Cataract Surgery from Routine to Complex : A Practical Guide [1 ed.] 9781617116889, 9781556429477

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COMPLEX A PRACTICAL GUIDE Cataract Surgery From Routine to Complex: A Practical Guide provides eye care professionals guidance on what to do and how to avoid potential complications in all aspects of cataract surgery, just as if the world’s experts were by your side. Drs. Randy Olson, George Jin, Ike Ahmed, Alan Crandall, Robert Cionni, and Jason Jones concisely provide a wealth of information, including a detailed list of key issues and considerations for virtually all the possible contingencies of the procedure. Some Topics and Sections Include: • Examination – Pupil size, ocular dominance, biometry, and more • IOL Choice – Monofocal: aspheric vs. traditional; presbyopia-correcting: mutifocal vs. accommodating; toric, and more • Routine Cataract Surgery – Microincision cataract surgery, OVD selection, current phacoemulsification techniques, and more

• Complex Cataract Surgery – Hypermature cataract, small pupil, pseudoexfoliation, nanophthalmos, pediatric cataract, and more • Intra-Operative Complications – Wound burn, posterior capsular rupture, shallow anterior chamber, and more • Patient Assessment – Visual acuity, refraction, visual quality, and more • Postoperative Complications – Endophthalmitis, toxic anterior segment syndrome, IOL dislocation, and more

Cataract Surgery From Routine to Complex also includes a companion website that provides more than 2 hours of learning with 38 edited and narrated video presentations, perfectly complementing the procedures discussed inside the text. Cataract Surgery From Routine to Complex is the combination of a practical guide with broad academic underpinnings along with current controversial subjects on cataract surgery, making it ideal for eye care professionals who wish to update their knowledge and translate it into improved surgical techniques and better cataract patient education.

CATARACT SURGERY FROM ROUTINE TO COMPLEX A PRACTICAL GUIDE

CATARACT SURGERY FROM ROUTINE TO

Includes Video Website Access

CATARACT SURGERY FROM ROUTINE TO

COMPLEX A PRACTICAL GUIDE

Randall J. Olson Ike K. Ahmed

■

Alan S. Crandall

■ ■

George J. C. Jin

Robert J. Cionni

■

Jason J. Jones

slackbooks.com MEDICAL/Ophthalmology

SLACK Incorporated

10-0811_Olson_CatSurg_cvr.indd 1

4/21/2011 3:24:07 PM

Randall J. Olson, MD Department of Ophthalmology and Visual Sciences University of Utah Salt Lake City, Utah

George J. C. Jin, MD, PhD Jones Eye Clinic Sioux City, Iowa Department of Ophthalmology and Visual Sciences University of Utah Salt Lake City, Utah

Iqbal Ike K. Ahmed, MD, FRCSC University of Toronto Toronto, Canada Department of Ophthalmology and Visual Sciences University of Utah Salt Lake City, Utah

Alan S. Crandall, MD Department of Ophthalmology and Visual Sciences Salt Lake City, Utah

Robert J. Cionni, MD Eye Institute of Utah Department of Ophthalmology and Visual Sciences University of Utah Salt Lake City, Utah

Jason J. Jones, MD Jones Eye Clinic Sioux City, Iowa and Sioux Falls, South Dakota

www.slackbooks.com

ISBN: 978-1-55642-947-7 Copyright © 2011 by SLACK Incorporated All rights reserved. No part of this book may be reproduced, stored in a retrieval system or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without written permission from the publisher, except for brief quotations embodied in critical articles and reviews. The procedures and practices described in this book should be implemented in a manner consistent with the professional standards set for the circumstances that apply in each specific situation. Every effort has been made to confirm the accuracy of the information presented and to correctly relate generally accepted practices. The authors, editor, and publisher cannot accept responsibility for errors or exclusions or for the outcome of the material presented herein. There is no expressed or implied warranty of this book or information imparted by it. Care has been taken to ensure that drug selection and dosages are in accordance with currently accepted/recommended practice. Off-label uses of drugs may be discussed. Due to continuing research, changes in government policy and regulations, and various effects of drug reactions and interactions, it is recommended that the reader carefully review all materials and literature provided for each drug, especially those that are new or not frequently used. Any review or mention of specific companies or products is not intended as an endorsement by the author or publisher. SLACK Incorporated uses a review process to evaluate submitted material. Prior to publication, educators or clinicians provide important feedback on the content that we publish. We welcome feedback on this work. Published by: SLACK Incorporated 6900 Grove Road Thorofare, NJ 08086 USA Telephone: 856-848-1000 Fax: 856-853-5991 www.slackbooks.com Contact SLACK Incorporated for more information about other books in this field or about the availability of our books from distributors outside the United States. Library of Congress Cataloging-in-Publication Data Cataract surgery from routine to complex : a practical guide / Randall J. Olson ... [et al.]. p. ; cm. Includes bibliographical references and index. ISBN 978-1-55642-947-7 (alk. paper) 1. Cataract--Surgery. 2. Intraocular lenses. I. Olson, Randall J. [DNLM: 1. Cataract Extraction--methods. 2. Lens Implantation, Intraocular--methods. 3. Outcome and Process Assessment (Health Care) WW 260] RE451.C355 2011 617.7’42059--dc22 2011005367 For permission to reprint material in another publication, contact SLACK Incorporated. Authorization to photocopy items for internal, personal, or academic use is granted by SLACK Incorporated provided that the appropriate fee is paid directly to Copyright Clearance Center. Prior to photocopying items, please contact the Copyright Clearance Center at 222 Rosewood Drive, Danvers, MA 01923 USA; phone: 978-750-8400; web site: www. copyright.com; email: [email protected] Please note that the purchase of this e-book comes with an associated Web site or DVD. If you are interested in receiving a copy, please contact us at [email protected]

Dedication We dedicate this book to all of those practitioners who have made cataract surgery the artful and successful procedure that it is today. Without you, this book would never have been possible, and we owe all our success and joy in this most amazing form of sight restoration to the collective wisdom and insight provided by the great international fraternity of cataract surgeons. We also dedicate this book to all of those who have helped and encouraged us along the long road to finish this book. We hope we have been able to give back a little of what we have received by this work.

Contents Dedication. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . v Acknowledgments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .xi About the Authors . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiii Contributing Author . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xiv Preface . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . xv

Section I

Preoperative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 1

Chapter 1

Patient Counseling . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .3 Randall J. Olson, MD Patient Education . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Patient Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4 Expectations . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .4

Chapter 2

Preoperative Examination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 George J. C. Jin, MD, PhD Pupil Size . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .5 Ocular Dominance . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 Biometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .6 Keratometry . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 Corneal Topography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 Optical Coherence Tomography . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .9 Preoperative Special Testing . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .10

Chapter 3

Cataract Assessment and Grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 Randall J. Olson, MD and George J. C. Jin, MD, PhD Cataract Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .19 Cataract Grading . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .25

Chapter 4

Evaluation and Treatment of Lid Margin and Ocular Surface Diseases . . . . . . . . . . . . . . . . . . . .29 Randall J. Olson, MD and George J. C. Jin, MD, PhD Dry Eye Syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .29 Blepharitis and Meibomian Gland Dysfunction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .32 Anterior Basement Membrane Dystrophy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 34

Chapter 5

Intraocular Lens Choice . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .37 Robert J. Cionni, MD and George J. C. Jin, MD, PhD Monofocal: Aspheric Versus Spherical Intraocular Lenses . . . . . . . . . . . . . . . . . . . . . . . . . . .37 Presbyopia-Correcting Intraocular Lenses: Multifocal and Accommodating . . . . . . . . . . . . .38 Toric Intraocular Lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 40 Monovision . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .41 Refractive Intraocular Lens Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 42

Chapter 6

Intraocular Lens Power Calculation in Primary Cataract Surgery . . . . . . . . . . . . . . . . . . . . . . . .45 George J. C. Jin, MD, PhD and Jason J. Jones, MD Intraocular Lens Power Calculation Formulas . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .45 Personalized Constants. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 46 Intraocular Lens Power for In-the-Bag and In-the-Ciliary Sulcus Placement . . . . . . . . . . . 46 Intraocular Lens Adjustment From the First Eye Outcome . . . . . . . . . . . . . . . . . . . . . . . . 46 Intraocular Lens Power Calculation in Extreme Short and Long Eyes . . . . . . . . . . . . . . . . .47

viii

Contents

Chapter 7

Intraocular Lens Power Calculation After Corneal Refractive Surgery . . . . . . . . . . . . . . . . . . . .51 George J. C. Jin, MD, PhD and Jason J. Jones, MD Problems of Intraocular Lens Power Determination . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .51 Calculation After Myopic Laser Vision Correction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .52 Methods of Calculation After Hyperopic Laser Vision Correction . . . . . . . . . . . . . . . . . . . .55 Methods of Calculation After Radial Keratotomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56 Selection of Intraocular Lens Calculation Methods . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .56

Chapter 8

Intraocular Lens Power Calculation in Special Occasions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59 George J. C. Jin, MD, PhD and Jason J. Jones, MD Piggyback Intraocular Lens Power . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59 Intraocular Lens Power for IOL Exchange . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .59 Intraocular Lens Power in Eyes After Previous Vitrectomy . . . . . . . . . . . . . . . . . . . . . . . . . 60 Intraocular Lens Power in Combined Silicone Oil Removal and Cataract Surgery . . . . . . . .61 Intraocular Lens Power in Eyes Undergoing Phacovitrectomy . . . . . . . . . . . . . . . . . . . . . . .61 Intraocular Lens Power in Eyes After Glaucoma Filtration Surgery . . . . . . . . . . . . . . . . . . .62 Intraocular Lens Power in Pediatric Cataract Surgery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . .62

Section II Intraoperative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 67 Chapter 9

Intraoperative Routine Issues . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69 Anesthesia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .69 Alan S. Crandall, MD Microincisional Cataract Surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .70 George J. C. Jin, MD, PhD and Randall J. Olson, MD Viscosurgical Device Selection . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .72 Randall J. Olson, MD and George J. C. Jin, MD, PhD Capsulorrhexis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .75 Jason J. Jones, MD Hydromaneuvers . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .79 Jason J. Jones, MD Current Phacoemulsification Techniques . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .81 Jason J. Jones, MD

Chapter 10

Managing Pre-Existing Astigmatism . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91 Randall J. Olson, MD and George J. C. Jin, MD, PhD Incisional Effect . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91 Limbal Relaxing Incisions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .91 Toric Intraocular Lenses . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .92

Chapter 11

Cataract Surgery in Special Cases . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95 Hypermature Cataract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .95 Iqbal Ike K. Ahmed, MD, FRCSC and Randall J. Olson, MD Small Pupil . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .98 Robert J. Cionni, MD Zonular Compromise . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .102 Robert J. Cionni, MD Pseudoexfoliation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .107 Jason J. Jones, MD and Alan S. Crandall, MD Posterior Polar Cataract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .111 Jason J. Jones, MD and George J. C. Jin, MD, PhD Pediatric Cataract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .113 Robert O. Hoffman, MD and Alan S. Crandall, MD

Contents

ix

Uveitic Cataract . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .118 Randall J. Olson, MD Combined Cataract and Glaucoma Surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .121 Alan S. Crandall, MD and Randall J. Olson, MD Cataract in High Myopia . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 124 Iqbal Ike K. Ahmed, MD, FRCSC; Jason J. Jones, MD; and George J. C. Jin, MD, PhD Nanophthalmos . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 128 Jason J. Jones, MD and George J. C. Jin, MD, PhD Cataract Surgery After Posterior Vitrectomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .134 Robert J. Cionni, MD Diabetes Mellitus . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .136 Randall J. Olson, MD Cataract Surgery in the Face of Marginal Corneal Endothelium . . . . . . . . . . . . . . . . . . . . .138 Randall J. Olson, MD Chapter 12

Intraoperative Complications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .149 Wound Burn . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .149 Randall J. Olson, MD Posterior Capsular Rupture . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .153 Jason J. Jones, MD and George J. C. Jin, MD, PhD Shallow Anterior Chamber . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .161 George J. C. Jin, MD, PhD; Randall J. Olson, MD; and Jason J. Jones, MD

Section III Postoperative . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 169 Chapter 13

Pharmaceutical Interventions . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171 George J. C. Jin, MD, PhD and Randall J. Olson, MD Nonsteroidal Anti-Inflammatory Drugs . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .171 Fourth-Generation Fluoroquinolones . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .172 New Corticosteroids . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .173

Chapter 14

Postoperative Patient Assessment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .177 George J. C. Jin, MD, PhD and Jason J. Jones, MD Visual Acuity . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .177 Refraction . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .177 Visual Quality . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .178 Unhappy Patients . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .178

Chapter 15

Postoperative Complications . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .181 Endophthalmitis . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .181 George J. C. Jin, MD, PhD Toxic Anterior Segment Syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .182 Randall J. Olson, MD Cystoid Macular Edema . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .184 George J. C. Jin, MD, PhD Posterior Capsular Opacification and YAG Capsulotomy . . . . . . . . . . . . . . . . . . . . . . . . . .185 Randall J. Olson, MD Intraocular Lens Tilt and Decentration . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .187 Jason J. Jones, MD and Iqbal Ike K. Ahmed, MD, FRCSC Intraocular Lens Dislocation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .188 Alan S. Crandall, MD and George J. C. Jin, MD, PhD Retained Lens Fragments . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .191 Iqbal Ike K. Ahmed, MD, FRCSC and George J. C. Jin, MD, PhD

x

Contents Anterior Capsular Contraction Syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .192 Jason J. Jones, MD Capsular Block Syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .194 Jason J. Jones, MD Retinal Detachment . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .195 Randall J. Olson, MD Intraocular Lens Opacification . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .196 George J. C. Jin, MD, PhD Uveitis, Glaucoma, Hyphema Syndrome . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .197 Randall J. Olson, MD

Chapter 16

Postoperative Enhancement . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .207 Corneal-Based Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .207 George J. C. Jin, MD, PhD and Randall J. Olson, MD Lens-Based Procedures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .210 Jason J. Jones, MD; George J. C. Jin, MD, PhD; and Alan S. Crandall, MD

Chapter 17

Cataract Surgery After Previous Refractive Surgery. . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .217 Cataract Surgery After Laser-Assisted in Situ Keratomileusis . . . . . . . . . . . . . . . . . . . . . . .217 George J. C. Jin, MD, PhD and Alan S. Crandall, MD Cataract Surgery After Surface Ablation . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .222 Randall J. Olson, MD and George J. C. Jin, MD, PhD Cataract Surgery After Radial Keratotomy . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .223 George J. C. Jin, MD, PhD and Randall J. Olson, MD

Chapter 18

Future of Cataract Surgery . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . .229 Randall J. Olson, MD

Financial Disclosures . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . . 233

Acknowledgments We wish to thank all the contributing authors for their hard work and commitment. This book would not have been possible without their help and encouragement. We are indebted to James Gilman for his assistance with preparations of the illustrations. We are grateful to the editorial team at SLACK Incorporated for their professional enthusiasm. Special gratitude must go to Jennifer Briggs, April Billick, Dani Karaszkiewicz, and Debra Toulson for their outstanding work and support. Randall J. Olson, MD George J. C. Jin, MD, PhD

About the Authors Randall J. Olson, MD completed his undergraduate training and medical schooling at the University of Utah in Salt Lake City (BA 1970, MD 1973), his residency at UCLA in 1977 in ophthalmology, and fellowships in cornea at the University of Florida in Gainesville and at the LSU Eye Center in New Orleans, where he joined the faculty in 1977 as Director of Corneal Services. Dr. Olson started as division chief in June 1979 at the University of Utah and has been Chair of the Department of Ophthalmology and Visual Sciences ever since, including the building of 2 eye centers and expansion from one to almost 50 faculty members. He has authored more than 300 professional publications and is a worldwide lecturer. Dr. Olson specializes in research dealing with intraocular lens complications and anterior segment surgery of the eye. He was selected as one of the 15 top experts in the field of cataract surgery in the United States in a peer survey conducted by Ophthalmology Times, has appeared in the last 4 editions of Best Doctors in America, and has been in the last 2 Cataract and Refractive Surgery Today editions honoring the top 50 professional opinion leaders in the field of cataract and refractive surgery. George J. C. Jin, MD, PhD is the director of clinical research at Jones Eye Clinic, Sioux City, Iowa. He is an adjunct professor of ophthalmology at the Moran Eye Center, Department of Ophthalmology and Visual Sciences, University of Utah, Salt Lake City, Utah. Dr. Jin earned his medical degree in China at Beijing University Medical School and completed his residency and PhD training at Peking Union Medical College and the Eye Research Center at the Chinese Academy of Medical Sciences. As an associate professor at the Chinese Academy of Medical Sciences, Dr. Jin was the first in China to perform combined surgery of extracapsular cataract extraction with IOL implantation and trabeculectomy. He was also the first surgeon to introduce glaucoma laser surgery to China. After the completion of 2 postdoctorate fellowship programs at the Department of Ophthalmology at West Virginia University and Bascom Palmer Eye Institute of Miami University, he joined the Eye Institute of Utah in 1990. Dr. Jin has published over 70 peer-reviewed papers in major ophthalmic journals. He is a reviewer for numerous ophthalmic journals and has authored chapters in several ophthalmic textbooks. His research interests concentrate on refractive, cataract, and glaucoma surgeries. Iqbal Ike K. Ahmed, MD, FRCSC is an assistant professor at the University of Toronto, where he also serves as the research fellowship director in the Department of Ophthalmology and as Director of the Glaucoma and Advanced Anterior Surgical Fellowship. He is also a clinical assistant professor at the University of Utah. Surgical management of glaucoma, the complex cataract, and management of cataract and intraocular lens complications are his areas of subspecialty expertise. Dr. Ahmed is actively involved in research and medical education at a national and international level. He has received many research grants and has designed diamond scalpels for glaucoma surgery; microsurgical instrumentation; and devices, implants, and techniques for the management of the dislocated cataract and glaucoma. Dr. Ahmed has published numerous peer-reviewed articles and book chapters and has won many awards and honors for papers, posters, and videos. He has given more than 500 scientific presentations and lectures around the world. He has served as course director for numerous surgical courses and directed the Third International Congress on Glaucoma Surgery in Toronto in 2006. Dr. Ahmed sits on the editorial boards of Ophthalmology, the Journal of Cataract and Refractive Surgery, and Techniques in Ophthalmology, among others, and he is a reviewer for numerous journals as well. Alan S. Crandall, MD graduated from the University of Utah, receiving his medical degree from the University of Utah School of Medicine. He completed his internship in surgery at the University of Pennsylvania Medical Center in Philadelphia as well as his residency and fellowship in ophthalmology at the Scheie Eye Institute, University of Pennsylvania. He joined the University of Utah Ophthalmology Department in 1981. Dr. Crandall is Professor and Senior Vice Chair of Ophthalmology and Visual Sciences, Director of Glaucoma and Cataract at the Moran Eye Center, University of Utah, in Salt Lake City, Utah. Dr. Crandall is a diplomat of the National Board of Medical Examiners as well as a member of the American Board of Ophthalmology. In addition, he is a member of the American Society of Cataract and Refractive Surgery, American Glaucoma Society, the European Society of Cataract and Refractive Surgeons, and the International Intra-Ocular Implant Club.

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About the Authors

Robert J. Cionni, MD is a board-certified ophthalmologist who specializes in cataract, lens implant, LASIK, and refractive surgeries, performing nearly 2000 surgeries each year. He has established himself as a leader in his specialty by pioneering some of the most advanced cataract and implant techniques. He is actively involved in clinical research, bringing the latest technologies to his patients, sometimes well before these technologies are available to other surgeons. He has authored numerous articles and textbook chapters about specialized cataract techniques and technologies and the management of complications. Dr. Cionni has designed special implants and surgical techniques to improve the surgical outcomes in patients with traumatic cataract and congenital lens subluxation, as found in many patients with Marfan syndrome. In addition, he teaches surgeons nationally and internationally about the use of these devices. Patients with these types of problems are referred to him from all over the world. Jason J. Jones, MD is President and Medical Director of Jones Eye Clinic in Sioux City, Iowa and Sioux Falls, South Dakota. He graduated magna cum laude from Harvard College and received his MD from New York University School of Medicine. He completed his residency training at the John A. Moran Eye Center, University of Utah, in 2003. Dr. Jones specializes in advanced techniques of phacoemulsification, anterior segment reconstruction, implantation of the latest design IOLs, as well as other anterior segment surgeries. He has authored numerous peer-reviewed publications and his active interests in clinical research are development of new intraocular lens technology and management of complex anterior segment surgery.

CONTRIBUTING AUTHOR Robert O. Hoffman, MD Professor, Ophthalmology and Visual Sciences Director, Pediatric Ophthalmology John Moran Eye Center University of Utah Salt Lake City, Utah

Preface Nothing in medicine has made such dramatic changes in the last 3 decades as the field of cataract surgery. In the mid-1970s, the standard was a 6-clock-hour incision with an intracapsular cataract extraction and aphakia. In fact, after a successful 2-hour cataract surgery, 3 days at bed rest with a bedpan in the hospital, 3 months of not leaning over below the waist, and limited activity, an older female patient who had undergone a first unassisted cataract surgery was ecstatic with her 20/20 vision with an aphakic correction at her 3-month postoperative visit. However, shortly after that when the patient tried to use her new glasses, she asked, “Is there anyway you can put my cataract back?” We have come a long way, and yet this field remains dynamic and continues to rapidly evolve. Today, as we write this, femtosecond-assisted cataract surgery is looking exciting and could be a player in short order. So any book is only up to date at the time it is written. Knowing this challenge of a rapidly evolving field, we have endeavored to use the vast collective experience and knowledge of all of our co-authors and combined these with a broad literature search and academic underpinnings to produce a work that is encyclopedic with short, crisp, practical, yet complete vignettes on virtually every subject. We hope that this book will not only prove informative about the current technology, but also provide an impetus to its continuing development. Did we succeed? Only you the reader can decide the level of our success. We do hope you find this an invaluable and interesting resource. So read on with our thanks, and if you see any of us, we would be glad to hear from you about how well we did in trying to meet our goal. Randall J. Olson, MD George J. C. Jin, MD, PhD

I

PREOPERATIVE

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PATIENT COUNSELING Randall J. Olson, MD of their cataract but the quality of life benefit generated by optimal vision after surgery. The goal for refractive cataract surgery patients is to restore the ability to read comfortably and see clearly at a variety of distances with maximum independence from spectacles. • Surgeons should offer high- quality, personalized, patient- based care with a multitude of new options for patients. Surgeons need to strongly consider moving from an old model that emphasizes resolving pathology to a new model that focuses on patient satisfaction. One of the leading causes for litigation in cataract surgery is the refractive surprise.8 In order to fully embrace the concept of refractive cataract surgery, surgeons have to measure the success of their surgery by the refractive outcomes and adjust accordingly. Today, surgeons should adopt a range of advanced cataract and refractive surgery options to individualize the treatment of a specific patient and his or her visual needs. Refractive cataract surgery is still in its infancy. Continuing improvements in technology and new concepts have been constantly refreshing our view in this new area of refractive cataract surgery. There is no perfect solution yet with the current technologies; however, success is usually achievable with good patient education; patient selection; realistic expectations; meticulous, unrushed surgical techniques; and careful pre- and postsurgery management.

The fusion of modern cataract and refractive surgery has created a new ophthalmologic subspecialty: refractive cataract surgery (RCS).1-7 The characteristics of this distinct subspecialty, including technology, patients, and surgeons, are as follows: • The development of premium refractive intraocular lenses (IOLs) such as presbyopia- correcting and toric IOLs, the evolution of phacoemulsification technology, as well as breakthrough technology such as partial coherence interferometry have ushered cataract surgery from a procedure for the removal of cataracts to one aimed at achieving the best possible postoperative refractive results. In addition, more potent corticosteroids, nonsteroidal antiinflammatory drugs, and antibiotics have improved patient care and reduced adverse events after cataract surgery. Refractive cataract surgery is not simply employing refractive IOLs; it involves the postcataract tuning up refractive procedures, including various refractive procedures available to refine the refractive outcomes after cataract surgery. • Cataract patients today are a different breed than usually encountered in the past. They are presenting for surgery at earlier ages with excellent corrected vision already a given. Those with mild incipient cataracts (minimally or not clinically significant cataracts) are also seeking a solution for their presbyopia and do not want to wait for surgery. Their interests are not only in the treatment

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Patient Education Elevated patient expectations and the surgeon’s need to meet them are the most important difference between refractive cataract surgery and traditional cataract surgery. For generations, patients have accepted the loss of unaided near vision as the price of having their cataracts removed. Now, refractive cataract surgery can provide patients with the opportunity of greater independence from spectacles. However, the current technology cannot always fulfill a patient’s desires, and the compromise in terms of optical quality and accuracy inherent in the refractive lens designs and biometry today are still the main cause for unsatisfactory outcomes. Patient education is the key to success. Patients should understand that although current refractive lenses provide an unprecedented range of vision, they are not perfect. The potential risks, side effects, different lens options, and the possible need for a second refractive procedure or IOL exchange should be discussed with each patient before surgery. Patients should be informed that each type of refractive lens has different issues regarding light phenomena such as halos and glare as well as different abilities with regard to range of vision. Furthermore, surgeons should understand their patients’ personalities, visual needs, and expectations. This allows them to determine which patients are suitable candidates for refractive IOLs. Every patient should complete a questionnaire to assess his or her goals for surgery. It is important to evaluate a patient’s desire for independence regarding intermediate and reading vision.

Patient Selection Indications for the use of refractive IOLs are still evolving. Careful patient selection is critical for successful implementation of this technology. The ideal candidates for a refractive IOL should be highly motivated for spectacle independence yet also have realistic expectations. Based on the Food and Drug Administration’s (FDA) clinical trials, Alcon (Fort Worth, TX), one of the lens manufacturers, has indicated that poor candidates for refractive lens operations include those who are hypercritical with unrealistic expectations for visual improvement, have excessive complaints about spectacles or contact lenses, drive at night for a living or whose occupation or hobbies depend on good night vision, are amateur or commercial airline pilots, have lifelong complaints about glare, are happy wearing glasses, and want guarantees on surgical outcomes. A profile analysis may be helpful to understand a patient’s psychological makeup with respect to his or her expectations and desires. Contraindications for refractive cataract surgery include patients with high amounts of astigmatism or

irregular astigmatism, such as those with a forme fruste; subclinical or frank keratoconus; maculopathy (epiretinal membranes, macular degeneration); clinically significant glaucoma, such as those with significant visual field defects or optic neuropathy; corneal disease, such as significant anterior basement membrane dystrophy, Fuchs’ corneal dystrophy, corneal scarring or opacity, marginal corneal degeneration, or any other corneal dystrophy; retinal conditions, such as diabetic retinopathy or previous vascular occlusion; and zonular problems predisposing to IOL decentration. Many of these pathologies can contribute to a significant loss of contrast sensitivity or other causes of diminished quality of vision, making these patients undesirable candidates for multifocal IOLs.

Expectations Adverse subjective visual phenomena, particularly halo and glare, were reported in 33% to 60% of patients with multifocal refractive IOLs in recent studies.9,10 Therefore, managing the patient’s expectations is a key component for successful refractive cataract surgery. The discussion should be frank, with neither over- or underemphasis of the concerns. With improving technology and increasing patient expectations, this will be an important element of a cataract surgeon’s skill set, and refractive lenticular surgery will eventually overtake regular cataract surgery as our most common surgical procedure in ophthalmology.

CHAPTER REFERENCES 1. Olson RJ, Mamalis N, Werner L, Apple DJ. Cataract treatment in the beginning of the 21st century. Am J Ophthalmol. 2003;136:146-154. 2. Linebarger EJ, Hardten DR, Shah GK, Lindstrom RL. Phacoemulsification and modern cataract surgery. Surv Ophthalmol. 1999;44:123-147. 3. Olson RJ, Werner L, Mamalis N, Cionni R. New intraocular lens technology. Am J Ophthalmol. 2005;140:709-716. 4. Obstbaum SA. White paper: utilization, appropriate care, and quality of life for patients with cataracts. J Cataract Refract Surg. 2006;32:1748-1752. 5. Fine IH, Hoffman RS, Packer M. Refractive lens exchange: the quadruple win and current perspectives. J Refract Surg. 2007;23:819-824. 6. Packer M, Fine IH, Hoffman RS. Refractive lens exchange. Focal Points. 2007;25:1-14. 7. Lane SS, Morris M, Nordan L, Packer M, Tarantino N, Wallace RB III. Multifocal intraocular lenses. Ophthalmol Clin North Am. 2006;19:vi, 89-105. 8. Brick DC. Risk management lessons from a review of 168 cataract surgery claims. Surv Ophthalmol. 1999;43:356-360. 9. Leyland M, Zinicola E. Multifocal versus monofocal intraocular lenses in cataract surgery: a systematic review. Ophthalmology. 2003;110:1789-1798. 10. Cillino S, Casuccio A, Di Pace F, et al. One- year outcomes with new- generation multifocal intraocular lenses. Ophthalmology. 2008;115:1508-1516.

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PREOPERATIVE EXAMINATION George J. C. Jin, MD, PhD Success with refractive cataract surgery depends not only on patient selection and focusing on the patient’s motivation and expectations, but also on careful preoperative assessment, which consists of determining the dominant eye, measuring the pupil, obtaining accurate biometry, employing more sophisticated intraocular lens (IOL) power calculations, and ensuring a patient’s medical candidacy.

quantitative measurement of the true scotopic or low mesopic pupil size because the pupil does not constrict when exposed to light in the infrared spectrum. Infrared pupillometry has shown that scotopic pupil diameter in myopic eyes is significantly larger than in emmetropic patients. The commonly used infrared pupillometers include Procyon (Procyon Instruments Ltd, London, UK), Colvard (Oasis Medical, Glendora, CA), and the recently introduced NeurOptics (NeurOptics Inc, Irvine, CA). A study showed that the digital infrared pupillometer (Procyon) has better repeatability and agreement in measuring scotopic pupil size than the handheld device (Colvard).4 A recent study compared these 3 devices and demonstrated that the NeurOptics pupillometer had the highest interobserver agreement and repeatability (Figure 2-1).5 Although topography also records pupil diameter, the results from the light setting required cannot compare to conditions in the real world. The optical and visual performance of a multifocal IOL is highly dependent on pupil size in terms of performance. A larger pupil (as a general rule, greater than 5.0 mm under scotopic light) correlated significantly with better distance visual acuity (VA) and decreased near VA with the ReSTOR lens (Alcon, Fort Worth, TX).1 Conversely, a patient with small pupils may do poorly in reading with the ReZoom (Abbott Medical Optics [AMO], Santa Ana, CA) because the

Pupil Size Pupil diameter measurement, especially in scotopic illumination, is an essential parameter in refractive lens surgery.1,2 Postoperative visual symptoms (glare, halo, and night driving difficulties) are mainly related to vision at low light levels because pupil diameter becomes larger than the functional optical zone and light may be scattered by the cornea under low illumination. Therefore, the accurate preoperative measurement of pupil diameter under low illumination is important to assess the potential for night vision symptoms postoperatively.3 A ruler or a strip with holes of increasing size (a Morton’s pupillometer) can be used to measure pupil size. However, pupillometers, which use various techniques, provide more accurate and reproducible measurement. Pupillometers with infrared technology enable

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Chapter 2 therefore, dominant eye determination can be helpful in surgical planning and IOL power selection. For example, using the Crystalens to aim for a myopic outcome (-0.75 D) in the nondominant eye and performing surgery on the nondominant eye first could help in the accuracy of obtaining close to plano for the dominant eye.

Biometry AXIAL LENGTH MEASUREMENT

Figure 2-1. NeurOptics infrared pupillometer. (Reprinted with permission from NeurOptics, Irvine, CA.)

central optical zone is primarily distance dominant. Accommodating lenses such as the Crystalens (Bausch & Lomb, Rochester, NY) are relatively pupil independent and may be a good option for patients with small pupils. IOLs that compensate for corneal spherical aberration will help reduce the influence of pupil size.6

Ocular Dominance Determination of the dominant eye is important in refractive cataract surgery and is especially helpful for patients who opt for monovision.7 The existence of ocular dominance has been demonstrated in various parameters such as degree of myopia in anisometropic myopia, accommodative responses, fixation and attention, eye movement in amblyopia, and unilateral macular hole.8 Ocular dominance can be quantitatively evaluated using binocular rivalry induced by retinometers.7,8 In practice, the dominant eye is usually determined using the hole-in-card test in which patients are asked to look at a target at 5 m with both eyes simultaneously through a 1-cm hole in the center of a piece of cardboard, and the eye that can be aligned with the target and the hole is the dominant eye. The eye that people used repeatedly to view distance objectives usually is the dominant eye. Right eye dominance is more common than left. A recent study found that 70% of men and 65% of women were right-eye dominant among the study population.9 The percentage of uncertain eye dominance was less than 1%.10 Clinically, for monovision correction, the nondominant eye is commonly corrected for near vision and,

One of the major sources of error in IOL power calculation is inaccurate axial length (AL) measurement.6,11 An error of 100 μm in AL measurement can lead to 0.28 D of postoperative error.6 In short eyes, this effect is amplified. Traditionally, AL is measured by A-scan ultrasound (US) using an applanation technique. With an immersion US technique, the US probe is kept 5.0 to 10.0 mm from the cornea by using a fluid shell, thus improving the accuracy of the measurements and decreasing variability of the AL.12,13 A partial coherence interferometer (PCI) with the IOLMaster (Carl Zeiss Meditec, Jena, Germany) has been shown to have advantages over conventional US technique, which allows highly precise, reproducible, and contact-free measurement with reduced dependence on the user’s experience. Currently, the most accurate measurements of AL are with the IOLMaster.12,14-16 With optical biometry, the AL is measured through the visual axis from the corneal vertex directly to the fovea instead of the anatomical axis from the anterior pole to the posterior pole as measured with US. This is particularly advantageous in highly myopic or staphylomatous eyes because it can be difficult to measure the true AL through the visual axis with a US probe. Optical biometry is also superior to US in the measurement of pseudophakic and silicone oil-filled eyes.17,18 However, the IOLMaster cannot be used in 3% to 10% of patients due to dense media opacity, including corneal opacity, some forms of cataract, vitreous hemorrhage, and low VA resulting in failed fixation.6,11 In such cases, immersion A-scan should be used to determine the AL. The results from Packer et al13 demonstrated that the near-perfect correlation of an immersion US and IOLMaster measurement results in a high level of accuracy of both methodologies. The signal-to-noise ratio (SNR) value is useful in confirming the good quality of AL readings with the IOLMaster; a higher SNR value indicates greater accuracy. SNR 3 mm in diameter are generally considered visually significant. Bilateral cataracts usually have a genetic basis and are associated with other diseases. Unilateral cases are usually isolated sporadic incidents and can be associated with other ocular abnormalities.2-5 Congenital cataracts have broad varieties of morphological configurations and may appear as polar (anterior and posterior polar cataract), capsular, lamellar (zonular), cortical, nuclear, or as a total cataract. a. Polar cataracts involve the lens capsule and adjacent cortex on the anterior or posterior

21

Figure 3-5. Posterior subcapsular cataract.

pole of the lens. Anterior polar cataracts are usually bilateral, small, nonprogressive, and do not impair vision. They may be seen in association with other ocular abnormalities such as microphthalmos, persistent pupillary membrane, and anterior lenticonus (Figure 3-6A). b. Congenital NCs are opacities within embryonic/fetal nuclei. They are usually bilateral and nonprogressive with a wide spectrum of severity (Figure 3-6B). c. Sutural cataract is an opacification of the Y-sutures in the lens nucleus. It is usually bilateral, symmetric, nonprogressive, and does not impair vision (Figure 3-6C). d. Cerulean cataract is a type of congenital CC and has a characteristic blue color with spoke-like opacities radiating from the center of the lens. It is usually nonprogressive (Figure 3-6D). e. Lamellar (zonular) cataracts are the most common type of congenital cataracts and involve specific layers or zones of the nucleus. They are usually bilateral and symmetric. Clinically, the opacity is visible between the clear nucleus and cortex (Figure 3-6E). f. Total (complete) cataracts involving the whole lens are usually bilateral, progressive, and result in profound visual impairment. 6. Posterior polar cataract (PPC) is a form of congenital cataract, which is signified by a distinctive, very sharply demarcated, round, discoid opacity located in the central posterior part of the lens adjacent to and merging with the posterior capsule (Figure 3-7). PPC is often very quiescent but will often change to a slowly progressive cataract late in life. In the early stages, it can be seen interfering with the normal light reflex and, when fully formed, it presents as a dense, circular plaque in the central

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B

D

C

E

Figure 3-6. (A) Congenital anterior polar cataract. (B) Congenital nuclear cataract. (C) Congenital sutural cataract. (D) Cerulean cataract. (E) Congenital lamellar cataract.

posterior capsule. The area of the capsule underlying a PPC is always very thin and may be nonexistent, so that no matter how it is approached, a capsular rupture may result.18,19 7.

Figure 3-7. Posterior polar cataract.

posterior part of the lens.17 The diagnosis of a PPC is straightforward by slit-lamp examination and does not require special diagnostic procedures beyond a full ophthalmic examination. Some PPCs have been confused with PSCs if a patient history is not available. The surgical significance of a PPC is an increased incidence of rupture of the

Cataract surgery in pseudoexfoliation (PXF) eyes20-22 is associated with a higher incidence of intraoperative and postoperative complications, most notably capsular tears, zonular dialysis, loss of lens material into the vitreous, vitreous loss, lens dislocation, late intraocular lens (IOL) dislocation, and postoperative intraocular pressure (IOP) spike.22 Pseudoexfoliation material can be seen throughout the anterior segment (pupillary border of the iris, in the angle, over the zonules and ciliary body, and on the anterior lens capsule). This is usually recognized as a “3-ring” formed by a central disk, a peripheral ring, and a clear zone in between. Peripupillary iris atrophy and transillumination defects are also often present. Phacodonesis and iridodonesis are commonly observed with ocular movements and are indicative of zonular weakness. NC is the most common type of cataract in PXF eyes (Figure 3-8).23,24

Cataract Assessment and Grading

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Figure 3-9. Christmas tree cataracts. Figure 3-8. Cataracts in PXF.

8. Christmas tree cataracts are a rare form of agerelated cataract. The highly retractile, multicolored, needle-shaped lenticular inclusions are seen within the deep perinuclear cortex of the lens (Figure 3-9). The individual needles run in all directions and the colors seem to vary according to the angle of the incident light. Christmas tree cataracts may be unilateral or asymmetrically bilateral and often are seen in otherwise clear lenses. They usually are identified on routine slit-lamp examination in patients in their sixth or greater decade of life. It has been suggested that the needles are cholesterol crystals23 or are formed as the result of an age-related aberrant breakdown of the crystalline lens induced by elevated Ca++ levels.24 Surgery in these eyes is usually uneventful, and many patients tolerate the lenticular changes just fine until other changes, such as nuclear sclerosis, are added to the picture. 9. Electric cataract 25-27 is the lens opacity resulting from electric shock. The clinical appearances of the cataract vary depending on the severity of the shock and the length of time between the shock and examination. Most changes occur beneath the anterior capsule and are characterized by multiple vacuoles of variable size or by punctate or irregular linear opacities. Scale-like opacities in the anterior cortex and vesicles and amorphous opacities in the posterior subcapsular area have also been reported (Figure 3-10). Opacities throughout the lens may be seen in more severe cases.28 Clinical cataract with visual symptoms can develop immediately or up to 5 years after the electric shock.27,29 Such cataracts usually have no attendant surgical risk; however, other ocular pathology from the electric shock (tear film, cornea, or retina) may impact visual potential.

Figure 3-10. Electric cataract.

10. Sunflower cataract (chalcosis of the lens) is a rare condition in which copper deposition is seen in the lens in patients with Wilson’s disease, a genetic disorder of copper metabolism. The copper deposits are in or beneath the lens capsule, usually on the anterior surface, giving a sunflower appearance with a disc-shaped green or yellowish opacity in the central lens. Radiating petals toward the periphery of the lens are also usually seen.30,31 Patients with sunflower cataract always have a Kayser-Fleischer (KF) ring, which is formed by the deposition of copper in Descemet’s’ membrane near the limbus of the cornea with color that ranges from greenish gold to brown30,32,33 (Figure 3-11). The KF ring and copper deposits in the lens may disappear following medical control of the disease or chelation of the copper.30,31,33 Pupil dilation is required for full visualization of the sunflower cataract. Surgical care is usually straightforward; however, making the clinical diagnosis can be life saving.

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Chapter 3

A

A

B B

Figure 3-11. (A) Sunflower cataract (chalcosis of the lens). (B) KF ring.

11. Lens-induced glaucoma and uveitis: a. Phacolytic glaucoma34,35 is the sudden onset of open-angle glaucoma caused by a leaking hypermature cataract or leaving residual cortex in the eye after surgery. In this cataract, the lens material may leak through a grossly intact capsule into the anterior chamber, causing severe, acute open-angle glaucoma by lens particles obstructing the trabecular meshwork or by the cellular response to either of these.34,35 In addition to the finding of a hypermature cataract, intense conjunctival and limbal injection, corneal edema, obvious flare, and cells and large white particles (monocytes swollen with lens material) in the anterior chamber are usually present and pathognomonic (Figure 3-12A). Definitive treatment requires cataract extraction.36,37 Surgery in such cases can be quite difficult, and choroidal hemorrhage, corneal edema due to the limited chamber space, and cystoid macular edema are complications that are more likely to occur.

C

Figure 3-12. (A) Phacolytic glaucoma. (B) Phacomorphic glaucoma. (C) Phacoanaphylaxis.

b. Phacomorphic glaucoma, a type of secondary acute angle-closure glaucoma, is due to angle closure by an enlargement or forward movement of the lens that can result in pupillary block or can just physically block the angle. This typically occurs in patients with swollen and rapid intumescent cataract38 but can occur from simple nuclear sclerosis, especially in patients with moderate or minimal chamber

Cataract Assessment and Grading depth (Figure 3-12B). Patients may present with acute eye pain, decreased vision, rainbowcolored halo around lights, and nausea, much as in primary angle-closure glaucoma. Signs of phacomorphic glaucoma include high IOP (40 mmHg or above; if the IOP has been very high, ciliary body shutdown may have occurred and the IOP may be normal or low), corneal edema, mid-dilated and irregular pupil, a shallow anterior chamber, and an advanced intumescent cataract. Gonioscopy is helpful, and optical coherence tomography (OCT) to determine the depth of the anterior chamber, anterior angle, and thickness of the lens is particularly helpful in making the diagnosis, especially if visualization of the anterior chamber is poor due to corneal edema.39 Phacomorphic glaucoma is a medico-surgical emergency. Removal of the inciting lens and debris is the definitive treatment of the lens-induced glaucoma.40 The expected complications are similar to those with phacolytic glaucoma. c. Phacoanaphylaxis (lens-induced phacoanaphylactic endophthalmitis/lens-induced uveitis) is a zonal granulomatous antigenic reaction to the lens proteins liberated or released through a ruptured lens capsule.41-44 It can occur in eyes with a hypermature cataract but mostly occurs after cataract surgery and trauma. Retained lens fragments after phacoemulsification may result in this condition (Figure 3-12C). The clinical features of phacoanaphylaxis are difficult to distinguish from other forms of postoperative uveitis. Lens-induced uveitis typically develops 1 to 14 days after traumatic or surgical capsular disruption but may come on much later. Clinical presentations include lid swelling, photophobia, decreased vision, ciliary injection, corneal haze, mutton-fat keratic precipitates, cells and flare, posterior synechiae, and pupillary membrane.41,42 In special cases, anterior chamber fine needle aspiration biopsy may be helpful in making the diagnosis.45

Cataract Grading A number of systems have been proposed to classify and grade lens opacities.46-52 The methods range from a subjective assignment of qualitative labels, such as none, mild moderate, severe or 0, 1+, 2+, 3+, 4+, to more rigorous sequential photographs of the lens by readers trained to assign scores based on comparisons with standard photographs that illustrate clinically important

25

states.53 The most used system for clinical research is the Lens Opacities Classification System III (LOCS III) system.51 Computerized analysis of digital images is another approach that has been developed to grade cataracts.54 These systems, which use slit-lamp photographs to compare to the standard reference photographs for grading, are more suitable for epidemiological studies. Anterior segment OCT provides reliable assessment of lens nucleus density and opacity.55 Scheimpflug imaging has been used for repeatable 360-degree lens density measurements, which could be helpful in longitudinal studies monitoring NCs. Scheimpflug imaging has also been correlated to the LOCS grading system clinically, especially for grading the nuclear density of the lens.6 Galan et al recently proposed a 9-point anatomical grading system that takes account of anatomical difficulties beyond the density of the cataract itself. One of its purposes is to facilitate communication between physicians.56 In a routine clinical setting, a simple, userfriendly, and reliable grading system based on slit-lamp examination is preferred.

OXFORD CLINICAL CATARACT CLASSIFICATION AND GRADING SYSTEM The Oxford Clinical Cataract Classification and Grading System (OCCCGS), which records and quantifies the features of the lens that are visible at the slit lamp, is one of the commonly used clinical methods.2,47 In this system, cataract features are classified morphologically, and individual features are graded by comparison with standard diagrams mounted adjacent to the slit lamp. Attention has been paid to relevant aspects of measurement theory, with equal interval steps between the grades. The image-degrading effect of the cataract is assessed using a resolution target projection ophthalmoscope. The method may be used in conjunction with photographic and image analyzing techniques. Studies have shown that the relationships between the OCCCGS and the LOCS III for NC and PSC are linear. Data from cataract studies using different clinical grading schemes can be compared.57

LENS OPACITIES CLASSIFICATION SYSTEM III The LOCS III contains 6 slit-lamp images for grading nuclear color and opalescence, 5 retroillumination images for grading CC, and 5 retroillumination images for PSC.51 This is the most frequently used method for

26

Chapter 3

clinical studies. In a recent study, a strong correlation was observed between nuclear lens density (NLD) measured using Scheimpflug and LOCS III grading.58 A grading system modified from LOCS II using a grading scale (1 to 4) to record the extent of nuclear, cortical, and posterior subcapsular opacity is useful for the clinical setting.59 In this system, nuclear sclerosis (NS) is graded by evaluating the average color and opalescence of the nucleus in a continuum for grade 1 (mild or early) to grade 4 (severe advanced milky or brunescent NS); CC is visualized in the aggregate and quantified on the basis of the percentage of intrapupillary space obscured and density; and the PSC is graded on the basis of percentage of the area of the posterior capsule obscured.59

WORLD HEALTH ORGANIZATION/ PREVENTION OF BLINDNESS AND DEAFNESS SIMPLIFIED CATARACT GRADING SYSTEM The World Health Organization/Prevention of Blindness and Deafness (WHO/PBD) simplified cataract grading system has been developed to facilitate epidemiological studies as well as to give an estimate of cases that are likely to be in need of surgery.52 In the WHO/PBD system, a slit lamp with 10x magnification and adjustable width, height, and angulation of the slit beam is required. Mydriatics such as tropicamide 0.5% and phenylephrine 2.5% to 10% need to be administrated in the eye after a drop of topical anesthetic has been instilled in order to increase absorption. The examination should be performed at least 20 minutes after mydriatic instillation or the diameter of the pupil should be at least 6.5 mm for a complete examination. The 3 levels reflecting progressive severity of nuclear, cortical, and PSC have been used in the classification in the WHO/PBD system. The examiner assigns a severity grade by comparing the degree of opacification in the slit-lamp appearance with the standard photographs. Three standard photos are used for grading NC: standard 1 (STD 1) shows significant NC, in which the nuclei are distinctly more opalescent than normally seen but the central clear zone is still easily distinguishable; standard 2 (STD 2) shows moderately advanced NC, in which the nuclear zone is more uniformly opaque and the central clear zone and the anterior and posterior nuclei are not clearly visible. The posterior part of the

zone is often more opaque and the red reflex is somewhat reduced in brightness. Standard 3 (STD 3) shows very advanced NC; the nuclear zone is densely opaque, with more or less uniform nuclear opacity extending to the edge of the nuclear zone. The red reflex is dull. Grade NC-0: < NC STD 1; grade NC-1: ≥ STD 1 but < STD 2; grade NC-2: ≥ STD 2 but < STD 3; grade NC-3: ≥ STD 3. For CC, the examiner determines the circumferential extent of discrete CC seen on retroillumination. A relatively short and broadly focused beam, positioned within the 3 or 9 o’clock border of the pupil, should be used. Only sharply and well-defined anterior and posterior cortical opacities seen on retroillumination at the slit lamp will be graded as CC. Isolated opacities should be added together to give the total circumference involved. Grade CC-0, cataract involves 26 mm. For the patient with extreme high myopia requiring a low- or minus-power IOL, a different lens constant may be required to achieve the intended refractive result.28 Applying separate sets of constants for plus-power and minus-power IOLs may reduce the systemic hyperopic outcomes after IOL implantation in extremely myopic eyes. Petermeier et al optimized all constants for lowpower (-5.00 to +5.00 D) IOLs and showed that the Haigis and SRK/T formulas are the most accurate for highly myopic eyes.27 IOLMaster lens constants from the User Group for Laser Interference Biometry Web site (www.augenklinik.uni-wuerzburg.de/ulib/c2.htm) may be helpful for selecting an appropriate constant. The use of B-scan ultrasonography to locate posterior pole staphylomas may improve the accuracy of IOL calculations in eyes with extreme myopia.

INTRAOCULAR LENS CALCULATION FOR LONG EYES

INTRAOCULAR LENS CALCULATION FOR SHORT EYES

Although AL measurement with optical biometry is preferred to ultrasound in highly myopic or staphylomatous eyes, there is a tendency for zero- and negative-powered lenses to overcorrect and lead to a

A few studies with short ALs have been reported.26,36,44-48 With a short AL, highly hyperopic eyes are more sensitive to errors in AL measurement and changes in the ELP. A change in the AL of 1 mm, from

TABLE 6-1

SULCUS POWER ADJUSTMENT BAG POWER (D)

SULCUS POWER (D)*

28.5 to 30.0

-1.50

17.5 to 28.0

-1.00

9.5 to 17.0

-0.50

5.0 to 9.0

0.0

*subtract from bag power Reprinted with permission from East Valley Ophthalmology. Calculating Bag vs. Sulcus IOL Power. Available at: http://www.doctor-hill.com/iol-main/bag-sulcus.htm. Accessed March 16, 2011.

and (3) subtracting the value determined in step 2 from the original predicted refractive target in the second eye (choosing an IOL with Holladay-predicted refraction of -0.50 D instead of plano). This novel technique needs to be further confirmed with additional studies.

Intraocular Lens Power Calculation in Extreme Short and Long Eyes

48

Chapter 6

20 to 21 mm, could result in a 5-D difference in the calculated IOL power. In an early study, Lyle and Jin44 compared different IOL formulas and demonstrated that the Holladay 1 formula aiming for -1.00 D achieves good visual and refractive results in eyes with a mean AL of 21.77 mm. In a recent study, MacLaren et al46 indicated that both the Haigis and Hoffer Q formulas were accurate in extremely hyperopic eyes (requiring IOL power of 30.0 D or greater). When comparing the accuracy of several IOL power formulas for eyes with AL 23.00 and the Hoffer Q for AL. Diehl et al36 developed a simple adjustment nomogram based on the manifest refractive spherical equivalent (MRSE) change induced by LASIK: Target = -0.018 (MRSE change)2 + 0.192 (MRSE) – 0.062 where Target is the target postoperative refractive error (D) to achieve emmetropia during IOL power calculation. The Holladay 1 formula is used for medium-long eyes (AL 24.5 to 26.0 mm), SRK/T for eyes with AL >26.0 mm, and Hoffer Q for eyes -4.0 D, aim for -1.0 D). The Shammas method16,17 calculates IOL power using corrected postoperative keratometry with a bestfit regression formula derived from a data set of 100 patients: Kc = 1.14 × Kpost – 6.8 where Kc is the corrected mean corneal power and Kpost is the actual keratometry reading in diopters. The emmetropic IOL power is calculated with the ShammasPL formula. If preoperative data are available, the corneal power is the result of the formula: Kc = Kpost (-0.23 × CRc) where Kc is refraction corrected K value, Kpost is the actual keratometry reading after LASIK, and CRc is the amount of myopic correction at the corneal plane. Better results were obtained with the optimized SRK/T formula.

54

Chapter 7

Methods That Use Topography

P = (TRI – 1)/r

The Rosa correcting factor method18 uses the R factor in the SRK/T formula:

where r is the corneal curvature in meters. TRI = -0.0006 × (AL × AL) + 0.0213 × AL + 1.1572, where AL is axial length. The BESSt formula, described by Borasio et al,14 is a formula that uses the cornea’s anterior and posterior radii of curvature from Pentacam (OCULUS Inc, Lynnwood, WA) measurements to estimate the post-refractive corneal power without any pre-refractive surgery data:

Y = 0.0276 AL + 0.3635 where AL is axial length and Y is the correcting factor. The postoperative radius, as measured by videokeratography (VKG), is multiplied by a correcting factor. The corneal power is obtained by the formula (1.3375 – 1) /corrected radius. The SRK/T is used for IOL power calculation. Based on this method, the formula may be expressed as Kc = Kpost/(0.0276 AL + 0.3635), where Kc is corrected corneal power and Kpost is corneal power after LASIK. Awwad’s no history method6 is as follows: K = 1.114 SimKpost – 6.06 where SimKpost is the average of the central annular values up to the 3.0-mm central area. K is the adjusted value that is used for IOL power calculation. The Maloney method4,7,40 uses the corneal power at the center of the topographic map. The central corneal power (Kpost) can be obtained by placing the cursor at the center of the axial map of the Humphrey Atlas topographer to get the reading: Kc = 1.114 × Kpost – 4.9 where Kpost is the central topographic power and Kc is the post-LASIK adjusted corneal power. The equation is best used with the SRK/T formula. The modified Maloney formula4,7,29 follows: Kc = 1.114 × Kpost – 6.1 The equation is recommended for use with the double-K Holladay 2 and Hoffer Q formulas. The Savini method41 uses postoperative SimK from topography (Kpost): K = 1.114 × Kpost – 4.98 The Haigis-L equivalent power formula15,42 is a theoretical equation derived by performing model calculations on a myopic Gullstrand eye using custom computer programs. This formula corrects the K value taken from the IOLMaster and is best used with the Haigis-L formula: Kc = 1.119 Kpost – 5.78 The Haigis-L formula is included in the operating software for the IOLMaster 4.0 and later versions. The Ferrara43 single-K variable refractive index method correlates the change in the corneal refractive index (TRI) after laser refractive surgery to the axial length. Corneal power (P) can be calculated using the formula:

Ftot = Fant + Fpost – (d/n) × (Fant × Fpost) where Ftot, Fant, and Fpost are the power of the total, anterior, and posterior corneal surfaces in diopters, respectively; d is the corneal thickness (μm); and n is the corneal refractive index. Equivalent K-reading (EKR) is measured by the Pentacam in the Holladay report. The EKR value at the 4.5-mm zone with the Holladay 2 formula is used for IOL power calculation after refractive surgery. A study by Holladay et al demonstrated the efficacy of this method and concluded that when the historical method was not available, directly measured EKR can be an alternative to provide the central corneal power prior to cataract surgery following refractive surgery.44 However, several recent studies45-47 indicated that the EKRs (using the version of 1.14 and 1.16r04) was inaccurate in virgin corneas and in those with a history of LASIK, photorefractive keratectomy (PRK), or radial keratotomy (RK) using current IOL power calculation formulas. Pentacam true net corneal power (the exact central keratometry value from the true net power map) can be used as a keratometry reading with the SRK/T formula to calculate IOL power for eyes with previous myopic refractive surgery. In a retrospective study, Kim et al48 used this method in 30 eyes that had previously undergone myopic corneal surgery, which resulted in 70% of eyes within ±0.50 D of the intended goal and 93% within ±1.00 D. The Orbscan II (Bausch & Lomb, Rochester, NY) total power method proposed by Sónego-Krone et al13 uses the 2-mm total mean power or the 4-mm total optical power assessed by the Orbscan II statistical analysis as accurate values of the corneal power for IOL power calculation in patients after myopic LASIK. In a study by Qazi et al,12 the Orbscan II 5.0-mm total axial power and 4.0-mm optical power combined with the Holladay 2 formula were recommended. Srivannaboon et al11 recommended using the central 4-mm total optical power. The Gaussian optics formula with Orbscan9,10 involves independent assessment of the radius of the anterior and posterior curvature. The K value obtained from the Gaussian optics formula (CalK) based on

Intraocular Lens Power Calculation After Corneal Refractive Surgery postoperative topography by Orbscan II was used for IOL power calculation. The Camellin-Calossi formula8 is a theoretical formula adjusting the corneal power and the prediction of ELP. The corneal power is calculated by using a relative keratometric index that is a function of the actual corneal curvature, type of refractive surgery, and induced refractive change: P = 1336 (4Radj – L)/(L – ACDpost) (4Radj – ACDpost) The Geggel pachymetric method49 uses a new corneal ratio (Geggel ratio) for adjusting IOL power in eyes after laser refractive surgery. The method involves using pre-IOL central and superior corneal pachymetric ratios to estimate the actual depth of ablation and then use this number in a regression formula to determine the diopter of IOL power to be added to the SRK/T formula. The author reported that 92% of eyes achieved postoperative refraction within -1.0/+0.5 D with the Geggel ratio modification.

ONLINE INTRAOCULAR LENS CALCULATORS The Hill-Wang-Koch postrefractive surgery IOL calculator is also the American Society of Cataract and Refractive Surgery (ASCRS) online calculator and a useful tool that provides multiple IOL powers from historical-based methods and objective methods or a combination of both to estimate the K value for IOL power calculation after myopic and hyperopic PRK or LASIK and RK.50 Other publicly available online IOL power calculators include Hoffer-Savini tool (www.eyelab.com), Warren Hill’s Web site for IOL power calculation (www.doctor-hill.com), and the OcularMD IOL calculator (www.ocularmd.com), which implements 10 methods. An average of the IOL power for each method is computed and displayed.51

INTRAOPERATIVE APHAKIC REFRACTION METHODS A new approach to determine IOL power measures the aphakic refraction after removal of the cataract and then uses a nomogram to calculate the IOL power, bypassing corneal power and axial length measurements. The Mackool algorithm52,53 is as follows: IOL Power = ASE × 1.75 + (A – 118.84)

55

With this method, a manifest refraction was performed at the vertex distance of 12.0 mm 30 minutes after removal of the cataract. The Ianchulev method54 is the following: IOL Power = ASE × 2.01449 With this method, ASE is the aphakic spherical equivalent measured with a portable Retinomax autorefractor (Nikon, Melville, NY) in the operating room after cataract extraction while the anterior chamber is inflated to normal status. The vertex distance for autorefraction is 13.1 mm. This method could be applied to most eyes, with the exception of those in highly myopic subjects.55 The Leccisotti method56 is as follows: IOL Power = 1.30 × ASE +1.45 The ASE is obtained with the portable Retinomax autorefractor set at 13.1 mm vertex distance in the operating room. Most recently, the ORange intraoperative wavefront aberrometer (WaveTec Vision, Aliso Viejo, CA) has been introduced for intraoperative wavefront measurements to determine whether the visual target was attained and to optimize IOL power prediction.

Methods of Calculation After Hyperopic Laser Vision Correction Hyperopic refractive surgery such as hyperopic LASIK is performed in the form of an annular ablation in the peripheral cornea to increase the steepness of the central cornea to achieve the desired refractive effect.57 In contradistinction to previous myopic patients, the measured keratometric values are usually lower than the actual power, leading to myopic results after cataract surgery in previously hyperopic patients unless adjustments are made. The higher the amount of hyperopic refractive surgery, the more underestimated the corneal power is by traditional means of keratometry (manual, automated, or topographic SimKs). Thus, adjusting the postoperative corneal topographic measurement according to the amount of LASIK-induced refractive change has been recommended to overcome the problem.32,58 Several methods are presented in the literature: • Wang et al59 presented a nomogram of adjustment of measurements from EyeSys and Atlas for estimating corneal refractive power in eyes following hyperopic LASIK:

56

Chapter 7 EffRPadj = EffRP + 0.162 × (SEpre – SEpost) – 0.279 • Feiz et al32 used a formula to calculate IOL adjustment after hyperopic LASIK: IOL adjustment = 0.751 – (0.862 × change SE) • Chokshi et al58 proposed a regression formula for IOL power adjustment when using the IOLavgk method in which the IOL was chosen based on the average post-LASIK keratometry reading (IOLavgk) from topography with the SRK/T formula: IOL adjustment = -(0.27 × change SE + 1.53) • The regression formula created by Masket 24 also can be used for previous hyperopic patients:

IOL Power Adjustment (D) = LSE × (-0.326) + 0.101 using the Hoffer Q or Haigis formula for baseline IOL power determination. • Awwad’s methods60: K = 0.917 × SimK + 4.016, or P = IOL (with SimK post) – 0.359 × (SEpre – SEpost) – 0.092 • The Haigis-L formula for both post-hyperopia and myopia LASIK/PRK eyes is available as part of the current ASCRS post-keratorefractive online calculator. Also, the Haigis-L formula installed in the IOLMaster, versions 5.4 and higher, allows IOL power calculation for eyes after myopic and hyperopic laser procedures.

Methods of Calculation After Radial Keratotomy With RK, the radial incisions are placed in the midperiphery of the cornea to induce midperipheral bulging with relative central flattening. Thus, special issues arise when post-RK patients require cataract surgery19,61-63: • Because no tissue is removed, it is assumed that similar changes occur in both anterior and posterior radii of curvature and the corneal thickness remains unchanged after RK, whereas after PRK/ LASIK, the ratio between anterior and posterior curvature increases and the central corneal thickness decreases. Therefore, the methods used for patients after PRK or LASIK are not appropriate for patients after RK.

• RK induces corneal irregularity that may prevent the use of manual or IOLMaster measurements in some patients. • Corneal instability due to delayed incisional wound healing may cause a progressive hyperopic change over time, and cataract surgery usually induces a temporary hyperopic change that often regresses as healing occurs. • RK eyes have increased higher order aberrations. Diurnal refractive fluctuation throughout the day may occur in some patients. Therefore, IOL power calculation after RK is less predictable than in normal eyes or eyes after LASIK. Several methods of adjusting the total corneal power for the IOL power calculation are recommended. Packer et al63 reported good results using the EffRP of the Holladay Diagnosis Summary on the EyeSys System and Holladay 2 formula to determine IOL power in eyes with previous RK. Awwad et al61 used the average topographic central corneal power (average of the mean powers of the central 3.0-mm area) with a double-K method and achieved excellent IOL power predictability. Chen et al62 recommended targeting myopia as the postoperative refractive error and using the flatter calculated K in the IOL determination. In Lyle and Jin’s study,19 an adjusted K and targeting myopic postoperative refractive error were used to achieve good results.

Selection of Intraocular Lens Calculation Methods Although multiple calculation methods have been proposed for IOL power calculation after corneal refractive surgery, no one method is definitive and perfect. Most of the methods were tested individually in a clinical setting involving a small number of patients, and some of them lack sufficient clinical data. Comparing the results of multiple methods is becoming common practice. Back-calculated K values generated by the Holladay IOL Consultant program have been suggested as the most logical benchmark to employ. Various methods should be applied and compared and the values that tend to cluster around a mean should be used to determine the corneal power. The most reliable corneal power value should be inserted in more than one modern formula (ie, Hoffer Q, SRK/T, Haigis-L, Holladay 2), and the highest IOL power should be selected in postmyopic refractive surgery patients.64 Randleman et al65 proposed a consensus-K technique, in which K values were measured or calculated by several methods

Intraocular Lens Power Calculation After Corneal Refractive Surgery including manual K, clinical history K, contact lens over-refraction, Feiz-Mannis values, and Hamed values (EffRPadj) as well as Shammas values. These Ks were compared for agreement between methods, the outlier values (more than 1.5 D different from the mean value) were eliminated, and a consensus K value was chosen based on a mean of the values most closely in agreement to use for IOL calculation with the Holladay 2 formula. With this strategy, less variability and higher predictability of refractive outcomes were achieved than all other methods tested. The publicly available online IOL power calculators, such as the Hill-Wang-Koch, Goldsberry, and OcularMD, are convenient and useful tools. In our practice, we routinely obtain corneal power with the IOLMaster, Pentacam, Humphrey Atlas topographer, and manual keratometer, choosing one of these measurements (usually the IOLMaster Ks) if these readings are in accordance; if not, measurements are repeated. The adjusted Ks derived from different methods are plugged into the Holladay 2, Binkhost II, and Haigis-L formulas. Our currently used methods after myopic LASIK include Masket, 24 Seitz, 2,37 Aramberri,30 Latkany, 23 Shammas,16 Haigis,42 Jin, 20 as well as the ASCRS online calculator.50 Various techniques to determine the current corneal power should be compared and the value around which results tend to cluster should be relied on. If the IOL powers from different methods show large discrepancies, we then compare the results and use the Jin-Lyle-Crandall method to finalize our estimate.

CHAPTER REFERENCES 1. Rosa N, Capasso L, Lanza M, Furgiuele D, Romano A. Reliability of the IOLMaster in measuring corneal power changes after photorefractive keratectomy. J Cataract Refract Surg. 2004;30:409-413. 2. Seitz B, Langenbucher A. Intraocular lens power calculation in eyes after corneal refractive surgery. J Refract Surg. 2000;16:349-361. 3. Lee AC, Qazi MA, Pepose JS. Biometry and intraocular lens power calculation. Curr Opin Ophthalmol. 2008;19:13-17. 4. Wang L, Booth MA, Koch DD. Comparison of intraocular lens power calculation methods in eyes that have undergone LASIK. Ophthalmology. 2004;111:1825-1831. 5. Hoffer KJ. Intraocular lens power calculation after previous laser refractive surgery. J Cataract Refract Surg. 2009;35:759765. 6. Awwad ST, Manasseh C, Bowman RW, et al. Intraocular lens power calculation after myopic laser in situ keratomileusis: estimating the corneal refractive power. J Cataract Refract Surg. 2008;34:1070-1076. 7. Maloney RK. Formula for determining corneal refractive power. J Cataract Refract Surg. 2009;35:211-212; author reply 212. 8. Camellin M, Calossi A. A new formula for intraocular lens power calculation after refractive corneal surgery. J Refract Surg. 2006;22:187-199.

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9. Lin JT. Error analysis of intraocular lens power in eyes after LASIK. J Refract Surg. 2006;22:127-128; author reply 128. 10. Cheng AC, Lam DS. Keratometry for intraocular lens power calculation using Orbscan II in eyes with laser in situ keratomileusis. J Refract Surg. 2005;21:365-368. 11. Srivannaboon S, Reinstein DZ, Sutton HF, Holland SP. Accuracy of Orbscan total optical power maps in detecting refractive change after myopic laser in situ keratomileusis. J Cataract Refract Surg. 1999;25:1596-1599. 12. Qazi MA, Cua IY, Roberts CJ, Pepose JS. Determining corneal power using Orbscan II videokeratography for intraocular lens calculation after excimer laser surgery for myopia. J Cataract Refract Surg. 2007;33:21-30. 13. Sonego-Krone S, Lopez-Moreno G, Beaujon-Balbi OV, Arce CG, Schor P, Campos M. A direct method to measure the power of the central cornea after myopic laser in situ keratomileusis. Arch Ophthalmol. 2004;122:159-166. 14. Borasio E, Stevens J, Smith GT. Estimation of true corneal power after keratorefractive surgery in eyes requiring cataract surgery: BESSt formula. J Cataract Refract Surg. 2006;32:2004-2014. 15. Haigis W. Corneal power after refractive surgery for myopia: contact lens method. J Cataract Refract Surg. 2003;29:13971411. 16. Shammas HJ, Shammas MC. No-history method of intraocular lens power calculation for cataract surgery after myopic laser in situ keratomileusis. J Cataract Refract Surg. 2007;33:31-36. 17. Shammas HJ, Shammas MC, Garabet A, Kim JH, Shammas A, LaBree L. Correcting the corneal power measurements for intraocular lens power calculations after myopic laser in situ keratomileusis. Am J Ophthalmol. 2003;136:426-432. 18. Rosa N, Capasso L, Romano A. A new method of calculating intraocular lens power after photorefractive keratectomy. J Refract Surg. 2002;18:720-724. 19. Lyle WA, Jin GJ. Intraocular lens power prediction in patients who undergo cataract surgery following previous radial keratotomy. Arch Ophthalmol. 1997;115:457-461. 20. Jin GJ, Crandall AS, Jin Y. Analysis of intraocular lens power calculation for eyes with previous myopic LASIK. J Refract Surg. 2006;22:387-395. 21. Hoffer KJ. Modern IOL power calculation: avoiding errors and planning for special circumstances. Focal Points. 1999;XVII(12): 1-15. 22. Khalil M, Chokshi A, Latkany R, Speaker MG, Yu G. Prospective evaluation of intraocular lens calculation after myopic refractive surgery. J Refract Surg. 2008;24:33-38. 23. Latkany R A, Chokshi AR, Speaker MG, Abramson J, Soloway BD, Yu G. Intraocular lens calculations after refractive surgery. J Cataract Refract Surg. 2005;31:562-570. 24. Masket S, Masket SE. Simple regression formula for intraocular lens power adjustment in eyes requiring cataract surgery after excimer laser photoablation. J Cataract Refract Surg. 2006;32:430-434. 25. Walter K A, Gagnon MR, Hoopes PC Jr, Dickinson PJ. Accurate intraocular lens power calculation after myopic laser in situ keratomileusis, bypassing corneal power. J Cataract Refract Surg. 2006;32:425-429. 26. Ladas JG, Stark WJ. Calculating IOL power after refractive surgery. J Cataract Refract Surg. 2004;30:2458; author reply 2458-2459. 27. Hamed AM, Wang L, Misra M, Koch DD. A comparative analysis of five methods of determining corneal refractive power in eyes that have undergone myopic laser in situ keratomileusis. Ophthalmology. 2002;109:651-658. 28. Savini G, Barboni P, Zanini M. Intraocular lens power calculation after myopic refractive surgery: theoretical comparison of different methods. Ophthalmology. 2006;113:1271-1282.

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Chapter 7

29. Koch DD, Wang L. Calculating IOL power in eyes that have had refractive surgery. J Cataract Refract Surg. 2003;29:20392042. 30. Aramberri J. Intraocular lens power calculation after corneal refractive surgery: double-K method. J Cataract Refract Surg. 2003;29:2063-2068. 31. Feiz V, Moshirfar M, Mannis MJ, et al. Nomogram-based intraocular lens power adjustment after myopic photorefractive keratectomy and LASIK: a new approach. Ophthalmology. 2005;112:1381-1387. 32. Feiz V, Mannis MJ, Garcia-Ferrer F, et al. Intraocular lens power calculation after laser in situ keratomileusis for myopia and hyperopia: a standardized approach. Cornea. 2001;20:792797. 33. Odenthal MT, Eggink CA, Melles G, Pameyer JH, Geerards AJ, Beekhuis WH. Clinical and theoretical results of intraocular lens power calculation for cataract surgery after photorefractive keratectomy for myopia. Arch Ophthalmol. 2002;120:431-438. 34. Holladay JT. Consultation in refractive surgery. Refract Corneal Surg. 1989;5:203. 35. Hoffer KJ. Intraocular lens power calculation for eyes after refractive keratotomy. J Refract Surg. 1995;11:490-493. 36. Diehl JW, Yu F, Olson MD, Moral JN, Miller KM. Intraocular lens power adjustment nomogram after laser in situ keratomileusis. J Cataract Refract Surg. 2009;35:1587-1590. 37. Seitz B, Langenbucher A, Nguyen NX, Kus MM, Kuchle M. Underestimation of intraocular lens power for cataract surgery after myopic photorefractive keratectomy. Ophthalmology. 1999;106:693-702. 38. Jarade EF, Abi Nader FC, Tabbara KF. Intraocular lens power calculation following LASIK: determination of the new effective index of refraction. J Refract Surg. 2006;22:75-80. 39. Jarade EF, Tabbara KF. New formula for calculating intraocular lens power after laser in situ keratomileusis. J Cataract Refract Surg. 2004;30:1711-1715. 40. Smith RJ, Chan WK, Maloney RK. The prediction of surgically induced refractive change from corneal topography. Am J Ophthalmol. 1998;125:44-53. 41. Savini G, Barboni P, Zanini M. Correlation between attempted correction and keratometric refractive index of the cornea after myopic excimer laser surgery. J Refract Surg. 2007;23:461466. 42. Haigis W. Intraocular lens calculation after refractive surgery for myopia: Haigis-L formula. J Cataract Refract Surg. 2008;34:1658-1663. 43. Ferrara G, Cennamo G, Marotta G, Loffredo E. New formula to calculate corneal power after refractive surgery. J Refract Surg. 2004;20:465-471. 44. Holladay JT, Hill WE, Steinmueller A. Corneal power measurements using scheimpflug imaging in eyes with prior corneal refractive surgery. J Refract Surg. 2009;25:862-868. 45. Shammas HJ, Hoffer KJ, Shammas MC. Scheimpflug photography keratometry readings for routine intraocular lens power calculation. J Cataract Refract Surg. 2009;35:330-334. 46. Tang Q, Hoffer KJ, Olson MD, Miller KM. Accuracy of Scheimpflug Holladay equivalent keratometry readings after corneal refractive surgery. J Cataract Refract Surg. 2009;35:11981203. 47. Savini G, Barboni P, Profazio V, Zanini M, Hoffer KJ. Corneal power measurements with the Pentacam Scheimpflug camera after myopic excimer laser surgery. J Cataract Refract Surg. 2008;34:809-813.

48. Kim SW, Kim EK, Cho EJ, et al. Use of the Pentacam true net corneal power for intraocular lens calculation in eyes after refractive corneal surgery. J Refract Surg. 2009;25:285-289. 49. Geggel HS. Pachymetric ratio no-history method for intraocular lens power adjustment after excimer laser refractive surgery. Ophthalmology. 2009;116:1057-1066. 50. Hill WE, Wang L, Koch DD. Hill-Wang-Koch IOL power calculator. Available at: http://iol.ascrs.org/. Accessed March 25, 2011. 51. Goldsberry DH. OcularMD IOL calculator. Available at: http://www.ocularmd.com. Accessed March 9, 2011. 52. Mackool RJ. The cataract extraction-refraction-implantation technique for IOL power calculation in difficult cases. J Cataract Refract Surg. 1998;24:434-435. 53. Mackool RJ, Ko W, Mackool R. Intraocular lens power calculation after laser in situ keratomileusis: aphakic refraction technique. J Cataract Refract Surg. 2006;32:435-437. 54. Ianchulev T, Salz J, Hoffer K, Albini T, Hsu H, Labree L. Intraoperative optical refractive biometry for intraocular lens power estimation without axial length and keratometry measurements. J Cataract Refract Surg. 2005;31:1530-1536. 55. Wong AC, Mak ST, Tse RK. Clinical evaluation of the intraoperative refraction technique for intraocular lens power calculation. Ophthalmology. 2010;117:711-716. 56. Leccisotti A. Intraoperative autorefraction for combined phakic intraocular lens explantation and cataract surgery. J Refract Surg. 2007;23:931-934. 57. Jin GJ, Lyle WA, Merkley KH. Laser in situ keratomileusis for primary hyperopia. J Cataract Refract Surg. 2005;31:776784. 58. Chokshi AR, Latkany R A, Speaker MG, Yu G. Intraocular lens calculations after hyperopic refractive surgery. Ophthalmology. 2007;114:2044-2049. 59. Wang L, Jackson DW, Koch DD. Methods of estimating corneal refractive power after hyperopic laser in situ keratomileusis. J Cataract Refract Surg. 2002;28:954-961. 60. Awwad ST, Kelley PS, Bowman RW, Cavanagh HD, McCulley JP. Corneal refractive power estimation and intraocular lens calculation after hyperopic LASIK. Ophthalmology. 2009;116:393400.e1. 61. Awwad ST, Dwarakanathan S, Bowman RW, et al. Intraocular lens power calculation after radial keratotomy: estimating the refractive corneal power. J Cataract Refract Surg. 2007;33:1045-1050. 62. Chen L, Mannis MJ, Salz JJ, Garcia-Ferrer FJ, Ge J. Analysis of intraocular lens power calculation in post-radial keratotomy eyes. J Cataract Refract Surg. 2003;29:65-70. 63. Packer M, Brown LK, Hoffman RS, Fine IH. Intraocular lens power calculation after incisional and thermal keratorefractive surgery. J Cataract Refract Surg. 2004;30:1430-1434. 64. Seitz B, Langenbucher A, Haigis W. Pitfalls of IOL power prediction after photorefractive keratectomy for high myopia—case report, practical recommendations and literature review. Klin Monatsbl Augenheilkd. 2002;219:840-850. 65. Randleman JB, Foster JB, Loupe DN, Song CD, Stulting RD. Intraocular lens power calculations after refractive surgery: consensus-K technique. J Cataract Refract Surg. 2007;33:18921898.

chapter

INTRAOCULAR LENS POWER CALCULATION IN SPECIAL OCCASIONS

8

George J. C. Jin, MD, PhD and Jason J. Jones, MD

Piggyback Intraocular Lens Power

anterior (ciliary sulcus) lens according to Table 8-1; and (5) select the appropriate polypseudophakic pair. This step-by-step instruction is very useful for determining piggyback IOL power for very short eyes.

There are several ways to calculate a piggyback intraocular lens (IOL) power. The Holladay R formula can be used to calculate power for the piggyback IOL in patients with residual refractive error after primary IOL implantation.1 Piggyback IOL power can also be calculated based upon the patient’s residual refractive error using the formula derived from Gayton et al2 and Gills and Fenzl3 (power of IOL to implant – error/0.75 + 1.0D). This simple formula estimates the piggyback IOL power by multiplying the spherical equivalent by 1.3 for a myopic refraction and by 1.5 for a hyperopic refraction.4 For primary implantation of IOL powers that exceed commercially available lens powers, the following recommendation of Dr. Warren Hill can be used to calculate the IOL power in the following logical steps5: (1) Measure the axial length as accurately as possible; (2) calculate the total IOL power needed at the plane of the capsular bag; (3) calculate the residual IOL power by subtracting the power of the lens to be implanted in the capsular bag from the total power needed as calculated in step 2; (4) adjust the power for the

Intraocular Lens Power for IOL Exchange One of the limitations of IOL exchange is the difficulty of predicting the power of the replacement IOL.5 In a recent study, we evaluated the correlations of refractive change and the change of IOL power and developed a theoretical equation that could be used for IOL power calculation for exchanges6,7 (Table 8-2). The Holladay R formula (contained within the Holladay IOL Consultant software package) and Hill online IOL power calculator (refractive vergence formula for pseudophakic and aphakic eyes) are useful to calculate the IOL power for exchange. The IOLMaster is designed for phakic eyes—when using the IOLMaster data in pseudophakic eyes, an adjustment of target refraction by 0.20 D (with the SRK II or SRK/T formula) to 0.65 D (with the Haigis formula) toward the hyperopic side of the desired refraction could be considered

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Olson RJ, Gin GJC, Ahmed IIK, Crandall AS, Cionni RJ, Jones JJ. Cataract Surgery From Routine to Complex: A Practical Guide (pp. 59-66) © 2011 SLACK Incorporated

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TABLE 8-1

TABLE 8-2

PIGGYBACK SULCUS-PLACED INTRAOCULAR LENS POWER ADJUSTMENT

NOMOGRAM OF INTRAOCULAR LENS POWER ADJUSTMENT FOR INTRAOCULAR LENS EXCHANGE

RESIDUAL BAG IOL POWER (D)

SULCUS ADJUSTMENT (D)

+30.00 to +25.50

Subtract -1.50

+25.00 to +15.50

Subtract -1.00

+15.00 to +8.50

Subtract -0.50

+8.00 to +1.00

No change needed

Reprinted with permission from East Valley Ophthalmology. Calculating Bag vs. Sulcus IOL Power. Available at: http://www.doctor-hill.com/iol-main/polypseudophakia_calculations.htm. Accessed March 16, 2011.

to achieve postoperative emmetropia.8 Also, the IOL calculation formulas requesting an anterior chamber depth (ACD) value, such as the Holladay 2 and Haigis, cannot be used in a pseudophakic eyes without any workaround.9 If there is lack of preoperative calculation, an anterior chamber (AC) IOL power can be estimated by subtracting 3.0 to 3.5 D from the posterior chamber (PC) IOL power calculated for capsular bag fixation.10

Intraocular Lens Power in Eyes After Previous Vitrectomy IOL calculation can be more difficult in eyes after previous pars plana vitrectomy (PPV) for several reasons, including the following: (1) ultrasound biometry does not accurately measure axial length in eyes that have had PPV, especially in eyes with silicone oil; (2) many vitrectomized eyes are highly myopic or have posterior staphyloma; (3) pre-existing vitreoretinal disorders, such as a macular hole or an epiretinal membrane, may compromise the accuracy of the measurements and affect the refractive error predicted after cataract surgery; and (4) an increase in ACD after vitrectomy may result in increased biometric inaccuracies. Based on our experience, as well as recommended by others, the following suggestions may be helpful for IOL power calculation in the vitrectomized eye11-17: • Use optical biometry. Optical biometry has shown to be superior to ultrasound biometry in vitrectomized eyes, especially in eyes with staphyloma and eyes filled with silicone oil.

PRERESIDUAL EXCHANGE HYPEROPIA, SE* (D) INCREASE THE IOL POWER (D)

RESIDUAL MYOPIA, DECREASE THE IOL POWER (D)

1.00

0.21

0.68

1.50

1.04

1.26

2.00

1.87

1.84

2.50

2.70

2.42

3.00

3.53

3.00

3.50

4.36

3.58

4.00

5.19

4.16

4.50

6.02

4.74

5.00

6.85

5.32

5.50

7.68

5.90

6.00

8.51

6.48

*Absolute value of SE. D = diopoters; SE = spherical equivalent. Reprinted from Ophthalmology, 114(3), Jin GJC, Crandall AS, Jones JJ, Intraocular lens exchange due to incorrect lens power, pp 417-424, Copyright (2007), with permission from Elsevier.

• Take biometry readings before vitrectomy and perform IOL power calculations in all patients scheduled for PPV. These calculations will serve as a future reference for cataract surgery. • When there is clinical doubt in the validity of the axial length (AL) measurement, obtain fellow eye information and calculate IOL power for the fellow eye as a reference. • Use different formulas such as the Haigis, SRK/T, and Holladay 2 to determine the IOL power. • Because a myopic shift in refraction was observed after cataract surgery in postvitrectomy eyes, some suggest a calculation adjustment in these eyes by aiming for slightly hyperopic refraction. • When using ultrasound biometry to measure the AL, 0.5 mm (the estimated depth of the foveolar crater after stage 3 macular hole repair) needs to be subtracted from the A-scan measurement.18

Intraocular Lens Power Calculation in Special Occasions

Intraocular Lens Power in Combined Silicone Oil Removal and Cataract Surgery Cataract develops in nearly 100% of eyes if silicone oil is maintained for more than 3 months and, in most cases, after silicone oil removal.19 Silicone oil-filled phakic eyes often need cataract removal, and IOL implantation and removal of the oil in one combined surgery avoids another procedure. The main cause affecting the accuracy of IOL power calculation for the combined procedure is the reliability of the AL measurement. Ultrasound biometry always gives a falsely longer AL measurement through silicone oil. This artifact can result from a different sound velocity through silicone oil replacing the vitreous body, multiple fluid interfaces interfering with appropriate transmission of the acoustic signal, sound absorption by the oil allowing poor acoustic penetration, and artifact induced by the foreign body substances within the silicone oil. In addition, a slower sound speed may exist in longer eyes. Many potential methods have been proposed to improve the reliability of AL measurement for this combined procedure: • Use conversion factors to calculate AL when the measurement is performed with ultrasound. The correction factor varies according to the type of oil used. There are 2 viscosities of silicone oil presently in use: 1000 and 5000 m/s. ¡ Hoffer’s20 equation: AL (true) – AL measured at 1000 × 1139/1000 (eyes filled with silicone oil at 1000 m/s) ¡ Murray et al 21: AL (corrected) – AL measured × Conversion factor 0.71 (eyes filled with silicone oil of 1300 centistokes) ¡ Ghoraba et al19 measured the AL by changing the sound speed in vitreous cavity to 987 m/s (for eyes with oil 1000 or 5000 m/s) • el-Baha et al used intraoperative A-scan measurement of AL after silicone oil removal. The postoperative results are equally predictable as those with the IOLMaster.22 It is useful when the IOLMaster cannot measure through a dense cataract. • Perform intraoperative retinoscopy after silicone oil removal with a streak retinoscope, using a standard vertex distance of 13.0 mm and a working distance of 50.0 cm.12 The IOL power is calculated with the formula: IOL Power – Spherical Equivalent (SE) measured × 2.01449

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• Measure the AL and keratometry using optical biometry (IOLMaster), which is the most accurate method for IOL power calculation in this combined surgery. This can be performed under the menu “silicone-filled eye.” Silicone oil does not influence AL when measured by means of noncontact optical biometry such as IOLMaster.13 • Measure the AL before silicone oil injection.14 This is limited by the possibility of macula-off retinal detachment and by use of a scleral buckle, which alters the AL. • Best guess method: Use the AL reading of the fellow eye and Ks of the eye with silicone oil.23 For eyes with a scleral buckle, anisometropia, or monocular patients, this method should be avoided. Also, for a silicone oil-filled eye, the IOL power can be adjusted by adding 3.0 to 3.5 D. • The Holladay 2 or Haigis formula is recommended. • Foldable silicone IOLs should be avoided in silicone oil-filled eyes because residual oil drops can condense on the lens surface. Acrylic IOLs are considered safer for this procedure because of the relative lack of silicone oil adherence.24

Intraocular Lens Power in Eyes Undergoing Phacovitrectomy Combined phacoemulsification and PPV, known as phacovitrectomy, has been reported as a safe and effective procedure to manage cases with vitreoretinal disease and cataract.25,26 Phacovitrectomy offers quick visual rehabilitation and a single recovery period, avoiding the need for additional surgery. However, IOL power calculation can be difficult in these eyes. Variable factors, such as coexisting vitreoretinal disease(s), the need for adjunctive intraocular silicone oil or gas tamponade, and additional encircling or scleral buckling procedure, might affect the IOL power calculation and postoperative refractive outcome. A postoperative myopic shift after phacovitrectomy is common and dependent on the underlying vitreoretinal diagnosis. The need for intraocular tamponade more often occurs in eyes with long AL, poor preoperative visual acuity, and the presence of preoperative foveal detachment.11,17,27 Several suggestions have been proposed for IOL power calculation in phacovitrectomy: • Use optical biometry to measure the AL.

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Chapter 8 • Use fourth-generation IOL formulas such as the Holladay 2 and Haigis. • The myopic shift is greater in eyes that undergo epiretinal membrane removal than those that have macular hole repair; therefore, choose an IOL power predicted to result in slight hyperopia (0.25 to 0.50 D) for patients having phacovitrectomy for an epiretinal membrane.11

Intraocular Lens Power in Eyes After Glaucoma Filtration Surgery Cataract surgery performed on eyes that have undergone prior successful glaucoma filtration surgery produces a large spread of pseudophakic refractive error, which tends to be more myopic than the preoperative calculation predicts. This is mainly due to a decrease in AL after a glaucoma-filtering procedure.28 Decreases in AL varied from 0.15 to 0.91 mm in several studies, and a greater decrease is associated with young age, myopia, exposure to an antifibrotic agent, and post-trabeculectomy intraocular pressure (IOP) drop greater than 30 mmHg.28-30 In addition, the diurnal fluctuation in choroidal thickness in glaucomatous eyes, with a mean change of 200 μm, may significantly affect the AL and therefore the accuracy of IOL power calculation.31 Suggestions for IOL power determination in these eyes are as follows28,29,31: • IOL power calculation should be based on AL measurement obtained prior to the initial trabeculectomy. • Use the mean value of multiple IOL power calculations taken at different times during the day. • Cataract surgery should be performed when the IOP stabilizes after trabeculectomy, thus reducing the pseudophakic refractive error.

Intraocular Lens Power in Pediatric Cataract Surgery Prompt removal of the lens opacity with effective correction of aphakia is the key to successful visual rehabilitation for childhood cataract. Primary IOL implantation

in children 2 years or older is now widely accepted.32,33 The use of IOLs for children younger than 2 years is controversial, however, because of poor outcomes due to the high rate of complications such as after-cataract, secondary glaucoma and vitreous hemorrhage.34,35 Apart from technical difficulties of placing the IOL in a secure position, there is no consensus on the ideal method of calculating the power of the required IOL. IOL power determination in pediatric cataract surgery is not only an issue of calculation, but also the decision of choosing the appropriate IOL power in different clinical situations such as the age of the children at surgery, laterality, and the type of cataract and its effect on vision (see the section on pediatric cataract in Chapter 11).

DIFFICULTIES FOR INTRAOCULAR LENS POWER DETERMINATION Difficulties for IOL power determination in pediatric cataract surgery include the following36,37: • Measurement problems: Keratometer and AL equipment design is intended and calibrated for adults who are seated and awake. Obtaining Ks and AL readings is difficult in infants and children. In most circumstances for children, these measurements are taken in the operating room under general anesthesia, which may affect the accuracy of the measurements. Also, some advanced technologies such as partial coherence interferometry may not be a viable option for infants and young children. • The commonly used IOL calculation formulas, including Holladay I, Hoffer Q, SRK/T and SRK II, are derived from data from adult eyes and are unsatisfactory in achieving target refraction in pediatric patients who have steeper, narrower corneas, shorter ALs, and shallower ACs.38 • Ocular growth of normal eyes: AL increases from a mean of 16.8 mm at birth to 23.6 mm in adulthood, whereas corneal power decreases from 51.2 to 43.5 D. Most of these changes occur in the first 2 years of life.39 However, normal children have a small amount of myopic shift in refraction because of the corresponding decrease of lens power. • Highly dynamic ocular changes occur in growing children after cataract surgery. Postoperative myopic shift, attributed to the presence of a stable IOL power in the growing eye, varies in pediatric patients undergoing IOL implantation. Children under age 2 years at surgery have greater variance and a larger myopic shift than those older

Intraocular Lens Power Calculation in Special Occasions than 2 years.39 The myopic shift is greatest in the younger age groups and persists until at least 8 years of age.40 The amount of myopic shift is also greater in eyes with high-power IOLs due to an optical phenomenon analogous to the effect of vertex distance.39

CONSIDERATIONS FOR INTRAOCULAR LENS POWER DETERMINATION • Age at surgery: Appropriate selection of IOL power according to the age at surgery is a challenge. Some authors suggest emmetropia or even myopia as an immediate result of surgery, which may assist with amblyopia management.41 Most surgeons prefer targeting moderate hyperopia (≥3 D but 0 D but 1 mm can cause relevant myopic shift and oblique astigmatism, respectively. In this era of aspheric IOLs, both tilt and decentration are additive in first eliminating any optical quality advantage and rapidly thereafter can degrade the image quality. If fixation is a concern, a more forgiving IOL in terms of tilt and decentration is a traditional spherical IOL, and most forgiving is an IOL that has neutral spherical aberration.

A

B

C

D

Figure 15-8. Accommodative IOL tilting. (A, B) Slitlamp image showing capsular retraction and fibrosis. (C) Pentacam (OCULUS, Inc, Lynnwood, WA) Scheimpflug image showing tilted AT-45 IOL. (D) Pentacam anterior segment tomography and IOL plane. (Reprinted from Am J Ophthalmol, 140(2), Cazal J, Lavin-Dapena C, Marin J, Verges C, Accommodative intraocular lens tilting, pp 341344, Copyright (2005), with permission from Elsevier.)

Prevention is the optimal strategy to address IOL tilt and decentration. Ensure that the lens is placed in the bag. If a vitrectomy is required, a thorough removal of prolapsed vitreous is mandatory when posterior capsule rupture or tears occur. If bag placement is not possible, optic capture by the anterior capsulorrhexis will help maintain centration, which means that a well-centered, appropriately sized (slightly smaller than the optic) capsulorrhexis is well worth the effort to provide this alternate fixation for the long-term centration of the IOL. When operating on an unstable capsule with weak zonules, a capsular tension ring is appropriate and indicated to help promote IOL centration. If the IOL is still unstable even with a capsular tension ring, then it is best to address this fixation concern at the time of surgery because the problem will not get better with time. It is imperative to ensure that the IOL is as well centered as possible at the end of surgery. An expanded selection of IOL sizes for various candidates with accommodative IOLs may be critical to achieving proper centration, and if centration is still a concern, then consider not using a premium or aspheric IOL. IOL tilt and decentration can be addressed with capsular tension ring (CTR) placement, IOL repositioning, IOL exchange, an anterior chamber IOL, an iris claw IOL, or a posterior chamber IOL with scleral or iris suture fixation (see next section).

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Chapter 15

Intraocular Lens Dislocation Alan S. Crandall, MD and George J. C. Jin, MD, PhD Posterior chamber IOL dislocation or decentration has been recognized as a principal complication of cataract surgery with the incidence ranging between 0.2% and 3.0%.97-99 Based on the latest survey, dislocation/decentration was the most common reason for IOL explantation among members of ASCRS and ESCRS.100 Early IOL dislocation occurs mostly in the first weeks after cataract surgery, and the common causes are poor IOL fixation and insufficient capsular support.101-103 Late IOL dislocation, defined as occurring more than 3 months after surgery, has been noted to have an increasing incidence over the last several years.97,101,102,104 With the widespread use of continuous curvilinear capsulorrhexis (CCC) and foldable IOL in-the-bag implantation, dislocation of the IOL within the capsular bag has become the major type of late IOL dislocation, in which the IOL moved within the capsular bag or the entire lens-bag complex decentered with late dislocations (Figure 15-9). Progressive zonular dehiscence and contraction of the capsular bag are common causes leading to this in-the-bag dislocation.101,102 The predisposing factors include pseudoexfoliation (PXF), trauma, uveitis, intraocular surgery (such as posterior vitrectomy), retinitis pigmentosa, as well as high myopia.101,102,106-109 PXF and vitreoretinal surgery were the most common associated conditions with late spontaneous dislocation of the entire lens-bag complex.101,110

Figure 15-9. A dislocated IOL bag complex that was removed intact from the eye. (Reprinted from J Cataract Refract Surg, 36(9), Zaugg B, Werner L, Neuhann T, et al, Clinicopathologic correlation of capsulorrhexis phimosis with anterior flexing of single-piece hydrophilic acrylic intraocular lens haptics, pp 1605-1609, Copyright (2010), with permission from Elsevier.)

IDENTIFYING INTRAOCULAR LENS DISLOCATION Patients often present with decreased or fluctuating visual acuity, monocular diplopia, glare and halos, edge effect, increased astigmatism, and iris chafing. The condition can manifest in a variety of forms based on the severity of dislocation/decentration. IOL dislocation/ decentration is directly observed by slit-lamp examination and can be assessed and graded using the pupil as a reference. Clinically significant dislocation can be classified as a decentration of at least 2 mm in any direction (Figure 15-10).99 Pseudophakodonesis (IOL movement with eye motion) is a common sign of IOL dislocation. If there is no obvious pseudophakodonesis, evaluation can be performed by asking the patient to gaze upward quickly, wait 5 seconds, and then to gaze downward

Figure 15-10. Clinically significant IOL dislocation in the bag.

quickly to induce IOL movement, which can be graded as none (0), slight or minor (1+, barely discernible), moderate (2+, obvious), or pronounced (3+, it will immediately drop into the vitreous; Figure 15-11).99

Postoperative Complications

189

suture is passed from the external surface, involve bringing the haptic outside the eye after making a knot, and then replacing the haptic back inside the eye.111,118,122 Common to all the techniques is to bury, cover, or rotate the knot.104,116,117,119

REPOSITIONING THE INTRAOCULAR LENS INTO THE CAPSULAR BAG

Figure 15-11. Grade 3 IOL dislocation.

SURGICAL MANAGEMENT Surgical management options for dislocated IOLs include IOL reposition, explantation, and exchange. The decisions are based on surgeon preference and the clinical features of an individual case with considerations of a number of factors such as the presence of comorbidities (glaucoma or retinal detachment), integrity of capsular and zonular remnants, and type and position of the lens. Other considerations may include the power of the lens, which may need adjustments if a retinal detachment repair has changed the shape of the eye or if the lens has been damaged. Although some selected cases with mild IOL subluxation can be treated with reassurance, observation, and miotic agents, most clinically significant IOL dislocations require surgical intervention.

INTRAOCULAR LENS REPOSITIONING Repositioning is theoretically the best option for managing dislocated IOLs, when feasible. Numerous techniques for the surgical repositioning and suturing of dislocated IOLs to the iris, sulcus, or pars plana have been described.104,111-115 IOL repositioning without scleral fixation suturing is a preferred technique if there is adequate capsular support. Scleral fixation sutures are used if capsular support is inadequate. Many of the scleral fixation techniques are described and can be divided into 2 groups: ab interno methods and ab externo methods.116-118 The ab interno methods, in which the suture is passed from the inside of the eye to the external surface, involve making a suture loop around the haptic inside the eye and fixating it to the sclera.119-121 The ab externo methods, in which the

If the lens is within the bag and is a 3-piece lens, iris fixation is the preferred technique by many surgeons. Iris suturing can be done with techniques described by McCannel,123 Chang,124 and Stark et al.125 If, as often happens, the bag contains substantial retained cortex or a large Soemmering’s ring, then the entire complex is elevated into the anterior chamber and bimanual vitrectomy (the new 23 gauge easily goes through the stab incisions) is used to remove the capsule and residual cortical material. Once this step is completed, the lens is then fixated to the iris (Figure 15-12). Do not do this with single-piece acrylic IOLs because uveitis, glaucoma, hyphema (UGH) syndrome will likely result. In-the-bag posterior chamber (PC)-IOL repositioning can be done using a closed system with less trauma and as an effective approach.111,126,127 This can be done with an ab externo technique with flaps 180 degrees apart. Hoffman116 has shown that limbal scleral pockets produce excellent scleral protection without the need for scleral or conjunctival sutures. This approach is rapidly gaining supremacy when scleral suture IOL fixation is necessary. For the placement of scleral sutures, a 26-gauge needle is used as a docking needle 1.5 mm posterior to the limbus with a double-arm 9-0 prolene suture. One of the needles is placed through the bag—typically under one of the haptics—and the other is placed above the complex, thus forming a lasso to be used as an artificial support system. Typically 2 sutures are placed 180 degrees apart to adequately fixate the IOL

Fixating the Intraocular Lens Into the Ciliary Sulcus or Pars Plana Fixating an IOL into the ciliary sulcus or pars plana can be done with or without scleral sutures depending on the situation.104,116,118,119,128-130 Again, one way to secure the complex without opening the conjunctiva is the technique described by Hoffman.116 Instead of a conjunctival opening, two 350-μm–deep incisions are made 180 degrees apart just at the corneal scleral edge. These are usually 2 mm in length. Then a crescent blade

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Chapter 15

OTHER CONSIDERATIONS

Figure 15-12. Iris fixation IOL. (Reprinted with permission from Jason Jones, MD.)

is used to dissect posteriorly at the 350-μm plane and it is carried posteriorly 2.5 to 3 mm. 9-0 Prolene sutures are then placed in a lasso technique going through the conjunctiva and the scleral dissection. The sutures are retrieved on the corneal side of the scleral pocket and then tied. The knots are automatically covered under the scleral flap, which need not be sutured104 (see Chapter 15 Video 1).

REMOVAL AND EXCHANGE OF A DISLOCATED INTRAOCULAR LENS IOL removal with or without exchange for a new IOL (anterior chamber [AC]-IOL or PC-IOL) is generally reserved for cases with damaged haptics, small optics, highly flexible haptics inappropriate for suturing or difficult to suture, or with coexisting pathology such as retinal detachment.104 The techniques for IOL removal and exchange are presented in greater detail elsewhere (see Chapter 16). Briefly, the dislocated IOL is pulled up into the AC through side ports using a hook and/or IOL forceps. If the IOL is dislocated into the vitreous cavity, pars plana vitrectomy is performed, after which the IOL haptic is grasped by an internal limiting membrane forceps and the IOL lifted up into the AC. Next, a 6.5- or 7.0-mm scleral or corneal incision is made for IOL explantation, or if careful, the IOL can be cut in half and removed through a 3 to 3.5 mm incision if not a polymethylmethacrylate (PMMA) IOL. After the IOL is removed through this incision, anterior vitrectomy is performed. Then a new PC-IOL is sutured using a modified ab interno technique either to the iris or the sclera (see Chapter 15 Video 2).

Several factors need to be considered when making a surgical management decision for a dislocated IOL. 1. The position of the lens will decide whether it must be combined with a retinal procedure. Certainly, if the lens is on the retina, the surgery must include a 3-port vitrectomy in order to retrieve the lens without risking retinal damage or choroidal hemorrhage. The eye pressure must be maintained with infusion to prevent these from occurring. 2. Once the lens is brought up out of the vitreous cavity, then you must decide whether to explant or reposition it. If the lens power is accurate, it depends on the anterior segment structure and the style of the lens. a. If the lens is a 3-piece design, then iris fixation with 10-0 prolene sutures using a Siepser sliding knot technique is preferable (if the iris is severely damaged, scleral fixation would be better). b. If the lens is PMMA, it can be implanted by scleral fixation if it is long enough. If not, then it should be explanted. Iris fixation of a 3-piece IOL or use of an anterior chamber IOL is acceptable if there are no glaucoma or anterior chamber abnormalities. c. If the lens is a single-piece acrylic lens and it is out of the bag, it should be removed because these IOLs are highly prone to uveal laceration if not in the capsular bag. It can be cut with the Mackool IOL cutters (MSI Precision) or other IOL cutters to keep the incision small and removed. Depending on the patient and your experience, either an AC-IOL or an iris-sutured 3-piece IOL is used. d. For management of a spontaneous dislocation of an in-the-bag lens in the presence of PXF syndrome, some lenses must be removed and exchanged for a new lens. Reasons may include power changes, plate haptics are very difficult to fixate, and silicone lenses may need exchanging if retinal pathology may include a need for silicone oil. Usually they can be refixated by the techniques already outlined.

DISLOCATION OF THE CTR-IOL CAPSULAR BAG Cataract surgeons have benefited from the use of capsular tension rings (CTRs) to prevent late-onset dislocation/decentration in high-risk eyes with complex zonular pathology such as PXF and trauma. However, dislocation/decentration of the entire CTR-IOL-CB (CB is

Postoperative Complications

Figure 15-13. Decentered CTR-IOL-CB within the retropupillary space.

capsular bag) complex can occur during cataract surgery or in the early or late period after surgery.131-135 In fact, our ability to salvage many of these eyes at the time of surgery has resulted in more of these eyes later showing IOL dislocation. The decentered CTR-IOL-CB complexes can be categorized as those subluxed within the retropupillary space/anterior vitreous or those completely dislocated into the posterior vitreous cavity (Figures 15-13 and 15-14).132 The surgical approach depends on the CTR position. In cases of a CTR-IOL-CB that has subluxed into the retro-pupillary space or anterior vitreous, an anterior approach can be taken. If the CTR-IOL-CB has completely dislocated posteriorly, 3-port pars plana vitrectomy (PPV) in combination with various techniques already described can be used to retrieve the complex from the vitreous.132-134,136 The CTR is a simple

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Figure 15-14. Complete dislocation of the CTR-IOL-CB complex onto the posterior pole. (Reprinted from Ophthalmology, 112(10), Ahmed IIK, Chen SH, Kranemann C, Wong DT, Surgical repositioning of dislocated capsular tension rings, pp 1725-1733, Copyright (2005), with permission from Elsevier.)

structure to use for scleral suture fixation and so resuturing the complex to the sclera with 9-0 Prolene sutures, once it is brought into the AC or the retro-pupillary space, is the usual approach.

SUMMARY When confronted with a dislocated lens, there are a number of different possible scenarios and surgical approaches. Careful planning preoperatively is necessary to insure a good outcome.

Retained Lens Fragments Iqbal Ike K. Ahmed, MD, FRCSC and George J. C. Jin, MD, PhD Dislocation of lens fragments into the posterior segment is an uncommon but vision-threatening complication of cataract surgery that has been reported to occur in 0.3% to 1.5% of cases (Figure 15-15). This complication occurs more commonly with phacoemulsification than with extracapsular cataract extraction (ECCE) and the incidence is related to the experience of the cataract surgeon.137 It mostly occurs when zonular dehiscence or posterior capsular rupture develops. The risk factors for vitreous loss and subsequent dislocation of lens material include small pupil, hard nucleus, deep-set eyes, patient movement during surgery, and trauma and PXF.138 (see sections in Chapter 11 on small pupil and PXF and Chapter 12 for posterior capsular rupture). Patients with this complication may have pain as well as decreased visual acuity commonly due to corneal edema, increased

IOP, marked intraocular inflammation, secondary endophthalmitis, CME, and retinal detachment.138-141 The appropriate management of this complication both during and after cataract extraction is crucial for preventing significant visual loss. The treatment strategies depend on the size of the lens fragment, type of lens material, and how long the lens has been in the eye. Small amounts of cortical material, some epinuclear material, and small nuclear chips can often be treated with topical and oral medication combined with close follow-up and monitoring for complications. However, pars plana vitrectomy and lensectomy are often required in cases with extensive nuclear material, increased inflammation, or in cases where uncontrolled IOP are present (Figure 15-16). Several suggestions for cataract surgeons have been proposed.141-144 They include the following:

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Figure 15-15. Retained intravitreal lens fragment after phacoemulsification and IOL implantation.

1. Vigorous attempts to retrieve intravitreal lens fragments during cataract surgery by the anterior segment surgeon-such as posterior irrigation with levitation, introduction of a cyclodialysis spatula to lift the fragment, or intraocular infusion of perfluorocarbon liquid-should be avoided because traction on the vitreous can lead to retinal tears and detachment. Many retinal experts feel that the cataract surgeon should clean up any anteriorly displaced vitreous and remaining cortex, place a lens, and refer on. Some experienced cataract surgeons are comfortable using posterior levitation and pars plana vitrectomy in cases of dropped nucleus. Whichever course is selected, do not exceed your comfort level and remember that the least controversial approach is to clean up the anterior segment and refer the patient to the retinal specialist. 2. Immediate management objectives for the cataract surgeon are to perform an anterior vitrectomy to remove any vitreous in the anterior chamber and cataract wound; remove nuclear fragments, epinucleus, and cortex from the anterior chamber and

Figure 15-16. B-scan of a nucleus fragment in the vitreous. (Reprinted with permission from Roger Pettit Harrie, MD.)

capsule bag; and place an IOL in the AC, ciliary sulcus, or capsule bag as anatomy allows and surgeon experience permits. Securing all wounds with sutures is preferred because any subsequent manipulation by the retinal surgeon will require a closed globe. Immediate discussion with and urgent referral to a posterior segment surgeon will result in definitive care in a venue where retinal complications can be addressed should they occur. 3. Retinal detachment and poor visual outcome are significantly related to a delayed interval between cataract surgery and posterior vitrectomy.145 Timely referral to a posterior segment surgeon for PPV and removal of lens fragments can result in a good visual outcome. Most authors agree that PPV should be performed within 3 weeks after cataract surgery.146 However, early intervention-from the same day to 3 days after cataract surgery for vitrectomy-is advocated by many surgeons.139,147 4. Adequate clinical follow-up and prompt treatment of postoperative complications such as glaucoma, CME, and retinal detachment is vital.

Anterior Capsular Contraction Syndrome Jason J. Jones, MD Anterior capsular contraction syndrome (ACCS) is a unique postoperative complication of CCC after cataract surgery.148-151 The progressive contraction of the anterior capsule opening usually occurs several weeks after cataract surgery and is accompanied by subcapsular fibrosis. The contraction typically progresses for up to approximately 3 months after surgery

(Figure 15-17).152 ACCS may lead to IOL decentration, tilting, buckling of lens optic or haptic, IOL dislocation, retinal detachment, and complete closure of the capsulorrhexis opening of the IOL.148-150,153 The degree of anterior capsule contraction is related to many predictors, including the lens capsule or zonular status, concurrent ocular pathology, IOL material and

Postoperative Complications

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Figure 15-17. Different shapes of anterior capsular phimosis.

design, and surgical complications.154-156 Among the various factors comprising IOLs, only optic material significantly affects the degree of anterior capsule contraction after cataract surgery. In particular, silicone optics, which tend not to adhere to the capsule, are associated with a greater degree of contraction (Figure 15-18).154 In severe cases, especially with risk factors such as diabetic retinopathy, retinitis pigmentosa, uveitis, or PXF syndrome, the decentration or tilt may result in reduced visual function. In less severe cases, capsule contraction may cause a degradation of image quality.155,156 Studies have shown that some degree of anterior capsule opacity and shrinkage probably occur after every case of cataract surgery.156,157 Concern about capsular contraction and opacification is even more important with multifocal and aspheric IOLs.155,156,158 Proliferation of residual lens epithelial cells (LECs) associated with increased collagen production is thought to be responsible for ACCS. It has been suggested that surgical trauma and contact with the IOL stimulate residual LECs to produce cytokines, which may affect

Figure 15-18. Capsular contraction has led to decentration of this silicone 3-piece IOL placed in the bag.

the epithelial cells and induce collagen production and fibrous proliferation, resulting in anterior capsule contraction and opacification.156,159,160 Removal of the anterior lens epithelial cells by anterior capsule polishing or aspiration could reduce ACCS and anterior capsule opacification (ACO).161-163 Postoperative relaxing radial incisions at the margin of the capsulorrhexis performed with an Nd:YAG and intraoperative hydrodissection can be used to reduce the capsular force on the IOL for early ACCS.149,160 In a recent study, Hayashi et al164 investigated the effect of 2 or 3 Nd:YAG laser relaxing incisions made in the anterior capsular rim to prevent ACCS and found that 3 incisions were more effective than 2. For advanced phimosis with IOL dislocation, surgical intervention such as IOL exchange may be necessary. There are several differences between ACCS and PCO: (1) ACCS is not due to posterior capsular epithelial cell migration as in PCO. ACCS involves anterior, cuboidal lens epithelial cell metaplasia with myofibroblastic transformation. (2) ACCS occurs earlier than PCO (several weeks up to 3 months after surgery as compared to 3 to 6 months or longer after surgery, respectively). (3) IOL material, optic design, haptic material, and design have a different effect on the development of ACCS and PCO. Studies show that ACCS occurs most frequently in patients with silicone-plate IOLs, prolene haptics, and IOLs with a square-edged optic design, although the latter is controversial.154 However, a randomized, double-blind trial revealed that neither the optic material nor the haptic design had an influence on the amount of ACO or capsulorrhexis contraction.155 Otherwise, the risk of PCO is significantly less in eyes implanted with a square- or sharp-edged optic than a round-edged profile. (4) Creating a larger CCC opening helps address the concern of progressive contraction; however, limiting the size of the CCC can be helpful in reducing the risk of PCO and maintaining a more predictable axial position of the IOL over time.

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Capsular Block Syndrome Jason J. Jones, MD Capsular block syndrome (CBS), or capsular bag distension syndrome, is a rare complication that occurs after phacoemulsification pursuant to blockage of the anterior CCC opening by the posterior chamber IOL.150,165-175 CBS is classified by the time of onset—intraoperative, early postoperative, and late postoperative165 —and usually occurs months to years after cataract surgery but can be seen as late as 7 years postoperatively.166 The characteristics of this syndrome include shallowing of the anterior chamber, anterior displacement of the IOL within the bag, a concurrent myopic shift, as well as increased IOP. The intraoperative CBS is discussed in the section on hydromaneuvers in Chapter 9. Postoperatively, these findings are due to capsular bag distension with accumulation of a liquefied substance between the lens optic and posterior capsule inside the capsular bag (Figure 15-19).167-170 The reported incidence of CBS is 0.3% to 1.6% of cases after cataract surgery.169-171 If left untreated, eyes with CBS may develop glaucoma, posterior synechiae, or PCO with debris in the capsular bag. CBS can also present as phacoanaphylactic endophthalmitis if cortical material is left in the capsular bag behind the IOL.172 This syndrome was first described by Davison in 1990 and subsequently recognized by others.173-175 Masket150 was the first to use the term capsular block syndrome in reference to postoperative capsular bag distension. Reported pathogenesis of the liquid that accumulates in the distended capsular bag includes dilute sodium hyaluronate or other viscoelastic components, residual irrigating solution, or collagen and extracellular matrix synthesized from the LECs.150,165,169,173,176 Although it is not clear what mechanism draws fluid into the capsular bag, the oncotic pressure generated by retained ophthalmic viscoelastic devices (OVDs), entrapped cortical material, and LECs have been proposed as the possible mechanism.153,177 Sugiura et al,178 using highperformance liquid chromatography, demonstrated that the main component of the liquid from capsular bags with CBS was sodium hyaluronate. Meticulous aspiration of all viscoelastic material behind the IOL is therefore critical for preventing CBS. The contact between the IOL and anterior capsule is the essential factor in the development of CBS. The causes for development of CBS include implantation of a lens with relatively soft haptics,150,169,173 patients with long axial length (AL),170 small CCC (4.5 to 5.0 mm),170,174 OVD trapped in the capsule bag,174,177 intraoperative forceful irrigation directed toward the IOL optic,179 high-power accommodating

Figure 15-19. Slitlamp photograph of early postoperative capsular block syndrome. (A) The anterior surface of the PC IOL. (B) The posterior surface of the PC IOL. The posterior capsule distends backward, and transparent liquid is accumulated between B and C. (Reprinted from J Cataract Refract Surg, 26(3), Sugiura T, Miyauchi S, Eguchi S, et al, Analysis of liquid accumulated in the distended capsular bag in early postoperative capsular block syndrome, pp 420-425, Copyright (2000), with permission from Elsevier.)

IOLs in short eyes,180 and implantation of a reversedoptic PC-IOL.181 CBS needs to be differentiated from liquefied after cataract, endophthalmitis, and phacoanaphylactic uveitis.165 Intraoperative peripheral anterior capsulotomy174 was recommended in eyes with a small CCC to prevent the syndrome. Anterior or posterior YAG capsulotomy has been used to treat CBS. This helps evacuate the fluid into the AC or vitreous cavity, leading to prompt resolution of the capsular block and IOL movement posteriorly. If the entrapped cortical material in the capsular bag causes inflammation, surgical intervention is needed to break the CBS and clear the material from the capsular bag.172 Recently, Mardelli179 described a technique of slit-lamp needle revision in eyes with CBS. After applying topical anesthesia and povidone-iodine, a 30-gauge needle was introduced in a beveled fashion across the peripheral cornea into the anterior chamber and used to gently push the IOL posteriorly into the capsular bag, breaking the seal of the optic against the anterior capsule and thus reversing the CBS. In 8 patients, this technique instantly resolved the CBS and the induced myopic shift. No patient experienced complications or had a recurrence of CBS.179

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Retinal Detachment Randall J. Olson, MD Retinal detachment (RD) is one of the most important and serious sight-threatening complications after cataract surgery with approximately half of patients not recovering better than 20/60 acuity182 (Figure 15-20). The incidence of RD after phacoemulsification varies in the literature, ranging from 0.41% to 2.7%, with about 50% of RD occur during the first year following cataract surgery.183-185 Risk factors for RD identified in the literature include predisposing factors unrelated to the surgical procedure (male sex, young age, increased AL, peripheral retinal degeneration, prophylactic treatment of retinal degeneration, history of RD in follow eye); surgical technique (phacoemulsification versus conventional ECCE, incision size and location, type of IOLs: anterior versus posterior chamber lenses); intraoperative complications (posterior capsular rupture, zonule dehiscence, vitreous loss); and postoperative factors (postoperative vitreous detachment, performance of YAG capsulotomy, length of follow-up).185-193 Among these factors, male sex, age younger than 50 years, AL greater than 25 mm and high myopia, RD in the fellow eye, and posterior capsule rupture constitute the major risk factors for RD after cataract surgery.183,185-187,190,191,194 The onset of postoperative vitreous detachment (PVD) should also be considered as an important risk factor for the development of RD after cataract surgery, particularly in eyes with lattice areas.192 Whether the performance of a YAG capsulotomy is related to the development of RD is still debatable. Earlier studies have reported that a YAG capsulotomy increases the risk of a RD 3.8 to 4.9 times.193,195 However, more recent studies found no evidence that a YAG capsulotomy increased the risk of RD, suggesting that we need to rethink the generally accepted claim of an increased RD risk after capsulotomy.184,185,187,188,190,192,196 There is controversy about prophylactic argon laser coagulation of degenerative lesions such as lattice degeneration and retinal tears. Lattice degeneration is the most important fundus lesion predisposing to retinal tears and RD.187,193 It is directly responsible for RD in 21% of patients with RD.197 Eyes with preoperative lattice degeneration and posterior PVD showed a higher incidence of RD than eyes without preoperative PVD or lattice degeneration.192 Therefore, some authors suggest adopting prophylactic treatment for any peripheral retinal lesion predisposing to RD, especially in highly myopic and lattice degeneration patients with an attached posterior hyaloids.186,189,192 Prophylactic treatment might be considered if there is evidence of

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Figure 15-20. Fundus photo of RD.

lattice degeneration in the fellow eye of patient with a history of RD in the first eye. However, other authors argue about the merit of prophylactic treatment for several reasons. First, less than 1% of patients with lattice degeneration develop a RD. Without other predisposing factors, lattice degeneration rarely causes a RD.197 Second, asymptomatic operculated retinal holes in

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lattice show almost no tendency toward clinical RD in phakic eyes.198 Finally, prophylactic retinopexy cannot always prevent RD. Treatment itself can cause retinal holes, and the severity of RD may be greater when it occurs after argon laser treatment.192,199 A large,

long-term, randomized study is necessary to determine the effect of prophylactic treatment of degenerative lesions on preventing the development of RD after cataract surgery.

Intraocular Lens Opacification George J. C. Jin, MD, PhD Opacification of the IOL is a potentially serious complication of IOL implantation, which occurs in or on the IOL itself and not on the posterior capsule.200-207 Opacification usually leads to IOL explantation and may be observed intraoperatively 208 or postoperatively from a few hours after implantation to many years after surgery. Several processes are involved in IOL opacification 200: formation of deposits/precipitates on the IOL surface or within the IOL substance; opacification by excess influx of water in hydrophobic materials; direct discoloration by capsular dyes or medications; coating by substances such as ophthalmic ointment and silicone oil; and a slowly progressive degradation of the IOL biomaterial. In most cases, late postoperative opacification was associated with calcification, either deposited on the surface of the IOL optic, haptics, or both, or infiltrated into IOL substance (Figure 15-21). There are 3 major types of calcification201: 1. Primary calcification is inherent in the IOL based on possible inadequate formulation of the polymer, fabrication of the IOL, or issues with the packaging process from the IOL manufacturing. 2. Secondary calcification occurs from the deposition of calcium onto the surface of the IOL, most likely as the result of environmental circumstances such as changes in the aqueous milieu surrounding the IOL associated with pre-existing or concurrent diseases or any condition that has disrupted the blood-aqueous barrier. Non–IOL-related opacification may occur with virtually all IOL designs implanted under various adverse conditions. 3. Pseudocalcification or false-positive calcification is when other pathology is mistaken for calcification. Opacification of hydrophilic acrylic IOLs (hydrogel IOLs) is attributed to the deposition of calcium phosphate crystallites.209 Two major hydrogel IOLs, the Hydroview (Bausch & Lomb) and MemoryLens (Ciba Vision, Atlanta, GA), have been associated with reports of high incidence of late IOL opacification requiring IOL

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Figure 15-21. IOL calcification.

exchange.210-212 Calcification of these IOLs can be misdiagnosed as PCO or some form of vitreous involvement and lead to unnecessary surgical procedures such as YAG capsulotomy or vitrectomies. Careful slit-lamp examination and special attention to the IOL optic surfaces for signs of granularity/opacification is important for correct diagnosis.213

Postoperative Complications

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Figure 15-22. Gross photographs of interlenticular opacification. (A) Frontal view: the lenses are aligned parallel to each other. (B) Sagittal view: note that the lenses are separated in the periphery but are in close contact in the center. (Reprinted from Am J Ophthalmol, 133(3), Werner L, Apple DJ, Pandey SK, et al, Analysis of elements of interlenticular opacification, Copyright (2002), with permission from Elsevier.)

A newly described complication involving the placement of multiple PC-IOLs, interlenticular opacification, 202,203 also called interpseudophakos Elschnig pearls 204 or red rock syndrome, 205 refers to postoperative opacification in the interface between the opposing surfaces of the piggyback PC-IOLs implanted in the capsular bag (Figure 15-22). One of the other newer calcification problems being seen with increasing

frequency is calcification of silicone IOLs in eyes with asteroid hyalosis (AH).200 This can be very insidious but eventually results in the need for IOL exchange. It is too early to know whether this is a common problem, and prudence may dictate that an eye with AH should not have a silicone IOL implanted until more is known about this problem.

Uveitis, Glaucoma, Hyphema Syndrome Randall J. Olson, MD Uveitis-glaucoma-hyphema (UGH), or Ellingson’s syndrome, is a known complication of IOL implantation, which has been described with all types of IOLs.214 It was rather common in the early days of IOLs in which uveitis was apparent with both cell and flare as well as elevated IOP. Careful examination always showed that many, if not all, of these cells represented a microhyphema and that this combination of symptoms was associated with a faulty IOL or complicated surgery.215 The problem, typically, was either a poorly finished IOL that was contacting the uvea, resulting in microlaceration of the tissue (Figure 15-23), or an appropriate IOL that had been placed inappropriately (today this is commonly seen as a single-piece acrylic IOL placed in the ciliary sulcus) and is eroding into tissue.216-218 In either scenario, the erosion of uveal tissue results in episodic bleeding, with red blood cells blocking the trabecular meshwork, resulting in markedly elevated pressure often for short periods of time. This is also called a white-out syndrome, where the bleeding would dramatically decrease vision for 30 to 60 minutes with aching due to the elevated pressure. However, by the time the

patient is seen everything is often normal with a cursory exam.219 The uveitis was in association with inflammation related to this process or was actually misdiagnosed with the inflammatory cells being red blood cells. Though the early problem was largely associated with closed-loop anterior chamber lenses, many of which were poorly finished (Figure 15-24), today this is most commonly associated with noncapsular bag fixated posterior chamber IOLs. Most anterior chamber lenses used today are very well finished and rarely result in this particular complication. What is often seen in sulcus fixation is that the tip of the haptic has eroded into the iris tissue, possibly because it was bent upon insertion, and that over time this can result in UGH syndrome.220-222 The most common UGH syndrome seen today is the placement of single-piece acrylic IOLs in the sulcus. These large, squared-off haptics were not made to be placed against the posterior iris or the sulcus tissue and will commonly erode these tissues and cause UGH syndrome.223 Although this is something that many surgeons may recognize, what is often missed is

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Figure 15-24. Photomicrograph showing the outline of the haptic from a closed-looped, anterior chamber IOL eroding into the iris root (hematoxylin and eosin [H&E] stain). (Reprinted with permission from Nick Mamalis, MD.)

though there are publications that have promoted this. Any IOL with a squared optic should also be used with caution in the sulcus. Though UGH syndrome may not result, if the posterior iris surface contacts the optic, pigment dispersion syndrome may occur.224,225

Figure 15-23. (A) A poorly finished anterior chamber IOL (2-looped, iris-fixed IOL) with broken iris fixation suture showing irregular pupil and posterior synechia with some loss of iris pigment. (B) Scanning electron microscopy of an explanted 2-looped, iris-fixated IOL with extensive adherence of iris tissue. (Reprinted with permission from Nick Mamalis, MD.)

the fact that a haptic that was in the capsule bag may be dislodged either from a leaky wound and flattening of the anterior chamber or at the end of the procedure with removal of the viscoelastic. This is an important reason to look carefully at the end of the procedure to make sure that both haptics are in the capsular bag and, if it is recognized that a haptic is out of the capsule after surgery, the dislodged haptic must be replaced in the capsular bag. Leaving a single-piece acrylic haptic out of the capsular bag is just asking for trouble. This also means that in complicated cases, a 3-piece IOL with a rounded anterior edge should always be available for those cases where a single-piece acrylic IOL cannot be placed in the capsular bag. Other causes of UGH syndrome today include scleral and iris-sutured IOLs. Though erosion may occur with other IOLs, single-piece acrylic IOLs are the primary culprit and are not made for this kind of fixation even

CLINICAL FEATURES AND DIAGNOSIS UGH usually presents weeks to months after uncomplicated cataract extraction and IOL implantation, but it may occur years after cataract surgery, with symptoms such as episodes of blurred vision, intermittent “white out,” photophobia, uveitic pain, and red eyes.219,220 An obvious UGH syndrome is quite apparent from both the combination of elevated pressure and red blood cells in the anterior chamber. At high magnification these cells can be seen to be very small and to have a coppery or slightly reddish tinge. When such is evident, the single most important thing to do is to ascertain exactly what the cause is. In all instances careful examination should be able to find the offending area or the reason why the IOL is causing the difficulty. Retroillumination will often show a loss of the pigment epithelium on the back of the iris in a segmented fashion, showing IOL contact with the iris, and often the area of greatest contact is the point where erosion and bleeding have actually occurred. By its ability to detect the haptic position, ultrasound biomicroscopy may be helpful in elucidating the cause of UGH syndrome and in deciding on the course of treatment.220,226 An unusual type of UGH is UGH plus; in addition to uveitis, glaucoma, and hyphema, vitreous hemorrhage and corneal decompensation may also be noted.227,228

Postoperative Complications

MANAGEMENT In the acute phase, treatment consists of topical cycloplegics, steroids, and IOP-lowering medication. Topical and oral carbonic anhydrase inhibitors are particularly effective, as are beta blockers. The prostanoids are generally not used in any situation in which the eye is already inflamed. All such medications should be seen as temporizing measures only in that the definitive treatment is surgical. Occasionally, a longstanding sulcus-fixated lens with only a few minor episodes (as long as the patient understands what is happening) can be followed; however, most such cases will end up being treated surgically. In general, the surgical approach is to try to relieve any area of uveal contact. For a haptic that is out of the capsular bag, this would entail reopening the bag– which can generally be done with viscodissection–and placing the haptic back in the bag. If any IOL cannot be replaced in the capsular bag or moved from contact with uveal tissue, however, the offending IOL should be removed and an IOL with a rounded optic and PMMA haptics should be placed in the sulcus if bag fixation is not possible. Generally, such treatment is curative of the problem.

SUMMARY Though UGH syndrome was reported as a common phenomenon, in particular with closed-looped anterior chamber IOLs, today this is most commonly associated with single-piece hydrophobic acrylic IOLs, which are placed in the sulcus or secondarily fixated on the iris or sutured to the sclera. Such lenses are only to be placed in the capsular bag. When the syndrome is encountered, even though medically the situation can be temporized, a surgical correction is virtually always indicated and is curative if appropriately managed.

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115. Chan CK, Agarwal A, Agarwal S. Management of dislocated intraocular implants. Ophthalmol Clin North Am. 2001;14:681693. 116. Hoffman RS, Fine IH, Packer M, Rozenberg I. Scleral fixation using suture retrieval through a scleral tunnel. J Cataract Refract Surg. 2006;32:1259-1263. 117. Ma K, Kang SY, Shin JY, et al. Modified Siepser sliding knot technique for scleral fixation of subluxated posterior chamber intraocular lens. J Cataract Refract Surg. 2010;36:6-8. 118. Kokame GT, Yamamoto I, Mandel H. Scleral fixation of dislocated posterior chamber intraocular lenses: temporary haptic externalization through a clear corneal incision. J Cataract Refract Surg. 2004;30:1049-1056. 119. Smiddy WE. Modification of scleral suture fixation technique for dislocated posterior chamber intraocular lens implants. Arch Ophthalmol. 1998;116:967. 120. Lee SC, Tseng SH, Cheng HC, Chen FK. Slipknot for scleral fixation of intraocular lenses. J Cataract Refract Surg. 2001;27:662-664. 121. Hanemoto T, Ideta H, Kawasaki T. Dislocated intraocular lens fixation using intraocular cowhitch knot. Am J Ophthalmol. 2001;131:265-267. 122. Nikeghbali A, Falavarjani KG. Modified transscleral fixation technique for refixation of dislocated intraocular lenses. J Cataract Refract Surg. 2008;34:743-748. 123. McCannel MA. A retrievable suture idea for anterior uveal problems. Ophthalmic Surg. 1976;7:98-103. 124. Chang DF. Siepser slipknot for McCannel iris-suture fixation of subluxated intraocular lenses. J Cataract Refract Surg. 2004;30:1170-1176. 125. Stark WJ, Michels RG, Bruner WE. Management of posteriorly dislocated intraocular lenses. Ophthalmic Surg. 1980;11:495497. 126. Koh HJ, Kim CY, Lim SJ, Kwon OW. Scleral fixation technique using 2 corneal tunnels for a dislocated intraocular lens. J Cataract Refract Surg. 2000;26:1439-1441. 127. Kwok AK, Cheng AC, Lam DS. Surgical technique for transcleral-fixation of a dislocated posterior chamber intraocular lens. Am J Ophthalmol. 2001;132:406-408. 128. Nakashizuka H, Shimada H, Iwasaki Y, Matsumoto Y, Sato Y. Pars plana suture fixation for intraocular lenses dislocated into the vitreous cavity using a closed-eye cow-hitch technique. J Cataract Refract Surg. 2004;30:302-306. 129. Han QH, Wang L, Hui YN. Transscleral suture technique for fixation of a dislocated posterior chamber intraocular lens. J Cataract Refract Surg. 2004;30:1396-1400. 130. Gabor SG, Pavlidis MM. Sutureless intrascleral posterior chamber intraocular lens fixation. J Cataract Refract Surg. 2007;33:1851-1854. 131. Moreno-Montanes J, Heras H, Fernandez-Hortelano A. Surgical treatment of a dislocated intraocular lens-capsular bag-capsular tension ring complex. J Cataract Refract Surg. 2005;31:270273. 132. Ahmed, II, Chen SH, Kranemann C, Wong DT. Surgical repositioning of dislocated capsular tension rings. Ophthalmology. 2005;112:1725-1733. 133. Lim MC, Jap AH, Wong EY. Surgical management of late dislocated lens capsular bag with intraocular lens and endocapsular tension ring. J Cataract Refract Surg. 2006;32:533-535. 134. Ma PE, Kaur H, Petrovic V, Hay D. Technique for removal of a capsular tension ring from the vitreous. Ophthalmology. 2003;110:1142-1144. 135. Deka S, Deka A, Bhattacharjee H. Management of posteriorly dislocated endocapsular tension ring and intraocular lens complex. J Cataract Refract Surg. 2006;32:887-889.

Postoperative Complications 136. Bhattacharjee H, Bhattacharjee K, Das D, Jain PK, Chakraborty D, Deka S. Management of a posteriorly dislocated endocapsular tension ring and a foldable acrylic intraocular lens. J Cataract Refract Surg. 2004;30:243-246. 137. Pande M, Dabbs TR. Incidence of lens matter dislocation during phacoemulsification. J Cataract Refract Surg. 1996;22:737742. 138. Monshizadeh R, Samiy N, Haimovici R. Management of retained intravitreal lens fragments after cataract surgery. Surv Ophthalmol. 1999;43:397-404. 139. Ho LY, Doft BH, Wang L, Bunker CH. Clinical predictors and outcomes of pars plana vitrectomy for retained lens material after cataract extraction. Am J Ophthalmol. 2009;147:587-594. e1. 140. Cohen SM, Davis A, Cukrowski C. Cystoid macular edema after pars plana vitrectomy for retained lens fragments. J Cataract Refract Surg. 2006;32:1521-1526. 141. Smiddy WE, Guererro JL, Pinto R, Feuer W. Retinal detachment rate after vitrectomy for retained lens material after phacoemulsification. Am J Ophthalmol. 2003;135:183-187. 142. Stewart MW. Managing retained lens fragments: raising the bar. Am J Ophthalmol. 2009;147:569-570. 143. Aaberg TM Jr, Rubsamen PE, Flynn HW Jr, Chang S, Mieler WF, Smiddy WE. Giant retinal tear as a complication of attempted removal of intravitreal lens fragments during cataract surgery. Am J Ophthalmol. 1997;124:222-226. 144. Schaal S, Barr CC. Management of retained lens fragments after cataract surgery with and without pars plana vitrectomy. J Cataract Refract Surg. 2009;35:863-867. 145. Merani R, Hunyor AP, Playfair TJ, et al. Pars plana vitrectomy for the management of retained lens material after cataract surgery. Am J Ophthalmol. 2007;144:364-370. 146. Stefaniotou M, Aspiotis M, Pappa C, Eftaxias V, Psilas K. Timing of dislocated nuclear fragment management after cataract surgery. J Cataract Refract Surg. 2003;29:1985-1988. 147. Wilkinson CP, Green WR. Vitrectomy for retained lens material after cataract extraction: the relationship between histopathologic findings and the time of vitreous surgery. Ophthalmology. 2001;108:1633-1637. 148. Hansen SO, Crandall AS, Olson RJ. Progressive constriction of the anterior capsular opening following intact capsulorhexis. J Cataract Refract Surg. 1993;19:77-82. 149. Davison JA. Capsule contraction syndrome. J Cataract Refract Surg. 1993;19:582-589. 150. Masket S. Postoperative complications of capsulorhexis. J Cataract Refract Surg. 1993;19:721-724. 151. Reyntjens B, Tassignon MJ, Van Marck E. Capsular peeling in anterior capsule contraction syndrome: surgical approach and histopathological aspects. J Cataract Refract Surg. 2004;30:908-912. 152. Hayashi K, Hayashi H, Nakao F, Hayashi F. Reduction in the area of the anterior capsule opening after polymethylmethacrylate, silicone, and soft acrylic intraocular lens implantation. Am J Ophthalmol. 1997;123:441-447. 153. Tadros A, Bhatt UK, Abdul Karim MN, Zaheer A, Thomas PW. Removal of lens epithelial cells and the effect on capsulorhexis size. J Cataract Refract Surg. 2005;31:1569-1174. 154. Hayashi K, Hayashi H. Intraocular lens factors that may affect anterior capsule contraction. Ophthalmology. 2005;112:286292. 155. Sacu S, Menapace R, Findl O. Effect of optic material and haptic design on anterior capsule opacification and capsulorrhexis contraction. Am J Ophthalmol. 2006;141:488-493. 156. Kato S, Suzuki T, Hayashi Y, et al. Risk factors for contraction of the anterior capsule opening after cataract surgery. J Cataract Refract Surg. 2002;28:109-112.

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157. Werner L, Pandey SK, Apple DJ, Escobar-Gomez M, McLendon L, Macky TA. Anterior capsule opacification: correlation of pathologic findings with clinical sequelae. Ophthalmology. 2001;108:1675-1681. 158. Jardim D, Soloway B, Starr C. Asymmetric vault of an accommodating intraocular lens. J Cataract Refract Surg. 2006;32:347-350. 159. Nishi O, Nishi K. Intraocular lens encapsulation by shrinkage of the capsulorhexis opening. J Cataract Refract Surg. 1993;19:544-545. 160. Tanaka S, Saika S, Tamura M, Ohnishi Y. Histological observation of complete closure of anterior capsulotomy in 2 cases. J Cataract Refract Surg. 2004;30:1374-1377. 161. Menapace R, Wirtitsch M, Findl O, Buehl W, Kriechbaum K, Sacu S. Effect of anterior capsule polishing on posterior capsule opacification and neodymium: YAG capsulotomy rates: threeyear randomized trial. J Cataract Refract Surg. 2005;31:20672075. 162. Sacu S, Menapace R, Wirtitsch M, Buehl W, Rainer G, Findl O. Effect of anterior capsule polishing on fibrotic capsule opacification: three-year results. J Cataract Refract Surg. 2004;30:23222327. 163. Hanson RJ, Rubinstein A, Sarangapani S, Benjamin L, Patel CK. Effect of lens epithelial cell aspiration on postoperative capsulorhexis contraction with the use of the AcrySof intraocular lens: randomized clinical trial. J Cataract Refract Surg. 2006;32:1621-1626. 164. Hayashi K, Yoshida M, Nakao F, Hayashi H. Prevention of anterior capsule contraction by anterior capsule relaxing incisions with neodymium:yttrium-aluminum-garnet laser. Am J Ophthalmol. 2008;146:23-30. 165. Miyake K, Ota I, Ichihashi S, Miyake S, Tanaka Y, Terasaki H. New classification of capsular block syndrome. J Cataract Refract Surg. 1998;24:1230-1234. 166. Wang JC, Cruz J. Late postoperative capsular block syndrome: entrapment of liquefied after-cataract by capsular bend. J Cataract Refract Surg. 2005;31:630-632. 167. Durak I, Ozbek Z, Ferliel ST, Oner FH, Soylev M. Early postoperative capsular block syndrome. J Cataract Refract Surg. 2001;27:555-559. 168. Baikoff G, Rozot P, Lutun E, Wei J. Assessment of capsular block syndrome with anterior segment optical coherence tomography. J Cataract Refract Surg. 2004;30:2448-2450. 169. Holtz SJ. Postoperative capsular bag distension. J Cataract Refract Surg. 1992;18:310-317. 170. Kim HK, Shin JP. Capsular block syndrome after cataract surgery: clinical analysis and classification. J Cataract Refract Surg. 2008;34:357-363. 171. Sorenson AL, Holladay JT, Kim T, Kendall CJ, Carlson AN. Ultrasonographic measurement of induced myopia associated with capsular bag distention syndrome. Ophthalmology. 2000;107:902-908. 172. Mardelli PG, Mehanna CJ. Phacoanaphylactic endophthalmitis secondary to capsular block syndrome. J Cataract Refract Surg. 2007;33:921-922. 173. Davison JA. Capsular bag distension after endophacoemulsification and posterior chamber intraocular lens implantation. J Cataract Refract Surg. 1990;16:99-108. 174. Yepez JB, de Yepez JC, Arevalo JF. Intraoperative peripheral anterior capsulotomy to prevent early postoperative capsular block syndrome. J Cataract Refract Surg. 2004;30:18401842. 175. Agrawal S, Agrawal J, Agrawal TP. Incomplete capsular bag distension syndrome after neodymium:YAG capsulotomy. J Cataract Refract Surg. 2006;32:351-352.

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176. Nishi O, Nishi K, Takahashi E. Capsular bag distention syndrome noted 5 years after intraocular lens implantation. Am J Ophthalmol. 1998;125:545-547. 177. Theng JT, Jap A, Chee SP. Capsular block syndrome: a case series. J Cataract Refract Surg. 2000;26:462-467. 178. Sugiura T, Miyauchi S, Eguchi S, et al. Analysis of liquid accumulated in the distended capsular bag in early postoperative capsular block syndrome. J Cataract Refract Surg. 2000;26:420-425. 179. Mardelli PG. Slitlamp needle revision of capsular block syndrome. J Cataract Refract Surg. 2008;34:1065-1069. 180. Alessio G, L’Abbate M, Boscia F, La Tegola MG. Capsular block syndrome after implantation of an accommodating intraocular lens. J Cataract Refract Surg. 2008;34:703-706. 181. Xiao Y, Wang YH, Fu ZY. Capsular block syndrome caused by a reversed-optic intraocular lens. J Cataract Refract Surg. 2004;30:1130-1132. 182. Haddad WM, Monin C, Morel C, et al. Retinal detachment after phacoemulsification: a study of 114 cases. Am J Ophthalmol. 2002;133:630-638. 183. Boberg-Ans G, Villumsen J, Henning V. Retinal detachment after phacoemulsification cataract extraction. J Cataract Refract Surg. 2003;29:1333-1338. 184. Russell M, Gaskin B, Russell D, Polkinghorne PJ. Pseudophakic retinal detachment after phacoemulsification cataract surgery: ten-year retrospective review. J Cataract Refract Surg. 2006;32:442-445. 185. Alio JL, Ruiz-Moreno JM, Shabayek MH, Lugo FL, Abd El Rahman AM. The risk of retinal detachment in high myopia after small incision coaxial phacoemulsification. Am J Ophthalmol. 2007;144:93-98. 186. Sheu SJ, Ger LP, Chen JF. Male sex as a risk factor for pseudophakic retinal detachment after cataract extraction in Taiwanese adults. Ophthalmology. 2007;114:1898-1903. 187. Tuft SJ, Minassian D, Sullivan P. Risk factors for retinal detachment after cataract surgery: a case-control study. Ophthalmology. 2006;113:650-656. 188. Olsen G, Olson RJ. Update on a long-term, prospective study of capsulotomy and retinal detachment rates after cataract surgery. J Cataract Refract Surg. 2000;26:1017-1021. 189. Lyle WA, Jin GJ. Phacoemulsification with intraocular lens implantation in high myopia. J Cataract Refract Surg. 1996;22:238-242. 190. Bhagwandien AC, Cheng YY, Wolfs RC, van Meurs JC, Luyten GP. Relationship between retinal detachment and biometry in 4262 cataractous eyes. Ophthalmology. 2006;113:643-649. 191. Erie JC, Raecker MA, Baratz KH, Schleck CD, Burke JP, Robertson DM. Risk of retinal detachment after cataract extraction, 1980-2004: a population-based study. Ophthalmology. 2006;113:2026-2032. 192. Ripandelli G, Coppe AM, Parisi V, et al. Posterior vitreous detachment and retinal detachment after cataract surgery. Ophthalmology. 2007;114:692-697. 193. Tielsch JM, Legro MW, Cassard SD, et al. Risk factors for retinal detachment after cataract surgery. A population-based case-control study. Ophthalmology. 1996;103:1537-1545. 194. Neuhann IM, Neuhann TF, Heimann H, Schmickler S, Gerl RH, Foerster MH. Retinal detachment after phacoemulsification in high myopia: analysis of 2356 cases. J Cataract Refract Surg. 2008;34:1644-1657. 195. Javitt JC, Tielsch JM, Canner JK, Kolb MM, Sommer A, Steinberg EP. National outcomes of cataract extraction: increased risk of retinal complications associated with Nd:YAG laser capsulotomy. The Cataract Patient Outcomes Research Team. Ophthalmology. 1992;99:1487-1497; discussion 14971498.

196. Jahn CE, Richter J, Jahn AH, Kremer G, Kron M. Pseudophakic retinal detachment after uneventful phacoemulsification and subsequent neodymium: YAG capsulotomy for capsule opacification. J Cataract Refract Surg. 2003;29:925-929. 197. Sodhi A, Leung LS, Do DV, Gower EW, Schein OD, Handa JT. Recent trends in the management of rhegmatogenous retinal detachment. Surv Ophthalmol. 2008;53:50-67. 198. Byer NE. What happens to untreated asymptomatic retinal breaks, and are they affected by posterior vitreous detachment? Ophthalmology. 1998;105:1045-1049; discussion 1049-1050. 199. Colin J, Robinet A, Cochener B. Retinal detachment after clear lens extraction for high myopia: seven-year follow-up. Ophthalmology. 1999;106:2281-2284; discussion 2285. 200. Werner L. Causes of intraocular lens opacification or discoloration. J Cataract Refract Surg. 2007;33:713-726. 201. Neuhann IM, Kleinmann G, Apple DJ. A new classification of calcification of intraocular lenses. Ophthalmology. 2008;115:7379. 202. Gayton JL, Apple DJ, Peng Q, et al. Interlenticular opacification: clinicopathological correlation of a complication of posterior chamber piggyback intraocular lenses. J Cataract Refract Surg. 2000;26:330-336. 203. Werner L, Apple DJ, Pandey SK, et al. Analysis of elements of interlenticular opacification. Am J Ophthalmol. 2002;133:320326. 204. Shugar JK, Schwartz T. Interpseudophakos Elschnig pearls associated with late hyperopic shift: a complication of piggyback posterior chamber intraocular lens implantation. J Cataract Refract Surg. 1999;25:863-867. 204. Park S, Ressiniotis T, Wood C. Intraocular lens pupillary capture after neodymium:YAG laser treatment of interlenticular opacification of posterior chamber piggyback intraocular lenses. J Cataract Refract Surg. 2006;32:1056-1058. 206. Jackson DW, Koch DD. Interlenticular opacification associated with asymmetric haptic fixation of the anterior intraocular lens. Am J Ophthalmol. 2003;135:106-108. 207. Spencer TS, Mamalis N, Lane SS. Interlenticular opacification of piggyback acrylic intraocular lenses. J Cataract Refract Surg. 2002;28:1287-1290. 208. Olson RJ, Caldwell KD, Crandall AS, Jensen MK, Huang SC. Intraoperative crystallization on the intraocular lens surface. Am J Ophthalmol. 1998;126:177-184. 209. Gartaganis SP, Kanellopoulou DG, Mela EK, Panteli VS, Koutsoukos PG. Opacification of hydrophilic acrylic intraocular lens attributable to calcification: investigation on mechanism. Am J Ophthalmol. 2008;146:395-403. 210. Balasubramaniam C, Goodfellow J, Price N, Kirkpatrick N. Opacification of the Hydroview H60M intraocular lens: total patient recall. J Cataract Refract Surg. 2006;32:944-948. 211. Altaie R, Loane E, O’Sullivan K, Beatty S. Surgical and visual outcomes following exchange of opacified Hydroview intraocular lenses. Br J Ophthalmol. 2007;91:299-302. 212. Theoulakis PE, Brinkmann CK, Petropoulos IK, Gatzogias MI, Katsimpris JM. Hydrogel intraocular lens exchange: fiveyear experience. Klin Monatsbl Augenheilkd. 2009;226:254257. 213. Haymore J, Zaidman G, Werner L, et al. Misdiagnosis of hydrophilic acrylic intraocular lens optic opacification: report of 8 cases with the MemoryLens. Ophthalmology. 2007;114:16891695. 214. Ellingson FT. The uveitis-glaucoma-hyphema syndrome associated with the Mark VIII anterior chamber lens implant. J Am Intraocul Implant Soc. 1978;4:50-53. 215. Apple DJ, Brems RN, Park RB, et al. Anterior chamber lenses part 1: complications and pathology and a review of designs. J Cataract Refract Surg. 1987;13:157-174.

Postoperative Complications 216. Aonuma H, Matsushita H, Nakajima K, Watase M, Tsushima K, Watanabe I. Uveitis-glaucoma-hyphema syndrome after posterior chamber intraocular lens implantation. Jpn J Ophthalmol. 1997;41:98-100. 217. Asaria RH, Salmon JF, Skinner AR, Ferguson DJ, McDonald B. Electron microscopy findings on an intraocular lens in the uveitis, glaucoma, hyphaema syndrome. Eye. 1997;11(6):827829. 218. Hagan JC III. A clinical review of the IOLAB Azar model 91Z flexible anterior chamber intraocular lens. Ophthalmic Surg. 1987;18:258-261. 219. Magargal LE, Goldberg RE, Uram M, Gonder JR, Brown GC. Recurrent microhyphema in the pseudophakic eye. Ophthalmology. 1983;90:1231-1234. 220. Piette S, Canlas OA, Tran HV, Ishikawa H, Liebmann JM, Ritch R. Ultrasound biomicroscopy in uveitis-glaucoma-hyphema syndrome. Am J Ophthalmol. 2002;133:839-841. 221. LeBoyer RM, Werner L, Snyder ME, Mamalis N, Riemann CD, Augsberger JJ. Acute haptic-induced ciliary sulcus irritation associated with single-piece AcrySof intraocular lenses. J Cataract Refract Surg. 2005;31:1421-1427. 222. Micheli T, Cheung LM, Sharma S, et al. Acute hapticinduced pigmentary glaucoma with an AcrySof intraocular lens. J Cataract Refract Surg. 2002;28:1869-1872. 223. 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;35:1445-1458.

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224. Woodhams JT, Lester JC. Pigmentary dispersion glaucoma secondary to posterior chamber intra-ocular lenses. Ann Ophthalmol. 1984;16:852-855. 225. Chang SH, Lim G. Secondary pigmentary glaucoma associated with piggyback intraocular lens implantation. J Cataract Refract Surg. 2004;30:2219-2222. 226. Foroozan R, Tabas JG, Moster ML. Recurrent microhyphema despite intracapsular fixation of a posterior chamber intraocular lens. J Cataract Refract Surg. 2003;29:1632-1635. 227. Trindade FC. Haptic-induced recurrent vitreous hemorrhage and increased intraocular pressure with a hydrophobic acrylic intraocular lens. J Cataract Refract Surg. 2009;35:399-402. 228. Sharma A, Ibarra MS, Piltz-Seymour JR, Syed NA. An unusual case of uveitis-glaucoma-hyphema syndrome. Am J Ophthalmol. 2003;135:561-563.

VIDEO REFERENCES Video 1. Phaco Iris Sutured IOL with Intraop CTS. Video 2. Scleral Fixation of Dislocated PCIOL with CTR.

Please see videos on the accompanying Web site at http://www.slackbooks.com/cataractsurgeryvideos

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16

POSTOPERATIVE ENHANCEMENT Corneal-Based Procedures George J. C. Jin, MD, PhD and Randall J. Olson, MD The residual refractive error is a major factor for unsatisfied patients after cataract surgery. The causes of refractive error include biometrical error, the formulas used for intraocular lens (IOL) power calculation, IOL power selection, instability or displacement of the IOL in the capsular bag, and IOL implantation in the ciliary sulcus. The methods being used to correct post-cataract refractive error include corneal-based and lens-based procedures.

LASER VISION CORRECTION Laser vision correction (LVC, including laser-assisted in situ keratomileusis [LASIK] and surface ablation) has been the preferred surgical technique by refractive surgeons for the enhancement after cataract surgery.1-8 It is the most feasible option for correcting both residual spheres and cylinders, especially for mild or moderate refractive error. LVC has been proven efficacious for myopic astigmatism but also mixed and hyperopic forms. In choosing between LASIK and surface ablation, surgeons need to consider whether potential safety concerns exist with placing a suction ring on an eye with an IOL. For patients who have a thin cornea, dry eye, or underlying basement membrane problem, surface

ablation should be considered. It is important to allow the refractive error, the nonsutured corneal wound, and best corrected visual acuity (BCVA) to stabilize after cataract surgery prior to any LVC procedures. It usually takes 6 to 8 weeks. Eyes that had previous LASIK, photorefractive keratectomy (PRK), or radial keratotomy (RK) may take longer to stabilize.

LASIK Patients generally prefer LASIK over PRK because of the faster recovery rate. Based on our recent study,9 the advantages and indications for LASIK could be summarized as the following: • LASIK performed after 3 months of phacoemulsification appears to be safe with regard to safety when using LASIK in post-cataract eyes. Complication related to cataract incisions or IOL position (lens dislocation or tilting) is not a major concern. • Cylinder reduction is more effective with LASIK than with lens exchange alone. In addition, LASIK appears effective in treating astigmatism after limbal-relaxing incisions (LRIs). • Mixed astigmatism is a common cause of dissatisfaction after cataract surgery, which could be successfully corrected with LASIK.

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• Laser procedures are effective and predictable for those desiring monovision after cataract surgery. • Once a LASIK flap has been established, additional optical adjustments can be performed successfully when needed. • Laser ablation offers greater flexibility and allows a more specific target end point than lens-based techniques. • LASIK seems to be safe and effective for eyes with previous YAG capsulotomy. Once a YAG capsulotomy has been performed, IOL exchange becomes more difficult and has more risks. The results of this study 9 also confirmed the observation in a study by Kuo et al1 that final uncorrected visual acuity (UCVA) in patients with LASIK enhancement after cataract surgery was not as good as that reported in primary laser refractive surgery patients in general. We suggest that a postoperative UCVA of 20/30 might be a more realistic goal for patients who have refractive procedures after cataract surgery. The one concern about LASIK is the aggravation of any underlying dry eye syndrome, which can result in dissatisfaction unless carefully monitored and treated. For those with severe dry eye, LASIK may not be a good option. Performing a customized treatment would be preferable for pseudophakic eyes because not only can it correct residual refractive error, it can also minimize spherical aberration and other higher order aberrations. However, it can be difficult to capture a good wavefront scan on eyes with IOLs. With LadarVision (Alcon, Fort Worth, TX), the tracker requires the pupil to be dilated at least 7 mm. In pseudophakic eyes, the ability to track the pupil edge may be affected by light reflected off the IOL. When considering wavefront-guided enhancement, it is important that a pushed-plus manifest refraction matches the wavefront map, the capsulorrhexis is large enough to be captured by the tracker, and the posterior capsule is clear. LASIK has been shown to be a safe and effective modality for correcting residual ametropia after multifocal IOL implantation, particularly when a femtosecond laser is used to create the flap.8,10 Studies show that aberrometry could not provide reliable measurements of wavefront aberrations and refraction of either the diffractive IOL (ReSTOR, Alcon)11 or refractive lens (ReZoom, Abbott Medical Optics [AMO], Santa Ana, CA).11,12 A wavefront-guided LASIK should not be recommended with refractive multifocal IOLs due to the difficulty in measuring accurate aberrometry readings with multifocal IOLs in the eye. Further study is needed to confirm the conclusions derived from these small sample studies.

Photorefractive Keratectomy PRK has been used successfully to treat residual refractive errors after cataract surgery.1,4,7,13,14 The

advantages that lead many surgeons to choose PRK over LASIK include the following: • PRK is a straightforward and simple technique without flap creation, thus avoiding any flaprelated complications such as flap tears, folds, and dislocation. It also avoids the epithelial defects during flap creation in older patients. • Complications with the use of suction in LASIK, such as mechanical distortion of the post-cataract eye during buildup of suction and the risk of a retinal vascular event in older patients due to the prolonged suction are avoided. • PRK is less likely to induce extreme dry eye. • PRK is preferred for patients with poorly adherent epithelium. As with other forms of refractive surgery, IOL power determination is a major challenge (see Chapter 7 section on IOL power calculation after PRK). Haze and myopic regression, which are usually seen after PRK, are not common in PRK performed after cataract surgery because of low correction of refractive error. However, proper postoperative therapy is important to prevent these complications. The therapy includes fitting a bandage contact lens, topical antibiotics, and anti-inflammatory treatment with topical steroids and nonsteroidal anti-inflammatory drugs (NSAIDs).

INCISIONAL APPROACHES Limbal-Relaxing Incisions Postoperative astigmatism remains one of the most important factors limiting uncorrected vision and decreasing patient satisfaction in an otherwise successful cataract surgery.15,16 Studies show that the amount of postoperative astigmatism has a greater effect on distance visual acuity than postoperative manifest refraction spherical equivalent in patients with multifocal IOLs.17 LRIs may be done for patients who have low amounts of astigmatism or when astigmatism is the only problem. LRIs offer several advantages over astigmatic keratotomy (AK), including less chance of causing a shift in the resultant cylinder axis and less chance of inducing irregular astigmatism. One of the lesser appreciated aspects of LRI for an eye undergoing cataract surgery is that the surgeon has to take into consideration not only the pre-existing cylinder but also the surgically induced cylinder created by the incision. These 2 factors create vector forces that have to be analyzed, resulting in a new axis and a new magnitude of astigmatism. However, for classic with-the-rule and against-the-rule astigmatism, the impact of incisional astigmatism for incisions less than 3.0 mm is minimal.

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TABLE 16-1

THE LINDSTROM NOMOGRAM OF ASTIGMATIC KERATOTOMY EXPECTED CORRECTION (D)

Age (years)

1 × 45 DEGREES 2 × 30 DEGREES

1 × 60 DEGREES

1 × 90 DEGREES 2 × 45 DEGREES

2 × 60 DEGREES

2 × 90 DEGREES

20

0.80

1.20

1.60

2.40

3.20

30

1.00

1.50

2.00

3.00

4.00

40

1.20

1.80

2.40

3.60

4.80

50

1.40

2.10

2.80

4.20

5.60

60

1.60

2.40

3.20

4.80

6.40

70

1.80

2.70

3.60

5.40

7.20

75

1.90

2.85

3.80

5.70

7.60

The columns refer to the number of incisions and the arc length of the incision. The optical zone is 7 mm. The blade depth is 100% of the paracentral pachymetry at the zone mark in the meridian of the astigmatism. Assume a coupling ration of 1:1. Reprinted with permission from Lombardo A, and Lindstrom RL. Astigmatic keratotomy. In Gills JP, ed. A Complete Surgical Guide for Correcting Astigmatism: An Ophthalmic Manifesto. Thorofare, NJ: SLACK, Incorporated; 2003.

Astigmatic Keratotomy AK is a relatively simple and effective means of treating postoperative astigmatism. It is more powerful than LRI. Arcuate or transverse incisions are performed at the conclusion of cataract surgery or during the postoperative period.18-21 The number of incisions, size of optical clear zone, and arc length of the incision are determined by nomograms. There are many nomograms available,18-20,22 but the basic principles are the same (Table 16-1).23 The technique of AK consists of the following18-20,22: (1) The amount and axis of astigmatism should be based on keratometry, topography, or both. Corneal topography is commonly used. (2) Consider AK for correcting astigmatism of 1.0 D to 3.0 D. (3) Avoid overcorrection of astigmatism, which will create a new axis of astigmatism and is poorly tolerated by patients. (4) In cases in which there is a significant difference between manifest and keratometric astigmatism after repeat measurement, it is better to avoid the surgery. (5) The AK is paced along the steep meridian. (6) The arcuate incisions should be performed at a 7.0- to 8.0-mm optical zone (OZ) because a small zone (smaller than 7 mm OZ) may increase the risk of inducing irregular astigmatism and postoperative glare. (7) A pachymetry reading is taken at the site of the AK and the blade is set to 90% of the corneal thickness (or 0.02 mm less than the pachymetry reading in the area of the intended incision). (8) Although AK is sufficiently effective in reducing the residual astigmatism after cataract surgery, the results of the procedure may be

variable, and fluctuation in refraction may occur.24-25 Recent study shows that arcuate keratotomy performed with the IntraLase (AMO) femtosecond laser using its side-cut function is a safe and effective treatment for high postoperative keratoplasty astigmatism.26

Mini-Radial Keratotomy Mini-RK, a modified RK procedure that limits the peripheral extent of the radial incisions to the 7.0-mm OZ, was introduced by Lindstrom.27 The potential advantages of mini-RK (incisions between the 3.0- to 7.0-mm OZ) compared to traditional RK (incisions between the 3.0- to 11.0-mm OZ) include less risk of infection, less diurnal fluctuations or progressive hyperopia, and less risk of traumatic rupture but almost identical effectiveness.28,29 The double-pass technique, which combines a center-to-periphery incision (the American technique) or a periphery-to-center incision (the Russian technique), is preferable. Incisions of 2 mm long approximately treat up to 1.00 D of myopia.27 When using mini-RK to correct residual myopia after cataract surgery, one should keep in mind that (1) mini-RK should be used to correct small amounts of residual myopia, operating on only one eye at a time; (2) a minimum number of incisions, usually 2 to 4, should be used to achieve the desired result; (3) the shortest possible incisions should be used; and (4) a large optical zone would be required for the incisions. Leave the central 5 mm of cornea untouched because a small clear zone could reduce image quality.

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Lens-Based Procedures Jason J. Jones, MD; George J. C. Jin, MD, PhD; and Alan S. Crandall, MD Lens-based procedures have their own merits for correcting residual refractive errors after cataract surgery. If the residual refractive error is high, or the patient is truly unhappy with the optical qualities of the implanted lens, an IOL exchange represents the best solution. Placing additional lenses in the eye (piggyback lens) is also an effective way to correct residual refractive error. For the unhappy patient with a multifocal IOL, a lens-based procedure should be performed after careful evaluation and appropriate treatment of other potential causes of diminished image quality (eg, ocular surface disease, capsular opacity, cystoid macular edema [CME], or lens decentration). Our study 9 shows the following: • Pseudophakic residual refractive error can be successfully managed with lens-based procedures. IOL exchange should be considered as an effective option for timely treatment of anisometropia in order to restore binocularity after cataract surgery. Lens-based procedures are preferable in cases where correction is desired soon after cataract surgery. When the postoperative refractive surprise is the result of an established cause such as an incorrect IOL power, a lens-based procedure can be performed sooner after cataract surgery than corneal refractive surgery because the stability of the incision need not be an obstacle to this surgical intervention. • In the case of a large postoperative refractive surprise, lens-based procedures may be more effective than LASIK in reducing high degrees of spherical error in the absence of significant cylinder. However, one should not trivialize the risk of lens-based procedures for reducing a small refractive error. • A lens-based procedure does not alter the anterior corneal surface and does not significantly change the corneal refractive power. On the other hand, laser procedures are limited by corneal stromal thickness and other corneal conditions such as dry eye severity, corneal scarring, or corneal degeneration. • Lens-based procedures are straightforward in that the original cataract wound can be reopened and the IOL exchanged soon after the initial surgery. However, one should be careful with second procedures regarding endothelial cell count, especially in eyes with a shorter axial length and/or shallower anterior chamber (AC) and in which

stability of refraction from the original surgery still needs to be established. • Lens-based procedures are a reasonable option if an implanted IOL interferes with a laser-tracking device.

PIGGYBACK INTRAOCULAR LENS The piggyback technique, originally developed to provide adequate power in highly hyperopic patients, has been extended to secondary cases in which additional power is added or subtracted to an unacceptably powered pseudophakic eye. Studies have shown that placing a secondary piggyback IOL in the ciliary sulcus and leaving the original IOL in place is a generally effective, safe, and easy procedure for correcting a pseudophakic refractive surprise.30-33 The advantages of secondary piggyback lenses over an IOL exchange are smaller incisions, decreased intraoperative maneuvers that could lead to capsule rupture, and a simpler method of IOL power calculation. However, potential complications such as interlenticular opacification, postoperative elevation of intraocular pressure, pupillary optic capture after dilation, iris chafing, CME, pigment dispersion syndrome, and uveitis-glaucoma-hyphema syndrome can occur after piggyback IOL implantation.34-36 Very few IOLs are designed for placement in the ciliary sulcus (and to the best of our knowledge none of these sulcusdesigned lenses are available in the United States), and the second lens should not be in the capsular bag or interlenticular opacification (ILO) may result (Figure 16-1). In a recent study, Chang et al37 suggested that single-piece acrylic IOLs placed in the sulcus increased the risk of postoperative complications and should never be used in this location. Fewer companies are producing silicone 3-piece IOLs that have been used in the past for these piggyback implantations. We therefore expect to hear reports of piggyback lenses using other materials, including hydrophobic acrylic, and await the results of such studies. Placement of 2 or 3 IOLs has been reported as successful in nanophthalmic eyes.30,38,39 The advantages of piggyback IOLs40-42 include the following: (1) a way to achieve the total lens strength required for emmetropia when higher IOL powers are not commercially available; (2) enhanced image quality of a piggyback

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211

INTRAOCULAR LENS EXCHANGE

Figure 16-1. Piggyback Clariflex (AMO) over Crystalens (Bausch & Lomb, Rochester, NY). A 3-piece IOL is placed in the ciliary sulcus as a piggyback lens to correct residual refractive error.

lens system over a single lens; and (3) the ability to provide better depth of the field of vision. However, some drawbacks have been noted with placing 2 acrylic IOLs in the capsular bag, which include the following43: • ILO, a significant complication of piggyback IOLs, results in a hyperopic shift and decreased visual acuity.34,41,44-46 ILO can be difficult to treat and may require explantation of both lenses and in some cases the capsular bag. • Two foldable IOLs in contact with each other can deform at the interface41 and alter (flatten) the IOLs’ curvatures within the contact zone. This central flattening may decrease the total power of the lenses, resulting in postoperative hyperopia. • The distortion of the lens material may increase aberrations and deteriorate the optical quality of the lenses. Placing one IOL in the bag and one in the sulcus with IOLs made of different materials may reduce the possibility of ILO. Many surgeons prefer to place a lower power, thin, biconvex silicone lens in the ciliary sulcus and a higher power aspheric acrylic lens in the capsular bag.44 The methods of calculating the piggyback IOL power are presented in Chapter 8 on IOL power calculation in special occasions. With the recent introduction of very high-power, foldable, aspheric, hydrophobic acrylic IOLs available in powers up to +40.00 D (AcrySof SN60AT, Alcon), the need for primary polypseudophakia is now much less frequent. Secondary polypseudophakia would be more often used to correct a refractive surprise in the postoperative period, and this can be performed months or even years after the original surgery.

Continuing improvement in surgical technique and instrumentation, evolution in IOL design, and better understanding of the behavior of different styles of IOLs have greatly improved the visual outcomes of cataract surgery, minimized the incidence of complications leading to IOL exchange, and changed the indications for IOL exchange. In a retrospective study performed between 1998 and 2004, Jin et al47 found that the most frequent indications for IOL exchange were incorrect IOL power calculation (41.2%) followed by IOL dislocation or decentration (37.3%) and glare (7.8%), compared to corneal decompensation (38.6%), abnormal IOL position (22.8%), CME (13.9%), and incorrect IOL power (13.9%) in a study performed between 1986 and 1990 in the same clinical setting (Table 16-2).48 Mamalis et al49 reported in a survey update in 2003 that the most common reason for IOL exchange was IOL dislocation/decentration, followed by incorrect IOL power, IOL calcification, and glare/optical aberrations. In a 5-year prospective study performed between 2002 and 2007, Leysen et al50 reported that IOL opacification (31%), IOL decentration (19%), IOL dislocation (18%), and capsule phimosis (14%) were the major causes of IOL exchange. Surgical removal or explantation of existing IOLs is a challenging procedure, especially for late IOL exchange because of the adherence between the IOL and the lens capsule, in particular with hydrophobic acrylic IOLs. Several methods have been described, such as viscodissection of the capsule/IOL interface, circumferentially enlarging the pre-existing capsulorrhexis, cutting the anterior capsular rim, cutting the IOL haptics from the optic and leaving the haptics in situ, transecting the IOL optic, and using YAG laser disruption of the IOL optic or haptic.50 The use of 2 side-port incisions is helpful for removing an IOL through small clear corneal incisions (Figure 16-2).51-53 Using these techniques, the capsule is often salvaged. An in-the-bag implantation, if the posterior capsule is intact and the bag emptied of the original lens, or sulcus implantation, with optic capture through the anterior capsule opening if anatomy allows, can often be undertaken. Scleral fixation of posterior chamber (PC)-IOLs used to be the predominant approach for IOL replacement during a lens exchange or secondary lens implantation when the posterior capsule was inadequate.54 Several modified methods for scleral fixation have been reported (see Chapter 16 Video 1).55,56 However, scleral fixation is considered a more complicated, time-consuming procedure by some, and axial tilt of the IOL may occur postoperatively. Increasingly popular is the fixation of a PC-IOL to the iris either when an IOL has dislocated or for IOL

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TABLE 16-2

COMPARISON OF CURRENT WITH PREVIOUS STUDY CURRENT STUDY

PREVIOUS STUDY

Time period

1998 to 2004

1986 to 1990

Rate of IOL exchange

0.77%

1.75%

Number of cases

51

101

Leading indication of IOL exchange

Incorrect IOL power (41.2%) Abnormal IOL power (37.3%) Glare (7.8%)

Bullous keratopathy (38.6%) Abnormal IOL position (22.8%) Incorrect power (13.9%) CME (13.9%)

IOL implanted at IOL exchange AC-IOL PC-IOL Scleral fixation

27.5% 72.5% 0

31.7% 69.0% 33.0%

Visual outcome BCVA 20/40 or better Loss of 2 lines of preop VA

90.2% 3.9%

50.5% 11.5%

Postop follow-up Mean Range

22.0 3 to 84

23.0 6 to 71

Reprinted from Am J Ophthalmol, 140(4), Jin GJC, Crandall AS, Jones JJ, Changing indications for and improving outcomes of intraocular lens exchange, pp 688-694, Copyright (2005), with permission from Elsevier.

A

B

Figure 16-2. (A, B) Two side-port incision technique permits complete access to the capsular bag.

placement where there is no capsular support (Figure 16-3). Furthermore, modern AC-IOLs pose no greater risk than use of PC-IOLs with respect to visual outcome and safety for IOL exchange. We believe that modern AC-IOLs are an acceptable option as well for IOL exchange in the absence of posterior capsule support.57 Current model AC-IOLs have flexible, nonlooped haptics, providing 4-point angle fixation (Figure 16-4). The modern AC-IOL is slightly vaulted anteriorly to prevent

iris stromal contact, is well finished, and comes in multiple lengths to permit appropriate sizing. Therefore, AC-IOLs are safe and effective for IOL exchange or secondary implantation to correct aphakia.37,57 One of the limitations of IOL exchange is the difficulty in predicting the power of the replacement IOL.58 The methods of IOL power calculation for IOL exchange are introduced in Chapter 8 on IOL power calculation in special occasions.

Postoperative Enhancement

A

B

C

D

213

Figure 16-3. (A) The IOL in a mustache fold is introduced into the AC. (B) The haptics are rotated posterior to the iris and the IOL released over a spatula to create pupil-optic capture. (C) Each haptic is secured to the mid-peripheral iris using a 10-0 prolene suture. (D) With the fixation sutures tied and cut on the knot, the optic is positioned posterior to the iris and the wounds secured.

patients, an IOL exchange for a different lens, usually monofocal, with a lower refractive index and rounded edges may be the only palliative option. IOL exchange is an effective option for the timely treatment of large postoperative refractive surprise if the source of the error is apparent and if the error is discovered early in the postoperative course. The same type of IOL and the same in-the-bag placement used for exchange of an IOL may increase the accuracy of correction.59,60 Nd:YAG capsulotomy preferentially should be delayed until it has been determined that IOL exchange will not be necessary.61

CHAPTER REFERENCES Figure 16-4. Well-finished 4-point fixation AC-IOL.

For multifocal lens implantation, the most common reason for exchanging such IOLs is unwanted visual images or dysphotopsia, such as intolerable glare and halos or poor quality of vision. For these unhappy

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Postoperative Enhancement 44. Shugar JK, Keeler S. Interpseudophakos intraocular lens surface opacification as a late complication of piggyback acrylic posterior chamber lens implantation. J Cataract Refract Surg. 2000;26:448-455. 45. Shugar JK, Schwartz T. Interpseudophakos Elschnig pearls associated with late hyperopic shift: a complication of piggyback posterior chamber intraocular lens implantation. J Cataract Refract Surg. 1999;25:863-867. 46. Eleftheriadis H, Marcantonio J, Duncan G, Liu C. Interlenticular opacification in piggyback AcrySof intraocular lenses: explantation technique and laboratory investigations. Br J Ophthalmol. 2001;85:830-836. 47. Jin GJ, Crandall AS, Jones JJ. Changing indications for and improving outcomes of intraocular lens exchange. Am J Ophthalmol. 2005;140:688-694. 48. Lyle WA, Jin JC. An analysis of intraocular lens exchange. Ophthalmic Surg. 1992;23:453-458. 49. Mamalis N, Davis B, Nilson CD, Hickman MS, Leboyer RM. Complications of foldable intraocular lenses requiring explantation or secondary intervention—2003 survey update. J Cataract Refract Surg. 2004;30:2209-2218. 50. Leysen I, Bartholomeeusen E, Coeckelbergh T, Tassignon MJ. Surgical outcomes of intraocular lens exchange: five-year study. J Cataract Refract Surg. 2009;35:1013-1018. 51. Karamaounas N, Kourkoutas D, Prekates C. Surgical technique for small-incision intraocular lens exchange. J Cataract Refract Surg. 2009;35:1146-1149. 52. Por YM, Chee SP. Trisection technique: a 2-snip approach to intraocular lens explantation. J Cataract Refract Surg. 2007;33:1151-1154.

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53. Osher RH. Crisscross lensotomy: new explantation technique. J Cataract Refract Surg. 2006;32:386-388. 54. Lyle WA, Jin JC. Secondary intraocular lens implantation: anterior chamber vs posterior chamber lenses. Ophthalmic Surg. 1993;24:375-381. 55. Lin CP, Tseng HY. Suture fixation technique for posterior chamber intraocular lenses. J Cataract Refract Surg. 2004;30:1401-1404. 56. Han QH, Wang L, Hui YN. Transscleral suture technique for fixation of a dislocated posterior chamber intraocular lens. J Cataract Refract Surg. 2004;30:1396-1400. 57. Evereklioglu C, Er H, Bekir NA, Borazan M, Zorlu F. Comparison of secondary implantation of flexible open-loop anterior chamber and scleral-fixated posterior chamber intraocular lenses. J Cataract Refract Surg. 2003;29:301-308. 58. Kora Y, Shimizu K, Yoshida M, Inatomi M, Ozawa T. Intraocular lens power calculation for lens exchange. J Cataract Refract Surg. 2001;27:543-548. 59. Salz JJ, Reader AL III. Lens implant exchanges for incorrect power: results of an informal survey. J Cataract Refract Surg. 1988;14:221-224. 60. Jin GJ, Crandall AS, Jones JJ. Intraocular lens exchange due to incorrect lens power. Ophthalmology. 2007;114:417-424. 61. Woodward MA, Randleman JB, Stulting RD. Dissatisfaction after multifocal intraocular lens implantation. J Cataract Refract Surg. 2009;35:992-997.

VIDEO REFERENCE Video 1. IOL Exchange.

Please see video on the accompanying Web site at http://www.slackbooks.com/cataractsurgeryvideos

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CATARACT SURGERY AFTER PREVIOUS REFRACTIVE SURGERY Cataract Surgery After LaserAssisted in Situ Keratomileusis George J. C. Jin, MD, PhD and Alan S. Crandall, MD Laser-assisted in situ keratomileusis (LASIK) has been performed in 16.3 million people worldwide since 1998.1 With clinical experience of over 20 years, LASIK technology has improved with small flying spot lasers, more reliable tracking systems, wavefront guided/optimized ablations, and femtosecond laser corneal flap creation. LASIK remains the predominant refractive surgical technique, featuring a rapid visual recovery, refractive stability, and an acceptable low complication rate.2,3 Based on a systemic literature review, worldwide, an average 95.4% of patients were satisfied with their outcome after LASIK. LASIK surgery should be considered among the most successful elective procedures.1 With time, clinicians can expect increasing numbers of patients with a history of previous LASIK surgery to develop cataracts that will require surgery. Although previous refractive surgery is a relative contraindication for refractive lens surgery, a large number of these patients are highly motivated for refractive cataract surgery. As patients who have undergone laser refractive surgery present with cataracts, they will have high visual expectation after cataract surgery. Careful patient selection is critical for successful implementation of presbyopic intraocular lenses (IOLs) for these patients. Cataract surgery for patients who have undergone previous LASIK procedures presents some

unique challenges. Beside the difficulty for IOL power calculation after LASIK (see Chapter 6 on IOL power calculation), LASIK-related complications such as postLASIK dry eye and problems with visual quality are among the most common conditions encountered by ophthalmologists.4

PROBLEMS WITH VISUAL QUALITY Night vision difficulties such as glare, image degradation (halos, starbursts), and decreased contrast sensitivity are major concerns after laser refractive surgery.5,6 In a study of 604 previously myopic patients responding to a questionnaire, halos were reported by 30%, glare by 27%, and starbursts by 25%.7 Factors contributing to an increased risk for postrefractive night vision disturbances include the patient’s own predisposing factors such as large pupils, large refractive errors, thin corneas, low ability of adaptation, and individual healing responses. Other factors contributing to poor corneal optics after LASIK include deep ablations, small optical treatment zones, poor quality of ablation and/or blend zones, decentrated treatments, and increased higher order

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aberrations.5,6,8 Postoperatively, flap striae, epithelial ingrowth, or flap misalignment may be associated with increased visual complications after LASIK.6 High levels of spherical aberrations (SA) have been linked to deterioration in visual function and contrast sensitivity in eyes after LASIK. After myopic LASIK, the cornea has been flattened at the apex so that the rays emerging from the center of the pupil will be parallel and focused at infinity, as expected for an emmetropic eye. At the same time, the more peripheral cornea is still highly curved and the eye remains myopic for marginal rays. This combination of emmetropia for paraxial rays and myopia for marginal rays constitute positive SA. Opposite to myopic LASIK, hyperopic LASIK induces a negative SA. Positive SA means that peripheral rays are bent too much and negative SA means that peripheral rays are not bent enough. Regardless of positive or negative SA, high levels of SA were associated with glare under mesopic as well as scotopic conditions in eyes after LASIK and correlated with a decrease in contrast sensitivity.9 Wavefront-guided ablations minimize the increase in higher order aberrations that frequently accompanies standard ablations and thus may improve the quality of vision for LASIK patients.10,11 The direct association between pupil size and the incidence of night vision disturbances has long been a debated topic in the literature.

some patients may experience dry eye symptoms chronically.13,16,17 The persistent nature of dry eye after LASIK is attributed in part to delayed tear clearance, and undercorrected aqueous is attributed in part to delayed tear clearance, undercorrected aqueous tear deficiency, and nonrecognized lipid tear deficiency.18 The most common presentation of post-LASIK dry eyes is corneal punctate epithelial keratopathy overlying the LASIK flap. Post-LASIK dry eye has to be treated aggressively before cataract surgery. Treatment options for moderate to severe dry eye include using artificial tears, punctal occlusion, and topical anti-inflammatory drops. Control of dry eyes prior to surgery through temporary or permanent punctal occlusion and concomitant control of conditions such as allergy or blepharitis is important. However, if there is a significant inflammatory component, often seen with meibomian gland dysfunction, punctual plugs may actually exacerbate the dry eye symptoms. A recent study revealed that topical cyclosporine is effective for promoting the recovery of corneal nerves after LASIK. After 3 months of treatment with topical cyclosporine, the flap area had significantly greater corneal sensitivity than the fellow untreated eye. The authors attribute the rapid corneal nerve recovery with topical cyclosporine to the fact that the corneal nerve cells are peripheral nerves with nonmyelinated nerve fibers and, thus, are very sensitive to local inflammatory cytokines, in contrast to central nervous system brain and spine nerve cells, which are myelinated.19

POST–LASER-ASSISTED IN SITU KERATOMILEUSIS POST–LASER-ASSISTED DRY EYE IN SITU KERATOMILEUSIS Post-LASIK dry eye occurs in up to 30% of patients ECTASIA

6 months postoperatively and gradually decreases over time in most cases.12-14 The risk of developing significant dry eye after LASIK is increased in patients who are older, female, and with higher refractive correction.13,15 Possible mechanisms contributing to LASIK-associated dry eye, elaborated by Ambrosio et al,12 include (1) interruption of afferent sensory nerve fibers in the cornea during flap formation, (2) decreased neurotrophic influences on epithelial cells, (3) decreased blinking rate, (4) decreased reflex and basal tear production, (5) change in corneal shape, (6) change in tear film distribution, (7) change in the relationship of the ocular surface to the upper lid, (8) increased evaporative tear loss, and (9) possible damage to limbal goblet cells by the microkeratome suction ring. Most of the dry eye symptoms that follow LASIK are the result of LASIKinduced neuro-epitheliopathy, or LINE syndrome, caused by the physical cutting of nerve fibers when creating a flap.12 The reduction in tear production and diminished tear film quality caused by post-LASIK dry eye will gradually recover in most patients. However,

Post-LASIK corneal ectasia is a rare complication in which a progressive deformation of the gross corneal anatomy occurs after surgery. The incidence is about 1 in 2500 (0.04%). Histopathologic and ultrastructural studies suggest that interlamellar and interfibrillar biomechanical slippage occurs when the cornea becomes ectatic after LASIK or photorefractive keratectomy (PRK) in the postoperative stress-bearing regions of the corneal stroma.20 Patients with high risk for ectasia include those with (1) preoperative central corneal pachymetry less than 500 μm; (2) residual stromal bed (RSB) less than 250 μm; (3) mean keratometry reading greater than 47 D; (4) oblique cylinder greater than 2 D; (5) high myopic correction greater than -12 D; (6) more than 2 retreatments; (7) abnormal topography such as forme fruste keratoconus; and (8) an Orbscan II “posterior float” (if obtained) greater than 50 μm.21-23 A corneal stromal sliver created by recutting a new flap during retreatment may also cause ectasia.24 In a retrospective

Cataract Surgery After Previous Refractive Surgery comparative trial, Randleman et al 21 reported that significant risk factors for the development of ectasia after LASIK include high myopia, forme fruste keratoconus, and low RSB. In their series, all patients had at least one risk factor other than high myopia, and significant differences remained even when controlling for myopia. The authors did not identify any patients who developed ectasia without recognizable preoperative risk factors.21 Based on subgroup logistic regression analysis, abnormal topography was the most significant factor that discriminated cases from controls, followed by RSB thickness, age, and preoperative corneal thickness, in that order.23 In a recent study, Binder25 reported that all eyes that developed keratectasia had abnormal preoperative topography. However, none with other risk factors developed ectasia. These studies suggest that corneal topography (CT) is more predictive of ectasia than any other criteria. Corneal ectasia may be related to the clinically observed lack of corneal wound healing at the edge of the flap that allows the cornea to bulge. In an animal study with rabbits, Abdelkader et al 26 demonstrated that adding sutures to the corneal flap after LASIK appeared to reduce the amount of corneal steepening when the intraocular pressure (IOP) is artificially increased up to 25 mmHg. An increase in the amount of myofibroblasts induced by the sutures may be responsible for this behavior. By stimulating a stronger woundhealing response at the edge of the flap, the cornea may better resist steepening under increased IOP conditions and improve the long-term stability of LASIK surgery in borderline thin corneas.26 Pre-cataract evaluation for patients after LASIK should include post-LASIK keratectasia screening tests, such as pachymetry and topography. CT is an important tool in modern refractive cataract surgery.27-29 CT is helpful in assisting the surgeon’s understanding of preoperative conditions such as irregular astigmatism, keratoconus, forme fruste keratoconus, pellucid marginal degeneration, and post-LASIK ectasia. These conditions will increase the risk for postoperative glare and halo, reduce quality of vision, and are relative contraindications for refractive cataract surgery. When analyzing preoperative topography, caution should be warranted whenever patients have an elevated inferior-to-superior value, asymmetric inferior steepening, or skewed radial axes (Figure 17-1). Local areas of steepening, superiorinferior asymmetry, and skewing of the radial axes above and below the horizontal meridian are all indicative of corneal ectasia. Current Placido-based topography systems are not perfect in screening for pre-existing corneal disorders because the posterior corneal curvature is implied and not directly measured. Different from a Placido-based anterior curvature device, the Pentacam (OCULUS, Lynnwood, WA; using a rotating Scheimpflug camera)

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Figure 17-1. CT shows typical change of keratoconus: local areas of steepening, superior-inferior asymmetry, and skewing of the radial axes above and below the horizontal meridian.

and the Orbscan (Bausch & Lomb, Rochester, NY; using a horizontal slit-scanning system) analyze elevation and curvature measurements on both the anterior and posterior surfaces of the cornea. These topographies are also helpful in evaluation of post-LASIK ectasia. Performing cataract surgery on post-refractive surgery ectasia patients is a technical challenge. Recently, Chiou et al30 reported a patient with bilateral ectasia following myopic PRK who was successfully treated with a 2-step approach: first a deep anterior lamellar keratoplasty was performed, and 6 weeks later, phacoemulsification with IOL implantation was performed. Another approach to treat corneal ectasia is riboflavin-induced corneal lamellar bending.

RETINAL DETACHMENT Retinal detachment (RD) after LASIK for myopic correction is uncommon, with a frequency of 0.03% to 0.06%.31,32 In a study by Qin et al,32 mean pre-LASIK myopia was -9.33 D (range -6.25 to 14.00 D). The mean interval between LASIK and RD development was 9.25 months (range 2 to 18 months). All RDs occurred spontaneously and were managed with vitreoretinal surgeries. In another study by Arevalo et al,31 mean pre-LASIK myopia was -7.02 D (range -1.50 to -16.00 D); RDs occurred a mean of 13.9 months (range 1 to 36 months) after LASIK. Most RDs and retinal breaks occurred in the temporal quadrants (71.4%). When considering cataract surgery for patents after LASIK, especially those who previously had highly myopic corrections, clinicians should be aware of retinal pathologic features and perform a thorough dilated indirect funduscopy with scleral depression and consider

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Figure 17-2. LASIK flap loss 3.5 years after LASIK. (Reprinted from J Cataract Refract Surg, 33(7), Tetz M, Werner L, Muller M, Dietze U, Late traumatic LASIK flap loss during contact sport, pp 1332-1335, Copyright (2007), with permission from Elsevier.)

treating any retinal lesion predisposing to the development of an RD. Referral to a retinal specialist for any complex case is generally advised. The vulnerability of such highly myopic eyes for vitreoretinal complications after LASIK warrants their close monitoring.33,34

FLAP HEALING The long-term vulnerability of the LASIK flap to dehiscence after trauma and late-onset LASIK flap dislocation has been reported.35-38 Although the occurrence of late traumatic flap dislocation is rare, it has been documented that even trivial sources of trauma can result in this complication, even years after the procedure (Figure 17-2).39,40 Jin and Merkley35 recently reported a case of LASIK flap dislocation 7 years after surgery. LASIK and automated lamellar keratectomy flap displacement has been seen as an intraoperative event during retinal surgery.41,42 In one case, the flap was freed during a scleral buckling procedure 5 months after automated lamellar keratectomy when the epithelial surface of the flap was débrided by the surgeon using a #64 Beaver blade to enhance visualization.41 Although there has been no case reported of flap displacement during cataract surgery, caution must be used when performing cataract surgery, and preoperative counseling should include a discussion of the risk of flap dislocation in patients who have had previous LASIK. The wound-healing reaction occurring at the stromal interface is less than that of the surrounding epithelial rim at the periphery of the flap, as demonstrated in a rabbit study43 and evidenced by the surgical experience when lifting the flap at the time of enhancement.43-45 Therefore, special attention should be paid to the location of a cataract surgery incision, which should be away

Figure 17-3. IFS: slit lamp shows a prominent fluid between the LASIK flap and stromal bed with significant diffuse corneal haze. (Reprinted from J Cataract Refract Surg, 25(7), Lyle WA, Jin GJC, Interface fluid associated with diffuse lamellar keratitis and epithelial ingrowth after laser in situ keratomileusis, pp 1009-1012, Copyright (1999), with permission from Elsevier.)

from the flap edge. There is little direct research upon which we can base guidelines for flap stability after LASIK or the safest interval for performing cataract surgery in eyes that had previously undergone LASIK. In a confocal microscopy study, Kitzmann et al46 found that the femtosecond laser flap was easily separated 4 months after it was created. Most surgeons agree that LASIK flaps are clinically stable 3 to 6 months after surgery.40,47

INTERFACE FLUID SYNDROME Interface fluid syndrome (IFS) is a rare flap-related complication first reported in the literature in 1999 by Lyle and Jin.48 Corneal edema with fluid accumulation in the interface is mostly caused by steroid-induced ocular elevation of IOP after LASIK with a misleading clinical picture simulating diffuse lamellar keratitis (DLK) or infectious keratitis and presenting with falsely low central applanation tonometry measurements.49-54 Management includes stopping topical steroids and starting topical antiglaucoma therapy (Figure 17-3). Cataract surgeons should be aware of this postLASIK syndrome for several reasons: 1. The frequency of steroid responses in the general population ranges between 5% and 36%; therefore, the incidence of IFS caused by steroid-induced ocular hypertension may be much greater than the number of published reports.49,55 2. Although IFS usually occurs in the early postoperative period, late-onset IFS has been seen 28 months56 to 4 years57 after initial LASIK.

Cataract Surgery After Previous Refractive Surgery

Figure 17-4. DLK diffuse, multifocal, dot-like, and granular haze in the interface of the cornea presented 3 year after LASIK. (Reprinted from J Cataract Refract Surg, 31(2), Jin GJC, Lyle WA, Merkley KH, Late-onset idiopathic diffuse lamellar keratitis after laser in situ keratomileusis, p 435, Copyright (2005), with permission from Elsevier.)

3. IFS resembles DLK,49,58 which is more common after LASIK, and the treatment option for DLK is steroid drops. To treat IFS, steroids need to be stopped. 4. Goldmann tonometry is inaccurate when measuring IOP in eyes with IFS. IOP measurement at the peripheral cornea (over the flap hinge) with a Tonopen or pneumotonometer may be more accurate.51,53 5. The post-cataract medications commonly include topical steroids and antibiotics. Limiting the instillation of topical corticosteroids and monitoring the IOP after routine cataract surgery may be helpful for preventing IFS.

DIFFUSE LAMELLAR KERATITIS AND CENTRAL LAMELLAR KERATITIS DLK is a well-documented complication of LASIK. It is a noninfectious interface infiltration or inflammation that typically occurs within the first month postoperatively.59,60 Late-onset DLK has been reported up to 3 years after LASIK without an obvious identifiable cause, however (Figure 17-4).61 Clinically, DLK can be classified into 4 stages according to clinical appearance and severity, ranging from nonvisually significant interface haze to dense, opaque corneal filtration and stromal melting.62 However, the ophthalmic community has not reached consensus on whether stage 4 DLK should be considered a progression from stage 3 or whether it is a completely different entity.63

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Figure 17-5. Slit-lamp photo of CLK shows central discrete interface haze and prominent deep flap folds. (Reprinted from J Cataract Refract Surg, 27(4), Lyle WA, Jin GJC, Central lamellar keratitis, pp 487-490, Copyright (2001), with permission from Elsevier.)

Central lamellar keratitis (CLK; central toxic keratopathy, central focal interface opacity, central flap necrosis) has been proposed to describe this distinct entity.64-67 The characteristics of CLK include (1) a dense central or paracentral circular interface haze; (2) prominent central deep flap folds; (3) a hyperopic shift with increased astigmatism and irregular astigmatism resulting loss of best corrected visual acuity (Figure 17-5).

PRESBYOPIC INTRAOCULAR LENS IMPLANTATION Preoperative assessments for some potential problems induced by LASIK such as irregular astigmatism, a decentered ablation, or large amounts of astigmatism are important. The issues of contrast sensitivity loss, the compounding of LASIK-induced spherical aberration, and the possibility of errors in effective lens position prediction with an accommodative lens are worth special attention. Remember, many biometry formulas adjust the effective lens position based on both the axial length and the corneal curvatures. A flattened cornea after LASIK would incorrectly suggest a shallower effective lens position than would otherwise occur. Some postLASIK patients coming for cataract surgery may have had their LASIK in the early years, with older technology that may affect corneal optics more than current lasers do. Corneal curvature changes, when combined with a multifocal lens, may produce even more reduction in contrast sensitivity. When selecting a proper IOL for patients after LASIK, it is important to know some

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details from the previous surgery including preoperative pachymetry, keratometry readings, refractive error treated, and type of laser used in the ablation. One important consideration in choosing conventional IOLs versus aspherical IOLs for a patient who has had LASIK is to understand what benefit a patient can get from the aspherical IOLs. Aspherical IOLs were designed to compensate for the positive SA of the cornea, simulating the natural function of the youthful crystalline lens.68 Implanting an aspheric IOL with negative SA such as the AcrySof SN60WF (SA -0.17 D; Alcon, Fort Worth, TX) or Tecnis Z900 (SA -0.27 D; Abbott Medical Optics [AMO], Santa Ana, CA) into an

eye with positive SA after myopic LASIK may reduce or eliminate the SA. On the other hand, hyperopic LASIK does not induce positive SA; a conventional spherical IOL with positive SA may be beneficial for hyperopic LASIK patients. Therefore, the original ReSTOR (Alcon) without aspheric modification is a better lens choice for hyperopic LASIK patients. A recent study by Blaylock et al69 indicated that better function with respect to vision-related quality of life and acceptance of bilateral spherical ReSTOR after LASIK were achieved in hyperopes with presbyopia than in myopic patients receiving similar ReSTOR IOLs, possibly due to the differences in induced SA.

Cataract Surgery After Surface Ablation Randall J. Olson, MD and George J. C. Jin, MD, PhD PRK was the most commonly performed refractive surgical procedure before LASIK became the procedure of choice and still has some advantages over LASIK, with less altered corneal structural integrity and flaprelated complications when treating low to moderate myopia.70,71 In laser-assisted subepithelial keratectomy or laser epithelial keratomileusis (LASEK), an epithelial flap is created with alcohol-assisted separation, whereas in Epi-LASIK, the epithelial separation is achieved with the use of an automated device, the epikeratome, and then is repositioned on the photoablated stroma. Both LASEK and Epi-LASIK may combine the advantages and eliminate the disadvantages or PRK and LASIK.72-79 However, the superiority of LASEK to PRK in the corneal wound-healing modulation remains speculative.80 In a recent study with meta-analysis of randomized controlled trials, Cui et al concluded that LASEK does not appear to have any advantage over PRK for correcting myopia in terms of the early, midterm, and mid- to long-term results.81 As in post-LASIK eyes, calculating the IOL power for cataract surgery after PRK and LASEK poses a great challenge to cataract surgeons (discussed in Chapter 6 on IOL power calculation). Also, as with other forms of refractive surgery, dry eye, night vision disturbances (glare and halos), and induced irregular astigmatism may be problems in post-PRK or LASEK patients undergoing cataract surgery. Persistent corneal haze/scarring as a late-stage complication after surface ablation is rare but it may impact the outcome of cataract surgery. Corneal haze, a condition of decreased corneal transparency, characterized by subepithelial fibrosis caused by an abnormal wound-healing response,82 is a well-recognized complication after PRK,71,83-87 and also seen

after LASEK.84 Risk factors associated with haze are (1) high myopic correction (>6 D), requiring ablation of > 70 μm85,86,88-91; (2) small optic zone ≤ 5.0 mm89; (3) atopic or autoimmune conditions84,92; (4) PRK after previous radial keratotomy (RK),93,94 especially in those with RK > 8 incisions, and corneal optic zone of ≤ 3.0 mm95; (5) ultraviolet exposure91,96; (6) repeated PRK 82; and (7) ocular surface disease such as dry eye and meibomian gland dysfunction.97 Corneal haze develops mostly between 1 and 3 months after surgery and declines slowly thereafter (regular post-PRK haze).91,98 However, late-onset corneal haze (LOCH) can occur up to 33 months after laser ablation.85,86,92 A scale from 0 to 4 can be used to quantify the haze: 0 = clear cornea; 0.5 = trace of opacity; 1 = mild, not affecting refraction; 2 = moderate, with difficult refraction; 3 = opacity that prevents refraction; 4 = unable to view anterior chamber.99 Persistent corneal haze or LOCH may have a negative impact on cataract surgery because not only does the loss of transparency result in visual loss, but the stromal reaction can induce corneal surface irregularity (Figure 17-6). Scar tissue might interfere with an accurate preoperative assessment of the refractive error as well as topography analysis (Figure 17-7). For significant haze (scale 2 or above), we recommend treating the haze prior to cataract surgery. In cases of late haze where the steroids do not effectively eliminate the corneal haze, additional surgery is required. In those cases, surgical débridement with manual blade scraping or excimer laser PTK, followed by application of mitomycin-C (MMC) 0.02% for 2 minutes to the exposed bed may be appropriate. Vigorous treatment of dry eye

Cataract Surgery After Previous Refractive Surgery

Figure 17-6. Corneal haze after PRK. (Reprinted with permission from Mark Mifflin, MD.)

and meibomian gland dysfunction, initiating postoperative regimens that include intensive corticosteroids, oral

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Figure 17-7. Corneal scar after PRK. (Reprinted with permission from Busin M, Arffa RC. Atlas of Microkeratome Assisted Lamellar Keratoplasty. Thorofare, NJ: SLACK Incorporated; 2007.)

vitamin C and E, and UV-blocking sunglasses, may be beneficial for those patients.

Cataract Surgery After Radial Keratotomy George J. C. Jin, MD, PhD and Randall J. Olson, MD Radial keratotomy (RK) was the dominant refractive procedure before laser refractive surgery developed. RK incisions permanently weaken the cornea. This structural weakening can cause several complications and side effects, including diurnal refractive fluctuation, progressive hyperopic shift, and the potential for traumatic rupture of the keratotomy scars, as well as corneal infection (Figure 17-8).100 The 10-year follow-up Prospective Evaluation of RK (PERK) study101 showed that 43% of eyes changed in the hyperopic direction by 1.00 D or more between 6 months and 10 years after RK. The mean rate of change was approximately 0.1 D per year, indicating a long-term instability of the refractive error. In addition to spherical refractive error, RK can induce both regular and irregular astigmatism. Ten percent of eyes manifested an increase in astigmatism of greater than 1.0 D postoperatively. The continuation of the biomechanical change in the cornea and delayed wound healing of RK incisions explains the progressive hyperopia and fluctuating vision years after surgery.102 An increasing number of the patients who have undergone RK in the past are presenting for cataract surgery now. The calculation of IOL power poses a great challenge in these patients. Although many formulas and methods have been described for IOL power calculation in postRK patients, there is no single method that is considered superior to all the others (see Chapter 6 on IOL power calculation).103-106 In addition, several issues need to be considered when performing cataract surgery

for this difficult subset of patients. Successful surgery requires not only a proper understanding of the preoperative, intraoperative, and postoperative courses of the patients, but also detailed patient counseling regarding these issues. The informed consent should make clear that lens power calculations are less precise, a secondary procedure such as an IOL exchange or a piggyback lens may be necessary, and the postoperative visual and refractive stability may take longer to recover.

INCISION DEHISCENCE Healing of the RK incisions is very slow, unpredictable, and often incomplete even years after surgery.102 Dehiscence of RK incisions has been reported during cataract surgery.107-109 There are no available data to establish the postoperative interval required for these corneal incisions to return to native strength.110 In one case, dehiscence occurred 14 years after RK.107 Persistent epithelial plugs in the incision and delayed incision remodeling process may predispose to incision rupture (Figure 17-9).108 Caution must be taken when performing cataract surgery for patients with previous RK 107-109: • Only use a clear corneal incision if there is sufficient distance between the RK incisions; otherwise, a scleral tunnel incision should be used.

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A

B

Figure 17-8. Slit-lamp photos of infiltration of RK incision.

• If a radial incision opens during surgery, this can be managed by suturing the incision and surgery can be safely completed after the incision is sutured. • Be gentle on the already compromised cornea with a lower flow and lower bottle height. • Patients should be advised about the possibility of intraoperative wound dehiscence.

IRREGULAR ASTIGMATISM Irregular astigmatism after RK occurs most commonly in eyes that111-114 (1) have had repeated surgeries; (2) have 8 or more incisions; (3) have incision(s) extending into the visual axis; (4) have a clear optical zone less than 3.0 mm; and (5) receive crossing incisions (astigmatic keratotomy [AK] or T cuts). Irregular astigmatism typically results from marked flattening in the meridians of intersecting incisions. Subepithelial fibrosis and corneal scars from multiple operations, irregular or uneven incisions, and other incisional complications such as posterior plaques at perforation sites,

Figure 17-9. Photo shows epithelial plug in the RK incision.

vascularization of scars, epithelial inclusions, debris, and deposits may also cause irregular astigmatism.113,115,116 The safest and most reliable treatment of post-RK irregular astigmatism is rigid gas-permeable contact lenses.112,117 Although surgical techniques such as topographic-linked corneal excimer ablation, excimer laser plano-scan surgery assisted by sodium hyaluronate, and penetrating keratoplasty have demonstrated some usefulness in treating irregular astigmatism induced by LASIK,118 there is no reported uniformly effective surgical treatment for post-RK irregular astigmatism. Where marked regular and irregular astigmatism are associated with an incision filled with an epithelial plug, removal of the plug and suturing this incision closed may help treat the underlying astigmatism. RK induces a multifocal cornea, irregular astigmatism, and other higher order aberrations,119,120 so prior RK patients are poor candidates for multifocal IOLs, especially those with severe irregular astigmatism. A monofocal IOL with aspherical feature may be the best choice for patients with post-RK irregular astigmatism because these patients are always hyperbolate.

REFRACTIVE INSTABILITY Postoperative central corneal flattening, hyperopic shift, and refractive fluctuation following cataract surgery may mimic the changes after initial RK or may be a continuation of change from the previous RK.102,107 Slow resolution of these changes may take many weeks before the patient’s vision and refraction stabilize after cataract surgery, so do not consider a lens exchange until at least 8 weeks after surgery. Persistent fluctuation may be more common in patients with more aggressive RK (more than 8 incisions, optic zone less than 3 mm, etc). In cases of significant wound gape and hyperopic shift, suture compression of the gaped incisions may alleviate both fluctuation and overcorrection.

Cataract Surgery After Previous Refractive Surgery

CHAPTER REFERENCES 1. Solomon KD, Fernandez de Castro LE, Sandoval HP, et al. LASIK world literature review: quality of life and patient satisfaction. Ophthalmology. 2009;116:691-701. 2. Reinstein DZ, Waring GO III. Have you seen the 10-year longterm safety data on LASIK? J Refract Surg. 2006;22:843-845. 3. Kato N, Toda I, Hori-Komai Y, Sakai C, Tsubota K. Five-year outcome of LASIK for myopia. Ophthalmology. 2008;115:839844.e2. 4. Jin GJC, Merkley KH, Crandall AS. Cataract surgery after laser in situ keratomileusis. Ophthalmol Int. 2008; 23-28. 5. Pop M, Payette Y. Risk factors for night vision complaints after LASIK for myopia. Ophthalmology. 2004;111:3-10. 6. Fan-Paul NI, Li J, Miller JS, Florakis GJ. Night vision disturbances after corneal refractive surgery. Surv Ophthalmol. 2002;47:533-546. 7. Bailey MD, Mitchell GL, Dhaliwal DK, Boxer Wachler BS, Zadnik K. Patient satisfaction and visual symptoms after laser in situ keratomileusis. Ophthalmology. 2003;110:1371-1378. 8. Schallhorn SC, Kaupp SE, Tanzer DJ, Tidwell J, Laurent J, Bourque LB. Pupil size and quality of vision after LASIK. Ophthalmology. 2003;110:1606-1614. 9. Chalita MR, Chavala S, Xu M, Krueger RR. Wavefront analysis in post-LASIK eyes and its correlation with visual symptoms, refraction, and topography. Ophthalmology. 2004;111:447453. 10. Schallhorn SC, Farjo AA, Huang D, et al. Wavefront-guided LASIK for the correction of primary myopia and astigmatism a report by the American Academy of Ophthalmology. Ophthalmology. 2008;115:1249-1261. 11. Schallhorn SC, Tanzer DJ, Kaupp SE, Brown M, Malady SE. Comparison of night driving performance after wavefront-guided and conventional LASIK for moderate myopia. Ophthalmology. 2009;116:702-709. 12. Ambrosio R Jr, Tervo T, Wilson SE. LASIK-associated dry eye and neurotrophic epitheliopathy: pathophysiology and strategies for prevention and treatment. J Refract Surg. 2008;24:396407. 13. De Paiva CS, Chen Z, Koch DD, et al. The incidence and risk factors for developing dry eye after myopic LASIK. Am J Ophthalmol. 2006;141:438-445. 14. Albietz JM, Lenton LM, McLennan SG. Dry eye after LASIK: comparison of outcomes for Asian and Caucasian eyes. Clin Exp Optom. 2005;88:89-96. 15. Davidorf JM. LASIK and dry eye. Ophthalmology. 2002;109:1948-1949; author reply 1949. 16. Bailey MD, Zadnik K. Outcomes of LASIK for myopia with FDA-approved lasers. Cornea. 2007;26:246-254. 17. Sugar A, Rapuano CJ, Culbertson WW, et al. Laser in situ keratomileusis for myopia and astigmatism: safety and efficacy: a report by the American Academy of Ophthalmology. Ophthalmology. 2002;109:175-187. 18. Di Pascuale MA, Liu TS, Trattler W, Tseng SC. Lipid tear deficiency in persistent dry eye after laser in situ keratomileusis and treatment results of new eye-warming device. J Cataract Refract Surg. 2005;31:1741-1749. 19. Peyman GA, Sanders DR, Batlle JF, Feliz R, Cabrera G. Cyclosporine 0.05% ophthalmic preparation to aid recovery from loss of corneal sensitivity after LASIK. J Refract Surg. 2008;24:337-343. 20. Dawson DG, Randleman JB, Grossniklaus HE, et al. Corneal ectasia after excimer laser keratorefractive surgery: histopathology, ultrastructure, and pathophysiology. Ophthalmology. 2008;115:2181-2191.

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21. Randleman JB, Russell B, Ward MA, Thompson KP, Stulting RD. Risk factors and prognosis for corneal ectasia after LASIK. Ophthalmology. 2003;110:267-275. 22. Klein SR, Epstein RJ, Randleman JB, Stulting RD. Corneal ectasia after laser in situ keratomileusis in patients without apparent preoperative risk factors. Cornea. 2006;25:388-403. 23. Randleman JB, Woodward M, Lynn MJ, Stulting R D. Risk assessment for ectasia after corneal refractive surgery. Ophthalmology. 2008;115:37-50. 24. Lyle WA, Jin GJ. Inferior corneal steepening after a partial flap without laser ablation mimicking corneal ectasia. J Cataract Refract Surg. 2003;29:1626-1629. 25. Binder PS. Analysis of ectasia after laser in situ keratomileusis: risk factors. J Cataract Refract Surg. 2007;33:1530-1538. 26. Abdelkader A, Esquenazi S, Shihadeh W, et al. Healing process at the flap edge in its influence in the development of corneal ectasia after LASIK. Curr Eye Res. 2006;31:903-908. 27. Shankar H, Taranath D, Santhirathelagan CT, Pesudovs K. Anterior segment biometry with the Pentacam: comprehensive assessment of repeatability of automated measurements. J Cataract Refract Surg. 2008;34:103-113. 28. Norrby S. Pentacam keratometry and IOL power calculation. J Cataract Refract Surg. 2008;34:3; author reply 4. 29. Reuland MS, Reuland AJ, Nishi Y, Auffarth GU. Corneal radii and anterior chamber depth measurements using the IOLmaster versus the Pentacam. J Refract Surg. 2007;23:368-373. 30. Chiou AG, Bovet J, de Courten C. Management of corneal ectasia and cataract following photorefractive keratectomy. J Cataract Refract Surg. 2006;32:679-680. 31. Arevalo JF, Ramirez E, Suarez E, et al. Rhegmatogenous retinal detachment in myopic eyes after laser in situ keratomileusis. Frequency, characteristics, and mechanism. J Cataract Refract Surg. 2001;27:674-680. 32. Qin B, Huang L, Zeng J, Hu J. Retinal detachment after laser in situ keratomileusis in myopic eyes. Am J Ophthalmol. 2007;144:921-923. 33. Arevalo JF, Mendoza AJ, Velez-Vazquez W, et al. Full-thickness macular hole after LASIK for the correction of myopia. Ophthalmology. 2005;112:1207-1212. 34. Chan CK, Arevalo JF, Akbatur HH, et al. Characteristics of sixty myopic eyes with pre-laser in situ keratomileusis retinal examination and post-laser in situ keratomileusis retinal lesions. Retina. 2004;24:706-713. 35. Jin GJ, Merkley KH. Laceration and partial dislocation of LASIK flaps 7 and 4 years postoperatively with 20/20 visual acuity after repair. J Refract Surg. 2006;22:904-905. 36. Miyai T, Miyata K, Nejima R, Shimizu K, Oshima Y, Amano S. Late-onset repetitive traumatic flap folds and partial dehiscence of flap edge after laser in situ keratomileusis. J Cataract Refract Surg. 2005;31:633-635. 37. Nilforoushan MR, Speaker MG, Latkany R. Traumatic flap dislocation 4 years after laser in situ keratomileusis. J Cataract Refract Surg. 2005;31:1664-1665. 38. Heickell AG, Vesaluoma MH, Tervo TM, Vannas A, Krootila K. Late traumatic dislocation of laser in situ keratomileusis flaps. J Cataract Refract Surg. 2004;30:253-256. 39. Tumbocon JA, Paul R, Slomovic A, Rootman DS. Late traumatic displacement of laser in situ keratomileusis flaps. Cornea. 2003;22:66-69. 40. Iskander NG, Peters NT, Anderson Penno E, Gimbel HV. Late traumatic flap dislocation after laser in situ keratomileusis. J Cataract Refract Surg. 2001;27:1111-1114. 41. Shakin EP, Fastenberg DM, Udell IJ, et al. Late dislocation of a corneal cap after automated lamellar keratoplasty and epithelial debridement for retinal surgery. Arch Ophthalmol. 1996;114:1420.

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42. Chaudhry NA, Smiddy WE. Displacement of corneal cap during vitrectomy in a post-LASIK eye. Retina. 1998;18:554-555. 43. Perez-Santonja JJ, Linna TU, Tervo KM, Sakla HF, Alio y Sanz JL, Tervo TM. Corneal wound healing after laser in situ keratomileusis in rabbits. J Refract Surg. 1998;14:602-609. 44. Melki SA, Talamo JH, Demetriades AM, et al. Late traumatic dislocation of laser in situ keratomileusis corneal flaps. Ophthalmology. 2000;107:2136-2139. 45. Jin GJ, Merkley KH. Conventional and wavefront-guided myopic LASIK retreatment. Am J Ophthalmol. 2006;141:660668. 46. Kitzmann AS, Bourne WM, Patel SV. Confocal microscopy of a femtosecond laser LASIK flap before separation. Am J Ophthalmol. 2007;143:691-693. 47. Lyle WA, Jin GJ. Results of flap repositioning after laser in situ keratomileusis. J Cataract Refract Surg. 2000;26:1451-1457. 48. Lyle WA, Jin GJ. Interface fluid associated with diffuse lamellar keratitis and epithelial ingrowth after laser in situ keratomileusis. J Cataract Refract Surg. 1999;25:1009-1012. 49. Dawson DG, Schmack I, Holley GP, Waring GO III, Grossniklaus HE, Edelhauser HF. Interface fluid syndrome in human eye bank corneas after LASIK: causes and pathogenesis. Ophthalmology. 2007;114:1848-1859. 50. Galal A, Artola A, Belda J, et al. Interface corneal edema secondary to steroid-induced elevation of intraocular pressure simulating diffuse lamellar keratitis. J Refract Surg. 2006;22:441447. 51. Lyle WA, Jin GJ, Jin Y. Interface fluid after laser in situ keratomileusis. J Refract Surg. 2003;19:455-459. 52. Nordlund ML, Grimm S, Lane S, Holland EJ. Pressure-induced interface keratitis: a late complication following LASIK. Cornea. 2004;23:225-234. 53. Hamilton DR, Manche EE, Rich LF, Maloney RK. Steroidinduced glaucoma after laser in situ keratomileusis associated with interface fluid. Ophthalmology. 2002;109:659-665. 54. Portellinha W, Kuchenbuk M, Nakano K, Oliveira M. Interface fluid and diffuse corneal edema after laser in situ keratomileusis. J Refract Surg. 2001;17:S192-S195. 55. Jones R III, Rhee DJ. Corticosteroid-induced ocular hypertension and glaucoma: a brief review and update of the literature. Curr Opin Ophthalmol. 2006;17:163-167. 56. Nakano EM, Kuchembuck M, Nakano K, Oliveira M, Alvarenga LS, Portellinha W. LASIK interface fluid accumulation caused by glaucoma associated with herpetic keratouveitis: case report. Arq Bras Oftalmol. 2007;70:165-167. 57. Kang SJ, Dawson DG, Hopp LM, Schmack I, Grossniklaus HE, Edelhauser HF. Interface fluid syndrome in laser in situ keratomileusis after complicated trabeculectomy. J Cataract Refract Surg. 2006;32:1560-1562. 58. Wheeldon CE, Hadden OB, Niederer RL, McGhee CN. Presumed late diffuse lamellar keratitis progressing to interface fluid syndrome. J Cataract Refract Surg. 2008;34:322-326. 59. Smith RJ, Maloney RK. Diffuse lamellar keratitis. A new syndrome in lamellar refractive surgery. Ophthalmology. 1998;105:1721-1726. 60. Stulting RD, Randleman JB, Couser JM, Thompson KP. The epidemiology of diffuse lamellar keratitis. Cornea. 2004;23: 680-688. 61. Jin GJ, Lyle WA, Merkley KH. Late-onset idiopathic diffuse lamellar keratitis after laser in situ keratomileusis. J Cataract Refract Surg. 2005;31:435-437. 62. Linebarger EJ, Hardten DR, Lindstrom RL. Diffuse lamellar keratitis: diagnosis and management. J Cataract Refract Surg. 2000;26:1072-1077. 63. Michieletto P, Balestrazzi A, Alegente M, Boccassini B. Stage 4 diffuse lamellar keratitis after laser in situ keratomileusis. Clinical, topographical, and pachymetry resolution 5 years later. J Cataract Refract Surg. 2006;32:353-356.

64. Moshirfar M, Madsen M, Wolsey D. Re: central toxic keratopathy: description of a syndrome in laser refractive surgery. Am J Ophthalmol. 2007;144:332; author reply 333-334. 65. Lyle WA, Jin GJ. Central lamellar keratitis. J Cataract Refract Surg. 2001;27:487-490. 66. Fraenkel GE, Cohen PR, Sutton GL, Lawless MA, Rogers CM. Central focal interface opacity after laser in situ keratomileusis. J Refract Surg. 1998;14:571-576. 67. Hainline BC, Price MO, Choi DM, Price FW Jr. Central flap necrosis after LASIK with microkeratome and femtosecond laser created flaps. J Refract Surg. 2007;23:233-242. 68. Awwad ST, Warmerdam D, Bowman RW, Dwarakanathan S, Cavanagh HD, McCulley JP. Contrast sensitivity and higher order aberrations in eyes implanted with AcrySof IQ SN60WF and AcrySof SN60AT intraocular lenses. J Refract Surg. 2008;24:619-625. 69. Blaylock JF, Si Z, Aitchison S, Prescott C. Visual function and change in quality of life after bilateral refractive lens exchange with the ReSTOR multifocal intraocular lens. J Refract Surg. 2008;24:265-273. 70. Alio JL, Muftuoglu O, Ortiz D, et al. Ten-year follow-up of photorefractive keratectomy for myopia of less than -6 diopters. Am J Ophthalmol. 2008;145:29-36. 71. Shojaei A, Mohammad-Rabei H, Eslani M, Elahi B, Noorizadeh F. Long-term evaluation of complications and results of photorefractive keratectomy in myopia: an 8-year follow-up. Cornea. 2009;28:304-310. 72. Autrata R, Rehurek J. Laser-assisted subepithelial keratectomy for myopia: two-year follow-up. J Cataract Refract Surg. 2003;29:661-668. 73. Kalyvianaki MI, Kymionis GD, Kounis GA, Panagopoulou SI, Grentzelos MA, Pallikaris IG. Comparison of Epi-LASIK and off-flap Epi-LASIK for the treatment of low and moderate myopia. Ophthalmology. 2008;115:2174-2180. 74. Herrmann WA, Hillenkamp J, Hufendiek K, et al. Epi-laser in situ keratomileusis: comparative evaluation of epithelial separation with 3 microkeratomes. J Cataract Refract Surg. 2008;34:1761-1766. 75. Katsanevaki VJ, Kalyvianaki MI, Kavroulaki DS, Pallikaris IG. One-year clinical results after epi-LASIK for myopia. Ophthalmology. 2007;114:1111-1117. 76. Kollias A, Ulbig MW, Spitzlberger GM, et al. Epi-LASIK using the Amadeus II microkeratome: evaluation of cut quality using light and electron microscopy. J Cataract Refract Surg. 2007;33:2118-2121. 77. Gamaly TO, El Danasoury A, El Maghraby A. A prospective, randomized, contralateral eye comparison of epithelial laser in situ keratomileusis and photorefractive keratectomy in eyes prone to haze. J Refract Surg. 2007;23:S1015-S1020. 78. Taneri S, Zieske JD, Azar DT. Evolution, techniques, clinical outcomes, and pathophysiology of LASEK: review of the literature. Surv Ophthalmol. 2004;49:576-602. 79. Yee RW, Yee SB. Update on laser subepithelial keratectomy (LASEK). Curr Opin Ophthalmol. 2004;15:333-341. 80. Ghirlando A, Gambato C, Midena E. LASEK and photorefractive keratectomy for myopia: clinical and confocal microscopy comparison. J Refract Surg. 2007;23:694-702. 81. Cui M, Chen XM, Lu P. Comparison of laser epithelial keratomileusis and photorefractive keratectomy for the correction of myopia: a meta-analysis. Chin Med J (Engl). 2008;121:23312335. 82. Hanna KD, Pouliquen YM, Waring GO III, Savoldelli M, Fantes F, Thompson KP. Corneal wound healing in monkeys after repeated excimer laser photorefractive keratectomy. Arch Ophthalmol. 1992;110:1286-1291. 83. Majmudar PA, Forstot SL, Dennis RF, et al. Topical mitomycin-C for subepithelial fibrosis after refractive corneal surgery. Ophthalmology. 2000;107:89-94.

Cataract Surgery After Previous Refractive Surgery 84. Mirza MA, Qazi MA, Pepose JS. Treatment of dense subepithelial corneal haze after laser-assisted subepithelial keratectomy. J Cataract Refract Surg. 2004;30:709-714. 85. Meyer JC, Stulting RD, Thompson KP, Durrie DS. Late onset of corneal scar after excimer laser photorefractive keratectomy. Am J Ophthalmol. 1996;121:529-539. 86. Lipshitz I, Loewenstein A, Varssano D, Lazar M. Late onset corneal haze after photorefractive keratectomy for moderate and high myopia. Ophthalmology. 1997;104:369-373; discussion 373-374. 87. Rajan MS, Jaycock P, O’Brart D, Nystrom HH, Marshall J. A long-term study of photorefractive keratectomy; 12-year followup. Ophthalmology. 2004;111:1813-1824. 88. Heitzmann J, Binder PS, Kassar BS, Nordan LT. The correction of high myopia using the excimer laser. Arch Ophthalmol. 1993;111:1627-1634. 89. Hersh PS, Stulting RD, Steinert RF, et al. Results of phase III excimer laser photorefractive keratectomy for myopia. The Summit PRK Study Group. Ophthalmology. 1997;104:15351553. 90. Kremer I, Kaplan A, Novikov I, Blumenthal M. Patterns of late corneal scarring after photorefractive keratectomy in high and severe myopia. Ophthalmology. 1999;106:467-473. 91. Stojanovic A, Nitter TA. Correlation between ultraviolet radiation level and the incidence of late-onset corneal haze after photorefractive keratectomy. J Cataract Refract Surg. 2001;27:404-410. 92. Cua IY, Pepose JS. Late corneal scarring after photorefractive keratectomy concurrent with development of systemic lupus erythematosus. J Refract Surg. 2002;18:750-752. 93. Maloney RK, Chan WK, Steinert R, Hersh P, O’Connell M. A multicenter trial of photorefractive keratectomy for residual myopia after previous ocular surgery. Summit Therapeutic Refractive Study Group. Ophthalmology. 1995;102:1042-1052; discussion 1052-1053. 94. Azar DT, Tuli S, Benson R A, Hardten DR. Photorefractive keratectomy for residual myopia after radial keratotomy. PRK After RK Study Group. J Cataract Refract Surg. 1998;24:303311. 95. Probst LE, Machat JJ. Conservative photorefractive keratectomy for residual myopia following radial keratotomy. Can J Ophthalmol. 1998;33:20-27. 96. Nagy ZZ, Hiscott P, Seitz B, et al. Ultraviolet-B enhances corneal stromal response to 193-nm excimer laser treatment. Ophthalmology. 1997;104:375-380. 97. Trattler WB, Barnes SD. Current trends in advanced surface ablation. Curr Opin Ophthalmol. 2008;19:330-334. 98. Caubet E. Course of subepithelial corneal haze over 18 months after photorefractive keratectomy for myopia [corrected]. Refract Corneal Surg. 1993;9:S65-S70. 99. Maldonado MJ, Arnau V, Navea A, et al. Direct objective quantification of corneal haze after excimer laser photorefractive keratectomy for high myopia. Ophthalmology. 1996;103:19701978. 100. Hoffmann F, Schuler A. Indications, results, and complications of refractive corneal surgery with mechanical methods. Curr Opin Ophthalmol. 1995;6:67-72.

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101. Waring GO III, Lynn MJ, McDonnell PJ. Results of the prospective evaluation of radial keratotomy (PERK) study 10 years after surgery. Arch Ophthalmol. 1994;112:1298-1308. 102. Binder PS, Nayak SK, Deg JK, Zavala EY, Sugar J. An ultrastructural and histochemical study of long-term wound healing after radial keratotomy. Am J Ophthalmol. 1987;103:432-440. 103. Awwad ST, Dwarakanathan S, Bowman RW, et al. Intraocular lens power calculation after radial keratotomy: estimating the refractive corneal power. J Cataract Refract Surg. 2007;33:1045-1050. 104. Chen L, Mannis MJ, Salz JJ, Garcia-Ferrer FJ, Ge J. Analysis of intraocular lens power calculation in post-radial keratotomy eyes. J Cataract Refract Surg. 2003;29:65-70. 105. Lyle WA, Jin GJ. Intraocular lens power prediction in patients who undergo cataract surgery following previous radial keratotomy. Arch Ophthalmol. 1997;115:457-461. 106. Packer M, Brown LK, Hoffman RS, Fine IH. Intraocular lens power calculation after incisional and thermal keratorefractive surgery. J Cataract Refract Surg. 2004;30:1430-1434. 107. Freeman M, Kumar V, Ramanathan US, O’Neill E. Dehiscence of radial keratotomy incision during phacoemulsification. Eye. 2004;18:101-103. 108. Budak K, Friedman NJ, Koch DD. Dehiscence of a radial keratotomy incision during clear corneal cataract surgery. J Cataract Refract Surg. 1998;24:278-280. 109. Behl S, Kothari K. Rupture of a radial keratotomy incision after 11 years during clear corneal phacoemulsification. J Cataract Refract Surg. 2001;27:1132-1134. 110. McDonnell PJ. Sight-threatening complications after radial keratotomy. Arch Ophthalmol. 1996;114:211-212. 111. McDonnell PJ, Caroline PJ, Salz J. Irregular astigmatism after radial and astigmatic keratotomy. Am J Ophthalmol. 1989;107:42-46. 112. Alio JL, Belda JI, Artola A, Garcia-Lledo M, Osman A. Contact lens fitting to correct irregular astigmatism after corneal refractive surgery. J Cataract Refract Surg. 2002;28:1750-1757. 113. Olson RJ, Biddulph MC. Hyperopia, anisometropia, and irregular astigmatism in a patient following revisional radial keratotomy. Ophthalmic Surg. 1992;23:782-783. 114. Grimmett MR, Holland EJ. Complications of small clear-zone radial keratotomy. Ophthalmology. 1996;103:1348-1356. 115. Patel SM, Tesser R A, Albert DM, Croasdale CR. Histopathology of radial keratotomy. Arch Ophthalmol. 2005;123:104-105. 116. Majmudar PA, Raviv T, Dennis RF, Epstein RJ. Subepithelial fibrosis after RK. J Cataract Refract Surg. 2000;26:14331434. 117. Forister JF, Sun A, Weissman BA. Progress report on a postradial keratotomy patient 20 years after surgery. Eye Contact Lens. 2007;33:334-337. 118. Alio JL, Belda JI, Shalaby AM. Correction of irregular astigmatism with excimer laser assisted by sodium hyaluronate. Ophthalmology. 2001;108:1246-1260. 119. Maguire LJ, Bourne WM. A multifocal lens effect as a complication of radial keratotomy. Refract Corneal Surg. 1989;5:394399. 120. Moreira H, Fasano AP, Garbus JJ, Lee M, McDonnell PJ. Corneal topographic changes over time after radial keratotomy. Cornea. 1992;11:465-470.

chapter

FUTURE

OF

18

CATARACT SURGERY

Randall J. Olson, MD The field of refractive cataract surgery is not static, and we can predict some advances that are on the horizon. Incisions are getting smaller, with the big question remaining whether that means they are better. Only good studies over time will tell us. Refractive intraocular lenses (IOLs) will get better and, all else being equal, accommodative IOLs will eventually win out over multifocal IOLs. Accommodative designs will always have superior optical properties without unwanted images when a single focus is the result. The Synchrony dual optic IOL (Abbott Medical Optics [AMO], Santa Ana, CA; Figure 18-1) should be Food and Drug Administration (FDA)-approved soon and has been documented to work according to its proposed mechanism of action (Figure 18-2) and improve near focus in quite a predictable way.1,2 It will be interesting to see how the market responds to this model, and, if not this particular model, some model in the future will have the accommodative range and visual quality that will make this very acceptable to virtually all who want it. Other designs, such as the powerful NuLens (NuLens Inc, Tel Aviv, Israel; Figure 18-3), where 10.00 D of accommodation have been documented in humans,3 are coming to us eventually. Refractive precision is also an important quality that will be part of future products.4 More surgeons now use aspheric IOLs (both monofocal and multifocal) to reduce spherical aberration in the optical system and

Figure 18-1. The dual optic Synchrony IOL. With accommodative effort, the anterior lens moves forward, thereby increasing refractive power. (Reprinted with permission from AMO, Santa Ana, CA.)

improve mesopic contrast sensitivity in particular.5-8 Eliminating spherical and cylindrical correction is already a mainstay of the refractive field, and the ability to guarantee more precision will have traction in our field.9,10 Furthermore, fully understanding what best

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A

B Figure 18-2. Ultrasound biomicroscopy showing movement of the Synchrony anterior lens secondary to accommodative effort in a patient.

Figure 18-3. The NuLens accommodative intraocular lens. Based on diving birds with a rigid iris to bulge the lens, creating substantial plus power to make up for the loss of corneal power while under water. (Reprinted with permission from NuLens Inc, Tel Aviv, Israel.)

constitutes superior vision when considering all higher order aberrations (HOA) will be demystified, and any product that can improve on optical quality, especially when uncorrected, will do well. Also, intraoperative wavefront aberrometry during cataract surgery may be helpful for IOL power determination. Innovation continues, and future technology will bring better opportunities. One interesting product already approved in Europe is the light-adjustable lens, which contains photosensitive silicone molecules that enable a postoperative adjustment of refractive power using ultraviolet light. Free-floating light-sensitive monomers come out of solution in direct proportion to the amount of the appropriate wavelength of light. What follows is a precise change in the IOL shape that mirrors the change in monomer still in solution (Figure 18-4). Human studies show precise results generally within ±0.25 D, and cylindrical change is approaching this standard.11,12 Furthermore, virtually all HOAs can be added or subtracted, with the potential for a whole new level of visual quality (Figure 18-5). Though the present model is locked in with removal of all monomer after correct adjustment, models that can be readjusted throughout life are on the drawing board and could

Figure 18-4. Schematics showing how the light-adjustable lens can both add and subtract refractive power depending on the pattern of light that is used.

be adapted to any accommodative IOL design for both utility and precision at a level unheard of today. Femtosecond laser-based technology can be used in cataract surgery for performing corneal relaxing incisions, capsulotomy, and breaking up the nucleus. Another possibility is medical treatment for cataracts. Do not be surprised that the refractive precision of lenticular procedures may become so good that refractive lens exchange may become more common than cataract surgery one day. Whatever we do, we need to do a better job of outcomes research in declaring something new as an advance. The paucity of good outcomes studies when looking at the present generation of refractive IOLs is discouraging, and what little we do have generally does not show superiority in spite of all the claims. We can and should do better. There are many factors that can influence our results, and tracking results is the best way to determine whether we should make adjustments for future treatments. Clinical studies with precise and accurate data collection are essential. The era of refractive cataract surgery is just beginning; evolution of the technology will continuously promise to further improve patient outcomes. The studies necessary to show true improvement are not

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Figures 18-5. A light-adjustable lens that has been irradiated to correct trefoil and the resultant effective shape change that ensued.

that difficult or expensive, so let’s make our decisions based on good clinical science with solid evidence-based studies and not anecdotal claims or studies focused on one aspect of the technology and not the total package.13

CHAPTER REFERENCES 1. Ossma IL, Galvis A, Vargas LG, Trager MJ, Vagefi MR, McLeod SD. Synchrony dual-optic accommodating intraocular lens. Part 2: pilot clinical evaluation. J Cataract Refract Surg. 2007;33:47-52. 2. McLeod SD, Vargas LG, Portney V, Ting A. Synchrony dualoptic accommodating intraocular lens. Part 1: optical and biomechanical principles and design considerations. J Cataract Refract Surg. 2007;33:37-46. 3. Alio JL, Ben-nun J, Rodriguez-Prats JL, Plaza AB. Visual and accommodative outcomes 1 year after implantation of an accommodating intraocular lens based on a new concept. J Cataract Refract Surg. 2009;35:1671-1678. 4. Olson RJ, Werner L, Mamalis N, Cionni R. New intraocular lens technology. Am J Ophthalmol. 2005;140:709-716. 5. Kohnen T, Klaproth OK, Buhren J. Effect of intraocular lens asphericity on quality of vision after cataract removal: an intraindividual comparison. Ophthalmology. 2009;116:1697-1706.

6. Packer M, Fine IH, Hoffman RS. Aspheric intraocular lens selection based on corneal wavefront. J Refract Surg. 2009;25:1220. 7. Su PY, Hu FR. Intraindividual comparison of functional vision and higher order aberrations after implantation of aspheric and spherical intraocular lenses. J Refract Surg. 2009;25:265-272. 8. Alfonso JF, Puchades C, Fernandez-Vega L, Montes-Mico R, Valcarcel B, Ferrer-Blasco T. Visual acuity comparison of 2 models of bifocal aspheric intraocular lenses. J Cataract Refract Surg. 2009;35:672-676. 9. Montes-Mico R, Ferrer-Blasco T, Cervino A. Analysis of the possible benefits of aspheric intraocular lenses: review of the literature. J Cataract Refract Surg. 2009;35:172-181. 10. Yamaguchi T, Negishi K, Ono T, et al. Feasibility of spherical aberration correction with aspheric intraocular lenses in cataract surgery based on individual pupil diameter. J Cataract Refract Surg. 2009;35:1725-1733. 11. Chayet A, Sandstedt C, Chang S, et al. Correction of myopia after cataract surgery with a light-adjustable lens. Ophthalmology. 2009;116:1432-1435. 12. Chayet A, Sandstedt CA, Chang SH, Rhee P, Tsuchiyama B, Schwartz D. Correction of residual hyperopia after cataract surgery using the light adjustable intraocular lens technology. Am J Ophthalmol. 2009;147:392-397.e1. 13. Olson RJ. Presbyopia correcting intraocular lenses: what do I do? Am J Ophthalmol. 2008;145:593-594.

FINANCIAL DISCLOSURES

Dr. Iqbal Ike K. Ahmed is a consultant for Alcon, AMO, and Carl Zeiss Meditec. Dr. Alan S. Crandall is a consultant for Alcon, AqueSys, ASICO, GLAUKOS, Omeros, and Mastel Surgical. He is on the Advisory Board for eSinomed, I-Science, iSportgames, Glaucoma Today, Omeros, Transcend Medical, and Vimetrics. He is on the Speaker’s Bureau for and receives travel reimbursement from Alcon and Allergan. He is also on the Editorial Board for Ocular Surgery News and Journal Cataract Refractive Surgery. Dr. Robert J. Cionni is a consultant for and receives a research grant from Alcon. He also receives royalties from Morcher Gmbh. Dr. Robert O. Hoffman has no financial or proprietary interest in the materials presented herein. Dr. George J. C. Jin has no financial or proprietary interest in the materials presented herein. Dr. Jason J. Jones is on the speakers panel for Alcon and ISTA and has received speaking honoraria from Zeiss. Dr. Randall J. Olson has no financial or proprietary interest in the materials presented herein.

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