. Corneal endothelial cell density (ECD) 6. Pupil diameter 7. External (white-to-white) or, better, internal diameters as angle-to-angle either sulcus-to-sulcus distance.

Determination of Visual Acuity and Refraction As previously mentioned, special attention must be paid to obtain a precise subjective refraction. Some important issues have to be taken into account to avoid miscalculations: •• Soft or rigid contact lenses must be removed 1 and 4 weeks respectively before the preoperative assessment. •• Cyclopentolate refraction has to be estimated •• The optometrist must be sure that subjective refraction is performed using a trial frame which guarantees a correct distance from the lens to the corneal vertex of 12 mm. This aspect starts to be relevant from 4 D and appears as essential given the high refractive defect which is usually intended to be corrected with PIOLs.

Dioptrical Power of the Cornea Keratometric values can be obtained manually with the Javal-Schiotz or more commonly by automated keratometers, corneal topographers, or slitscanning corneal analyzers. They provide information about the elevation of both, the anterior and the back surfaces of the cornea. Other equipments include Orbscan (Bausch and Lomb, Rochester, NY, United States), Pentacam (Oculus, Wetzlar, Germany), Galilei (Ziemer, Port, Switzerland), or the Sirius (CSO, Firenze, Italy). Although stable and nonsevere ectatic diseases such as keratoconus are not considered today a counter-indication for the implantation of PIOLs, the surgeon must be aware of the existence of this pathology due to the obvious limitations regarding the postoperative visual acuity and the impossibility of safely correcting residual refractive errors by using excimer laser ablations.16,17

Corneal Thickness An untreated residual stromal bed (RSB) of at least 300 microns is accepted today to be safe after excimer laser surgery to avoid an iatrogenic weakness which could lead to progressive corneal deformity (ectasia).18-20 As it is possible for the surgeon to estimate the thickness of the flap in LASIK treatments and

Present Status of Phakic Intraocular Lenses in Modern Refractive Surgery

the rate of ablated cornea for each diopter to be treated, a safe RSB can be preserved if accurate measurements of central corneal thickness (CCT) are performed before surgery. So, corneal pachymetry is compulsory before taking a decision about whether excimer laser ablation or PIOL implantation is the technique of choice. Once a PIOL has been indicated, the estimation of the CCT is also important to determine the ACD consisting of the distance from the corneal endothelium to the anterior surface of the lens. A minimum ACD ranging from 2.7 mm to 3.0 mm is normally considered as compulsory for most of PIOLs in order to avoid postoperative complications such as endothelial cell damage or pupillary block.9 A precise calculation of CCT is necessary because many of the devices (in particular ultrasonic biometers) used for estimating the ACD perform the measurement from the corneal epithelium and so the CCT must be subtracted from this.

Anterior Chamber Depth The calculation of the anterior chamber depth (ACD) is fundamental for two reasons. First, it must be verified that there is sufficient space for its implantation without the risk of causing any damage to the internal structures or interference with the aqueous circulation. Secondly, as previously pointed out, the ACD value is used in the formulas to calculate the lens power. Table 8.3 contains the minimum requirements for ACD recommended by the manufacturers of most implanted PIOLs.9 The surgeon can use different devices for estimating this parameter, mainly echographic instruments [A-scan biometers, ultrasound biomicroscopy (UBM)] and optical systems [slit lamp or Scheimpflug corneal analyzers, anterior segment optical coherence tomography (OCT)]. A-scan biometry with a 20 MHz transducer is routinely used when estimating the power of a pseudophakic IOL before cataract or clear lens surgery. Apart from the subtraction of the CCT as mentioned before, it is important to avoid the compression of the cornea and misalignments of the eyeball. The first could cause a significant reduction in the true ACD and can be avoided by using immersion biometry. It is necessary to remember that after performing an immersion A-scan technique the echo from the front corneal surface will be detected separately and it will appear as an additional peak that TABLE 8.3: Minimum requirements regarding anterior chamber depth recommended by the manufacturers of most implanted PIOLs.9 ACD Requirements (Measured from Endothelium) Kelman Duet

>3 mm

Artisan-Verisyse/Artiflex-Veriflex

2.85 mm

ICL

2.85 mm for myopia, 3.0 mm for hyperopia

PRL

2.5 mm

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B

A

Figs. 8.4A and B: Immersion USG for biometry.

can be seen in Figure 8.4A. Correct orientation of the US probe can be checked by ensuring that all (cornea, lens, and retina) peaks reach an identical height in the graph obtained (Fig. 8.4B). Although, the determination of a central ACD value is compulsory even from the medicolegal point of view, obtaining a measurement of over the 2.7–3 mm usually required by the manufacturers—does not exclude the possibility of complications derived from the space of the anterior chamber such as angle closure. In this way, the anterior segment shape, angle aperture and iris configuration may differ in cases presenting the same ACD.21 A full examination of the anterior segment anatomy with very high frequency (VHF) ultrasonography as detailed later may assist the surgeon to perform safe implantations. Optical slit lamp or Scheimpflug corneal analyzers such as Orbscan (Bausch and Lomb, Rochester, NY, United States), Pentacam (Oculus, Wetzlar, Germany), Galilei (Ziemer, Port, Switzerland), or the Sirius (CSO, Firenze, Italy) can provide information about the ACD not only on the visual axis but on the whole space. However, it must be taken into account that measurements away from the visual axis can be affected by inaccuracy with these systems. However, anterior segment OCT is an excellent tool for measuring and imaging the complete anterior chamber as later described (Fig. 8.5).

Corneal Endothelial Cell Density The implantation of a PIOL may represent a threat to the corneal endothelium by different mechanisms. Physical permanent or transient contact (i.e. when rubbing the eye), insufficient ACD or subclinical inflammations have been involved in such damage.3 In fact, some models of PIOLs such as ICare (Corneal Laboratories, Inc.), GBR or Vivarte (Ioltech) were withdrawn from the market due to their well-reported ability to deteriorate the corneal endothelium.22

Present Status of Phakic Intraocular Lenses in Modern Refractive Surgery

Fig. 8.5: Anterior chamber image measured by anterior segment OCT (VISANTE Carl Zeiss Meditec Inc™, Germany).

More recently, AlconTM (Fort Worth, TX, United States) stopped the distribution of the AcryS of Cachet PIOL in several countries after detecting some cases of endothelial cell damage. Therefore, it is mandatory to analyze the corneal endothelial cell population before considering PIOL implantation. Although it is known that contact specular microscopes provide more accurate examinations than noncontact analyzers, the use of the former is normally reserved for experimental clinical research due to the simplicity in using the latter. It is accepted that at least 75–150 cells must be studied because of the heterogeneous distribution of the cells on the endothelial surface.23 Cell density, polymorphism and differences in size all need to be taken into account when evaluating the indemnity of the endothelium, although most clinical protocols establish the limit for implantation at a determined value ECD. It has been reported that there is a significant reduction in the number of cells during the first years after birth and that after the age of 20 a constant decrease in density should be expected estimated at a rate of 0.57–0.6% per year.24-26 It has also been reported that the endothelium has a considerable ability for functional reserve as just 10–15% of the total number of cells are capable of maintaining the cornea clear when critical values down to 500 cells/mm2 are reached.27 Taking into account the unavoidable damage caused by intraocular surgery, the presence of a PIOL in eyes with an ECD lower than 2,000 cells/mm2 should be excluded in patients over 25 and lower than 2,500 cells/mm2 in younger candidates. Although the ability of the different models to damage the corneal endothelium has proven to be different (greater for AC- and less for PC-PIOLs), similar requirements are demanded for all manufacturers.28

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In the same way, it has been suggested that PIOLs should be removed from the eye with ECD close to 1,500 cells/mm2 or when a significant drop of more than 50% compared to the preoperative ECD has been demonstrated.28 However, some authors have proposed theoretical regression models that would allow an estimation of the number of years in which a cornea could reach a critical value of ECD that would affect its clearness (around 500–700 cells/mm2).3

Pupil Diameter None of the PIOLs currently available have an optic diameter greater than 6 mm. As under scotopic conditions, some patients can experience a mydriasis which exceeds such magnitude, the existence of visual disturbances during the night is not an extraordinary phenomenon. In general terms, the chance of suffering photic symptoms during the night is lower with posterior chamber lenses than with angle-supported or iris-fixated lenses because the former are located behind the iris which increases the effective optical zone size.21 Anyway, in order to evaluate the risk of suffering these problems, a measurement of the pupil size must be performed under mesopic and scotopic conditions. A Holladay-Godwin pupillary gauge (ASICO, United States) can be easily used by the examiner placing the card close to the ocular surface and comparing the size of the pupil with the different calibrated black circles. More objective and accurate records can be performed by using pupillometers equipped with infrared light such as the Colvard pupillometer4 and computerized technologies like the Procyon P 3000 (Procyon, Stirling, United Kingdom) and the pMetrics (LIGI, Taranto, Italy).

External (White-to-White) or Internal Diameters (Angle-to-Angle and Sulcus-to-Sulcus Distance) The correct sizing of PIOLs is one of the most important and challenging aspects when considering their implantation. Given the impossibility of obtaining the exact measurements of the structures which will host the intraocular lens without using expensive technology, most of the manufacturers of AS- and PCPIOLs provide nomograms which try to estimate the angle-to-angle distance or the sulcus-to-sulcus as a function of the horizontal corneal diameter (whiteto-white distance). This measurement can be performed simply by using a manual caliper such as the Holladay-Godwin pupillary gauge (ASICO, United States) or a surgical one, but also by using devices which are present in many clinics such as optical biometers (IOL Master, Carl ZeissTM, Germany), or some corneal analyzers such as the Orbscan (Bausch and Lomb, Rochester, NY, United States), Pentacam (Oculus, Wetzlar, Germany), Galilei (Ziemer, Port, Switzerland), or the Sirius (CSO, Firenze, Italy). However, some authors have demonstrated the inaccuracy of the nomograms based on the white-to-white distance in predicting the exact angle-to-angle or—even more difficult—the sulcus-to-sulcus diameter.29-32

Present Status of Phakic Intraocular Lenses in Modern Refractive Surgery

In this way, some optical and ultrasonic devices may assist the surgeon to measure more accurately the angle-to-angle or sulcus-to-sulcus diameters, respectively. Visante OCT, Carl Zeiss Meditec Inc. is a noncontact high-resolution crosssectional imaging technique that uses low coherence interferometry to provide in vivo cross-sectional images of ocular structures with a spatial resolution of 10–20 mm. Using a 1310 nm infrared wavelength allows increased penetration in scattering tissues, such as the sclera and iris, and is able to perform up to 4,000 axial scans/s).33 The Visante OCT is designed to image the shape, size, and position of the structures of the anterior segment and make precise measurements of the distances between these, including corneal thickness and surface profile, anterior segment biometry (ACD, angle-to-angle distance, angle size in degrees), pupil diameter, and the thickness and radii of curvature of the crystalline lens. It has also proved useful in determining PIOL position and relation to the crystalline lens.34-36 The knowledge of the exact dimensions of the anterior chamber should assist the surgeon to adequately size the anterior chamber PIOLs (AC-PIOLs). Furthermore, this technology allows the quantification of the elevation of the anterior pole of the crystalline lens over the straight line which marks the angle-to-angle distance, which is called crystalline lens rise (CLR). If such a parameter is over 600 microns, the surgeon should exclude the case for the implant of a PIOL because of the high-risk to the eye of suffering PIOL-lens contact or pupillary block.35 Ultrasound biomicroscopes can be used for imaging both anterior and posterior chambers of the anterior pole of the eyeball. These devices use highfrequency ul­trasounds, between 35 MHz and 100 MHz, obtaining a resolution that is 10 times greater than 10 MHz conventional echographs. The resolution increases with the frequency of oscillation, but at the same time decreases the penetration in the tissues. So using UBM, it is possible to explore structures up to a depth of 4–5 mm, with a resolution of 40–50 μm, making it possible to create images for structures which are not accessible to optical devices such as the anterior chamber angle, iris, lens, zonules and ciliary body.37-41 Safety distances have been determined by UBM from the parts of the PIOLs to different structures of the eye such as the corneal endothelium or the crystalline lens,42,43 although some materials such as polymethyl methacrylate (PMMA) of rigid PIOLs cause interferences which makes measurement of the separation between the optic and the structures located below impossible. The first UBM (Paradigm P40) on the market explored the anterior segment of the eye using US at 50 MHz and providing excellent resolution. But one of the limitations for its use was the width of the explored field which made it impossible to measure the angle-to-angle or sulcus-to-sulcus distances. The newer model Paradigm P60 (Paradigm Medical Industries, Inc.) uses probes with US emitted at frequencies of 12.5 MHz, 20.0 MHz, 35.0 MHz, and 50.0 MHz. The best resolution is obtained by the 50.0 MHz probe, but for measuring the angle-to-angle or sulcus-to-sulcus distances, it is necessary to employ the 35 MHz probe.44

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Fig. 8.6: Ultrasonic biomicroscopic image.

The ultrasonic biomicroscope Paradigm P40 (Paradigm Medical Industries, Inc.) has been used for creating this image. The image is a photographic montage performed by the specular duplication of one 5 mm × 5 mm picture (Fig. 8.6). The Artemis 2 system (Ultralink LLC) uses a 50 MHz transducer that explores using an arc-scanning system which allows the imaging of the whole anterior segment. A complex software is able to generate 3-D biometric maps of the eye based on the exploration of several meridians.45,46

PHAKIC INTRAOCULAR LENS TYPES AVAILABLE ON THE MARKET •• Angle-supported phakic IOLs •• Iris-supported phakic IOLs •• Lens-supported phakic IOLs.

Angle-supported Phakic Intraocular Lenses In the decade of the 1950s, the first models of AC-PIOLs for correcting myopic defects were implanted, although without functional success in many cases due to the concurrence of complications such as endothelial cell damage, iritis, pupil ovalization or UGH (uveitis, glaucoma, hyphema) syndrome.47,48 During the last two decades of the past century, different models of ASPIOLs such as ZB1,4,49 and the ZB 5M50-52 (Domilens Corp.), the NuVita MA 20 (Bausch and Lomb),17,47,53,54 and the ZSAL-4 (Morcher GmbH)1,4,17 were marketed with designs able to avoid many of the previously mentioned

Present Status of Phakic Intraocular Lenses in Modern Refractive Surgery

complications. However, all these models were made with rigid materials (mainly PPMA), forcing the surgeon to perform incisions of 6–7 mm for their implantation inside the anterior chamber of the eye. This was an obvious limiting factor regarding the safety, refractive predictability, and delayed visual recovery after the surgery. The first models of total or partially foldable AS-PIOLs (Vivarte/GBR (Ioltech) and the I-Care (Corneal Laboratories, Inc.) were withdrawn from the market in 2006 and 2008, respectively, because of safety concerns related to endothelial cell loss.22 The same reasons led Alcon to stop the marketing of the fully foldable AcrySof Cachet in 2013. The only AS-PIOL which can be inserted by a small incision, approved by the FDA and CE mark currently on the market in Spain is the Kelman Duet PIOL. Tables 8.4 and 8.5 show the refractive results reported by the most relevant clinical studies using different models of PIOLs including AS-PIOLS.

TABLE 8.4: Comparison of different models of PIOLs in representative studies (model, spherical equivalent and dioptrical range). Refractive results after implanting different models of PIOLs Study

Follow-up

Model of PIOL

no eyes

Spherical equivalent (D)

PerezSantonja et al. (2000)

24 months

ZSAL-4 (Morcher)

23

–19.56 ± 1.76

–16.75 a –23.25

Leccisotti et al. (2005)

12 months

ZSAL-4 (Morcher)

190

–14.37 ± 4.40

–5 a –30

Alió et al. (2007)

12 months

Kelman Duet (Tekia)

169

–15.01 ± 4.53

–8.75 a –26

Javaloy et al. (2007)

12 years

ZB5M (Domilens)

225

–17.23 ± 7.69

–8.5 a –20

Budo et al. (2000)

3 years

Artisan (Ophtec)

518

–12.95 ± 4.35

–5 a –20

Tahzib et al. (2007)

10 years

Artisan (Ophtec)

89

–10.36 ± 4.69

–3.75 a –25.25

Stulting et al. (2008)

3 years

Artisan (Ophtec)

662

–12.4 ± 3.2

–4.6 a –21.9

Pallikaris et al. (2004)

24 months

PRL (Ciba Vision)

34

–14.70 ± 2.65

–10.5 a –20.75

Donoso y Castillo (2006)

12 months

PRL (Ciba Vision)

53

–17.27 ± 4.58

–8.75 a –31.5

Sanders et al. (2004)

3 years

ICL (STAAR)

526

–10.06 ± 3.74

–3 a –20

Alfonso et al. (2011)

5 years

ICL (STAAR)

188

–11.17 ± 3.40

–1.5 a –20

Range (D)

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Gems in Ophthalmology—Cataract Surgery TABLE 8.5: Comparison of different models of PIOLs in representative studies (model, safety, efficacy and refractive predictability). Study

Model of PIOL

Safety index

Efficacy index

Spherical equivalent % having ± 0.5 D

% having ± 1.0 D

PerezSantonja et al (2000)

ZSAL-4 (Morcher)

1.45

1.12

56.5

82.6

Leccisotti et al. (2005)

ZSAL-4 (Morcher)

1.25

0.78

19

40

Alió et al. (2007)

Kelman Duet (Tekia)

1.37

1.19

57.72

81.3

Javaloy et al. (2007)

ZB5M (Domilens)

1.50

1.26

33.92

39.28

Budo et al. (2000)

Artisan (Ophtec)

1.31

1.03

57.1

78.8

Tahzib et al. (2007)

Artisan (Ophtec)

1.10

0.80

43.8

68.8

Stulting et al. (2008)

Artisan (Ophtec)

–

–

71.7

94.7

Pallikaris et al. (2004)

PRL (Ciba Vision)

–

–

44

79

Donoso y Castillo (2006)

PRL (Ciba Vision)

1.40

1.0

–

71.2

Sanders et al. (2004)

ICL (STAAR)

67.5

88.2

Alfonso et al. (2011)

ICL (STAAR)

38

62

1.27 ± 0.33

0.89 ± 0.35

The Kelman Duet Angle-supported Phakic Intraocular Lens The Kelman Duet Implant (Tekia Inc., Irvine, CA, United States) is a two-part, AS-PIOL that is implantable through a small incision. The main advantage of this specific kind of lens is the exchangeability of both the lens haptic and optic. It is known that the human myopic eye may experience optical and refractive changes such as progressive myopia, presbyopia, or changes in lens asphericity throughout the life span. Exchangeability of the optic is an option that allows the implant to be adapted for these future refractive changes. This fact is one of the most important improvements in design provided by the Kelman Duet lens.55,56 Background and development: Anterior chamber lenses have had major successes, as well as some failures in the past. Most of these failures were due to deficiencies in the lens design. The tripod and multiflex designs have proved to produce good results. The duet lens is based on the successful principle of

Present Status of Phakic Intraocular Lenses in Modern Refractive Surgery

the tripod design. The main aim of the designers of this lens was to increase their versatility by introducing the concept of the partial exchangeability of the phakic implants and to reduce the invasiveness by creating a lens which could be inserted through a small auto-sealed incision. Design considerations: The Kelman Duet lens was designed to fulfill the following 10 conditions. 1. The haptic is designed to enter into the eye without an attached optic. This allows it to be snaked into place through an incision of approximately 2 mm. As the optic, when in place, will not be totally immobile with regard to the haptic, compressive forces on the haptic at the angle will not be transmitted to the optic, greatly increasing the flexibility of the haptic, without sacrificing stability. On examination of the assembled implant, one can see that the optic merely rides along the bayonet structures of the haptic, without being compressed when the haptic is moderately compressed (Figs. 8.7A and B). 2. The haptic is slightly larger than the diameter of the anterior chamber. It can be placed at the angle without undue compression of ocular angle tissue and its stability there, and maintains the haptic at the clock hour at which it was placed, with no tendency to propel into the chamber. 3. It is so designed that if haptic flex at a point away from the periphery, so that the haptic does not touch the peripheral endothelium. 4. There is a delicate balance between rubbing against the iris and rubbing against the peripheral endothelium, since the distance between these two is the least at the angle. The design of the implant has taken this

A

B

Figs. 8.7A and B: (A) The separated components and (B) the complex hapticoptic assembled of the Kelman Duet angle supported PIOL.

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into consideration. The implant was designed to allow the iris to dilate and constrict without touching the implant. 5. Damage to the endothelium while inserting an anterior chamber implant can occur prior to the unfolding of the implant; if the surgeon angles the implant upward toward the cornea, damage is more likely to occur during the unfolding. In other anterior chamber lenses, the haptics, which measure 12–13 mm from end to end, are much more likely to unfold against the endothelium than the tabs on the duet lens, which measure 7–8 mm, end to end. Haptics never unfold, but are snaked in, as previously described. 6. In other flexible anterior chamber lenses, the unfolding haptics can touch the natural lens. In the duet lens, the haptics are inserted in the horizontal plane, so that contact with the natural lens is much less likely. The unfolding optic, with the smaller overall dimension, is also less likely to touch the natural lens. 7. In planning surgery on a young person’s eye, the advantages of a minimal incision are obvious. Less astigmatism, infection, loss of chamber with unwanted endothelial contact, etc. are considerations which make the smallest incision the best incision. Due to its unique structure, the optic of the Kelman Duet lens can be greatly compressed without fear of damaging the haptic, which has already been inserted. 8. The insertion of the Kelman Duet lens is quite simple. It can be performed one-handed, or two-handed. 9. The removal of the optic is also quite simple, and is basically the reverse maneuver of the insertion. 10. It is not always easy to accurately predict the power of an implant to bring the eye to emmetropia, especially in high myopes. With the duet implant, it is a simple procedure to de-insert the optic, cut it in half for removal, and then couple a new optic with an adjusted power to the haptic, which is still in place.

Insertion Technique To obtain the deepest anterior chamber possible, it is advisable to use glycerin orally 1 hour prior to surgery and to perform ocular massage, similar to that used prior to cataract surgery. In sizing the lens, white-to-white plus 1 mm is used. The two-handed insertion is described here, but once the surgeon has experience, he may find that only one hand will be necessary. •• A 1 mm shelved incision is made at the 6 o’clock position, followed by a shelved incision (2.75 mm) at the 12 o’clock position. •• After injecting a miotic substance, viscoelastic material is inserted to replace the aqueous and to deepen the chamber slightly. It is important to direct the flow of the viscoelastic so that the anterior chamber is deepened, rather than directing it posterior to the iris, which would actually shallow the anterior chamber. •• It is advisable to perform a peripheral surgical iridotomy at this moment. •• The haptic is snaked into the anterior chamber through the 12 o’clock incision. At this time, it is easy, especially with gonioscopy to verify that

Present Status of Phakic Intraocular Lenses in Modern Refractive Surgery

Fig. 8.8: Kelman Duet phakic intraocular lens implanted.

••

•• •• •• •• ••

the three endplates are properly placed in the angle. It is also quite easy to reposition any of the endplates if necessary. The foldable optic is loaded into the inserter, and the tabs are verified to be pointing up as they progress down the tunnel of the inserter. This will guarantee a correct orientation of the anterior and posterior surfaces of the optic. The optic is inserted and allowed to unfold in the anterior chamber. The first hook is introduced at 3 o’clock, and is then used to hold the nearest tab of the optic and bring it over the bayonet on the haptic. The second hook is inserted through the 9 o’clock incision, and is used to place the other haptic over the bayonet. Now the hooks are removed (Fig. 8.8). Gonioscopy is again performed to verify the placement of the feet. The viscoelastic is gently and slowly irrigated out of the eye. The use of conventional irrigation-aspiration equipment is not advised, since the size of these devices may cause de-insertion of the optic, or displacement of the feet.

Latest Personal Update on Managing the Duet Kelman Phakic IOL We have recently performed a prospective, analytical, experimental noncontrolled study on 138 eyes of 83 patients, 32.6% male and 67.39% female. The mean age of these patients was 34.15 ± 8.52 years. The same surgeon (JLA) operated all the patients in the same center (Vissum Alicante, Spain), and it was the same ophthalmologist who evaluated the cases in both the preoperative and postoperative visits.

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Eyes affected by high myopia or compound myopic astigmatism of patients aged over 20 and under 50 years were included. Previous surgical procedures and the usual criteria for phakic IOLs were considered as exclusion criteria. A total of 53 eyes completed the 1 year follow up. After surgery a protocol of visits was established: Patients were examined 1 day, 1 week, and 1, 3, 6, and 12 months postoperatively. During this period, no eyes were operated for the correction of residual refractive errors.

Results A total of 138 eyes of 83 patients were implanted with the Kelman Duet lens. Thirty-six (26.08%) of these eyes were re-treated with LASIK to eliminate residual refractive error. These eyes were excluded from the analysis of the final refractive outcomes. The mean preoperative data of the patients and their corresponding standard deviations are shown in the Table 8.6.

Visual Acuities The preoperative uncorrected visual acuity (UCVA) was less than 0.1 in all of our patients. One year after the surgery, this improved to 0.81 ± 0.27 SD (0.124 ± 0.18 logMAR). The change in the UCVA was statistically significant (T paired data, p < 0.001). Regarding the best corrected visual acuity (BSCVA), the mean preoperative BSCVA was 0.69 ± 0.25 SD (0.197 ± 0.19 logMAR). One year after surgery, the BSCVA was markedly improved to 0.91 ± 0.23 SD (0.056 ± 0.123 logMAR).

Efficacy The efficacy of any refractive procedure is determined by the number or percentage of eyes with a postoperative UCVA ranging from 0.5 to 1.0. TABLE 8.6: The main refractive data (expressed in diopters) and the best corrected visual acuities (decimal scale) corresponding to the eyes included in the study. n

Mean

Standard deviation

Standard error ±

Maximum values

Minimum values

Sphere

138

–13.86

4.29

0.37

–7.00

– 24.50

Cylinder

138

–1.51

0.98

0.08

0.00

– 4.75

Spherical equivalent

138

–14.61

4.29

0.37

–7.25

–24.88

Defocus equivalent

138

15.366

4.352

0.371

26.5

7.5

BCVA

138

0.69

0.25

0.02

1.20

0.15

Power of the implanted IOL

136

–13.92

3.33

0.29

– 8.00

– 20.00

Present Status of Phakic Intraocular Lenses in Modern Refractive Surgery

The efficacy index is the ratio between the preoperative BSCVA and the preoperative UCVA. At the end of the 1 year follow up, we reported that 82.46% had a postoperative UCVA ≥ 0.5 and 35.09% had a UCVA ≥ 1.0. The efficacy index after 1 year was 1.17. At all of the postoperative follow-up visits, the postoperative UCVA was always higher than the preoperative BSCVA.

Predictability The predictability is expressed in terms of the number or percentage of eyes that have a postoperative spherical equivalent within ± 1 D or ± 0.5 D of the desired preoperative correction. In this study, we reported that after 1 year of follow up, 46.29% of eyes were within ± 0.5 D and 79.62% were within ± 1 D. The mean preoperative spherical equivalent refraction was –14.61 D ± 4.29 (range: –7.25 to –24.88 D). At the end of the follow-up period, we reported that the mean postoperative spherical equivalent refraction was –0.69 D ± 0.85.

Safety The safety of any refractive procedure is determined by the number of lines of BSCVA gained or lost by the patients. The safety index is the ratio between the mean postoperative BSCVA and the mean preoperative BSCVA. Until the first month of follow-up, the percentage of cases that lost more than two lines of BSCVA was 0.89% after the third month of follow-up to the end of the study no eyes lost more than two lines of BSCVA. The safety index after 1 year was 1.32.

Intraocular Pressure A slight increase in the intraocular pressure (IOP) was observed in the immediate postoperative period which returned to preoperative levels at 3 months. In those cases where we detected an increase in pressure, this was treated with β-blockers. No eyes suffered from pupillary block glaucoma.

Endothelial Cell Loss Damage to the corneal endothelium remains a constant problem concerning phakic lenses. In our study, the mean preoperative ECD was 2794.83 ± 434.06 cells/mm2. Endothelial morphometric data are shown in Table 8.7. Statistically significant differences were found between preoperative and 3 months postoperative ECD (T-test; p 26 mm), but not for a very short eye (L < 22 mm) which requires the Hoffer formula. Haigis 3-constant optimization allows the curve-fit by both parallel shift and rotation of the curve, such that it covers a wider range of axial length. However, the above Haigis formula also assumed thin-IOL and excludes the role of IOL configurations for different IOL types.

OPTICAL BIOMETRY Since the introduction of IOL Master (Fig. 9.1), optical biometry has been gaining popularity due to the fact that it offers an easy, contact-free method to quickly and accurately assess the axial length. The axial length measured by optical biometry is not, however, directly comparable to ultrasound biometry. Ultrasound biometry measures the distance from the anterior cornea to the inner limiting membrane, while optical biometry measures from the cornea to the retinal pigment epithelium. Thus, the measured axial length obtained from ultrasound and optical biometry cannot be expected to yield the same values. Hitzenberger et al.5 found that the axial lengths measured by optical biometry were 0.18 mm longer than those measured by the immersion technique and 0.47 mm longer than those measured by the applanation technique. Kiss et al.6 reported a mean difference in the measured axial length obtained with optical biometry and immersion biometry of 0.22 mm (range = –0.24 to + 0.57 mm;

Intraocular Lens Power Calculation

Fig. 9.1: Intraocular lens master.

R = 0.99, P < 0.05). In order to be able to continue to use the A-constants and other formula constants developed over the years with ultrasound biometry, readings taken with the IOL Master were calibrated against the immersion ultrasound biometry. Haigis et al.7 found that the postoperative refraction was predicted correctly within ±1 D in 86% and within ±2 D in 99% of all cases using the immersion biometry data. A similar result was obtained using optical biometry. Kiss et al.6 also reported that the refractive outcome in cataract patients using optical biometry was comparable to that achieved with immersion biometry. Other investigators have demonstrated greater accuracy and reproducibility with the IOL master, as infrared laser-based measurement techniques using a 780-nm wavelength has an inherent advantage over a sound-based system with a frequency of 10 MHz and a resolution of 200 mm. Olsen8 reported an average absolute IOL prediction error of 0.65 D with ultrasound and 0.43 D with optical biometry (P < 0.00001). Sixty-two percent of predictions using optical biometry were within ±0.5 D compared with 45% with ultrasound. Another report showed no significant difference in the axial length obtained using optical biometry between different operators.7 Vogel et al.9 reported intraobserver and interobserver variability (standard deviation) of ±25.6 and ±21.5 mm, respectively, for axial length measurements using the IOL master. Optical biometry has several advantages over ultrasound biometry. One is that the axial length measurement is performed through the visual axis since the patient is asked to fixate into the laser spot. In highly myopic or staphylomatous eyes, this can be particularly advantageous because sometimes it may be difficult to measure the true axial length through the visual

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axis with an ultrasound probe. Optical biometry is also superior to ultrasound in the measurement of pseudophakic and silicone oil-filled eyes. For optical biometry, it is not as critical how the media change because the correction factor that must be applied is much smaller than in ultrasound biometry. The preoperative axial length measurement obtained with the IOL master was shown to be 0.07 mm longer than postoperative measurements (P < 0.001); this difference in axial length appears small, but statistically significant, correlated with the Lens Opacities Classification System III nuclear cataract score.9-11 Accurate measurements require that the infrared laser be able to pass through the eye and return to the interferometer. Therefore, opacities along the visual axis can block the infrared laser. Reliable measurements may not be obtained in eyes with tear film abnormalities, corneal pathology, mature and posterior subcapsular cataracts, vitreous opacities, maculopathy, and retinal detachment. In addition, the patient must be able to maintain fixation. Various groups have reported that 8–20% of patients cannot be measured with optical biometry due to poor fixation, dense cataract or corneal pathology.12-16 Freeman and Pesudovs16 reported that posterior subcapsular cataract with a Lens Opacities Classification System III score of greater than 3.5 and mature cataracts accounted for 16% of measurement failures. Cortical and nuclear cataracts did not seem to affect measurements. The new IOL master (Fig. 9.1) Advanced Technology software upgrade (version 5) is designed to enhance the signal-to-noise ratio in order to improve measurement of the axial length in eyes with media opacity. The new algorithm combines the individual measurement signals to form a composite signal. Peaks in each signal are combined, resulting in amplification of the signal, while random noise in the signal cancels each other out. The software then looks for the highest peak in this composite signal. The results of unpublished studies conducted by Warren Hill showed that the standard IOL master is capable of measuring 50–60% of patients for all classes of cortical density. With Advanced Technology, 87% of patients with cortical densities above 3.0 can be measured, 100% of patients with a nuclear color grading up to 3 can be measured, 93% of patients with a nuclear color grading above 3 can be measured, 100% of all eyes with a posterior subcapsular density up to grade 5 can be measured and 72% of eyes with a posterior subcapsular density above grade 5 can be measured.

INTRAOCULAR LENS POWER CALCULATION IN SPECIAL SITUATIONS Polypseudophakia When the calculated IOL power exceeds that available, and placement of a single IOL would result in an unacceptable refractive outcome, one option is for the surgeon to place two IOLs in the eye at the same operative session. The previous practice of stacking two acrylic lenses in the capsular bag has since been abandoned due to occasional problems with interlenticular opacification and reduced visual acuity. When primary polypseudophakia is indicated, the IOL

Intraocular Lens Power Calculation

calculation is carried out in six logical steps. First of all, the axial length should be measured as accurately as possible. Even a relatively small axial length error in extreme axial hyperopia can result in a significant postoperative refractive error. The axial length in this setting is best measured using the IOL master. Immersion 10 MHz A-scan biometry is a reasonable, but less accurate alternative. Secondly, the total IOL power is calculated at the plane of the capsular bag. For IOL power calculations in the setting of extreme hyperopia, the Holladay II formula is recommended. Hoffer Q, or a fully optimized version of the Haigis formula (a0, a1 and a2 optimized) are reasonable alternatives. Then the residual IOL power is calculated followed by power adjustment for the anterior (ciliary sulcus) lens. The power of the anterior IOL is calculated followed by appropriate polypseudophakia lens pair selection.

Postkeratorefractive Surgery Intraocular lens power calculations following keratorefractive surgery should not be carried out using standard keratometry combined with any one of several popular two-variable third generation theoretic formulae, such as SRK/T without a special correction. A major shortcoming of most third generation, two-variable formulae, such as SRK/T, is that they often assume that the anterior and posterior segments of the eye are mostly proportional and use only the axial length and keratometric corneal power to estimate the postoperative location of the IOL, known as the ELPo. Unless a specific correction is made for this situation, the artifact of centrally flattened Ks following keratorefractive surgery will have these formulae assume a falsely shallow post operative ELPo. The end result is that without a special correction, following LASIK these formulae will typically recommend less IOL power than is actually required. This is a second and little-recognized source of unanticipated postoperative hyperopia following keratorefractive surgery for myopia. Summary of IOL powers, generated by several forms for central corneal power estimation has been shown in Table 9.2. TABLE 9.2: Corneal power (Dc) calculation after refractive surgery. 1. Clinical-history method

Dc = Kpre - RC RC = Refractive correction of LASIK

2. Contact lens method

Dc = B + P + Rw – Rno B = Base curve P = Power of CL Rw = Refractive error Rno = Bare refraction

3. Shammas method

Dc = 1.114 Kpost – 6.8

4. Maloney topography method

Dc = 1.114 Ktopo – 5.5

5. Koch method

Dc = 1.114 Ktopo – 6.1

6. Shammas refraction method

Dc = (1.114 Kpost – 6.8) – 0.23 (RC)

7. Hoffer mean-value method

Dc = 337.5 (1/r1 + 1/r2)/2

8. Lin Gaussian-optics (I)

Dc = 1.117 Kpost – 41/r2

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Silicone Oil–Filled Eyes Silicone oil is sometimes temporarily placed in the vitreous cavity for recurrent retinal detachments in eyes with proliferative vitreoretinopathy, proliferative diabetic retinopathy, cytomegalovirus retinitis, giant retinal tears, and following perforating injuries. An axial length measurement by ultrasound of an eye in which the vitreous cavity has been filled with silicone oil is an exercise with many potential pitfalls, especially if the silicone oil has become emulsified. The additional power that must be added to the original IOL calculation for a convex-plano IOL (with the plano side facing toward the vitreous cavity) is determined by the following relationship17 Ns = Refractive index of silicone oil (1.4034) Nv = Refractive index of vitreous (1.336) AL = Axial length in mm ACD = Anterior chamber depth in mm. Additional IOL power (diopters) = [(Ns – Nv)/(AL – ACD)] × 1,000. For an eye of average dimensions, and with the vitreous cavity filled with silicone oil, the additional power needed for a convex-plano PMMA IOL is typically between +3.0 D and +3.5 D. Another rather easy and reliable method is by using PCI with the IOL master.

Piggy Back Intraocular Lens In 1993, Holladay18 elegantly described a method for pseudophakic and aphakic IOL power calculations, independent of axial length. When significant refractive deviations are seen, the refractive vergence formula is very helpful in understanding how much optical power must be added to or subtracted from an eye at the level of the anterior chamber, ciliary sulcus, or capsular bag. This formula also works well for the phakic and aphakic eye. The power of the IOL to be implanted is determined by the following: 1336 1336 − 1336 1336 − ELP0 − ELP0 1000 1000 + K0 + K0 1000 1000 −V −V Pr eRx DPostRx ELPo = Effective lens position Ko = Net corneal power IOLe = IOL power V = Vertex distance PreRx = Preoperative refraction DPostRx = Desired postoperative refraction IOL e =

Intraocular Lens Power Calculation

Corneal Transplantation There is presently no method that can be used to accurately carry out IOL power calculations prior to corneal transplantation combined with cataract removal and IOL implantation. This is because it is impossible to know the central power of the donor graft prior to surgery. Simply basing preoperative calculations on a “best guess” of postoperative corneal power (such as 44.0 D) will quite often lead to an unpleasant postoperative refractive surprise. It is a much better idea to instead carry out corneal transplantation with cataract removal, but without IOL implantation. The lens implantation would then be carried out at a later time, as a secondary procedure. After 4–8 months, when the corneal curvature has stabilized, and corneal astigmatism has been minimized, a careful aphakic refraction is performed and simulated keratometry by topography is used to estimate central corneal power.

Accuracy of Intraocular Lens Power Calculation A second person should repeat the axial length measurements, keratometry readings, and re-run the IOL power calculations for both eyes if: The IOL power for emmetropia is greater than 3.00 diopters different than anticipated. There is a difference in IOL power of greater than 1.00 diopter between the two eyes. If the patient has had prior excimer laser-based keratorefractive surgery and the calculated IOL power for standard phacoemulsification is less than +17.0 D or greater than +23.0 D.

CONCLUSION With increasing patient expectations, the first step to obtain an accurate IOL power calculation is to be able to identify the patient’s visual goals, especially if they have specific vocational or avocational needs. Using today’s technology, it is possible to consistently have postoperative refractive outcomes within –0.25 D of the targeted refraction. In order to achieve these results, attention to proper patient selection, accurate keratometry and biometry, appropriate IOL power formula selection with optimized lens constant, and proper configuration of the capsulorhexis are required. Ultimately, the part with the highest variability and inaccuracy is going to determine the outcome. The accuracy of IOL biometry can be improved by implementing the following: Minimizing variability and improving consistency by assigning a single properly calibrated instrument and experienced technician for the work-up, repeating and verifying measurements by a second person when necessary, using the IOL master or immersion biometry rather than an applanation technique, using one of the newer IOL power calculation formulae and personalizing the lens constants for each formula, tracking your refractive outcomes, and optimizing your surgical technique by making the capsulorhexis round, centered, and slightly smaller

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than the lens optic can all help to optimize your postoperative outcomes. By understanding the advantages and limitations of the current technology and following these guidelines, it is possible to consistently achieve highly accurate results.

REFERENCES 1. Gale RP, Saldana M, Johnston RL, et al. Benchmark standards for refractive outcomes after NHS cataract surgery. Eye. 2009;23(1):149-52. 2. Brandle J, Haigis W. IOL calculation in long and short eyes. In: Hoyos GA, Dementiev JE (Eds). Mastering the Techniques of IOL Power Calculations. New Delhi: Jaypee Brothers Medical Publishers (P) Ltd.; 2005. 3. Hoffer KJ. The Hoffer Q formula: A comparison of theoretic and regression formulas. J Cataract Refract Surg. 1993;19:700-12. 4. Holladay JT, Prager TC, Chandler TY, et al. A three-part system for refining intraocular lens power calculations. J Cataract Refract Surg. 1988;14:17-24. 5. Hitzenberger CK, Drexler W, Dolezal C, et al. Measurement of the axial length of cataract eyes by laser Doppler interferometry. Invest Ophthalmol Vis Sci. 1993;34:1886-93. 6. Kiss B, Findl O, Menapace R, et al. Refractive outcome of cataract surgery using partial coherence interferometry and ultrasound biometry: clinical feasibility study of a commercial prototype II. J Cataract Refract Surg. 2002;28:230-4. 7. Haigis W, Lege B, Miller N, et al. Comparison of immersion ultrasound biometry and partial coherence interferometry for intraocular lens calculation according to Haigis. Graefes Arch Clin Exp Ophthalmol. 2000;238:765-73. 8. Olsen T. Improved accuracy of intraocular lens power calculation with the Zeiss IOL Master. Acta Ophthalmol Scand. 2007;85:84-7. 9. Vogel A, Dick HB, Krummenauer F. Reproducibility of optical biometry using partial coherence interferometry: intraobserver and interobserver reliability. J Cataract Refract Surg. 2001;27:1961-8. 10. Lam AK, Chan R, Pang PC. The repeatability and accuracy of axial length and anterior chamber depth measurements from the IOL Master. Ophthalmic Physiol Opt. 2001;21:477-83. 11. Chylack LT, Wolfe JK, Singer DM, et al. The Longitudinal Study of Cataract Study Group: the Lens Opacities Classification System III. Arch Ophthalmol. 1993;111:831-6. 12. Prinz A, Neumayer T, Buehl W, et al. Influence of severity of nuclear cataract on optical biometry. J Cataract Refract Surg. 2006;32:1161-5. 13. Connors IR, Boseman IP, Olsen RJ. Accuracy and reproducibility of biometry using partial coherence interferometry. J Cataract Refract Surg. 2002;28:235-8. 14. Kiss B, Findl O, Menapace R, et al. Biometry of cataractous eyes using partial coherence interferometry. J Cataract Refract Surg. 2002;28:224-9. 15. Rajan MS, Keilhorn I, Bell JA. Partial coherence laser interferometry vs conventional ultrasound biometry in intraocular lens power calculations. Eye. 2002;16:552-6. 16. Freeman G, Pesudovs K. The impact of cataract severity on measurement acquisition with IOL Master. Acta Ophthalmol Scand. 2005;83:439-42. 17. Shamnas HJ. IOL lens power calculation: Ultrasound Measurement of the Challenging Eye. Thorofare, NJ: Slack Incorporated; 2004. pp. 113-23. 18. Holladay JT. Refractive Power Calculations for Intraocular Lenses in the Phakic Eye. Am J Ophthalmol. 1993;116:63-6.

CHAPTER

10

Scleral Fixated Intraocular Lens

Naresh Babu, Supreet Singh Juneja

INTRODUCTION Implantation of an intraocular lens (IOL) in the capsular bag during routine cataract surgery is the standard of care; however, surgeons must be comfortable with alternative techniques in the event of complications that preclude this placement. Loss of posterior capsule integrity is a well-documented complication of cataract surgery with an incidence of 0.69–6.7% in recent studies.1,2 If this occurs, surgeons must assess intraoperatively whether sufficient support for IOL placement in the capsular bag or ciliary sulcus exists. If capsule support is inadequate, neither option is viable. Several IOL types can be used in the absence of capsule support, including angle-supported and iris-fixated anterior chamber (AC) IOLs and iris-fixated and sclera-fixated posterior chamber IOLs (PCIOLs). Due to the ease of insertion, angle-supported AC IOLs have been the predominant IOL choice in patients with compromised capsule support. Unfortunately, early closedloop IOLs had a high complication rate, including fibrosis of the angle with subsequent glaucoma, corneal endothelial cell loss with resultant bullous keratopathy, pupil block, and cystoid macular edema.3 Nowadays, the flexible open-loop AC IOL has proved to be well tolerated and has fewer complications than its predecessor. Because of the AC IOLs’ earlier problems, the scleralfixated IOL is thought to be tolerated better long term given its more anatomical positioning and the reduced likelihood of aniseikonia.4 Recent reports refute this notion, concluding that the flexible open-loop AC IOL has similar if not better outcomes than the sclera-fixated IOL.5,6 However, in some instances, neither capsule nor iris support is available, making the scleral-fixated IOL the only option. Because of their anatomic location, sclera-fixated PCIOLs have a theoretic advantage over other IOLs in regard to complications, especially in eyes

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after trauma and in young patients.7-9 They provide better visual acuity and binocularity, lead to a lower incidence of strabismus than contact lenses, and avoid the complications of ACIOLs, which are seen more with rigid closed-loop IOLs than with open-loop and iris-claw IOLs. However, the surgical technique of sclera-fixated IOL is much more difficult than other IOL implantations, it results in sutures tracking into the eye, and there is surgical manipulation in the region of the ciliary body, which can cause hemorrhage.5,10 Serious postoperative complications, such as knot and suture erosion,11-13 IOL tilt, suture breakage, endophthalmitis, retinal detachment (RD),14 choroidal hemorrhage,12 elevated intraocular pressure (IOP),15-18 and open-angle glaucoma, are well documented. Complication rates within 12 months of surgery are reported to below17 and similar in children and adults.19 However, over the long term, unacceptably high rates of suture breakage and IOL dislocation in young patients have been recorded.7

SUTURES The Ethicon TG-160-2 and Ethicon CIF-4 (Ethicon, New Jersey) can be used for ab interno methods. The Ethicon STC-6 straight needle is used in both methods. In general, 10-0 polypropylene has been the suture material of choice.20

Placement of Scleral Sutures Originally, suturing techniques involve passing the needle from inside to outside (ab interno) the eye. Although this method may be quicker and is easier when penetrating keratoplasty is performed concomitantly, it is a blind procedure.21 As its name suggests, the outside to inside (ab externo) technique involves passing the needle from outside to inside, and was described by Lewis.22 This is also undertaken blindly in that the intraocular exit point of the needle is unseen, but by knowing the entry point, sulcus positioning of the suture is more predictable.23,24 With the ab externo technique, the AC can remain closed during needle passes. This avoids collapse of the ciliary sulcus in the hypotonic eye, thus facilitating accurate suture placement.25

Scleral Suture Fixation Techniques Simple Knotting Over the Sclera In this technique, IOLs are attached to the sclera with two points of fixation. Formed polypropylene suture knot and suture ends over the sclera are covered by conjunctiva and the Tenon’s capsule. However, despite its simplicity with regard to suture technique, conjunctival erosion is very common after this procedure.26 Serious complications, such as endophthalmitis, may also be seen.

Corneal Autografts for External Knots The knots are covered with autologous lamellar corneal patches during the combined keratoplasty and scleral fixation.27 The patch is then covered with

Scleral Fixated Intraocular Lens

conjunctiva.2 This method is safer with regard to sutural erosion but a corneal autograft protuberance is made over the sclera, which is seen as a disadvantage.

Covering with Fascia Lata or Dura Mater Autologous fascia lata or lyophilized dura mater is used to cover the external knots. These patches are then covered with conjunctiva, which provides very good protection against suture exposure. However, removing fascia lata or supplying dura mater allografts could increase difficulty and cost. Moreover, during the postoperative period, externally recognizable patches on the eye may lead to physiological and cosmetic disturbances.28,29

Covering with Scleral Flaps Covering with scleral flaps appears to be a favorable technique for scleral fixation. First, triangular limbal-based scleral flaps (3 mm × 1 mm) are fashioned. A previously formed knot on the sclera is placed under a triangular flap then this flap is closed and remains sutureless at the end of surgery. With this technique, the maintenance of knot security within the sclera has benefits with regard to suture exposure, but if the flap is too thin, it can easily be dehisced, macerated, or punctured. In addition, the knot may reposition through the scleral bed into the eye.12

Continuous-loop Fixation Technique In this technique, the needle is passed through the haptic’s eyelet/s and punctures the sclera in two places. One end of the suture is tied to the other end of the suture. The suture knot is then rotated in through the incision and out through the sclera. The knots are then rotated into the eye.22 Therefore, with this type of arrangement, a few knot-related problems are expected to arise. On the other hand, as each haptic requires two points of scleral fixation, a total of four-needle punctures need to be made in the sclera, and thus there is a relatively higher risk of developing complications compared with the conventional two-needle punctures. In addition, suture knot rotation may cause IOL torque and tilt.

Four Points of Fixation Underneath the Superficial Scleral Flap Herein, the suture knot is rotated in the same manner as during the previously mentioned procedure. The difference between the two procedures is in the fashioning of an L-shaped scleral flap for covering the suture.30 This technique minimizes the possibility of conjunctival erosion, suture exposure, and thinning of sclera, but the longer surgical time is considered to be a disadvantage.

Limbal-groove Incision and Double-suture Fixation The limbal-groove incision and double-suture fixation method allow for a twopoint fixation.31 Two 3-mm scleral grooves are created horizontally at 3 and 9 o’clock, 0.5–0.75 mm from the limbus. The suture knot is trimmed and rotated into the scleral groove. This method allows the suture knot to be buried in the eye without the use of scleral flaps. There is a risk of suture knot protrusion.

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Trans-scleral Fixation of Intraocular Lenses through Sclerotomy In vitrectomy surgery, after the haptic is pulled close to the sclerotomy site, a suture is tied to the haptic of IOL from outside through the sclerotomy site. The remaining suture material is buried within the sclerotomy lips. Therefore, the risk of suture exposure is minimized. In this procedure of IOL fixation, the haptics should be situated symmetrically opposite each other. In addition, scleral suturing may cause damage to the retina.32

Scleral Incision Technique During this procedure, a radial scleral incision is made and sutured with the knot buried within the incision. Problems associated with depth of incision and suture exposure are sometimes seen.33

Scleral Fixation without Conjunctival Dissection This technique is a variation of the traditional triangular scleral flap for scleral fixation and involves performing a conjunctival peritomy and dissecting a scleral flap anteriorly from a position 2–3 mm posterior to the limbus. Surgery begins in clear cornea and dissects a scleral pocket posteriorly, avoiding the need for scleral cautery. Conjunctival dissection is also avoided and sutured wound closure is unnecessary. A larger surface area can be created for suture passes than with triangular sclera flaps or scleral grooves.34 However, scleral dissection and suture management are incredibly intricate.

Scleral Tunnel Technique This is also a modified scleral flap technique. After dissecting conjunctiva, a conventional scleral tunnel is fashioned with a crescent blade. Passage of a double-armed suture through the roof of the scleral tunnel with subsequent retrieval of the suture ends through the external incision for tying facilitates scleral fixation.35 However, the technique seems to be logical for preventing suture exposure, as a thin flap can easily be dehisced, macerated, or punctured with suture knot.

Knotless Scleral Fixation Knotless scleral fixation describes the technique for implanting an IOL by scleral fixation sutures. This has the advantages of knotless fixation of the haptics and an out-in approach for passing the needle through the sclera.36 Probably, the worst complication with this procedure is suture loosening, which could result in IOL decentration and tilt.

Knot and Suture Burying into the Sclera without Flap, Tunnel, Incision, or Groove The needle is passed through the sclera in a lamellar fashion next to where the suture protrudes from the sclera. Afterward, the free end with the needle

Scleral Fixated Intraocular Lens

and the other end are tied using a classic suture-tying method. As the suture is being tied, a free end with the needle and a second piece in the form of a loop appear. A very small loop is required for the burial technique. Thus, when the suture is being tied, the suture attached to the IOL should be gripped at the point closest to the scleral entry and knotted. Thus, the suture loop becomes smaller. For the burial procedure, the free-stranded needle is passed through the loop and passed again in the same direction, so a secondary loop is made over the first one. The free end is passed through the recently formed loop once more. Thus, the free needle grips the loop bound to the sclera. The needle is inserted into the sclera at the point closest to the preformed knot and advanced in a lamellar fashion. The needle is retrieved after it is advanced more than the length of the loop onto which the sutures are held. The loop tied to the pulled suture is rotated and buried in the sclera. The suture mounted on the needle is seen at the scleral wound. If the suture is cut at the exit site, its end is retained in the sclera, providing entire burial of the loop and the end mounted on the needle (Fig.10.1).37 Author evaluated the sclera-sutured free 150 suture ends after a minimum 24 months of follow-up in 75 eyes of 75 patients and observed no intraoperative or postoperative complications related to the suture burial technique itself.38

Fixation of the Haptics in a Limbus-parallel Sclera Tunnel t2 No Glue No Sutures Technique (Figs. 10.2 to 10.5) This is our preferred technique. A 270° conjunctival peritomy is done. Two partial thickness scleral grooves of 4 mm are fashioned 1.5 mm from the limbus, parallel to it at 10-8 o’ clock and 4-2 o’ clock using 25-G trocar. Two sclerotomies

Fig. 10.1: Scleral pocket made with 23-G microvitreoretinal (MVR) blade.

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Fig. 10.2: Externalization of the haptic.

Fig. 10.3: Tucking of the haptic into the scleral pocket.

are made at the edges of the grooves using 23-G syringe. Three 23-G sclerotomy ports are made at 3 mm from the limbus in inferotemporal, superotemporal, and superonasal quadrants, respectively. Anterior vitrectomy is done routinely. Using a clear corneal incision, a foldable lens is introduced into the AC. Using a 25-G vitrectomy forceps, inserted through the sclerotomies at the edges of

Scleral Fixated Intraocular Lens

Fig. 10.4: Tucking of the other haptic.

Fig. 10.5: Well-centered intraocular lens (IOL) after the procedure.

the grooves, the haptics are taken out and put into their respective grooves at 10-8 o’ clock and 4-2 o’ clock. In this procedure, no suture is required, no blind procedure for passing the needle. This technique can be modified to make a corneoscleral tunnel and insert a nonfoldable three-piece IOL also.

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Many methods have been described to allow scleral fixation. Experienced surgeons have achieved excellent results with trans-sclerally sutured PCIOLs. Common to all scleral fixation technique is the need to cover, bury or rotate suture knots to prevent overlying conjunctival erosion and subsequent endophthalmitis. Each of these is different with regard to technical difficulty, potential postoperative problems and complications. For example, the sutures may erode through the scleral flaps and cause irritation. They may also loosen or break and cause either tilting or dislocation of the optic. In addition, a persistent suture extending between intraocular and extraocular environments may provide a track for bacteria to enter the eye and establish endophthalmitis. A choroidal hemorrhage and detachment can occur from inadvertent injury to the ciliary body. The incidence of suprachoroidal hemorrhage is a function of procedure duration and intraoperative manipulation. Factors that increase the risk of hemorrhage include older age, history of hypertension, peripheral vascular disease, glaucoma, aortic stenosis, emphysema, eye surgery (risk increases with more procedures), and a need for excessive intraoperative manipulation (e.g. if concomitant procedures, such as removal of residual lens material, extensive vitrectomy, repair of large iris defects or iridoplasty are needed). Moreover, traction on the peripheral retina or vitreous during suture placement in the sulcus may increase the risk of RD. Numerous suggestions have been made to improve the accuracy of sulcus penetration, move away from ab interno suture techniques, and move toward the ab externo approach, mirror systems, transillumination, and endoscopy.10 In conclusion, surgeons should be experienced in their particular scleral fixation technique and receive continual training in all of the techniques. This represents great savings in terms of time, supply costs, and improved patient and surgeon satisfaction in both the short- and long-term.

REFERENCES 1. Misra A, Burton RL. Incidence of intraoperative complications during phacoemulsification in vitrectomized and nonvitrectomized eyes: prospective study. J Cataract Refract Surg. 2005;31:1011-4. 2. Bhagat N, Nissirios N, Potdevin L, et al. Resident-performed phacoemulsification cataract surgery at New Jersey Medical School. Br J Ophthalmol. 2007;91:1315-7. 3. Dick HB, Augustin AJ. Lens implant selection with absence of capsular support. Curr Opin Ophthalmol. 2001;12:47-57. 4. Evereklioglu C, Er H, Bekir NA, et al. Comparison of secondary implantation of flexible open-loop anterior chamber and scleral-fixated posterior chamber intraocular lenses. J Cataract Refract Surg. 2003;29:301-8. 5. Kwong YYY, Yuen HKL, Lam RF, et al. Comparison of outcomes of primary scleral-fixated versus primary anterior chamber intraocular lens implantation in complicated cataract surgeries. Ophthalmology. 2007;114:80-5. 6. Donaldson KE, Gorscak JJ, Budenz DL, et al. Anterior chamber and sutured posterior chamber intraocular lenses in eyes with poor capsular support. J Cataract Refract Surg. 2005;31:903-9.

Scleral Fixated Intraocular Lens 7. Vote BJ, Tranos P, Bunce C, et al. Long-term outcome of combined pars plana vitrectomy and scleral fixated sutured posterior chamber intraocular lens implantation. Am J Ophthalmol. 2006;141:308-12. 8. Wagoner MD, Cox TA, Ariyasu RG, et al. Intraocular lens implantation in the absence of capsular support; a report by the American Academy of Ophthalmology (Ophthalmic Technology Assessment). Ophthalmology. 2003;110:840-59. 9. Epley KD, Shainberg M, Lueder GT, et al. Pediatric secondary lens implantation in the absence of capsular support. J AAPOS. 2001;5:301-6. 10. Hannush SB. Sutured posterior chamber intraocular lenses: Indications and procedure. Curr Opin Ophthalmol. 2000;11:233-40. 11. Holland EJ, Daya SM, Evangelista A, et al. Penetrating keratoplasty and transscleral fixation of posterior chamber lens. Am J Ophthalmol. 1992;114:182-7. 12. Solomon K, Gussler JR, Gussler C, et al. Incidence and management of complications of transsclerally sutured posterior chamber lenses. J Cataract Refract Surg. 1993;19:488-93. 13. Uthoff D, Teichmann KD. Secondary implantation of scleral-fixated intraocular lenses. J Cataract Refract Surg. 1998;24:945-50. 14. Asadi R, Kheirkhah A. Long-term results of scleral fixation of posterior chamber intraocular lenses in children. Ophthalmology. 2008;115:67-72. 15. Krause L, Bechrakis NE, Heimann H, et al. Implantation of scleral fixated sutured posterior chamber lenses: a retrospective analysis of 119 cases. Int Ophthalmol. 2009;29:207-12. 16. Heidemann DG, Dunn SP. Transsclerally sutured intraocular lenses in penetrating keratoplasty. Am J Ophthalmol. 1992;113:619-25. 17. Johnston RL, Charteris DG, Horgan SE, et al. Combined pars plana vitrectomy and sutured posterior chamber implant. Arch Ophthalmol. 2000;118:905-10. [online]. Available from http://archopht. ama-assn.org/cgi/reprint/ 118/7/905. pdf [Accessed March 30, 2018]. 18. Heidemann DG, Dunn SP. Visual results and complications of transsclerally sutured intraocular lenses in penetrating keratoplasty. Ophthalmic Surg. 1990;21:609-14. 19. Furuta M, Tsukahara S, Tsuchiya T. Pupillary elongation after anterior chamber lens implantation. J Cataract Refract Surg. 1986;12:273-5. 20. Pannu JS. A new suturing technique for ciliary sulcus fixation in the absence of posterior capsule. Ophthalmic Surg. 1997;19:751-4. 21. Apple DJ, Price FW, Gwin T, et al. Sutured retropupillary posterior chamber intraocular lenses for exchange of secondary implantation. The 12th annual binkhorst lecture, 1988. Ophthalmology. 1989;96:1241-7. 22. Lewis JS. Ab externo sulcus fixation. Ophthalmic Surg. 1991;22:692-5. 23. Arkin MS, Steinert RF. Sutured posterior chamber intraocular lenses. Int Ophthalmol Clin. 1994;34:67-85. 24. Duffrey RJ, Holland EJ, Agapitos PJ, et al. Anatomic study of transsclerally sutured intraocular lens implantation. Am J Ophthalmol. 1989;108:300-9. 25. Althaus C, Sundmacher R. Intraoperative intraocular endoscopy in transscleral suture fixation of posterior chamber lenses: consequences for suture technique, implantation procedure, and choice of PCL design. Refract Corneal Surg. 1993;9:333-9. 26. Özmen AT, Dogru M, Ertürk H, et al. Transsclerally fixated intraocular lenses in children. Ophthalmic Surg Lasers. 2002;33:394-9. 27. Bucci FA Jr, Holland EJ, Lindstrom RL. Corneal autografts for external knots in transsclerally sutured posterior chamber lenses. Am J Ophthalmol. 1991;112:353-4.

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Gems of Ophthalmology—Cataract Surgery 28. Bashshur Z, Ma’luf R, Najjar D, Noureddin B. Scleral fixation of posterior chamber intraocular lenses using fascia lata to cover the knots. Ophthalmic Surg Lasers. 2002;33:445-9. 29. Anand R, Bowman RW. Simplified technique for suturing dislocated posterior chamber intraocular lens to the ciliary sulcus. Arch Ophthalmol. 1990;108:1205-6. 30. Rao SK, Gopal L, Fogla R, et al. Ab externo 4-point scleral fixation. J Cataract Refract Surg. 2000;26:9-10. 31. Bergren RL. Four-point fixation technique for sutured posterior chamber intraocular lenses. Arch Ophthalmol. 1994;112:1485-7. 32. In YS, Kim JH, Song BJ. Transscleral fixation of a dislocated IOL through sclerotomy. J Cataract Refract Surg. 2004;30:1163-6. 33. Monteiro M, Marinho A, Borges S, et al. Evaluation of a new IOL scleral fixation technique without capsular support. J Fr Ophthalmol. 2006;29:1110-7. 34. Hoffman RS, Fine IH, Packer M. Scleral fixation without conjunctival dissection. J Cataract Refract Surg. 2006;32:1907-12. 35. Han Q, Chu Y. Combined suture-in-needle and scleral tunnel technique for scleral fixation of intraocular lens. J Cataract Refract Surg. 2007;33:1362-5. 36. Szurman P, Petermeier K, Aisenbrey S, et al. Z-suture: a new knotless technique for transscleral suture fixation of intraocular implants. Br J Ophthalmol. 2010;94:167-9. 37. Baykara M. Suture burial technique in scleral fixation. J Cataract Refract Surg. 2004;30:957-9. 38. Baykara M. Long-term results of a suture burial technique. Eur J Ophthalmol. 2008;18:368-70.

CHAPTER

11

Recent Advances in Anterior Capsulotomy Arup Chakrabarti

INTRODUCTION Continuous curvilinear capsulorhexis (CCC) is one of the most challenging and perhaps influential steps in phacoemulsification.1,2 It plays a very crucial role in various aspects of phacoemulsification. A properly constructed capsulorhexis allows endocapsular maneuvers, limits the fluidic turbulence entirely within the confines of the capsular bag, and serves as the foundation for stable inthe-bag intraocular lens (IOL) fixation. On the other hand, an incomplete capsulorhexis or a rhexis margin tear is likely to compound the difficulty of each subsequent step of the procedure in a cascading effect. Anterior capsular tears have the potential to run away to the equator and further propagate as a wraparound tear involving the posterior capsule. The mean incidence of anterior capsular tears with manual capsulorhexis has been reported to be 2.3–5.1%.3,4 A CCC should be appropriately sized with a diameter slightly smaller than the IOL optic so as to completely overlap the optic, reducing the incidence of posterior capsular opacification through a shrink-wrap effect. However, while attempting to ensure that the anterior capsule overlaps the IOL edge by 360° after implantation, there may be a tendency to size the manual CCC to somewhat smaller than the average diameter than ideal to compensate for unintended variations in centration, diameter, and circularity.5 This may introduce difficulties and complications in the surgery. Also given the wide variability of the surgeon skills and expertise, there may be significant variation in the CCC rim and optic overlap. Findl et al. reported 18% of cases with no rhexis overlap of the IOL.6 Beyond the safety implications of basic rhexis sizing and location, there is new evidence that a perfectly centered, round capsulotomy results in less IOL tilt and decentration and a more predictable effective lens position, leading to more accurate refractive results.7

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Since 1986 when Howard Gimbel and Thomas Neuhann first described the procedure, CCC had always been performed manually. The manual approach increased the vulnerability and vagaries of a manual technique as discussed above. And there was a need to have an approach to overcome the drawbacks of the manual approach. The concept of performing a manual capsulotomy underwent a renaissance, when Zoltan Nagy in 2008 performed capsulotomy using the femtosecond laser (FSL). With this automation, the cataract surgeon could get the better of the uncertainties associated with the manual procedure. Femtosecond capsulorhexis has already been detailed in a different section. In a nutshell with FSL capsulotomy, the surgeon could accurately and reproducibly perform a capsulotomy of a desired predetermined size. The femtolaser capsulotomy was always circular, with little chance of capsulorhexis runaway to the periphery. However, there are significant drawbacks of this procedure—an extremely prohibitive cost, need to use a second room to house the laser in most of the FSL platforms, disruption of the smooth surgical flow, and longer operating time per case. The running and maintenance cost of this equipment was also high. Although patients today can opt for femtosecond laser-assisted cataract surgery (FLACS), there remains a need for a simpler, safer, more cost-effective, and more predictable solution so that all surgeons can construct the ideal capsulotomy every time. In this regard, there are four new modalities that have come up which have the potential to vie with FSL capsulotomy in terms of the various advantages and the disadvantages of femtorhexis. These are: •• Zeptoprecision pulse capsulotomy (PPC) •• CAPSULaser •• ApertureCTC™ Continuous Thermal Capsulotomy™ System •• VERUS ophthalmic caliper (Mile High Ophthalmics, Denver, CO, United States). In this section, these modalities of capsulotomies have been discussed.

ZEPTO PRECISION PULSE CAPSULOTOMY In cataract surgery, today the emphasis is on a properly sized, well centered, round capsulorhexis constructed in a reproducible manner. As discussed elsewhere, femtorhexis does all that but comes at a cost, including—high price tag, alteration of the patient flow, and a reordering of the familiar sequence of surgical steps that a surgeon is so accustomed to. Precision pulse capsulotomy is a novel8 capsulotomy method which retains all the advantages of a femtorhexis but lacks in the disadvantages.

Recent Advances in Anterior Capsulotomy

EQUIPMENT Zepto PPC is a novel handheld capsulotomy device developed by Mynosys (Zepto, Mynosys Cellular Devices, Inc.).9 It consists of a small console driving a disposable handpiece and a nanoengineered capsulotomy tip (Figs. 11.1A to C). The tip is made of a circular microfabricated nitinol ring which is designed at the micron scale to perform uniform cutting of the capsule, surrounded by a soft, thin silicone suction cup. Nitinol is a superelastic shape memory alloy which allows a ring 5 or 5.5 mm in diameter to be compressed for insertion through a clear corneal incision (CCI) and reassumes its natural circular shape once it is released inside the anterior chamber (AC). A retractable metal push rod elongates the ring and silicone shell into a thinner profile that can be inserted through a 2.2-mm incision. The original circular shape of the device is restored once the push rod is retracted.8 After juxtaposing the silicone cup to the anterior capsule, suction is activated which apposes the nitinol ring to the capsule. The second console button is then activated, which delivers a rapid train of 4-millisecond-long electrical pulses to the nitinol ring. Rapid phase transition of water molecules trapped between the capsule and nitinol edge causes the stretched capsular membrane to cleave mechanically and simultaneously around the entire 360° of the apposed anterior capsule without cauterizing it8 (Figs. 11.2A to C). Precision pulse capsulotomy is limited to the anterior capsule without any collateral thermal changes in the underlying cortex. The transparent silicone suction cup contains a central window that allows the patient to fixate on the microscope light while positioning the device in the AC. Collateral thermal

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Figs. 11.1A to C: (A) Disposable handpiece; (B) Control console that provides power and suction for the capsulotomy; (C) Capsulotomy tip made up of a soft, clear silicone suction cup (SC) that houses a circular, collapsible, super-elastic nitinol capsulotomy ring (NCR) to perform the capsulotomy and an extendable-retractable push rod (PR) that helps to compress the capsulotomy tip for entry through a 2.2-mm corneal incision.

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Figs. 11.2A and B

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Fig. 11.2C Figs. 11.2A to C: Schematic diagram showing mechanism of action of precision pulse capsulotomy (PPC). (A) PPC device placed near or on the surface of the anterior lens capsule (blue). A cross-section of the nitinol ring is shown (red); (B) When suction is applied through the SC of this PPC device, the bottom edge of the nitinol ring gets tightly apposed to the lens capsule and increases the tensile stress on the anterior capsule. This is evenly distributed circumferentially in the capsule membrane along the nitinol ring edge (black-dashed arrows). During this process, water molecules are trapped in between the nitinol ring and the capsule surface(*); (C) The nitinol ring, energized by the brief multipulse train of very short 4-millisecond electrical discharges, causes rapid phase transition of the trapped water molecules resulting in sudden volume expansion against the capsule. This event causes simultaneous and instantaneous 360° mechanical cleavage of the capsule which is already under great tensile stress (white arrow) along the circular path of the nitinol ring.

damage during intraocular use is avoided by (1) the extremely brief nature of the energy application which itself is localized to the edge of the nitinol ring and (2) insulation provided by the silicone suction ring cover and the surrounding OVD.

TECHNIQUE After the AC is formed with OVD, the capsulotomy device is inserted and centered on the corneal reflex or in accordance with the surgeon’s preference. The ring and surrounding cup are positioned on the anterior capsular surface prior to engaging the suction via the console. Suction brings the capsule in direct uniform apposition against the bottom edge of the nitinol ring. Once activated, as already described, a rapid series of microsecond-long electrical pulses achieve the capsulotomy.

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STUDY RESULTS Precision pulse technology can create a perfect and round capsulotomy without tags in a consistent and reproducible manner almost instantaneously. Zonular traction: It is no more traumatic to the zonular apparatus than a manual CCC as borne out by Miyake-Apple imaging in human cadaver eye studies. Thermal phenomenon with respect to peak temperature rise adjacent to the nitinol ring and overlying corneal endothelium was found to be insignificant, returning to the baseline in 2–4 seconds. Absence of collateral tissue trauma (corneal edema, inflammation, and capsular opacification, etc.) was demonstrated in a comparison testing of PPC and manual CCC in paired eyes of live rabbits.9

Strength of Zepto PPC Capsulotomy Margin in Relation to Femtorhexis and Manual Continuous Curvilinear Capsulorhexis In a study comparing manual, FSL, and PPC edge tear strength in 44 paired human cadaver eyes, Vance M Thompson et al. showed that the PPC consistently produced a significantly stronger capsulotomy edge than that produced by FSL or manual method.10 The reason for this is perhaps the fact that the PPC does not involve tissue cauterization, or burning which may create a less extensible capsulotomy. Five previous studies comparing the tear strength of the capsulotomy edge were with respect to manual CCC versus the femtorhexis (Catalys-Abbott, Victus-Bausch & Lomb, LENSAR, and LenSx) and used porcine eyes for the same.11-15 Human cadaver eyes are more likely to be superior in providing an accurate biomechanical model of the lens capsule in a cataract population.16 There was no statistically significant difference in capsulotomy edge tear strength between FSL capsulotomy and manual CCC in this study. The tear strength of the capsulotomy edge is also a function of the capsulotomy diameter which was confirmed in a study in porcine eyes for diameters between 4 mm and 5.5 mm.9 The human anterior lens capsule becomes progressively thicker with increasing distance from its geometric center and is thickest in the midperipheral 5-mm diameter.7,17 Hence, a theoretical difference in edge strength is expected between a 5-mm and 5.5mm diameter capsulotomy than a smaller one. Since the capsulotomy size in the current study was comparable, the observed differences of three- to fourfold in tear strengths could only be due to different capsulotomy methods. The PPC capsulotomy derives its strength from its unique morphology which is absent in manual CCC and FSL capsulotomy9 (Figs. 11.3A to D). In the first ever published clinical report on PPC, Kevin Waltz et al. shared their surgical experience of PPC in 38 eyes undergoing phacoemulsification in routine and challenging cases.18 Patient mix had a variety of comorbidities, including significant pterygium interfering with capsulotomy path visualization

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Figs. 11.3A to D: Cadaver eye specimens demonstrating capsule edge schematic and scanning electron microscopy (SEM) micrographs from cadaver eye specimens. (A) Schematic diagram demonstrating the morphologic features of the precision pulse capsulotomy (PPC) edge. To be noted are the cut edge (red arrow) and the slightly everted functional capsulotomy edge during surgery (green arrow); (B) PPC specimen tilted at an angle to show both the cut edge and the functional edge. The PPC cut edge (area indicated by the red arrow and bracket) shows collagen annealing characterized by random, rounded topologic features. The novel PPC cutting method combined with simultaneous suction results in a unique PPC functional capsulotomy edge characterized by a slight up turning near the cut edge. Hence, approximately 20 µm of the everted undersurface of the intact capsule (area indicated by the green arrow and bracket in B) is contacted by the instrument forces exerting at the capsulotomy plane; (C) Higher magnification view of the rounded PPC functional capsulotomy edge (green arrow and bracket) from the same specimen, viewed head on, at the plane of the capsulotomy opening. The PPC functional edge is actually the smooth, defect-free underside of the lens capsule for maximal edge integrity during surgery; (D) View of the manual continuous curvilinear capsulorhexis (CCC) edge face prepared at the same time as the sample shown in Band C. In contrast to the smooth PPC functional edge face (C), the CCC edge face (D) associated with manual CCC is rough containing linear striations in the collagen matrix.

(2), poorly dilated pupils less than or equal to 4.0 mm in diameter (3), grade 4 cataracts (12), and 6 clock hours of zonular dialysis (1). In their experience, the learning curve for PPC was short and it could be seamlessly integrated into the surgical routine. The PPC device provided

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consistently round, precise (average 5.5-mm diameter) free-floating capsulotomies with complete 360° symmetrical IOL optic overlap with no evidence of tissue burning or cauterization. The device was amenable for centration on the pupil or anywhere on the capsular bag as per the surgeon’s choice. Its design features were useful and greatly facilitated their handling in challenging cases involving poorly dilated pupils, intumescent cataracts, and zonulopathy. The ease of use, consistency, and efficiency of PPC capsulotomy might support its use under many practice scenarios.

ADVANTAGES OF ZEPTO PRECISION PULSE CAPSULOTOMY Zepto PPC reproducibly automates the anterior capsulotomy which is round, well centered, and perfectly sized with a predetermined diameter (Fig. 11.4). The disposable device does not disrupt the conventional workflow and seamlessly fits into a familiar surgical sequence in place of cystitome/ capsulorhexis forceps without increasing the procedural time. The technology is easily integrated to the surgeon’s practice due to lower cost of the unit. Hence, the indications for its use may be easily extended to include routine cases. The capsulotomy can be centered on the visual axis which is an advantage in multifocal IOL technology. It can be used in small pupil situations either after the insertion of pupillary dilatation devices or even through the unmodified pupil due to favorable design of the zepto tip. Capsular staining may be avoided in routine and even in white cataract situations. Zepto PPC provides enhanced

Fig. 11.4: Well-centered toric intraocular lens (IOL) after zepto. Source: Dr David Chang

Recent Advances in Anterior Capsulotomy

surgical safety with reduced incidence of capsular tears than femtorhexis due to the stronger capsulotomy edge of the former. Zepto PPC is an inexpensive device that automates in a reproducible manner the anterior capsulotomy without adversely affecting the patient workflow and has the potential to find widespread application even in routine cataract patients.

CAPSULASER CAPSULaser (CAPSULaser; Los Gatos, CA, United States) is an innovative laser technology (Fig. 11.5) used to create a circular capsulotomy relying on continuous thermal energy. Pavel Stodulka first demonstrated this technique of performing anterior capsulotomy using the “CAPSULaser” in a patient with white intumescent cataract. The laser is conveniently mounted on the microscope (Fig. 11.6).19,20 After making the CCI, with a well-dilated pupil, the anterior capsule is stained with trypan blue (TB) dye to create a chromatically selective anatomical target for the laser. The AC is then irrigated with balanced salt solution to completely remove the TB and then reformed with an OVD. Unlike femto, which is pulsed, this laser is continuous. A wave of this continuous laser is used to scan the TB stained anterior capsule in a circle, and in a 3-second pass, a circular continuous capsulotomy varying in diameter from 4.5 mm to 7.0 mm is created (Figs. 11.7 and 11.8). This technique is fast, safe, and elegant for

Fig. 11.5: The CAPSULaser device console.

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Fig. 11.6: The CAPSULaser device is mounted on a standard operating microscope.

Fig. 11.7: The laser is well focused and well centered. Source: Dr Richard Packard.

Recent Advances in Anterior Capsulotomy

Fig. 11.8: The capsulotomy is performed in one pass by the CAPSULaser. Source: Dr Richard Packard.

the surgeon. The device has been able to generate free floating, well-centered, and circular anterior capsulotomies in a consistent manner (Figs. 11.9A and B). According to the manufacturer, during the procedure, a peak local temperature of 67°C is reached for an instant. Infrared imaging and thermocouple measurements have demonstrated momentary increase of the temperature of the iris, corneal endothelium, and retina by less than 0.2°C during fashioning of the capsulotomy with the CAPSULaser. In the region of irradiation, the laser energy facilitates the molecular phase change of type IV collagen to elastic amorphous collagen. As the collagen undergoes this phase change, it creates the capsulotomy with a rim that has the high degree of elasticity and tear strength associated with amorphous collagen. Under the microscope as well as using SEM (Fig. 11.10), the edge of the capsulotomy appears very smooth and elastic. The capsulotomy expansivity, i.e. the extension beyond capsulotomy/stretchability, was higher with CAPSULaser capsulotomy when compared to manual procedure (Fig. 11.11). CAPSULaser has completed preclinical testing on porcine and human cadaver eyes. Preliminary clinical results with CAPSULaser have been reported in 20 patients with 24 months follow-up. The important points noted in this study are: •• Absence of pupil constriction after laser use •• No AC reaction postoperatively •• Clear corneas

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Figs. 11.9A and B: Free-floating capsules. Source: Dr Richard Packard.

•• Endothelial count as expected •• Capsulotomies well-centered and no capsulotomy contraction •• No change in IOL position. Comparable results have been obtained in subsequent patients totaling 400 eyes. A CE marking trial has been submitted.

Recent Advances in Anterior Capsulotomy

Fig. 11.10: Scanning electron microscopy (SEM) of the capsulotomy disk edge: The capsulotomy edge appears very smooth. Source: Dr Richard Packard.

Fig. 11.11: The CAPSULaser capsulotomy resisting tearing despite extension of up to 12 mm. Source: Dr Richard Packard.

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Advantages of CAPSULaser The CAPSULaser method is dependent on the familiar cataract surgery techniques and relies upon the surgeon to control and position the location of the capsulotomy. There is little disruption to the standard operation theater protocol and the patient flow since the small laser device is attached to the surgical microscope.

APERTURECTC™ CONTINUOUS THERMAL CAPSULOTOMY™ SYSTEM ApertureCTC Continuous Capsulotomy System (International Biomedical Devices, Inc., Mount Pleasant, SC, United States) introduced by Mark Packer,20 is another device on the horizon to generate an automated capsulorhexis in a reproducible manner. In this system, a microincision-compatible ring delivers thermal energy on the anterior capsule to create the capsulotomy (Fig. 11.12). The device has three components: ApertureCTC Console (Fig. 11.13): The ApertureCTC Console serves as the energy source for the system. The patented algorithm provides continuous, controlled, low-level energy to the cutting elements on the capsulotomy tip. ApertureCTCTM Handpiece (Fig. 11.14): The ApertureCTC handpiece connecting to the capsulotomy tip is used to control and introduce the capsulotomy tip

Fig. 11.12: The 360° ring extends from an ergonomic handpiece and allows uniform contact with the anterior capsule. Source: Dr Mark Packer, MD.

Recent Advances in Anterior Capsulotomy

into the AC. It is designed to resemble a typical phaco handpiece with which the surgeon is already very familiar. ApertureCTCTM Precision Capsulotomy Tip (Fig. 11.15): The ApertureCTC precision capsulotomy tip is a ring-shaped single-use component available in sizes between 4.5 mm and 6.5 mm with 0.5-mm increments. It may be inserted through an incision greater than or equal to 1.8 mm. The 360° ring (Fig. 11.12) attached to the tip of the ergonomic handpiece retracts at the sides as it fits through a small corneal incision. Once placed on the anterior capsule, the ring is expanded back to its original shape, allowing uniform contact with the anterior capsule under the protection of an OVD without the need for vacuum suction. The procedure can be completed in milliseconds. As the ring is retrieved, it automatically captures and removes the perfectly circular cap. The disposable tip is discarded after the case. The continuity of the 360° thermal element overcomes the inevitable gap required by radiofrequency devices with loop wire or ring cutting elements. The ApertureCTC continuous capsulotomy system by virtue of being a simple and less expensive procedure has the potential to be accepted by a large number of surgeons throughout the world to design the anterior capsulotomy with geometric precision in a highly consistent manner. The ApertureCTC has not yet been cleared or approved for use in Europe or the United States. After the completion of preclinical studies, clinical trials of the ApertureCTC technology are planned.

Fig. 11.13: ApertureCTCTM console. Source: Dr Mark Packer, MD.

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Fig. 11.14: ApertureCTCTM handpiece. Source: Dr Mark Packer, MD.

Fig. 11.15: ApertureCTCTM precision capsulotomy tip. Source: Dr Mark Packer, MD.

Recent Advances in Anterior Capsulotomy

VERUS OPHTHALMIC CALIPER (MILE HIGH OPHTHALMICS, DENVER, CO, UNITED STATES) The VERUS ophthalmic caliper (Figs. 11.16A and B) provides cataract surgeons with a stable guide for sizing and centering the capsulorhexis in cataract surgery. Made from medical grade silicone, it has a closed-ring configuration

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Figs. 11.16A and B: The VERUS ophthalmic caliper (Mile High Ophthalmics, Denver, CO, United States). Source: (A) Dr Malik Kahook.

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with a micropatterned surface on both sides to enhance lateral stability when in contact with a wet surface.21 It is designed for single use and is provided in sterile packaging within a protective cartridge. It comes in two models with an outer diameter of 6.2 mm and an inner diameter of either 5 mm or 5.5 mm. The 5-mm device requires an incision greater than 2 mm for safe insertion and removal from the anterior chamber.

HANDLING OF THE DEVICE After forming three-fourths of the AC with a dispersive OVD (Viscoat), the caliper device is inserted into the AC using a McPherson/Utrata forceps. The silicone ring is properly centered in accordance with the surgeon’s preference and tapped in place every 2-clock hour against the anterior capsule with a Sinskey hook and the AC is further pressurized with the OVD. Complete filling of the AC locks the device down affording additional stability (Figs. 11.17A to C). Capsulorhexis is initiated at the center of the capsule with a bent 26-gauge cystitome and a capsular flap is raised. The flap is torn a little shy of the inner margin of the caliper and from there, the capsulorhexis is continued with the Utrata forceps. The leading edge of the capsulorhexis is moved tangentially up to the inner margin from which point the flap is walked along the inner margin till it is completed 360°. The capsulorhexis flap always maintains a vertical orientation with respect to the ring device and it may be necessary to repeatedly grasp and regrasp it. The ring is elevated off the anterior capsule with the Utrata forceps and removed from the eye. In a retrospective analysis, Kahook et al. compared 40 consecutive surgeries where capsulorhexis was performed with the VERUS device versus 40 cases where capsulorhexis was performed manually.22 The capsulorhexis was complete in both the groups. The study reported that capsulorhexis size, circularity, and centration were closer to the target when performed with the versus compared to the manual technique (P < 0.05). Complete anterior capsular overlap on the anterior optic surface of the IOL was noticed in all VERUS cases unlike in the manual capsulorhexis group. VERUS device aided capsulorhexis required only 30 seconds more to accomplish than the manual capsulorhexis. The VERUS ophthalmic caliper has multiple advantages. It is cost-effective compared to the other modalities and hence is likely to be beneficial in cost compromised settings especially in the developing world. It effortlessly streams into the surgical protocol with least disruption to the surgeon’s surgical flow. It is also effective resulting in a well-centered and perfectly sized capsulorhexis in a very consistent manner. The capsulorhexis can be centered around any point as desired by the surgeon. Though the device may show a tendency to lose grip on the anterior capsule during the capsulorhexis, it can be re-centered by gently tapping with the Utrata forceps and incremental injection of OVD. If the leading edge tends to run to the periphery, it can be visualized through the transparent device and brought

Recent Advances in Anterior Capsulotomy

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Figs. 11.17A and B

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Fig. 11.17C Figs. 11.17A to C: (A) The VERUS ophthalmic caliper centered and apposed against the anterior capsule stained with trypan blue (0.06%); (B) The VERUS ophthalmic caliper in situ after the round capsulorhexis; (C) Round and well-centered capsulorhexis after the removal of the VERUS ophthalmic caliper.

back to the inner rim by a radially directed tear, and then the tangential tearing is continued. Proper device centering is paramount to result in a uniform anterior capsular overlap on the IOL optic surface.

REFERENCES 1. McCannel CA, Reed DC, Goldman DR. Ophthalmic surgery simulator training improves resident performance of capsulorhexis in the operating room. Ophthalmology. 2013;120(12):2456-61. 2. Dooley IJ, O’Brien PD. Subjective difficulty of each stage of phacoemulsification cataract surgery performed by basic surgical trainees. J Cataract Refract Surg. 2006;32:604-8. 3. Unal M, Yücel I, Sarici A, et al. Phacoemulsification with topical anesthesia: resident experience. J Cataract Refract Surg. 2006;32(8):1361-5. 4. Abell RG, Davies PE, Phelan D, et al. Anterior capsulotomy integrity after femtosecond laser-assisted cataract surgery. Ophthalmology. 2014;121(1):17-24. 5. Davidorf JM. Impact of capsulorhexis morphology on the predictability of IOL power calculations. Paper presented at: American Academy of Ophthalmology Annual Meeting; November 11, 2012. Chicago, IL. 6. Findl O. Influence of rhexis size and shape on postoperative tilt, decentration and anterior chamber depth. In: The XXXI Congress of the ESCRS (European Society of Cataract and Refractive Surgeons). Amsterdam, The Netherlands; 2013. 7. Packer M, Teuma EV, Glasser A, et al. Defining the ideal femtosecond laser capsulotomy. Br J Ophthalmol. 2015;99(8):1137-42.

Recent Advances in Anterior Capsulotomy 8. Chang DF. Precision pulse capsulotomy. Cataract Refract Surg Today. 2016;1:1-3. 9. Chang DF, Mamalis N, Werner L. Precision pulse capsulotomy: Preclinical Safety and Performance of a New Capsulotomy Technology. Ophthalmology. 2016;123(2):255-64. 10. Thompson VM, Berdahl JP, Solano JM, et al. Comparison of manual, femtosecond laser, and precision pulse capsulotomy edge tear strength in paired human cadaver eyes. Ophthalmology. 2016;123:265-74. 11. Friedman NJ, Palanker DV, Schuele G, et al. Femtosecond laser capsulotomy. J Cataract Refract Surg. 2011;37:1189-98. 12. Auffarth GU, Reddy KP, Ritter R, et al. Comparison of the maximum applicable stretch force after femtosecond laser-assisted and manual anterior capsulotomy. J Cataract Refract Surg. 2013;39:105-9. 13. Nagy Z, Takacs A, Filkorn T, et al. Initial clinical evaluation of an intraocular femtosecond laser in cataract surgery. J Refract Surg. 2009;25:1053-60. 14. Naranjo-Tackman R. How a femtosecond laser increases safety and precision in cataract surgery? Curr Opin Ophthalmol. 2011;22:53-7. 15. Palanker DV, Blumenkranz MS, Andersen D, et al. Femto-second laser-assisted cataract surgery with integrated optical coherence tomography. Sci Transl Med. 2010;2:58ra85. 16. Krag S, Andreassen TT. Biomechanical measurements of the porcine lens capsule. Exp Eye Res. 1996;62:253-60. 17. Barraquer RI, Michael R, Abreu R, et al. Human lens capsule thickness as a function of age and location along the sagittal lens perimeter. Invest Ophthalmol Vis Sci. 2006;47:2053-60. 18. Waltz K, Thompson VM, Quesada G. Precision pulse capsulotomy: initial in simple and challenging cataract surgery cases. J Cataract Refract Surg. 2017;43:606-14. 19. Stodulka P. Laser capsulotomy: simple, fast, cost effective—First experience with a new laser. Paper presented at: the XXXIII Congress of the ESCRS. Barcelona, Spain September 5-9, 2015. 20. Packer, M. Continuous Thermal capsulotomy: a simple solution for a longstanding problem. CRSTEurope, 2015. 21. Powers MA, Kahook MY. New device for creating a continuous curvilinear capsulorhexis. J Cataract Refract Surg. 2014;40:822-30. 22. Kahook MY, Cionni RJ, Taravella MJ, et al. Continuous Curvilinear Capsulorhexis Performed with the VERUS Ophthalmic Caliper. J Refract Surg. 2016;32(10):654-8.

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Phacoemulsification in White Cataracts Rohit Om Prakash, Shruti Mahajan, Tushya Om Prakash

INTRODUCTION White cataracts offer one of the biggest challenges during phacoemulsification. White cataracts are associated with difficult capsulorhexis execution, tough nuclear management and high incidence of complications. The white tip of the iceberg aptly symbolizes the intricacies involved in managing white cataracts. White cataract is morphologically characterized by completely opaque crystalline lens that occludes the red reflex. White cataracts occur as a result of varied etiologies and can present with diverse morphologies at any age. A significant number of white cataracts are senile mature or hypermature cataracts. They may also present as congenital total cataract, traumatic, complicated, or radiation-induced white cataracts. The senile white cataracts are more frequently seen in the underdeveloped and developing countries.1-5

CLASSIFICATION White cataracts are classified to facilitate better management strategies.

Age Group Classification •• Congenital/developmental cataract •• Presenile cataract •• Senile cataract.

Morphological Classification •• White mature cortical cataract •• Intumescent cortical cataract

Phacoemulsification in White Cataracts

•• White nuclear cataract •• Hypermature morgagnian cataract •• Hypermature absorbed sclerotic cataract.

Etiological Classification •• •• •• •• ••

Age-related cataract Traumatic cataract Metabolic cataract Complicated cataract Radiation-induced cataract.

Ultrasonographic Classification6 •• Type I: Intumescent white cataracts with cortex liquefaction and high internal acoustic reflections. •• Type II: White cataracts with voluminous nuclei, little amount of whitish solid cortex, and low internal acoustic reflections. •• Type III: White cataracts with fibrosed anterior capsule and low internal echospikes.

PATHOPHYSIOLOGY The white cataract classically gives a white reflex in the eye known as leukocoria. The senile white cataract with total opacification has varied pathophysiology in different morphological conditions.7-11

White Mature Cortical Cataract The white mature cataract forms when the cortical fibers become opaque and pearly white due to oxidative damage with age. There is associated variable degree of nuclear sclerosis.

Intumescent White Cataract As the cataract is maturing, the cortical layers undergo progressive hydration. The excessive hydration can be caused due to the changes in the semipermeability of the lens capsule or osmotic changes in the lens. This causes swelling of the lens forming an intumescent cataract. The anterior chamber subsequently becomes shallow. The nucleus undergoes only a slight change till this stage.

White Nuclear Cataract As the age progresses, the nucleus undergoes a progressive sclerosis. A white nuclear cataract forms which morphologically appears as sclerotic nucleus underlying dense white opaque cortical cataract.

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Hypermature Morgagnian Cataract In a matured cataract, the cortical fibers degenerate leading to accumulation of liquefied lens protein in the capsular bag. It is identified as a hypermature Morgagnian cataract, the sclerosed nucleus floats or sinks down in the liquefied milky cortex.

Hypermature Absorbed Sclerotic Cataract As the maturity progresses, the liquefied cortex gets absorbed spontaneously leaving behind a sclerosed nucleus forming a hypermature absorbed sclerotic cataract. The anterior capsule is fibrosed with calcium deposits and giving a white appearance masking the sclerosed nucleus.

CLINICAL PRESENTATION OF WHITE CATARACTS Clinically, white cataract presents white reflex in the pupil with absence of red reflex. The anterior chamber depth may vary depending upon the morphological type of white cataract. In intumescent cataract (Fig. 12.1), the anterior chamber depth may be less than 3.0 mm and may be more than the normal in hypermature absorbed cataract. There may be a fibrosed anterior capsule with calcification. The cortex may be opacified or it may be liquefied. There is a dense nucleus of variable degree of sclerosis with absence of epinucleus. The zonules may be weak causing either subtle or marked phacodonesis. There may be associated vitreous syneresis resulting in a floppy posterior capsule.1

PREOPERATIVE WORKUP •• Visual potential: In mature cataracts, perception of light and accurate projection of rays is imperative for guarding the postoperative prognosis.

Fig. 12.1: Intumescent cataract.

Phacoemulsification in White Cataracts

•• Macular function tests should be performed. •• Pupillary reaction: A thorough evaluation of pupillary reaction should be done. If anisocoria is present, underlying cause should be investigated. Sluggish reaction can occur in sphincter tear, pseudoexfoliation, or postuveitis. Relative afferent pupillary defect (RAPD) should be ruled out with swinging flash light test. •• Slit-lamp evaluation: A thorough evaluation should be done in undilated and dilated pupil. In undilated pupil, peripheral and central anterior chamber depth is evaluated to prevent iatrogenic acute angle closure in narrow angles/intumescent cataracts. Anterior chamber angle abnormality, preoperative inflammation or signs of previous uveitis, and iris neovascularization should be cautiously observed. In unilateral white mature cataracts occurring at a young age, signs of Fuchs’ heterochromic uveitis should be evaluated. The pupil should be dilated to look for the extent of dilatation, posterior synechiae, cataract morphology, anterior capsular fibrosis/calcification/rupture, zonular weakness, and any subtle or obvious phacodonesis (Tables 12.1 to 12.3). •• Ocular alignment: To rule out sensory amblyopia. •• B-scan ultrasound: To rule out any retrolenticular pathology for postoperative prognosis. •• Biometry: –– Optical biometry: Optical biometry cannot supersede ultrasound because of failure to acquire scans in dense white cataracts. –– Ultrasound A scan: Ultrasound biometry is successful in all types of mature cataracts and hence scores over optical biometry.12 •• Fixation to light: Monocular fixation of light is essential for cooperation during the surgery. A peribulbar or retrobulbar block is planned in cases without monocular fixation.

MANAGEMENT Preoperative In white intumescent mature cataracts, neodymium-doped yttrium aluminum garnet (Nd:YAG) laser performed preoperatively can be useful in making a small opening in the anterior capsule.13 This allows the cortical fluid to egress out into the anterior chamber. The routine phacoemulsification can follow within 30 minutes of the procedure. When the cortex fluid egresses out, the chances of peripheral extension of the capsulorhexis are minimal. In hypermature morgagnian and intumescent cataracts, 250 mL of 20% mannitol is given an hour prior to the surgery to decrease the posterior segment pressure and reduce the vitreous volume.14,15

Anesthesia In bilateral mature cataracts or cases with difficult fixation of light monocularly, a peribulbar or retrobulbar block is indicated. To allow effective diffusion of

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Anterior chamber depth

Convexity of anterior lens surface

Optically empty spaces in anterior cortex (water vacuoles/clefts)

White mature cortical

Pearly white, uniformly soft cortex with soft nucleus

Van Herick (VH) grade III or IV

Less or same as normal crystalline lens

Very few or none

Intumescent white (Fig. 12.1)

Snow white, diffusely flocculent cortex

VH grade I or II

More than normal crystalline lens

May or may not be there (if present, can be either a few or multiple)

White nuclear

Chalky white, slightly flocculent cortex with large brown nucleus

VH grade III or IV

Same as normal crystalline lens

None because of compactly packed cortex

Hypermature morgagnian

Milky white, liquefied cortex with variably sized nucleus sunken in the capsular bag

VH grade II or III

More than normal crystalline lens but lesser than intumescent white cataract

None because of completely liquefied cortex

Hypermature absorbed sclerotic

Egg-shell white due to calcified or fibrotic anterior capsule, little or no cortex, shrunken hard nucleus

VH grade IV

Less convex than a normal crystalline lens due to very little cortex

None because of minimal or no cortex

the anesthetic agent, pressure with a Honan balloon/Super pinky/mercury bag is advised.16,17 This basic step can prevent thrust from the posterior segment, thereby reducing the incidence of Argentinian sign.

Capsulorhexis Achieving a continuous curvilinear capsulorhexis in white cataract remains a challenge. At times, the fibrotic, rigid, and calcified anterior capsule compromises its visibility as it does not allow uniform staining with Trypan blue dye. This poor visibility is further masked by the milky cortex egressing out as soon as the capsule is punctured.18,19 Furthermore, the complexity increases due to predisposition of mature intumescent and hypermature morgagnian cataracts for Argentinean tear. Argentinean tears occur due to the decreased control because of centrifugal force acting in a convex anterior capsule masking of visibility by the egressing

Phacoemulsification in White Cataracts TABLE 12.2: Topographic evaluation of white cataracts. Tomographic evaluation Anterior chamber angle (degrees)

Lens densitometry

164.5 (109–220)

>45 (30–39)

62.5–100%

159.68 (85–223)