Premium and Specialized Intraocular Lenses [1 ed.] 9781608058327, 9781608058334

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Premium and Specialized Intraocular Lenses Edited by

Guy Kleinmann Kaplan Medical Center Rehovot Israel

Ehud I. Assia Meir Medical Center Kfar Saba Israel &

David J. Apple Laboratories for Ophthalmic Devices Research USA

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CONTENTS Foreword

i

Preface

iii

List of Contributors

iv

CHAPTERS 1.

Introduction: The Evolution of Intraocular Lenses Brain Zaugg, Guy Kleinmann and David J. Apple

3

2.

Aspheric Intraocular Lenses Yoel Greenwald and Guy Kleinmann

21

3.

Blue Filtering Intraocular Lenses Randall J. Olson

44

4.

Toric Intraocular Lenses for Pseudophakia Jaime Javaloy and Jorge L. Alió

53

5.

Multifocal IOLs – Clinical Indication and Pearls for Successful Application and Clinical Results Gerd U. Auffarth, Adi Abulafia and Guy Kleinmann

81

6.

Accommodative and Dual Optic Intraocular Lenses Mark Packer, H. Burkhard Dickand and George Beiko

102

7.

Phakic Intraocular Lenses Jose L. Güell, Thomas Kohnen, Daniel Kook and Merce Morral

129

8.

Supplementary IOLs for Pseudophakic Refractive Error Correction Guenal Kahraman and Michael Amon

201

9.

Special Intraocular Lenses for Small Incisions Irit Bahar, Yoav Nahum and Guy Kleinmann

215

10. Light Adjustable Lens Peter J. Ness, Nick Mamalis and Liliana Werner

230

11. Iris Prostheses: Overview and Design Michael E. Snyder and Kristiana Neff

241

12. Full Size Lens Fani Segev and Ehud I. Assia

265

13. Ocular Telescopic Devices Eli Rosen, Ehud I. Assia and Guy Kleinmann

281

The Future of IOLs I. Howard Fine

310

Index

312

i

FOREWORD Cataract surgery accompanied with implantation of an intraocular lens implant remains the most commonly performed surgery in the field of ophthalmology. It is estimated that over 18,000,000 cataract surgeries are performed each year in the world. Perhaps even more amazing, experts in the public health field tell us that in spite of this large number of cataract surgeries, every year more people suffer from visual and functional handicap secondary to cataract. In the advanced countries, approximately 8 per 1000 population undergo cataract surgery each year, and in the USA where surgeons and health care resources are widely available, the number is 10 per thousand. If these are the ideal numbers in a world with unlimited resources, we should be doing 50,000,000 cataract surgeries per year, or 2.5 times the number currently performed. In most cases, an intraocular lens is implanted, today usually a posterior chamber IOL .We are all aware that intraocular lens implantation began with Sir Harold Ridley’s first surgery on November 29, 1949, and that this brilliant innovator started with and persisted throughout his decades of innovation in implanting intraocular lens implants exclusively in the posterior chamber after extracapsular cataract extraction. History has confirmed the wisdom of this preference. Intraocular Lens Implant Surgery, while at a high state of development, continues to evolve as a combination of innovative surgeons and a well capitalized supporting industry work their magic through the innovation cycle. There remain many unmet needs in the field of intraocular lens implantation. With growing demand in the face of reduced healthcare financial resources, we need in many parts of the world more efficient and economical models of surgery. Even in advanced countries, the variability of outcome one surgeon and one patient to another is a concern, and should respond to improved technology and education. At the cutting edge, specialized intraocular lens implants customized to the needs and desires of a small cohorts of patients are being developed and utilized. In the future, we can imagine a single lens implant customized to the needs, optics and ocular anatomy of the individual patient. These new and unique intraocular lens implants are the subject of this fascinating new book on “Premium and Specialized Intraocular Lenses’ edited by Guy Kleinmann, Ehud I. Assia and the late David J. Apple. In this book we are treated to an introductory chapter on ‘The Evolution of

ii

Intraocular Lenses” that was likely one of my friends David Apple’s last works to be published. For me ,this chapter alone makes the book worthy of acquiring, as it is a priceless summary by Dr. Apple and two of his close colleagues regarding his thoughts near the end of his extraordinary career. Following this fascinating and historical summary are Chapters on Accommodating IOL’s, Telescopic IOL’s, Supplementary IOL’s, Full Size IOL’s, and Iris Prosthesis. The authors selected are experienced and knowledgeable. Each of the Chapters is well written, illustrated and full of cutting edge information and clinical pearls not easily accessed in any other source. The book is an easy read, and I learned many clinically useful details regarding these specialized IOL’s. I recommend this book to the cataract surgeon who wishes to stay current with the newest emerging technologies in the intraocular lens and iris implantation field. I thank the editors for a well written, concise and clinically useful summary of the state of the art, and for another opportunity to learn from my much missed friend and colleague David J. Apple.

Richard L. Lindstrom Adjunct Professor Emeritus University of Minnesota Department of Ophthalmology Founder and Attending Surgeon Minnesota Eye Consultants; Visiting Professor University of California Irvine Gavin Herbert Eye Institute, Irvine California USA

iii

PREFACE We are living in exciting times. The field of IOL has moved forward significantly since the first IOLs that Sir Harold Ridley implanted back in the early 50th. We can guarantee an excellent far uncorrected vision to our patients in most cases where no other ophthalmic pathology exists. The field of premium IOL and special intraocular devices is the new frontier. With advances in surgical technology, IOL power calculation and patients leading a more active lifestyle well into their seventies and beyond, cataract surgery can no longer be considered a functional procedure to remove an opacified lens, and visual acuity alone can no longer be considered the sole criterion of surgical success. As cataract surgery has evolved from a sightsaving operation to a refractive procedure, quality of vision and optical outcomes have become of crucial importance, with the goal being to improve not only acuity, but also quality of life. Lower order visual aberrations such as astigmatism can be effectively reduced by a combination of spectacle correction, corneal surface modification and/or specialized IOLs, improving quality of vision in pseudophakic patients to a great degree. Range of vision can be addressed with multifocal and accommodative IOLs, higher order aberration can be treated with aspheric IOLs, and extra-protection for the blue light is being promised by the blue blocking IOLs. Attempt to implant the IOLs trough a smaller and smaller corneal incisions focusing on lowering the induced astigmatism. The advances in the IOL field are not focused only on premium IOL. Special cases like aphakia and end stage AMD also get attention and special solutions. In this book we have tried to summarize the up to date knowledge and to base it on evidence based medicine as much as possible. We hope that you will find this book a useful tool in understanding and practicing premium and special intraocular devices.

Guy Kleinmann

Ehud I. Assia

David J. Apple

Kaplan Medical Center Rehovot Israel

Meir Medical Center Kfar Saba Israel

Laboratories for Ophthalmic Devices Research USA

iv

List of Contributors Adi Abulafia Ein-Tal Eye Center, Tel Aviv, Israel Brain Zaugg Laboratories for Ophthalmic Devices Research, Sullivan's Island, SC, USA Daniel Kook Department of Ophthalmology, Goethe-University, Frankfurt am Main, Germany David J. Apple Laboratories for Ophthalmic Devices Research, Sullivan's Island, SC, USA Ehud I. Assia Department of Ophthalmology, Meir Medical Center, Kfar-Saba, Sackler School of Medicine, Tel Aviv University, Israel Eli Rosen Ophthalmology Department, Meir Medical Center, Kfar Saba, Israel Fani Segev Department of Ophthalmology, Meir Medical Center, Kfar-Saba, Sackler School of Medicine, Tel Aviv University, Israel George Beiko Assistant Clinical Professor of Ophthalmology, McMaster University, 180 Vine St., Suite 103, St. Catharines, Ontarios, Canada L2R 7P3 Gerd U. Auffarth International Vision Correction Research Centre (IVCRC), Dept. Ophthalmology, Univ. of Heidelberg, INF 400, 69120 Heidelberg, Germany

of

v

Guenal Kahraman Academic Teaching Hospital of St. Johns Vienna, Barmherzige Brüder Wien, Department of Ophthalmology, Johannes von Gott-Platz 1; 1020 Vienna, Austria Guy Kleinmann Ophthalmology Department, Kaplan Medical Center, Rehovot, Israel; Affiliated with Hadassah Hospital and the Hebrew University School of Medicine, Jerusalem, Israel H. Burkhard Dick Professor & Chairman, Center of Visual Sciences and Department of Ophthalmology, Ruhr University Eye Hospital, In der Schornau 23 – 25, Bochum, Germany 44892 I. Howard Fine Drs. Fine, Hoffman & Packer, LLC, 1550 Oak St., Ste. 5, Eugene, OR 97401, USA Irit Bahar Department of Ophthalmology, Rabin Medical Center, Petah Tikva, Israel Jaime Javaloy Department of Cornea and Refractive Surgery, VISSUM, Instituto Oftalmológico de Alicante, Miguel Hernández University School of Medicine, Alicante, Spain Jorge L. Alió Department of Cornea and Refractive Surgery, VISSUM, Instituto Oftalmológico de Alicante, Miguel Hernández University School of Medicine, Alicante, Spain Jose Luis Güell Instituto Microcirugia Ocular (IMO), Barcelona, Spain Kristiana Neff Cincinnati Eye Institute, Volunteer Assistant Professor of Ophthalmology, University of Cincinnati School of Medicine, Cincinnati, USA

vi

L. Werner Intermountain Ocular Research Center, Director, Ocular Pathology, John Moran, Eye Center, University of Utah, 65 Mario Capecchi Dr. Salt Lake City, UT 84132, USA Mark Packer Clinical Associate Professor, Oregon Health & Science University, 4075 Southpointe Dr. Eugene, OR 97405, USA Merce Morral Instituto Microcirugia Ocular (IMO), Barcelona, Spain Michael Amon Academic Teaching Hospital of St. Johns Vienna, Barmherzige.Brüder Wien, Department of Ophthalmology, Johannes von Gott-Platz 1; 1020 Vienna, Austria Michael E. Snyder Cincinnati Eye Institute, Volunteer Assistant Professor of Ophthalmology, University of Cincinnati School of Medicine, Cincinnati, USA Nick Mamalis Intermountain Ocular Research Center, Director, Ocular Pathology, John Moran Eye Center, University of Utah, 65 Mario Capecchi Dr. Salt Lake City, Utah 84132, USA P.J. Ness Intermountain Ocular Research Center, Director, Ocular Pathology, John Moran, Eye Center, University of Utah, 65 Mario Capecchi Dr. Salt Lake City, UT 84132, USA Randall J. Olson Department of Ophthalmology and Visual Sciences and CEO of the John A. Moran Eye Center at the University of Utah School of Medicine, Salt Lake City, Utah 84132, USA

vii

Thomas Kohnen Department of Ophthalmology, Goethe-University, Frankfurt am Main, Germany Yoav Nahum Department of Ophthalmology, Rabin Medical Center, Petah Tikva, Israel Yoel Greenwald Ophthalmology Department, Kaplan Medical Center, Rehovot, Israel; Affiliated with Hadassah Hospital and the Hebrew University School of Medicine, Jerusalem, Israel

Send Orders for Reprints to [email protected] Premium and Specialized Intraocular Lenses, 2014, 3-20 3

CHAPTER 1 Introduction: The Evolution of Intraocular Lenses Brain Zaugg1, Guy Kleinmann1,2,* and David J. Apple1 1 2

Laboratories for Ophthalmic Devices Research, Sullivan's Island, SC, USA and Ophthalmology Department, Kaplan Medical Center, Rehovot, Israel Abstract: The development of foldable lenses, and perhaps more importantly, the small-incision capsular surgical techniques that accompany them, have been instrumental in achieving a vast reduction in cataract surgery complications. The excellent optical and visual rehabilitory benefits of small incision phacoemulsificationfoldable intraocular lens (IOL) surgery, including reduced astigmatism, quick recovery, and many other advantages, are well known. This modern procedure has achieved a state of vision restoration as well as vision rehabilitation. Modern cataract surgery is now a genuine form of refractive surgery. The history of cataract surgery with IOLs is one of the extensive trial and errors, with many dead ends. By far, the most important and basic element required for success with IOLs is fixation. Indeed, the generations of IOLs are named according to the type of fixation used during each era. The six generations that we identify signify the continuous movement forward, as surgeons attempted to improve IOL fixation. The move from Ridley's initial lens (Generation I) to the early anterior chamber lenses and iris-fixated lenses (Generations II and III) were basically attempts to overcome decentration issues (recall that Ridley’s IOL had no haptics). In addition, the move toward a second generation of anterior chamber lenses (Generation IV), usually implanted after intracapsular cataract extraction (ICCE), was in part caused by a desire to avoid the posterior capsule opacification (PCO) or secondary cataract that often occurred after early methods of extracapsular cataract extraction (ECCE). The last generation includes “specialized” IOLs, which are the focus of this book.

Keywords: Intraocular Lenses, History, Evolution. INTRODUCTION: THE EVOLUTION OF INTRAOCULAR LENSES (GENERATIONS I TO VI) The evolution of cataract surgery has been long and very slow, with little change from antiquity until the late 18th to early 19th century (Figs. 1-3). *Address correspondence to Guy Kleinmann: Ophthalmology Department Kaplan Medical Center, POB 1, Rehovot, 76100, Israel; Tel: +972-8-9441353; Fax: +972-89441821; E-mail [email protected] Guy Kleinmann, Ehud I. Assia and David J. Apple (Eds) All rights reserved-© 2014 Bentham Science Publishers

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Figure 1: Illustrations from a 1966 facsimile of a 1583 German atlas of “renaissance” eye surgery, showing the ancient technique of couching. Top: Frontal view. Bottom: an example of ornamental couching needles. (from: Bartisch, G., Augendienst, Dresden, Germany, 1583).

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Premium and Specialized Intraocular Lenses 5

Figure 2: Daviel’s description of extracapsular surgery (ECCE) in 1755 showed remarkable foresight. This figure shows the steps of the procedure from entrance into the eye from what is almost a clear corneal incision (labeled Fig. 40 in this sketch) to extracapsular removal of the cataract (labeled Fig. 44). (Translated legends: Fig. 40: Incision with lance-shaped keratome [Aiguille pointue]; Fig. 41: Extending the incision with the Aiguille; Fig. 42: Completion of the incision with scissors, Fig. 43: Opening of the capsule [anterior capsulotomy]; Fig. 44: Removal of the cataractous lens).

Figure 3: By the early 20th Century, intracapsular cataract extraction (ICCE) had become popular. A. Front cover of a classic monograph by Dr. Henry Smith. B. An illustration from Smith’s book with a schematic illustration of a lens extraction by suction.

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Apple and associates have classified the development of intraocular lenses (IOLs) into six generations, based primarily on mode of lens fixation (Fig. 4). Each step forward, beginning with Sir Harold Ridley's 1949-1950 invention, represented an advance in both surgical technique and IOL design and quality. A brief overview of each generation, with a description of the numerous failures and successes occurring in each throughout almost 50 years of development, is provided to help the reader understand how we have arrived at the excellent procedure available today.

Figure 4: Six generations of IOLs, 1949 to present. Each generation is named according to the mode of IOL fixation.

Generation I, The Ridley IOL There is no doubt that credit for the invention and first implantation of the IOL belongs solely to Sir Harold Ridley of London (Fig. 5). Details regarding Sir Harold and his invention are provided in a 1996 monograph by Dr. David Apple (DJA) and John Sims, Harold Ridley and the Invention of the Intraocular Lens. DJA, Ridley’s official biographer, also published a comprehensive text outlining this in 2006 (David J. Apple, MD, Sir Harold Ridley and his Fight for Sight, Slack, 2006). D. Peter Choyce of London, who was involved in many of the early IOL and refractive procedures, was the earliest colleague and supporter of Ridley. He not

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Premium and Specialized Intraocular Lenses 7

only played a significant role in guiding the implantation procedure through its evolutionary process (indeed, he was present in the operating theatre on several of the very first cases), but was also a major spokesman for Ridley’s cause in the dark days between 1950 and 1980 when there was much criticism of the implant.

Figure 5: Sir Harold Ridley, photograph circa 1986.

The first Ridley implants (Figs. 6 and 7) were manufactured by Rayner, Ltd., London, UK. Sir Harold's IOL was a biconvex disc that was designed in conjunction with Mr. John Pike, an optical scientist at Rayner. It was designed for implantation in the posterior chamber. Ridley filmed several of his early operations. Sir Harold's first lens was implanted as a two-step procedure. The extracapsular cataract extraction (ECCE) was performed on November 29, 1949. Rather than permanently implanting the IOL, he chose to wait and implant it secondarily a few months later, on February 8, 1950, after the eye was quiet and suitable for implantation.

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Figure 6: Ridley IOL. Ridley's original IOL was manufactured by Rayner, Ltd., UK. Note the early brochure describing the Ridley lens and a superimposed, a schematic illustration showing a sagittal section of the anterior segment of the eye with a Ridley IOL and a frontal and side sketch of the lens. A

Fig. 7: contd….

Introduction

Premium and Specialized Intraocular Lenses 9

B

Figure 7: Ridley PC-IOLs from the first manufacturing batch (lot), late 1940s – retained and secured by Sir Harold at his retirement home near Salisbury. A. Gross photograph of this memento. B. Scanning electronic micrograph (SEM) of another Ridley IOL, showing equatorial rims from the manufacturing process.

From his very first cases, Ridley encountered the two major problems of lens implantation that have nagged ophthalmologists for over half a century; namely, IOL malposition and PCO. Regarding the malposition, the main reasons for the decentrations were often attributed to excessive weight of the implant. However, two other important causes, which were directly applicable to the implantation procedure were 1) the IOL did not have appropriate fixation haptics, and 2) the anterior capsulotomy, in which he essentially opened and removed almost all of the anterior capsule in a very irregular fashion, almost always leaving a relatively jagged and irregular anterior edge, was insufficient for good equatorial fixation of the edge of the lens. It did not permit stable and permanent fixation of the pseudophakos. These shortcomings have, of course, been overcome with modern surgical techniques by the addition of appropriate haptics, and, especially by the invention and perfection of continuous curvilinear capsulorrhexis (CCC) by Doctors Howard Gimbel and Thomas Neuhann. These, especially the continuous CCC came much later—not until the mid-to-late 1980s. The problem of lens decentration is largely solved now that advanced surgical techniques are available.

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After PCO developed in his first cases, Ridley quickly realized the need for copious irrigation and removal of lens substance. Not until the mid-to-late 1980s was the significance of this observation truly appreciated and applied, with the development of improved nucleus and cortical removal techniques. Especially important was the development of phacoemulsification and hydrodissectionenhanced removal of the cortex. In 2001, we published a list of six factors (3 surgical and 3 IOL-related) that, when applied using modern surgical procedures, have helped reduce the incidence of PCO to less than 10% (Fig. 8).

Figure 8: A relatively simple, understandable, clinically useful, and widely accepted list of the most important factors related to the prevention of PCO based on analysis performed in our laboratory (From Apple and Associates, 2001).

Generation II The movement toward Generation II, the early anterior chamber (AC) IOLs implanted after intracapsular cataract extraction (ICCE), was initiated to circumvent the two above mentioned complications of the Ridley lens — malposition and PCO. This generation (Fig. 9) represents the first attempt at implantation of various AC IOLs. The first AC IOL was implanted by Baron of France in 1952. A quick glance at this figure immediately explains why this lens failed; namely, because

Introduction

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the excessive built-in anterior vaulting of the entire pseudophakos caused inappropriate contact with the corneal endothelium. At this time, surgeons began to pay attention to the fragility of the corneal endothelium and the severe problem of corneal decompensation, a problem that has plagued all subsequent generations of IOL implantations, especially AC IOLs. This was our predecessors' first lesson in avoidance of any type of intermittent or constant corneal contact with a pseudophakos. This is mandatory to prevent corneal decompensation (including pseudophakic bullous keratopathy [PBK]) and other secondary intraocular changes, such as cystoid macular edema (CME). Corneal problems persisted well into Generations III and IV, with many IOL designs and surgical techniques. Today's surgeon-in-training who is learning modern, high-quality PC IOL implantation of foldable lenses through a small incision, is much better able to avoid cornea-related problems, but awareness of the delicate nature of the corneal endothelium should always be maintained, even today.

Figure 9: Generation II, the original AC-IOL design of Baron (1952). This lens and other similar designs failed because of the close proximity of the pseudophakos to the corneal endothelium, with inevitable subsequent corneal decompensation. It was during this generation that surgeons began to appreciate the fragility of the corneal endothelium.

Generation III The move toward Generation III, iris-fixated IOLs (Figs. 10 and 11), represented an attempt to fixate the IOL more posterior from the cornea to avoid the disastrous corneal problems encountered in the previous decade.

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Figure 10: Schematic illustrations of two iris clip IOL designs (above, left and right) and analogous drawings of Binkhorst's two-loop irido-capsular design (below). The latter was intended for placement of the posterior haptics into the capsular bag after ECCE.

Figure 11: Scientific illustration of 4 loop iris clip IOL designs implanted after ICCE (above) and an irido-capsular IOL implanted after ECCE (below).

This step was an improvement. However, at this time surgeons learned about the very delicate nature of the uveal tissues when brought into contact with elements of a pseudophakos. Physical contact of IOL haptics, especially metal haptics

Introduction

Premium and Specialized Intraocular Lenses 13

(Fig. 12), with uveal tissue often caused inflammation and its sequelae, including corneal decompensation, CME, and membrane formation.

Figure 12: Iris-supported IOLs (medallion style) with metal loops. Iris-fixated IOLs were developed to enhance fixation and avoid the decentration that occurred with some of the Ridley designs and to avoid the corneal complications of the early AC-IOLs. It was soon found that contact with the delicate tissues of the iris, especially with metal haptics such as these, caused a myriad of complications. Further experimentation with anterior chamber lenses therefore ensued, leading to generation IV.

At this time, Cornelius Binkhorst made an important modification to his early four-loop iris clip lens, creating the two-loop iridocapsular lens. With the newer design, the optical component remained in front of the iris but the haptics were inserted into the capsular bag after ECCE. This step represented an important return to ECCE and capsular fixation; both had largely been abandoned since the time of Ridley's first implant. Generation IV Generation IV, (Figs. 13 and 14), a move again to the AC, was an attempt to avoid the complications of the iris-fixated IOLs.

Figure 13: The modern generation of AC-IOLs is characterized by much better vaulting with improved protection of the cornea (compare this illustration with Fig. 9). The transition toward modern AC-IOLs began in the industrialized world about 1987, but was delayed until after 1992 in the developing world.

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Figure 14: Illustrations of the two modern style AC-IOLs that are now available for implantation. Both are characterized by no-hole fixation elements. On the left is a four-point fixation design, currently the most commonly used worldwide. On the right is a Kelman-Choyce-Clemente design, a three-point fixation design, developed by Peter Clemente, MD, in Munich, Germany, which we believe represents today’s state-of-the art.

With most activity between ca. 1963 and 1992, this was a transitional period in which numerous designs were attempted, some successful, but many ends in failure. Details regarding this process are documented in several references from our Center and are not reiterated here. This generation again called our attention to the problem of direct or indirect, constant or intermittent corneal contact. In addition, at this time problems of erosion of small-diameter round-loop fixation haptics into delicate uveal tissues were recognized. These were common with many of the closed-loop IOL designs of that era, and caused severe problems due to tissue contact and chafing. Many of these lenses had to be removed and were often replaced by retro-pupillary sutured IOLs, which sometimes induced other complications. During this period, the concept of a protective membrane was recognized; i.e., the usefulness of any sort of fibrous or hyaline-elastic membrane (callus) that could be situated between the fixation element of the IOL and adjacent delicate, vascular uveal tissues. With respect to AC IOLs, it was learned that Choyce-style haptics or footplates (Figs. 15 a and 15 b) provided markedly improved results. Stable fixation could be achieved whenever a fibrous scar or callus formed at the site of contact within the AC angle recess. All successful modern AC IOLs now have solid Choyce-style haptics or footplates as fixation elements. In contrast, the

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principle of a solid versus fenestrated haptic in the case of modern silicone plate IOLs is based on another principle in which solid or small hole footplates are less satisfactory for establishing good fixation of the IOL in the capsular bag than are large hole footplates.

A

B

Figure 15: Choyce style haptics or footplates. A. Scanning electron micrograph showing the profile of a solid fixation element of a Choyce-style footplate or haptic. It is well-polished and tissue-friendly (original magnification x75). B. Photomicrograph of the site of a Choyce-style footplate (empty space because the biomaterial dissolves during processing). Note the fibrous membrane or “callus” that forms shortly after implantation. This effectively separates the pseudophakos biomaterial from direct contact with the trabecular meshwork, the canal of Schlemm (above) and the adjacent uveal tissue of the AC recess. The barrier formed by this type of membrane is entirely analogous to that formed by the surrounding lens capsule in the case of inthe-bag fixed PC-IOLs (hematoxylin and eosin stain, original magnification x200).

Generation V Generation V occurred as surgeons returned to ECCE and PC IOLs. Cornelius Binkhorst of Holland clearly deserves recognition as a visionary and thoughtful investigator who spearheaded the now permanent transition toward ECCE. Early on, he recognized the advantages of in-the-bag (capsular) fixation, which led to the important transition toward Generation V. Most fixation of the early posterior chamber lenses throughout Generation V was uveal (one or both haptics out of the capsular bag) (Fig. 16).

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Fiigure 16: Scheematic illustrattion of sulcus fixation f of PC-IIOLs.

Asymmetric A fixation cau uses an almo ost automatiic decentrattion of the IIOL optic an nd any contaact with adjaacent uveal tissues t by eiither the IOL L optic com mponent or th he haptic com mponent—v very common n in any form m of out-of-tthe-bag fixaation—has th he potential to cause tissue t chang ges due to chafing. T This was veery much ex xaggerated in i the early 1980s 1 when lens manufa facture was ppoor, often w with sharp ed dges to the IOL I optic co omponent (Fiigs. 17A andd B).

A

B Fiigure 17: Scaanning electron n micrograph (SEM) of edgge formation oof early IOLs. A. Poorly fin nished early PC-IOL optic (O O) edges (E) (o original magniification x100)). B. Haptic-opptic junction off an early PC-IIOL, showing imperfect i stakiing of the haptiic loop (L) intoo the lens opticc (O) with a laarge space arou und the loop. (aarrows = sharp--edged surfacees) (original maagnification x1100).

Introduction

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Tissue chafing commonly caused transillumination defects (Fig. 18) with pigmentary dispersion. Subsequent breakdown of the blood-aqueous barrier could cause sequelae such as inflammation or even hemorrhage; e.g., the UGH syndrome.

Figure 18: When uveal contact with any component of the pseudophakos (optic or haptic) occurred (as was often the case with sulcus-sulcus or asymmetric bag-sulcus fixation), tissue chafing with significant clinical sequelae sometimes occurred. This clinical photograph shows a transillumination defect of the iris caused by chafing of the lens optic edge against the posterior iris pigment epithelium. This could create a pigmentary dispersion syndrome and even lead to pigmentary glaucoma. Such changes were particularly prone to occur with early, poorly polished IOLs.

Improved polishing techniques began to appear by the mid-to-late 1980s (Fig. 19). This, coupled with better in-the-bag fixation techniques, has largely solved the problem.

Figure 19: By the late 1980s, improved polishing techniques were implemented and high-quality lenses, as noted here, evolved. This high-power scanning electron micrograph shows the loopoptic junction of a well-made three-piece PC-IOL.

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Concurrently, surgeons became aware of the marked superiority of in-the-bag capsular fixation, a fact that was rarely appreciated during the 1970s and early 1980s, and indeed, remained highly controversial even through the late 1980s. Also during the 1980s, there was extensive experimentation with haptic fixation and PC-IOL designs. After many false starts, the advantages of total in-the-bag fixation became apparent. Ridley himself preferred in-the-bag fixation, but he and his contemporaries found this difficult because of the relatively unsophisticated surgical techniques available in the mid-twentieth century. Successful transition toward in-the-bag fixation defined the transition from Generation V (precapsular surgery era) to Generation VI (capsular surgery era). As PC-IOLs were reintroduced in the mid-1970s, John Pearce in England and Axis Anis and William Harrs in the United States were leading advocates of capsular fixation of PC-IOLs. Irrefutable evidence that clearly established the efficacy of in-the-bag fixation and delineated its overwhelming advantages was provided in the senior author’s (DJA) laboratory in Salt Lake City, especially utilizing the Miyake-Apple posterior video/photographic technique (Fig. 20).

Figure 20: A human eye obtained postmortem with PC-IOL viewed from behind (Miyake-Apple posterior video/photographic technique) shows a transitional phase, still with asymmetric fixation of haptics, but with improved centration of the IOL and relatively good cortical clean up, with residual cortical material still visible to the left and above. The decentration caused by the asymmetric fixation seen here (inferior haptic in-the-bag and superior haptic in the ciliary sulcus is compensated by the use of a large diameter, 7 mm optic).

Introduction

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This formed the basis of what is required for successful foldable implantation today. Indeed, one major false start with foldable lenses occurred in the mid-tolate 1980s. Some of the early foldable designs at that time were either intentionally or unintentionally implanted into the ciliary sulcus (usually one haptic in the bag and one haptic in the sulcus), creating an unnecessarily high incidence of complications. Generation VI-a This era was a crucial period in which surgeons learned and began to apply important new techniques needed to advance to Generation VI-a, in which most importantly, the transition to viscoelastics, CCC, hydro-dissection-enhanced cortical clean up and modern ECCE and phaco made the future implementation of foldable IOLs possible. In Generation VI-a, the move toward consistent in-thebag (capsular) fixation was underway (Fig. 21).

Figure 21: Generations V and VI (most activity circa 1977 to the present) form the basis for modern foldable IOL insertion via a small incision after phacoemulsification. Note that each generation is divided into two groups, ranging from Generation V-a, the early years (circa 1977 to 1982) when ECCE PC-IOL implantation was first being attempted and researched, to Generation V-b, the important transitional period when modern capsular surgery techniques were first being attempted (circa 1982 to 1987), culminating in the two subgroups of Generation VI (circa 1987 to 1992). Generation VI-a was the period when high-quality capsular surgery using mostly rigid

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lenses inserted via large incisions was common (circa 1987 to 1992). Generation VI-b (circa 1992 to present) is the era of small-incision phacoemulsification surgery with implantation of the foldable IOL designs that we discuss here.

It is noteworthy that the first attempts at implantation of soft IOLs, the forerunners of today's foldable IOLs began during the early phase of Generation V, from the later 1970s until the early 1980s. These designs culminated in modern foldable IOLs manufactured primarily from three groups of biomaterials: silicone and hydrophobic and hydrophilic acrylic materials. Generation VI-b This generation is represented by the evolution of various “specialized” IOL designs, mostly used for refractive purposes or vision correction — lenses that are now creating great interest. These include both specialized IOLs intended for use both after classic ECCE/phaco surgery in aphakic eyes, e.g. multifocal and accommodative IOLs, as well as use in phakic eyes, i.e. refractive AC IOLs and the Artisan IOL. We have noted how Ridley “opened up the capsular bag” for various techniques. Strampelli in Italy, Barraquer in Spain, and Peter Choyce in England were leading pioneers of refractive IOL surgery. The jury is still out regarding the preferred category of refractive IOLs, both in terms of value compared to corneal procedures, and with respect to which type: anterior chamber, posterior chamber or iris-fixated. ACKNOWLEDGEMENTS Declared none. CONFLICT OF INTEREST The authors confirm that this chapter content has no conflicts of interest.

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CHAPTER 2 Aspheric Intraocular Lenses Yoel Greenwald1,* and Guy Kleinmann2 1

Ophthalmology Department, Kaplan Medical Center, Rehovot, Israel and Hadassah Hospital and the Hebrew University School of Medicine, Jerusalem, Israel 2

Abstract: During the aging process, the spherical aberration (SA) induced by the natural lens shifts from negative to positive values, impairing optical quality. Standard spherical intraocular lenses (IOLs) similarly induce positive SA. To deal with this problem aspheric IOLs have been designed to induce a negative or neutral SA, effectively reducing optical SA in a manner similar to the lens in a young phakic eye. It has been postulated that implanting an aspheric IOL would improve image clarity over that provided by a standard spherical IOL because of reduced optical aberrations. Multiple simulations, as well as clinical trials evaluating mesopic and photopic contrast sensitivity, have shown that aspheric IOLs indeed provide improved spectacle corrected contrast function over comparable spherical IOLs. This is especially true for under scotopic conditions where maximal pupillary dilation increases the magnitude of optical SA errors. However, the clinical significance of these contrast improvements for the average cataract patient has been called into question for many reasons, primarily because senile miosis effectively minimizes the magnitude of post-operative optical SA. Recent efforts to use aspheric IOLs to individualize post-operative ocular SA have shown promising visual results; however the ideal post-operative spherical aberration has not yet been determined. Further study into optimizing the interaction between the full spectrum of higher order aberrations in the pseudophakic eye may be useful in defining the future role for aspheric IOL technology in enhancing visual function in pseudophakia.

Keywords: Cataract, intraocular lens, pseudophakia, spherical aberration, contrast sensitivity, visual acuity. INTRODUCTION With advances in surgical technology and patients leading a more active lifestyle well into their seventies and beyond, cataract surgery can no longer be considered a functional procedure to remove an opacified lens, and visual acuity alone can no *Address correspondence to Yoel Greenwald: Ophthalmology Department, Kaplan Medical Center, Rehovot, Israel; Affiliated with Hadassah Hospital and the Hebrew University School of Medicine, Jerusalem, Israel; Tel: +972-8-9441351; Fax: +972-8-9441821; E-mail: [email protected] Guy Kleinmann, Ehud I. Assia and David J. Apple (Eds) All rights reserved-© 2014 Bentham Science Publishers

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longer be considered the sole criterion of surgical success. As cataract surgery has evolved from a sight-saving operation to a refractive procedure, quality of vision and optical outcomes have become of crucial importance, with the goal being to improve not only acuity, but also quality of life. Lower order visual aberrations such as astigmatism can be effectively reduced by a combination of spectacle correction, corneal surface modification and/or specialized IOLs, improving quality of vision in pseudophakic patients to a great degree. The purpose of aspheric lenses is to continue this process of optimizing image quality by minimizing higher order aberrations (HOAs) in the pseudophakic eye. (a)

Aberration in the Younger Eye +

Cornea Retina

-

Lens

(b)

+/- Neutral Vision is sharp

Aberration in the Older Eye +

Cornea Retina

+

Lens

+/+ Vision is Not sharp

Figure 1: Spherical aberration in the younger and older eye. (a) The corneal positive spherical aberration in counteracted by the negative spherical aberration of the young phakic lens, and augmented (b) by the positive spherical aeration of the older phakic lens.

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The aim in minimizing HOAs is to improve visual function by returning the pseudophakic eye to a more ‘youthful’ state. In humans, the magnitude of ocular HOAs has been estimated to increase significantly between the ages of 20 and 70 [1]. In young patients, the magnitude of ocular HOA is often lower than the levels induced by the cornea alone, indicating that the young crystalline lens partially negates corneal HOAs such as coma [1, 2]. With age and concomitant changes in the dimensions and composition of the phakic lens, rather than negating corneal HOAs, the elderly phakic lens increases HOAs over the level induced by the cornea alone (Fig. 1). The purpose of the aspheric IOL is to lower the total optical HOA level by minimizing a particular fourth order HOA known as spherical aberration (SA). SA is a symmetrical HOA induced in an optical system when peripheral rays have a different focus than central rays. WHY FOCUS ON CORRECTING SPHERICAL ABERRATION? There are a number of reasons why advances in IOL design technology have specifically targeted SA reduction out of the many different HOAs that affect visual function in pseudophakia. First, the major internal optic HOA in elderly pseudophakic patients with pupils larger than 4 mm has been shown to be SA [3] and the level of total HOAs in pseudophakic patients with an average pupil size of 4.1 mm has been shown to be correlated with mesopic contrast sensitivity [4]. Therefore, reducing SA could potentially improve mesopic contrast sensitivity. Second, unlike other HOAs, ocular SA has been shown to progressively and consistently increase with age [1, 5]. Increased SA is therefore associated with the progressive decline in quality of vision associated with aging. It is hoped that by reducing SA, aspheric IOLs can restore ‘youthful’ quality of vision. Another major reason SA correction has been targeted is that SA is a rotationally symmetrical aberration and therefore is a relatively easy HOA to correct with an artificial lens. An IOL that modifies ocular SA will be equally effective in any rotational orientation. OCULAR SPHERICAL ABERRATION The major contributors to ocular SA are the cornea and the lens. The SA of the cornea is positive [6, 7]. This means when central rays are focused on the retina,

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peripheral rays are focused in front of the retina. Several large studies [6-8] have determined that the average SA induced by the cornea for a 6 mm aperture is approximately +0.27 um, a value that remains relatively unchanged with age [7]. The magnitude of corneal SA error is progressively lower for smaller apertures. As pupil diameter increases, more off axis peripheral rays are focused in front of the retina increasing the magnitude of the SA. Approximate magnitudes of corneal SA at decreasing aperture diameters are 0.13 um at 5 mm, 0.051 um at 4 mm and 0.016 um at 3 mm [9]. Therefore, the effect of this aberration is sensed most acutely under scotopic conditions when pupils are maximally dilated. Based on the progressive decline in corneal SA with pupil diameter, many simulations [8-12] have shown that although there is expected to be improvement in visual function in reducing SA with a 5 mm pupil, there is quite possibly no clinical benefit to correcting SA with a 3 mm pupil. In young people the crystalline lens counteracts positive corneal SA by exhibiting a negative SA and as a result ocular SA remains low. With age the crystalline lens undergoes changes and the SA induced by the lens becomes progressively more positive. Although there is interpatient variability, on average by ages 40-50 the lens SA has risen such that ocular SA is greater than zero, with lenticular SA continuing to progressively higher positive values [5]. As corneal SA is consistently positive, and ocular SA is a combination of the corneal and lenticular SA, ocular SA changes form a value near zero in young people to a progressively higher positive value with age. By the age when most patients present for cataract surgery the lens is a major factor in inducing a positive ocular SA. Typical spherical IOLs act similarly to the aged crystalline lens in that they induce a positive SA by over-refraction at the lens periphery. The SA induced by a given spherical IOL is proportional to the lens power [8] and increases with pupil dilation. This raises total ocular SA over and above the level already induced by the cornea. For this reason, spherical IOLs are also expected to reduce visual function below optimum levels post-operatively (Fig. 2). Aspheric IOLs are different. Through a modification of one or both of the IOL interfaces, aspheric IOLs do not induce a positive SA. Aspheric IOLs can even be modified to induce a negative SA similar to the role of the crystalline lens in

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yo oung peoplee, potentially y eliminatin ng ocular SA A altogetherr. If all othher factors reemain constant, a given n pseudophaakic eye willl have a loower ocular SA if an asspheric IOL L is implanteed in place of o a sphericcal IOL [13--20] (Fig. 3)). But the qu uestion remaains, can red ducing SA produce p a cliinically meaaningful impprovement in n quality of vision? v

Fiigure 2: Illustrration of the ad ddition of the positive spheriical aberrationn of a sphericall IOL to the po ositive sphericcal aberration of o the cornea. For this reasoon, spherical IIOLs are also expected to reeduce visual function below optimum o levelss post-operativvely.

Fiigure 3: Illustrration of the sh harpest focus expected e by a ffull neutralizatiion of the positive corneal sp pherical aberraation by a neg gative sphericaal aberration I OL. This has the potential to improve viisual acuity.

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SIMULATIONS Optical simulations have long suggested that aspheric IOLs have the potential to improve quality of vision. One early article [21] noted that although the potential to improve visual quality existed, these specialized IOLs would need to be well centered to outperform spherical IOLs. If the aspheric IOL was not well centered then quality of vision would be reduced in comparison with a standard spherical IOL of similar power due to HOAs induced by the aspheric surface. The authors suggested that given the state of cataract surgery circa 1991, typical IOL decentration meant that there was no general benefit to aspherizing surfaces of IOLs. More recent articles [11] have confirmed the prediction of improved quality of vision with a well centered aspheric IOL, especially under reduced lighting conditions that stimulate pupil dilation. Although aspheric IOLs tend to be most sensitive to decentration [11] errors, both IOL tilt and decentration reduce the benefit of an aspheric IOL designed to neutralize corneal SA. A study performed by Holliday et al. simulated the effect of IOL tilt and decentration with an IOL designed to fully correct an SA of 0.27 um at a 6 mm aperture. For a 5 mm pupil, an IOL designed to fully correct this corneal SA outperformed a spherical IOL at up to 7 degrees of tilt and 0.4 mm decentration. Today, with continuous circumlinear capsulorhexis and in-the-bag IOL placement, the average amount of IOL decentration is approximately 0.3 mm and the average IOL tilt is less than 3 degrees [22]. Therefore in patients with a 5 mm pupil, an SA correcting aspheric IOL would be expected to provide a clinical benefit despite an average amount of tilt and decentration. THE IOLs The first aspheric IOL to appear commercially was the Tecnis Z9000, a foldable, 3-piece silicone IOL manufactured by Abbott Medical Optics. The Tecnis Z9000 is a CeeOn Edge IOL model 911 with a modified prolate anterior surface. This alteration lowers the refractive power of the IOL at its periphery, inducing a negative spherical aberration (SA). This negates the effects of over-refraction at the periphery of the optical zone at the cornea responsible for corneal induced spherical aberration. The Tecnis Z9000 and the related Tecnis Z9002 and Tecnis

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ZA9003, were designed to fully negate the average corneal SA by inducing a negative SA at 6 mm of -0.27 µm (Fig. 4).

Figure 4: The Technis aspheric IOL – The first implantable aspheric lens with negative spherical aberration.

Another aspheric IOL, the AcrySof IQ, was developed by Alcon. It has the same ultraviolet and blue light filtering chromophores as those found in the single piece acrylic AcrySof Natural IOL [SN60AT, Alcon] (Fig. 5). The unique feature of the AcrySof IOL is the posterior aspheric surface that adds -0.20 um of spherical aberration to the eye at the 6.0 mm optical zone. This only partially corrects corneal SA, leaving the average patient with residual positive SA. A small amount of residual SA could benefit the patient by increasing depth of field, allowing the patient to better tolerate some residual ametropia and be less dependent on spectacle correction for near tasks.

Figure 5: The AcrySof IQ– A hydrophobic acrylic intraocular lens.

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In order for aspheric IOLs that induce negative SA, such as the Tecnis or Acrysof IQ, to be maximally beneficial they need to be well centered and without tilt [21]. If the aspheric IOL is not well centered, the induced HOAs from the malpositioned aspheric can cause the IOL to perform worse than a spherical IOL decentered to the same degree [12, 21]. Decentered spherical IOLS are expected to increase ocular coma and other aberrations as well [9] but not to the same degree. In light of this problem, Bausch and Lomb introduced the SofPort Advanced Optics model LI61AO (Fig. 6). The SofPort IOL is an equiconvex silicone lens with prolate anterior and posterior surfaces. The aim of the IOL is to be perfectly aspheric and not induce HOA with tilt or decentration. Unlike the Acrisof IQ or Tecnis IOLs which are designed to outperform spherical IOLs only up to a specific limit of tilt and/or decentration [9], the Sofport IOL should outperform a spherical IOL at a much larger range of optic orientations [22]. However, because the SofPort does not reduce corneally induced SA, a well centered Tecnis or AcrySof IQ IOL with minimal decentration or tilt should theoretically outperform the Sofport IOL in the average patient.

Figure 6: The Sofport AO - An aspheric silicone IOL designed to leave the spherical aberration of the corneal surface unchanged.

A simulation performed by Halladay et al. [8] predicted that a Tecnis IOL centered within 0.4 mm and tilted less than 7 degrees, would exceed the optical performance of a conventional spherical IOL. A separate study by Baumeister et al. [23] compared the level of HOAs and simulated visual function parameters

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in patients in which one eye received a Tecnis IOL and the other eye received the Sensar AR40e, a spherical IOL. Scheimpflug imagery determined mean IOL tilt and decentration to be less than 3 degrees and 0.3 mm respectively. At this level, Holladay et al. [8] predicted the Tecnis IOL would improve visual function. Although the Tecnis IOL did significantly reduce total HOA levels with 6.0 mm pupils, simulations with 6 mm pupils indicated that visual function with best spectacle correction was not significantly improved. One explanation for this discrepancy is that the Holladay simulation [8] overestimated the benefit of the Tecnis IOL by assuming it would completely eliminate ocular SA through its negation of the average corneal SA. In reality, negating the average SA will leave many pseudophakic patients with significant residual SA if their pre-operative SA is significantly different from the population average. The corneal SA in cataract patients has been shown to range between 0.055 um and 0.544 um at 6 mm [7]. The simulation by Holladay et al. also used monochromatic light. Simulations using monochromatic light may overestimate the benefit of the elimination of SA by not incorporating the general blurring effect of chromatic aberration into the models. Other simulations [24, 25] that have predicted improved visual function with aspheric IOLs at pupil sizes greater than 4-5 mm also used monochromatic light in their models and as such, their results need to be understood in the context of this limitation. Also in doubt is the utility of correcting SA when many simulations have shown little to no expected benefit with 3 mm pupils. The 70-year-old pupil is approximately 2 mm smaller than the 20 year-old pupil [26]. This helps reduce deterioration of visual quality with increased age and increased corneal and lenticular HOA. It also limits the benefit of SA correction with aspheric IOLs. One simulation [26] estimated that for a patient with a 4 mm pupil, a centered spherical IOL and full spectacle correction, fully neutralizing SA adds less benefit than would be gained by correcting 0.25D of defocus. This potential benefit increases with increased pupil size, but with senile miosis it is unclear whether these effects are clinically significant. In light of these doubts as to the clinical benefits of aspheric IOLs, let us turn to the results of clinical studies which compared spherical and aspheric IOLs.

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CLINICAL STUDIES COMPARING ASPHERIC AND SPHERICAL INTRAOCULAR LENSES Ocular Aberrations The following review includes reports comparing spherical and aspheric IOLs, as well as reports comparing aspheric IOLs to each other. The IOLs that appear most often in the literature were the first to be made commercially available and so the review focuses on these three models: the Tecnis, AcrySof IQ and SofPort IOLs. In recent years, other aspheric IOLs appeared on the market. These new models tend to imitate the basic strategy of one of the three IOLs mentioned above (Table 1); they either fully correct the average corneal SA like the Tecnis, partially correct the average corneal SA like the AcrySof IQ or are aberration free like the SofPort. Table 1: Selected aspheric intraocular lenses and their induced asphericity IOL Asphericity with a 6 mm Pupil [µm] Tecnis Z series (AMO)

-0.27

Acrysof IQ (Alcon)

-0.2

SeeLens AF (Hanita)

-0.14

ReStore aspheric (Alcon)

-0.1

Staar Affinity (STAAR Surgical)

-0.02

Sofport AO (B&L)

0

Spherical Aberration All reviewed studies comparing spherical and aspheric IOLs found significantly lower ocular SA in eyes with an aspheric IOL. Eyes implanted with either the Tecnis [14, 16, 18-20, 27-30] or AcrySof [31-34] IOLs had significantly lower ocular SA even at 3 and 4 mm apertures, while the SofPort [35-38] IOL significantly lowered SA at a 5 mm aperture. In studies comparing different aspheric IOLs [35, 38-40] the trend was for the residual SA at 6 mm with a Tecnis IOL to be approximately 0 um, with the AcrySof IQ 0.1 um and with the SofPort AO about 0.2 um. Considering that the average corneal SA at 6 mm in the population is 0.27 um [6-8], and the SA correction at 6 mm in the Tecnis (-0.27

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um), AcrySof IQ (-0.20 um) and SofPort AO (0) IOLs, these results are in line with pre-operative expectations. It can be concluded that all three aspheric IOLs affect post-operative SA in the pseudophakic eye to the degree intended and significantly reduce SA in comparison with spherical IOLs. Higher Order Aberrations The effectiveness of aspheric IOLs at significantly reducing the level of total ocular HOAs is less clear. The Tecnis IOL was found to not significantly reduce total ocular HOAs at 4mm [16, 18-20, 27, 29] in comparison with a variety of spherical IOLs. At 5 mm two studies [15, 41] found no significant reduction in HOAs with the Tecnis and one study [tc4] found lower total HOAs. Two studies found the Tecnis IOL reduced HOAs at 6 mm [20, 41], while three studies [27, 29, 42] found no significant reduction. Many of these trials compared the Tecnis with an IOL with a different shape, optic angulation, refractive index and material. This confounding factor makes it difficult to clearly determine whether differences in HOAs were induced by IOL asphericity alone or whether other factors played a role. When HOAs at 4mm were compared between a Tecnis Z9000 and the 911 Edge (a spherical IOL with the same platform) one study found HOAs significantly reduced at 4 mm [14] and the other study found no difference [18]. Nearly all of the trials that tested the AcrySof IQ compared it to the Alcon Acrisof Natural [SN60AT], a spherical IOL with the same basic design and material as the AcrySof IQ. At a 4 mm aperture, eyes with the IQ had significantly lower HOAs in comparison with the SN60AT in one trial [32], and no significant difference was found in two other trials [31,33]. At 5 mm, four trials found significantly lower HOAs in eyes implanted with the IQ [43-46] and two other trials found no difference [33, 39]. All three HOA magnitude comparisons performed at 6 mm [31-33] found that the IQ significantly reduced HOAs. The trend in both of these groups of studies is that the Tecnis and AcrySof IQ are more likely to reduce the magnitude of ocular HOAs at wider pupil diameters. This result is in line with expectations because the IOLs are designed to reduce

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only SA, and the magnitude of the SA correction is greater at larger aperture diameters where SA forms a larger proportion of total HOA magnitude. In contrast, spherical IOLs increase ocular SA, especially at larger aperture diameters, which magnifies the difference between aspheric and spherical IOLs with pupil dilation. In fact, it is possible that the reduced HOA levels are due to not implanting a spherical IOL that induces HOAs, rather than the magnitude of SA correction in the aspheric IOL. Studies which compared the Tecnis, AcrySof IQ and SofPort IOLs to each other [39, 47] found no difference in HOA magnitude at any aperture diameter between 4 and 6 mm. Still the question remains, even if aspheric IOLs effectively reduce HOAs compared with spherical IOLs, do they provide any clinical benefit? VISUAL ACUITY Nearly all reports in the literature have concluded that there is no evidence that aspheric IOLs improve visual acuity post-operatively [13, 15-17, 19, 20, 27, 29, 30, 32-38, 41, 43, 44, 46-55]. Two papers did find a small but statistically significant BCVA advantage in eyes implanted with the Tecnis 9000 [28,56]. One of these compared the Tecnis 9000 to the Alcon SA60AT [56], a result not corroborated by another similar study which compared the same two IOLs [27]. Given the weight of evidence in the literature it can be concluded that high contrast photopic BCVA measurements are not significantly improved by implanting an aspheric IOL in the place of a standard spherical IOL. CONTRAST SENSITIVITY Contrast sensitivity measurements, more than visual acuity, have been shown to predict functional vision and visual performance for a range of object scales. A significant improvement in contrast sensitivity might, if present, support the widespread implantation of aspheric IOLs despite the lack of evidence demonstrating improved visual acuity. Comparative studies of aspheric and spherical IOLs have been carried out mainly under either photopic or mesopic testing conditions at between 1.5 and 18 cycles per degree (cpd).

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PHOTOPIC CONTRAST SENSITIVITY Tecnis Fourteen studies compared photopic contrast sensitivity between eyes with a Tecnis IOL and those with spherical IOLs. Seven studies [27-28, 41, 49, 56-58] found the group with the Tecnis IOL to have significantly better photopic contrast sensitivity at one or more spatial frequency. In seven other studies [15-16, 19, 2930, 48, 59] no significant difference was found between IOLs at any spatial frequency. A significant benefit, if present, was most likely to be found at 6 cpd, where six studies [27, 28, 49, 56-58] found the Tecnis to significantly outperform the spherical IOL. A problem with many of these comparative studies involving the Tecnis IOL is that the spherical and aspheric IOLs often differed in more ways than just the aspheric surface. Differences in material and design of the IOLs may have played a role in the results. In the two studies that compared the Tecnis IOLs with spherical IOLs using the same platform, [15, 30] both found no significant difference in photopic contrast sensitivity. AcrySof IQ Nine articles compared the Acrysof IQ to the Acrisof Natural model SN60AT, an IOL with the same platform. Five showed no improved photopic contrast sensitivity at any spatial frequency [32, 34, 44, 46, 52], while four showed improved contrast sensitivity at one or more spatial frequencies [43, 51, 54, 60]. As with the Tecnis IOL, benefit of an aspheric IOL was most likely to be found at 6 cpd, although only three studies demonstrated a significant benefit at that spatial frequency [43, 54, 60]. In summary, while there is some evidence that aspheric IOLs can improve photopic contrast sensitivity, especially at around 6 cpd, the contradictory outcomes in the literature make it difficult to draw definitive conclusions. It is possible that the small study populations in many of these studies, the large majority of which contained less than 50 eyes per subgroup, did not provide enough power for a small benefit of aspheric IOLs to achieve statistical significance. Even if true, it is unclear if this small benefit would provide the average patient with any clinically significant improvement in quality of vision.

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Another point to consider is that at a luminance of 85 cd/m2, where most of these photopic measurements were performed, the average pupil diameter in the population analyzed was approximately 3 mm [17, 32, 35, 36, 43, 52, 56]. At this aperture width, no significant improvement in the magnitude of HOAs with aspheric IOLs has been demonstrated as shown previously. If an improved HOA level is associated with improved visual function, it is more likely that improved contrast sensitivity will be conclusively found to occur at the larger pupil diameters induced by reduced lighting conditions. MESOPIC CONTRAST SENSITIVITY Tecnis Twelve studies compared mesopic contrast sensitivity between eyes with spherical IOLs and eyes with a Tecnis IOL. In nine of these studies [16, 27, 28, 30, 41, 49, 56, 58], a significant advantage was found with the Tecnis IOL at one or more spatial frequency and only three reports [19, 29, 59] found no significant difference. A benefit, if present, was most likely to be found at a spatial frequency of 3 or 6 cpd where seven reports found the Tecnis provided improved contrast sensitivity. AcrySof IQ Results with the AcrySof IQ also suggested a significant benefit with aspheric IOLs. All seven studies [43, 44, 46, 51, 52, 54, 60] found the aspheric IOL to provide the recipient with significantly better mesopic contrast sensitivity at one or more spatial frequency. Six of these studies found significantly improved contrast sensitivity at a spatial frequency of 3 cpd. These mesopic contrast sensitivity measurements were performed at a median luminance of 3-6 cd/m2 where the average pupil diameter in the study population is of about 4 mm [28, 32, 35, 43, 44, 48, 52, 56, 61]. At this larger pupil diameter there is more potential benefit in correcting SA as it causes a larger proportion of total HOAs. As expected by simulations, contrast sensitivity improved significantly under these conditions, with a large majority of studies showing a benefit for aspheric IOLs over spherical counterparts at one or more spatial frequency. But the question remains: are these benefits clinically significant?

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SUBJECTIVE VISUAL FUNCTION Two studies compared patient satisfaction with aspheric and spherical IOLs. One [48] compared subjective visual function in patients with bilaterally implanted Tecnis 9000 or AcrySof MA60AC IOLs and found no difference in Visual Function-14 scores. Another study [50] compared the AcrySof IQ to the AcrySof SA60AT and found no statistically significant differences in vision- related quality of life with the National Eye Institute Visual Functioning Questionnaire [NEI VFQ-25], despite significantly lower HOAs and SA levels in eyes with the aspheric IOL. The authors explained this discrepancy by stating that many people in their patient population performed few tasks requiring highly functioning nighttime contrast sensitivity like night driving. More careful patient selection may have improved the subjective benefit enjoyed by trial subjects. OPTIMAL SPHERICAL ABERRATION CORRECTION A more fundamental flaw than poor patient selection in many of the comparative studies between spherical and aspheric IOLs is the assumption that any single aspheric IOL should be a one-size-fits-all solution. In one study the corneal SA in patients presenting for cataract surgery ranged from 0.055 um and 0.544 um at 6 mm [7]. Implanting a Tecnis IOL into each patient may leave a large group with an average post-operative ocular near zero [17], but individual patients with nearly no preoperative SA would end up with a highly negative final ocular SA. As a consequence, the group would experience suboptimal benefit from the aspheric IOL. Selecting an IOL based on the patient’s specific corneal SA error and aiming for a particular value of post-operative asphericity may provide more predictable results for each patient. The goal of targeting a patient-specific pseudophakic ocular SA relies on the assumption that cataract surgery induces predictable changes in corneal SA. A study by Marcos et al. [62] suggested that this is indeed the case with small corneal incision cataract surgery. Phacoemulsification surgery with a 3.2 mm superior incision and the implantation of a Tecnis of AcrySof IQ IOL did not significantly alter corneal SA from pre-operative values.

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A clinical trial by Packer [63] took a group of cataract patients and targeted zero post-operative SA in each patient. Pre-operative corneal SA was measured and a Tecnis, AcrySof IQ or SofPort IOL was chosen so the arithmetic sum of the IOL and corneal SA came closest to zero. Total post-operative ocular SA in this group measured [-0.013 +/- 0.072 um]. The standard deviation in this population was lower than in other trials of similar size with aspheric IOLs, indicating that it is possible to effectively target a specific post-operative ocular SA. If targeting a particular SA value is possible, what should be the target value? No Residual Spherical Aberration The assumption in most of the literature reviewed thus far is that ideally there should be no residual ocular SA. This is supported by Peirs [64] who compared letter acuity and contrast sensitivity for two different values of SA in 4 young phakic patients with 4.8 mm pupils. The first condition was 0.154 um of SA at a 4.8 mm pupil, the average amount of SA in pseudophakic patients with a spherical IOL and the second condition was complete correction of the subject’s SA. Average contrast sensitivity improved 32% with complete negation of ocular SA, which was statistically significant. It should be noted that pupil size in these subjects was greater than that that found in the average pseudophakic patient under all but scotopic conditions [15, 55]. Therefore, the effect of negating SA in elderly pseudophakic patients is likely overestimated. However, the study does suggest that achieving a postoperative SA of 0 could have a clinically significant effect on contrast sensitivity under conditions where pupil size is larger. Residual Positive Spherical Aberration It has also been suggested that targeting a post-operative SA of +0.10 at 6 mm is a better choice [65] than targeting zero residual SA. This line of thinking is supported by Levy et al. [66] who found a mean total SA of +0.110 +/- 0.077 um at 6 mm in 35 young patients with ‘supernormal’ vision [uncorrected visual acuity ≥20/15]. However, there is no logical basis for the implication that the patient’s SA was responsible for supernormal visual acuity. In fact, the authors found that the SA level in this population was comparable to a group of preoperative myopic patients considering refractive surgery [+0.128 + 0.074 um] [67].

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Nevertheless, a trial by Beiko [65] tested the theory of a post-operative SA of +0.10. He selected a group of patients with corneal SA greater than +0.33 um [average +0.370 + 0.024 um, range +0.337 to +0.411 um] and implanted a Tecnis IOL with -0.27 um of SA correction. The result in this group was compared to an unselected group of patients with an average preoperative corneal SA of +0.291 + 0.081 um at 6 mm [range +0.149 to +0.419 um] who also received a Tecnis IOL. The first group demonstrated significantly better mesopic and photopic contrast sensitivity at multiple spatial frequencies. This interesting finding would need to be confirmed in a larger trial that compared visual function between groups targeting +0.10 or 0 residual ocular SA. This trial does further support the notion that it is possible to target a particular final ocular SA in a small group of patients. No Single Spherical Aberration is Best It can also be argued that there is no single ideal target SA value, and that the optimal SA value depends on patient-specific factors. A study by Applegate et al. examined the effect on visual acuity of combining various pairs of aberrations [68]. They found that certain combinations of aberrations could improve letter acuity above the levels induced by either aberration alone. A report by Wang and Koch [69] carried out a simulation examining the effect of varying ocular SA levels while leaving all other HOAs intact in 154 emmetropic eyes. For a 4 mm pupil size, best image quality was obtained in over 90% of eyes with a residual SA of between -0.05 and +0.05 um. However, for a 6 mm pupil size the range of ideal ocular SA was much wider and centered around -0.05 um. Therefore, specific pseudophakic ocular SA that optimized visual function depended on the interaction of many different corneal HOAs as well as pupil size. Another consideration is the potential benefit of residual SA. Increased ocular SA is associated with increased depth of focus [70, 71] and improved distance corrected near visual acuity. With higher SA, fewer incoming rays converge at the focal point of the eye. While this decreases optimum image quality at best focus, the off-center rays provide improved visual function at other points along the visual axis. When SA is corrected, fewer rays are focused at other points along the visual axis, reducing both depth of focus and distance corrected near acuity. The trade-off between optimized contrast sensitivity when SA is minimized and

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increased tolerance to defocus with higher residual SA should be considered when determining a patient’s ideal post-operative HOA profile. Which Patients Should Receive Aspheric IOLs? Although aspheric IOLs can improve visual function in comparison with spherical IOLs and the available technology allows for the targeting of a specific pseudophakic ocular SA, we do not yet know how to optimally correct ocular SA. Gaining maximal benefit from the technology will likely require individualizing patient asphericity [65, 72], a change that would necessitate preoperative calculations of corneal SA and other HOAs. Even if this information is collected, it is unclear how it should be used to determine the optimal aspheric IOL correction. Still, collecting this data may be a necessary first step before the role of aspheric IOL technology can be established. There is another concern with aspheric IOLs. Given senile miosis, their purported advantage would only be clinically significant in a subgroup of elderly cataract patients who perform a significant amount of contrast-dependent tasks under mesopic or scotopic conditions, like night driving. The benefits might be more apparent in younger patients with larger pupil sizes who undergo refractive lens exchange or surgery for a congenital cataract. The role of an aberration-free SofPort IOL might be to reduce induced HOAs if an increased risk of optic tilt or decentration exists, for example with significant pseudoexfoliation. However, it is likely that all these indications add up to only a small proportion of cataract patients. A third factor to consider is that while cataract surgery technology has improved, exact emmetropia is not achieved in all eyes. Studies have shown that aspheric IOLs have the potential to improve visual function with best spectacle correction in place, but many pseudophakic patients do not wear spectacle correction and find their uncorrected vision adequate for most, if not all tasks of daily living. As the popularity of multi-focal IOLs indicates, many cataract patients are willing to accept less than optimal visual function in order to remain spectacle-free. Patients with uncorrected defocus and astigmatism that have accepted reduced acuity from best-corrected values are less likely to derive clinically significant benefit from

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targeting a specific post-operative ocular SA. Blur from the uncorrected lower order aberrations often decreases letter acuity. This defocus would dwarf any benefit a patient may derive from minimizing ocular SA, which can only improve contrast sensitivity in eyes with best spectacle correction in place. One contraindication for aspheric IOLs is patients after hyperopic refractive laser correction. These patients often have negative corneal SA and an aspheric lens would magnify this problem. SUMMARY The implantation of an artificial IOL is a once-in-a-lifetime opportunity to enhance visual function. It is clear that reducing HOAs has the potential to improve quality of vision and that aspheric IOLs can play a role in achieving this goal. However, the available information today suggests that only a small proportion of cataract patients would derive clinical benefit from aspheric IOL technology. Even among these patients it is unclear how the available IOLs should be employed. Future developments, including new multi-focal aspheric IOLs, may expand the applications of this interesting technology as we move toward the goal of optimizing visual function in pseudophakia. ACKNOWLEDGEMENTS Declared none. CONFLICT OF INTEREST The authors confirm that this chapter content has no conflicts of interest. REFERENCES [1] [2]

Artal P, Berrio E, Guirao A, Piers P. Contribution of the cornea and internal surfaces to the change of ocular aberrations with age. J Opt Soc Am A Opt Image Sci Vis 2002;19[1]:13743. Iseli HP, kov M, Bueeler M, et al. Corneal and total wavefront aberrations in phakic and pseudophakic eyes after implantation of monofocal foldable intraocular lenses. J Cataract Refract Surg 2006;32[5]:762-71.

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Hayashi K, Yoshida M, Hayashi H. Correlation of higher-order wavefront aberrations with visual function in pseudophakic eyes. Eye 2008;22[12]:1476-82. Ishii Y, Okamoto C, Hiraoka T, et al. Mesopic contrast sensitivity and ocular higher-order aberrations in eyes with conventional spherical intraocular lenses. Am J Ophthalmol 2009;148[2]:298-302. Amano S, Amano Y, Yamagami S, et al. Age-related changes in corneal and ocular higherorder wavefront aberrations. Am J Ophthalmol 2004;137[6]:988-92. Beiko GH, Haigis W, Steinmueller A. Distribution of corneal spherical aberration in a comprehensive ophthalmology practice and whether keratometry can predict aberration values. J Cataract Refract Surg 2007;33[5]:848-58. Wang L, Dai E, Koch DD, Nathoo A. Optical aberrations of the human anterior cornea. J Cataract Refract Surg 2003;29[8]:1514-21. Holladay JT, Piers PA, Koranyi G, et al. A new intraocular lens design to reduce spherical aberration of pseudophakic eyes. J Refract Surg 2002;18[6]:683-91. Altmann GE, Nichamin LD, Lane SS, Pepose JS. Optical performance of 3 intraocular lens designs in the presence of decentration. J Cataract Refract Surg 2005;31[3]:574-85. Terwee T, Weeber H, van der Mooren M, Piers P. Visualization of the retinal image in an eye model with spherical and aspheric, diffractive, and refractive multifocal intraocular lenses. J Refract Surg 2008;24[3]:223-32. Tabernero J, Piers P, Benito A, et al. Predicting the optical performance of eyes implanted with IOLs to correct spherical aberration. Invest Ophthalmol Vis Sci 2006;47[10]:4651-8. Pieh S, Fiala W, Malz A, Stork W. In vitro strehl ratios with spherical, aberration-free, average, and customized spherical aberration-correcting intraocular lenses. Invest Ophthalmol Vis Sci 2009;50[3]:1264-70. Rekas M, Krix-Jachym K, Zelichowska B, et al. Optical quality in eyes with aspheric intraocular lenses and in younger and older adult phakic eyes: comparative study. J Cataract Refract Surg 2009;35[2]:297-302. Bellucci R, Morselli S, Pucci V. Spherical aberration and coma with an aspherical and a spherical intraocular lens in normal age-matched eyes. J Cataract Refract Surg 2007;33[2]:203-9. Denoyer A, Le Lez ML, Majzoub S, Pisella PJ. Quality of vision after cataract surgery after Tecnis Z9000 intraocular lens implantation: effect of contrast sensitivity and wavefront aberration improvements on the quality of daily vision. J Cataract Refract Surg 2007;33[2]:210-6. Ohtani S, Gekka S, Honbou M, et al. One-year prospective intrapatient comparison of aspherical and spherical intraocular lenses in patients with bilateral cataract. Am J Ophthalmol 2009;147[6]:984-9. Chen WR, Ye HH, Qian YY, et al. Comparison of higher-order aberrations and contrast sensitivity between Tecnis Z9001 and CeeOn 911A intraocular lenses: a prospective randomized study. Chin Med J [Engl] 2006 5;119[21]:1779-84. Bellucci R, Morselli S, Piers P. Comparison of wavefront aberrations and optical quality of eyes implanted with five different intraocular lenses. J Refract Surg 2004;20[4]:297-306. Kasper T, Bühren J, Kohnen T. Visual performance of aspherical and spherical intraocular lenses: intraindividual comparison of visual acuity, contrast sensitivity, and higher-order aberrations. J Cataract Refract Surg 2006;32[12]:2022-9.

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Kasper T, Bühren J, Kohnen T. Intraindividual comparison of higher-order aberrations after implantation of aspherical and spherical intraocular lenses as a function of pupil diameter. J Cataract Refract Surg 2006;32[1]:78-84. Atchison DA. Design of aspheric intraocular lenses. Ophthalmic Physiol Opt 1991;11[2]:137-46. Eppig T, Scholz K, Löffler A, et al. Effect of decentration and tilt on the image quality of aspheric intraocular lens designs in a model eye. J Cataract Refract Surg 2009;35[6]:1091100. Baumeister M, Bühren J, Kohnen T. Tilt and decentration of spherical and aspheric intraocular lenses: effect on higher-order aberrations. J Cataract Refract Surg 2009;35[6]:1006-12. Mencucci R, Menchini U, Volpe R, et al. Intraocular lenses with surface aspherization: Interferometric study. J Cataract Refract Surg 2007;33[9]:1624-30. Franchini A. Compromise between spherical and chromatic aberration and depth of focus in aspheric intraocular lenses. J Cataract Refract Surg. 2007;33[3]:497-509. Dietze HH, Cox MJ. Limitations of correcting spherical aberration with aspheric intraocular lenses. J Refract Surg 2005;21[5]:S541-6. Kim SW, Ahn H, Kim EK, et al. Comparison of higher order aberrations in eyes with aspherical or spherical intraocular lenses. Eye 2008;22[12]:1493-8. Mester U, Dillinger P, Anterist N. Impact of a modified optic design on visual function: clinical comparative study. J Cataract Refract Surg 2003;29[4]:652-60. Muñoz G, Albarrán-Diego C, Montés-Micó R, et al. Spherical aberration and contrast sensitivity after cataract surgery with the Tecnis Z9000 intraocular lens. J Cataract Refract Surg 2006;32[8]:1320-7. Ohtani S, Miyata K, Samejima T, et al. Intraindividual comparison of aspherical and spherical intraocular lenses of same material and platform. Ophthalmology 2009;116[5]:896-901. Awwad ST, Lehmann JD, McCulley JP, Bowman RW. A comparison of higher order aberrations in eyes implanted with AcrySof IQ SN60WF and AcrySof SN60AT intraocular lenses. Eur J Ophthalmol 2007;17[3]:320-6. Awwad ST, Warmerdam D, Bowman RW, et al. Contrast sensitivity and higher order aberrations in eyes implanted with AcrySof IQ SN60WF and AcrySof SN60AT intraocular lenses. J Refract Surg 2008;24[6]:619-25. Cadarso L, Iglesias A, Ollero A, et al. Postoperative optical aberrations in eyes implanted with AcrySof spherical and aspheric intraocular lenses. Refract Surg 2008;24[8]:811-6. Kohnen T, Klaproth OK, Bühren J. Effect of intraocular lens asphericity on quality of vision after cataract removal: an intraindividual comparison. Ophthalmology 2009;116[9]:1697-706. Caporossi A, Martone G, Casprini F, Rapisarda L. Prospective randomized study of clinical performance of 3 aspheric and 2 spherical intraocular lenses in 250 eyes. J Refract Surg 2007;23[7]:639-48. Caporossi A, Casprini F, Martone G, et al. Contrast sensitivity evaluation of aspheric and spherical intraocular lenses 2 years after implantation. J Refract Surg 2009;25[7]:578-90. Pepose JS, Qazi MA, Edwards KH, et al. Comparison of contrast sensitivity, depth of field and ocular wavefront aberrations in eyes with an IOL with zero versus positive spherical aberration. Graefes Arch Clin Exp Ophthalmol 2009;247[7]:965-73.

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Shentu X, Tang X, Yao K. Spherical aberration, visual performance and pseudoaccommodation of eyes implanted with different aspheric intraocular lens. Clin Experiment Ophthalmol 2008;36[7]:620-4. Cui H, Hu R, Zhang Y, Lou D. Comparison of pseudophakic visual quality in spherical and aspherical intraocular lenses. Can J Ophthalmol 2009;44[3]:274-8. Johansson B, Sundelin S, Wikberg-Matsson A, et al. Visual and optical performance of the Akreos Adapt Advanced Optics and Tecnis Z9000 intraocular lenses: Swedish multicenter study. J Cataract Refract Surg 2007;33[9]:1565-72. Tzelikis PF, Akaishi L, Trindade FC, Boteon JE. Spherical aberration and contrast sensitivity in eyes implanted with aspheric and spherical intraocular lenses: a comparative study. Am J Ophthalmol 2008;145[5]:827-33. Padmanabhan P, Rao SK, Jayasree R, et al. Monochromatic aberrations in eyes with different intraocular lens optic designs. J Refract Surg 2006;22[2]:172-7. Mester U, Kaymak H. Comparison of the AcrySof IQ aspheric blue light filter and the AcrySof SA60AT intraocular lenses. J Refract Surg 200;24[8]:817-2 Nanavaty MA, Spalton DJ, Boyce J, et al. Wavefront aberrations, depth of focus, and contrast sensitivity with aspheric and spherical intraocular lenses: fellow-eye study. J Cataract Refract Surg 2009;35[4]:663-71. Rocha KM, Soriano ES, Chamon W, et al. Spherical aberration and depth of focus in eyes implanted with aspheric and spherical intraocular lenses: a prospective randomized study. Ophthalmology 2007;114[11]:2050-4. Tzelikis PF, Akaishi L, Trindade FC, Boteon JE. Ocular aberrations and contrast sensitivity after cataract surgery with AcrySof IQ intraocular lens implantation Clinical comparative study. J Cataract Refract Surg 2007;33[11]:1918-24. Nabh R, Ram J, Pandav SS, Gupta A. Visual performance and contrast sensitivity after phacoemulsification with implantation of aspheric foldable intraocular lenses. J Cataract Refract Surg 2009;35[2]:347-53. Moorfields IOL Study Group, Allan B. Binocular implantation of the Tecnis Z9000 or AcrySof MA60AC intraocular lens in routine cataract surgery: prospective randomized controlled trial comparing VF-14 scores.J Cataract Refract Surg 2007;33[9]:1559-64. Packer M, Fine IH, Hoffman RS, Piers PA. Prospective randomized trial of an anterior surface modified prolate intraocular lens. J Refract Surg 200;18[6]:692-6. Lin IC, Wang IJ, Lei MS, et al. Improvements in vision-related quality of life with AcrySof IQ SN60WF aspherical intraocular lenses. J Cataract Refract Surg 2008;34[8]:1312-7. Pandita D, Raj SM, Vasavada VA, et al. Contrast sensitivity and glare disability after implantation of AcrySof IQ Natural aspherical intraocular lens: prospective randomized masked clinical trial. J Cataract Refract Surg 2007;33[4]:603-10. Rocha KM, Soriano ES, Chalita MR, et al. Wavefront analysis and contrast sensitivity of aspheric and spherical intraocular lenses: a randomized prospective study. Am J Ophthalmol 2006;142[5]:750-6. Sandoval HP, Fernández de Castro LE, Vroman DT, et al. Comparison of visual outcomes, photopic contrast sensitivity, wavefront analysis, and patient satisfaction following cataract extraction and IOL implantation: aspheric vs. spherical acrylic lenses. Eye 2008;22[12]:1469-75. Trueb PR, Albach C, Montés-Micó R, Ferrer-Blasco T. Visual acuity and contrast sensitivity in eyes implanted with aspheric and spherical intraocular lenses. Ophthalmology 2009;116[5]:890-5.

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Denoyer A, Denoyer L, Halfon J, et al. Comparative study of aspheric intraocular lenses with negative spherical aberration or no aberration. J Cataract Refract Surg. 2009;35[3]:496-503. Bellucci R, Scialdone A, Buratto L, et al. Visual acuity and contrast sensitivity comparison between Tecnis and AcrySof SA60AT intraocular lenses: A multicenter randomized study. J Cataract Refract Surg 2005;31[4]:712-7. Kershner RM. Retinal image contrast and functional visual performance with aspheric, silicone, and acrylic intraocular lenses. Prospective evaluation. J Cataract Refract Surg 2003;29[9]:1684-94. Packer M, Fine IH, Hoffman RS, Piers PA. Improved functional vision with a modified prolate intraocular lens. J Cataract Refract Surg 2004;30[5]:986-92. 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[3]:265-72. Takmaz T, Genç I, Yıldız Y, Can I. Ocular wavefront analysis and contrast sensitivity in eyes implanted with AcrySof IQ or AcrySof Natural intraocular lenses. Acta Ophthalmol 2008; 87[7]:759-763. Cuthbertson FM, Dhingra S, Benjamin L. Objective and subjective outcomes in comparing three different aspheric intraocular lens implants with their spherical counterparts. Eye 2009;23[4]:877-83. Marcos S, Rosales P, Llorente L, Jiménez-Alfaro I. Change in corneal aberrations after cataract surgery with 2 types of aspherical intraocular lenses. J Cataract Refract Surg 2007;33[2]:217-26. Packer M, Fine IH, Hoffman RS. Aspheric intraocular lens selection: the evolution of refractive cataract surgery. Curr Opin Ophthalmol 2008;19[1]:1-4. Piers PA, Fernandez EJ, Manzanera S, Norrby S, Artal P. Adaptive optics simulation of intraocular lenses with modified spherical aberration. Invest Ophthalmol Vis Sci 2004;45[12]:4601-10. Beiko GH. Personalized correction of spherical aberration in cataract surgery. J Cataract Refract Surg 2007;33[8]:1455-60. Levy Y, Segal O, Avni I, Zadok D. Ocular higher-order aberrations in eyes with supernormal vision. Am J Ophthalmol 2005;139[2]:225-8. Wang L, Koch DD. Ocular higher-order aberrations in individuals screened for refractive surgery.J Cataract Refract Surg 2003;29[10]:1896-903. Applegate RA, Marsack JD, Ramos R, Sarver EJ. Interaction between aberrations to improve or reduce visual performance. J Cataract Refract Surg 2003;29[8]:1487-95. Wang L, Koch DD. Custom optimization of intraocular lens asphericity. J Cataract Refract Surg 2007;33[10]:1713-20. Guirao A, Redondo M, Geraghty E, et al. Corneal optical aberrations and retinal image quality in patients in whom monofocal intraocular lenses were implanted. Arch Ophthalmol 2002;120[9]:1143-51. Nio YK, sonius NM, Geraghty E, et al. Effect of intraocular lens implantation on visual acuity, contrast sensitivity, and depth of focus. J Cataract Refract Surg 2003;29[11]:207381. Packer M, Fine IH, Hoffman RS. Aspheric intraocular lens selection: the evolution of refractive cataract surgery. Curr Opin Ophthalmol 2008;19[1]:1-4.

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CHAPTER 3 Blue Filtering Intraocular Lenses Randall J. Olson* Department of Ophthalmology and Visual Sciences and CEO of the John A. Moran Eye Center at the University of Utah School of Medicine, Salt Lake City, Utah 84132, USA Abstract: Intraocular lenses (IOL) that filter some blue light were introduced in the 1990s and were suggested to reduce the risk of Age related macular degeneration and uveal melanoma. The potential benefits and harm from blocking blue light has been debated. In this chapter we will discuss the evidence for the protective effects and the negatives of these IOLs.

Keywords: Intraocular lens, blue light, macular degeneration, color vision, lipofuscin, melanoma, insomnia, melatonin, melanopsin, retinal damage, phototoxicity, compliment system, antioxidants, cataract, oncogenesis, scotopic vision, mesopic vision, circadian rhythm, suprachiasmatic nuclei, depression. INTRODUCTION Intraocular lenses (IOL) that filter some blue light (Fig. 1) are commonly used in ophthalmology today and continue to be controversial in regard to their indication and potential downsides. The general theory for their use has to do with light toxicity. It is well known that blue light is the most energetic in the visible light spectrum and, so the theory goes, if partially blocked would be less likely to cause retinal damage [1]. The major concern is age-related macular degeneration (AMD) and, therefore, reducing the amount of blue light coming into the eye would, hopefully, decrease the incidence of age-related macular degeneration, which is certainly a scourge in our aging population today. The questions that are outstanding in this ongoing debate are: 1.

Is there, in fact, significant evidence that blue light impacts agerelated macular degeneration in any way, and

2.

Are there any important additional downsides in association with blocking blue light?

*Address correspondence to Randall J. Olson: Department of Ophthalmology and Visual Sciences and CEO of the John A. Moran Eye Center at the University of Utah School of Medicine, Salt Lake City, Utah 84132, USA; Tel: 801-585-6622; Fax: 801-581-8703; E-mail: randallj.olsonehsc.utah.edu Guy Kleinmann, Ehud I. Assia and David J. Apple (Eds) All rights reserved-© 2014 Bentham Science Publishers

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Figure 1: A blue filtering AcrySof single piece IOL (Alcon Surgical, Fort Worth, TX).

To further understand the reason why blue light blocking was considered important, it is important to look at the acute retinal toxicity curve for blue light. This is also very similar to the toxicity curve for lipofuscin (Fig. 2) in the retinal pigment epithelium and, therefore, it was felt that light toxicity over time might impact macular degeneration [2]. Furthermore, there have been population studies that did show correlation between cataract surgery and an increased incidence of macular degeneration afterword [3, 4]. Between these two areas of study, blocking blue light was felt to be a reasonable thing to do.

Figure 2: The blue light toxicity curve which closely follows the excitation curve for lipofuscin in the retinal pigment epithelium (courtesy of Martin Mainster, MD).

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Looking specifically at the debate regarding macular degeneration and blue light at this time, however, while two population studies did show that cataract surgery increased the incidence of macular degeneration, the majority of population studies or large case control studies have not show a correlation between cataract surgery or a lifetime of light exposure and macular degeneration [5-14]. Furthermore, while light toxicity was popularly considered an important part of macular degeneration when blue filtering IOLs were introduced, at this time it is clear that dysregulation of the compliment system is far and away the most important cause of macular degeneration today [15]. Additionally, environmental factors such as smoking and diet, in particular a diet low in certain antioxidant compounds, do also relate to macular degeneration [16]. Light toxicity, on the other hand, is generally not considered important in macular degeneration causation today. That said, just as we know that macular degeneration is largely related to the immune system, other genetic abnormalities and is modulated by other factors and just because someone’s genetics, smoking and diet appear to be much more important does not mean that light necessarily is uninvolved as a risk factor in the process. So in order to prove the hypothesis that blocking blue light would be important in macular degeneration, it has always been apparent that this would require a randomized, double-masked clinical trial, which at one time had been proposed. We have, however, had the age-related eye disease study (AREDS) which looked specifically at some of the antioxidants and their impact on macular degeneration as well as the natural history of macular degeneration. This is the most rigorous and thorough study on the natural history of macular degeneration as well as cataracts that has ever been undertaken and we now have results that have been followed up now for over fifteen years after cataract surgery. What has been found through this particular study over time is that cataract surgery and removal of an aging and cataractous lens, which clearly blocks substantially more blue light than a blue filtering IOL, did not increase the incidence of macular degeneration at any time point [16]. If, indeed, blocking blue light was important in macular degeneration prevention, then this large and rigorous study, which followed patients with early macular degeneration both before and after cataract surgery, should have found a difference. Not only did they not find a difference,

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in some of their analyses cataract surgery was actually protective which would not be possible if blue light toxicity was a part of macular degeneration pathogenesis. An explanation for contradictory evidence given by the authors of the AREDS publication [16] as to why some studies did show an association with cataract surgery and macular degeneration is the problem of detecting macular degeneration before cataract surgery. Cataracts themselves can make fine examination of the retina difficult and often the focus is more on the cataract until vision is not fully recovered and the macular degeneration becomes obvious only after surgery. What is clear is that the AREDS results are so strong, rigorous and long term that a double-masked clinical trial is unlikely to ever occur; however, the AREDS study is definitive enough that it seems extremely unlikely that blocking blue light, if it is a factor at all, is of very minor clinical importance in regard to macular degeneration. One additional advantage being proposed is that blocking blue light may decrease the incidence of uveal melanoma [17]. This rationale is based on the melanoma cell culture model of Burnier, and the finding that welders have an increased risk of ocular melanoma [18]. Extrapolating acute cell culture toxicity to uveal melanoma is a stretch, and welders are also exposed to large amounts of UV-B radiation which is much more likely to cause DNA damage that might result in oncogenesis than blue light. Furthermore, the incidence of uveal melanoma is extremely small and this entire body of evidence is theoretical. There is probably no good way of proving any uveal melanoma protective effect for blue filtering IOLs in that a prospective masked clinical trial with the very low incidence of this problem is difficult to even contemplate; however, this also is now being proposed as an additional theoretical advantage for blue light filtering IOL use. So if the evidence for any blue filtering IOL advantage is inconclusive at best and, in fact, with the AREDS study quite conclusively showing that clear IOLs do not increase AMD risk when compared to cataractous lenses that block much more blue light than blue filtering IOLs, then, if there are no downsides, why not use them just in case they might help even a little? In fact, there have been three proposed negatives to date. They are:

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1.

That there is a difference in the perception of the color of blue.

2.

That scotopic rod vision is more impacted by a blue filtering IOLs than a clear IOL.

3.

That blue filtering IOLs can negatively impact the melanopsinmelatonin sleep cycle system.

To take each one of these in turn, first in regard to color vision, there is no question that if a clear lens is placed in one eye and a blue filtering lens is placed in the other eye, that many patients can look at white paper and perceive a small difference [19]. This same group showed that blue filtering IOLs adversely impact blue cone sensitivity when studied with short-wavelength automated perimetry, and they did not see any difference in photopic contrast sensitivity; another purported advantage of blue filtering IOLs. They did document a loss in mesopic contrast sensitivity with blue filtering IOLs when compared to clear IOLs. In general, however, color perception does not seem to be much of a clinical problem even thought one artist with a blue filtering IOL in one eye and not in the other did insist that the blue filtering IOL be exchanged for a clear IOL [20]. So other than in the rare individual with mixed clear and blue filtering IOLs, color perception does not appear to be clinically important. Mesopic contrast sensitivity differences on the other hand may have impact on some areas of daily function and deserves further study. Regarding night vision there is no controversy about the fact that the rod visual excitation curve is more in the blue spectrum than are cones and, therefore, blue filtering IOLs have more impact on night vision than would a clear lens [21]. While this can be theoretically calculated with some differences of opinion as to the exact amount, the overall amount of rod vision lost would appear to be small and there has not been any study to date showing that this is of clinical importance. While this may be a factor in those who have an unusual need for their scotopic vision, most people in modern society still use their cones for much of what they do including night driving and, therefore, this theoretical disadvantage is unclear as to whether it is of much importance.

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Of the three reasons why blue blocking IOLs may be a problem, impact on melanopsin is the most recent, and one that was not apparent when blue blocking lenses were first introduced. Visual light is important in regulating our circadian rhythm. It is also well documented that as we age we have a tendency to have sleep disruption and insomnia as an increasing problem [22]. As an extreme example, totally blind people have free running circadian cycles unaffected by daylight and report a lifetime of recurrent jet-lag almost as disabling as blindness itself [23]. Astronauts for instance do not have enough ambient light in their environment and also suffer from free running circadian cycles with resultant insomnia and reduced performance [24]. None of this is controversial. The new part of this overall debate, however, relates to blue light sensitive retinal ganglion cells (photoreceptive retinal ganglion cells – pRGCs) which have only recently been discovered and antedate the entire blue filtering IOL controversy [25]. The pRGCs are the primary mediators of numerous circadian, neuroendocrine and neurobehavioral responses. pRGCs provide lighting information to diverse non-visual (non-image-forming) brain centers including the suprachiasmatic nuclei (SCN) which serve as the body’s master biological clock. The SCN exert functional control over circadian aspects of physiology. The timing and strength (amplitude) of SCN rhythmic signals are affected by light exposure. Light deficiency may attenuate SCN function and its control of physiological and hormonal rhythms which in turn can result in a cascade of adverse events. The pRGCs peak excitation is in the blue range (about 460nm) so that blue filtering IOLs would decrease excitation of these blue light specific ganglion cells. Decreased excitation could translate into disturbed circadian cycles with the potential for aggravation of many common age-associated problems including insomnia, decreased performance, impaired cognition, and depression [26]. The real question is do we have any evidence that any of this is clinically important? While still theoretical at this time, the calculated decrease in excitation of these regulating blue sensitive ganglion cells is in the same range as improvements in insomnia that have been documented in elderly patients after cataract surgery [27, 28]. At this point there is no definitive clinical study proving that blue filtering IOLs impact insomnia, and one small retrospective study that

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did not show a difference in reported insomnia between clear and blue filtering IOLs [29]. Unfortunately, this study has neither the power nor the rigor to definitively clarify this controversy. Of the three blue filtering IOL concerns, however, impact on circadian rhythm would appear to be the one, although still theoretical, potentially of greatest clinical importance. In conclusion, what we can say about blue filtering IOL controversies at this time is that we would need a very large randomized clinical trial to definitively answer the question of whether or not macular degeneration is impacted by any filtering of blue light. However, with the AREDS study and their long term follow up of the natural history of macular degeneration after cataract surgery, there is no evidence that blue filtering IOLs have any impact on macular degeneration and, therefore, it would appear to be extremely unlikely that blue light has any meaningful clinical impact on macular degeneration. Regarding blue filtering IOLs and uveal melanoma, the evidence is theoretical and based on melanoma cell culture studies and epidemiological evidence with welders. Welders risk is theoretically more likely to be to UV-B exposure than to blue light. It would take an impossibly long and large study to show whether filtering blue light might make a difference, and, even if there is a difference, we would have to see if any difference is of clinical importance. Furthermore, if blue light is an uveal melanoma concern, wearing good sunglasses would be a better preventative measure, and they carry no potential downsides. In regard to potential downsides of blue filtering IOLs, it is clear that color vision perceptual concerns with blue blocking IOLs as well as night vision are unlikely to be of much clinical importance even though both are impacted to some extent by blue light filtration. Impact on circadian rhythm would appear to be the theoretical greater concern but, again, we have no clinical study at this time that directly supports this conclusion. The two Asplund articles are the closest evidence we have, and both are indirect evidence only [3, 4]. So the disadvantages, with the possible exception of impact on our circadian cycle, appear minimal, and the evidence for efficacy is weak at best. Therefore, these

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controversies, even though we do have some clarifying information at this time, will continue. ACKNOWLEDGEMENTS Declared none. CONFLICT OF INTEREST The author confirms that this chapter content has no conflicts of interest. REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]

Schwiegerling J. Blue-light-absorbing lenses and their effect on scotopic vision. J Cataract Refract Surg. 2006;32:141-4. Sparrow J, Miller AS, Zhou J. Blue light-absorbing intraocular lens and retinal pigment epithelium protection in vitro. J Cataract Refract Surg. 2004;30:873-88. Taylor HR, West S, Munoz B, et al. The long-term effects of visible light on the eye. Arch Ophthalmol. 1992;110:99-104. Tomany SC, Cruickshanks KJ, Klein R, et al. Sunlight and the 10-year incidence of agerelated maculopathy: the Beaver Dam Eye Study. Arch Ophthalmol. 2004;122:750-7. Arnarsson A, Sverrisson T, Stefansson E, et al. Risk factors for five-year incident agerelated macular degeneration: the Reykjavik Eye Study. Am J. Ophthalmol. 2006;142:41928. Clemons TE, Milton RC, Klein R, et al. Risk factors for the incidence of Advanced Agerelated Macular Degeneration in the Age-related Eye Disease Study (AREDS) AREDS report no. 19. Ophthalmology. 2005;112:533-9. Delcourt C, Carriere I, Ponton-Sanchez A, et al. Light exposure and the risk of age-related macular degeneration: the Pathologies Oculaires Lie´es a` l’Age (POLA) study. Arch Ophthalmol. 2001;119:1463-88. Fletcher AE, Bentham GC, Agnew M, et al. Sunlight exposure, antioxidants, and agerelated macular degeneration. Arch Ophthalmol. 2008;126:1396-403. Hirvela H, Luukinen H, Laara E, et al. Risk factors of age-related maculopathy in a population 70 years of age or older. Ophthalmology. 1996;103:871-7. McCarty CA, Mukesh BN, Fu CL, et al. Risk factors for age-related maculopathy: the Visual Impairment Project. Arch Ophthalmol. 2001;119:1455-62. Darzins P, Mitchell P, Heller RF. Sun exposure and age-related macular degeneration. An Australian case-control study. Ophthalmology. 1997;104:770-66. Hyman LG, Lilienfeld AM, Ferris FL 3rd, et al. Senile macular degeneration: case-control study. Am J Epidemiol. 1983;118:213-27. Khan JC, Shahid H, Thurlby DA, et al. Age related macular degeneration and sun exposure, iris colour, and skin sensitivity to sunlight. Br Ophthalmol. 2006;90:29--32.

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[14] [15]

[16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29]

Randall J. Olson

Risk factors for neovascular age-related macular degeneration. The Eye Disease Casecontrol Study Group. Arch Ophthalmol. 1992;110:1701-8. Abrera-Abeleda MA, Nishimura C, Smith JL, Sethi S, McRae JL, Murphy BF, Silvestri G, Skerka C, Józsi M, Zipfel PF, Hageman GS, Smith RJ. Variations in the complement regulatory genes factor H (CFH) and factor H related 5 (CFHR5) are associated with membranoproliferative glomerulonephritis type II (dense deposit disease). J Med Genet. 2006 Jul;43(7):582-9. Epub 2005 Nov 18.. Chew EY, Sperduto RD, Milton RC, et al. Risk of advanced age-related macular degeneration after cataract surgery in the Age-related Eye Disease Study: AREDS report 25. Ophthalmology. 2009;116:297-303. Marshall JC, Gordon KD, McCauley CS, et al. The effect of blue light exposure and use of intraocular lenses on human uveal melanoma cell lines. Melanoma Res. 2006; 16: 537--41. Schmidt-Pokrzywniak A, Stang A, Bornfeld N, et al. Risk of uveal melanoma. Ophthalmology. 2007;114:1418. Wirtitsch MG, Schmidinger G, Prskavec M, et al. Influence of blue-light-filtering intraocular lenses on color perception and contrast acuity. Ophthalmology. 2009;116:39-45. Olson MD, Miller KM. Implanting clear intraocular lens in one eye and yellow lens in the other eye: case series. Am J Ophthalmol. 2006;141:957-99. Mainster MA. Blue-blocking intraocular lenses and pseudophakic scotopic sensitivity. J Cataract Refract Surg. 2006; 32:1403-44. Turner PL, Mainster MA. Circadian photoreception: ageing and the eye’s important role in systemic health. Br J Ophthalmol. 2008;92:1439-44. Lewy AJ, Emens JS, Lefler BJ, et al. Melatonin entrains free-running blind people according to physiological dose-response curve. Chronobiol Int. 2005;22:1093-106. Dijk DJ, Neri DF, Wyatt JK, et al. Sleep, performance, circadian rhythms, and light-dark cycles during two space shuttle flights. Am J Physiol Regul Intergr Comp Physiol. 2001;281:R1647-64. Berson DM, Dunn FA, Takao M. Phototransduction by retinal ganglion cells that set the circadian clock. Science. 2002;295:1070-3. Turner PL, Van Someren EJ, Mainster MA. The role of environmental light in sleep and health: effects of ocular aging and cataract surgery. Sleep Med Rev. 2010;14:269-80.3. Asplund R, Ejdervik Lindblad B. The development of sleep in persons undergoing cataract surgery. Arch Gerontol Geriatr. 2002;35:179-87. Asplund R, Lindblad BE. Sleep and sleepiness 1 and 9 months after cataract surgery. Arch Gerontol Geriatr. 2004; 38:69-75. Landers JA, Tamblyn D, Perriam D. Effect of blue-light-blocking intraocular lens on the quality of sleep. J Cataract Refract Surg. 2009;35:83-8.

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CHAPTER 4 Toric Intraocular Lenses for Pseudophakia Jaime Javaloy1, 2,* and Jorge L. Alió1, 2 1

Department of Cornea and Refractive Surgery, VISSUM, Instituto Oftalmológico de Alicante, Spain and 2Miguel Hernández University School of Medicine, Alicante, Spain Abstract: After the development of non-astigmatic cataract surgery, a new generation of intraocular lenses, able to manage previously existing corneal astigmatism, has experienced a great expansion. Different choices for the surgeon include the possibility of correcting simultaneously presbyopia, special designs for sulcus implantations and customized dioptric powers. The keys to success when implanting these IOLs are correct power calculation and correct surgical management with pre-surgical marking of the cylindrical axis and ensuring correct alignment at the end of the procedure.

Keywords: Astigmatism, correction, toric IOL. INTRODUCTION Astigmatism as a refractive error is a visually disabling problem affecting the general population, most especially those afflicted with cataracts. Around 15% to 20% of cataract patients have at least 1.5 diopters (D) of corneal or refractive astigmatism [1]. Besides treatment of diseases, modern understanding of medicine involves improvement in quality of life. This has led to the growing impact of refractive surgery on a worldwide basis. The current trend to minimize residual refractive defects after cataract surgery has promoted the development of different models of pseudophakic IOLs able to correct both cylindrical and spherical defects and even presbyopia. Nowadays, cataract extraction is considered not only a therapeutic solution; but also a refractive solution for correcting astigmatic errors [2, 3]. *Address correspondence to Jaime Javaloy: Instituto Oftalmológico de Alicante. Avda Denia, sn. Edificio VISSUM, Alicante, Spain; Tel: 00-34-965 150 025; E-mail: [email protected] Guy Kleinmann, Ehud I. Assia and David J. Apple (Eds) All rights reserved-© 2014 Bentham Science Publishers

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Two major milestones in cataract surgery in the last decade have contributed greatly to the reduction of postoperative astigmatism. One is the shift to smaller incision sizes, which reduced the need for suturing, thus decreasing induced astigmatism and corneal aberrations [4, 5]. Microincision cataract surgery (MICS), which by definition is surgery performed through incisions of less than 2.0mm, has played a leading role in this progression [4]. These astigmaticallyneutral MICS incisions not only reduce surgical trauma but more importantly, decrease surgically induced astigmatism (SIA), resulting in better corneal optical quality, and thus improving visual outcome. Another significant development is the emergence of surgical options to correct pre-existing astigmatism simultaneously to cataract surgery. Corneal astigmatism, to date, can, be managed intraoperatively by: -

Selective positioning of the phacoemulsification incision,

-

Astigmatic keratotomy using corneal or limbal relaxing incisions (LRIs),

-

Excimer laser refractive procedures such as photorefractive keratectomy, laser in situ keratomileusis and laser-assisted subepithelial keratomileusis;

-

And implantation of toric pseudophakic posterior chamber IOL’s [6, 7].

However, correction of astigmatism either by flattening the cornea through positioning the incisions or by astigmatic keratotomy may lead to unpredictable outcomes, variable healing responses and may have long-term mechanical instability [8-11]. Furthermore, correction by LRI is limited to only up to a few dioptres [12]. Excimer laser refractive surgery on the other hand can be costprohibitive or contraindicated in pathological or abnormal corneas [8]. MingoBotin et al. demonstrated the superiority of toric IOL over peripheral relaxing incision for corneal cylinder ranging between 1.0 and 3.0 D [13], while Poll et al. showed this only for corneal cylinder of 2.26 D and above [14].

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In contrast, toric IOL implantation offers a predictable, stable and safer way to reduce pre-existing astigmatism. Combined with small incisions, cataract surgery techniques can provide a greater opportunity to correct cylindrical errors intraoperatively, thus improving visual quality leading to spectacle independence. The concept of neutralizing congenital corneal astigmatism using a rigid PMMA toric intraocular lens was first developed by Shimizu in 1992, the same year in which Grabow and Shepherd implanted the first foldable silicone toric plate haptic IOL. Essential pearls for achieving successful surgery with a toric lens are appropriate selection of IOL power and adequate rotational stability which avoid the induction of astigmatism and reduce preexisting astigmatism [4, 11, 15]. INDICATIONS AND PREOPERATIVE CANDIDATES FOR TORIC IOLs

ASSESSMENTS

OF

Except for the specific contraindications detailed below, there are no other reasons besides financial ones for not implanting toric IOLs in eyes suffering corneal astigmatism greater than 1.5D in the “non-astigmatic cataract surgery age”. These contraindications can include: -

Irregular corneal astigmatism.

-

Any condition which could lead to intra or postoperative misalignment of the axis or inadequate centring of the optics such as:

-

o

Evidence or suspicion of zonular instability.

o

Crystalline lens subluxation.

o

Sulcus implant (if specific adequate models of toric IOLs for sulcus implantation are not available).

Important ectopic intraoperatively).

pupil

(pupiloplastia

should

be

performed

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-

Refractive but not corneal astigmatism (lens induced preoperative cylinder).

-

Extracapsular extraction or surgical techniques causing unpredictable surgical induced astigmatism.

Preoperative assessment does not differ from the routine exams to be done before cataract surgery except for the need to perform manual keratometry or topographic exam, discarding values obtained from automatic keratometers. PSEUDOPHAKIC TORIC IOL CALCULATIONS Most marketed toric IOLs provide online links or DVD’s which contain programs for calculating the cylindrical and spherical IOL powers after completing a questionnaire. These forms usually require keratometric values, preoperative corneal cylinder, surgically induced astigmatism (power and axis for all these parameters), axial length and anterior chamber depth. Subjective refraction data is not normally requested in order to avoid the influence of any lenticular astigmatism, which will be eliminated when the cataractous lens is removed. It is normally recommended that manual keratometry and topographic data are taken into account, but not values obtained from automatic keratometers. Manual keratometry measurements are operated depended so IOL master measurements and later the LENSTAR measurements were suggested as possible options. In the case of customized IOLs the company will send the surgeon one or a pair of personalized IOLs after offering him some expected postoperative refractions. Dr. Koch and his colleagues suggested that the axis of the cylinder with or against the rule influence the IOL calculation due to the internal (posterior cornea) cylinder (mean overestimation of WTR astigmatism of 0.5D, mean underestimation of ATR astigmatism of 0.3 D) and the on-going shift from with the rule astigmatism to against the rule astigmatism he suggested under correction of with the rule astigmatism and over correction of against the rule astigmatism. They published the Baylor nomogram to deal with the influence of the posterior cylinder.

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MODELS OF PSEUDOPHAKIC TORIC IOLs There are two models of toric IOLs with fixed torus available for the surgeon on the market. However, this obviously limits the accuracy for correcting with precision the huge amount of possible spherocylindrical combinations. A. TORIC IOLS WITH FIXED TORUS 1) Staar Toric IOL STAAR AA4203TF (Staar Surgical, Monrovia, California) The Staar Surgical Toric Lens was the first toric intraocular lens approved by the US Food and Drugs Administration (FDA) for use in the United States (1998). This plate haptic silicone lens provides a full range of spherical powers but only two cylinder power options: 2.00 and 3.50D of astigmatism at the IOL plane which corresponds to a correction of 1.54 or 2.30 respectively at the height of the cornea. Furthermore, the rotational stability of the lens has been proven to be deficient [8]. There are two sizes available: 10.8 mm in the TF version and 11.2 mm in the TL version. The lenses are designed for implantation in the capsular bag with an injector, (Fig. 1).

Figure 1: The Staar Toric IOL STAAR AA4203TF.

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2) AcrySof Toric IOL (Alcon Laboratories, Inc., Fort Worth, Texas) The AcrySof Toric lens (Fig. 2) is composed of an acrylic polymer that has UV and blue-light absorbers. The lens is built on the same platform as the AcrySof Single-Piece monofocal models SA60AT and SN60AT IOLs (Alcon Laboratories, Inc.), 6.0 mm optic, 13.0 mm overall length, and can be folded or injected to be inserted inside the eye. The posterior surface of the IOL is marked with indentations of the haptic/optic junction that denote the flat meridian of the IOL. The marks (3 dots in each haptic/optic junction) form an imaginary line representing the plus cylinder axis. The toric lens has the same advantages regarding the design of the lens such as PCO prevention, rotational stability and ease of manoeuvre during surgery. The truncated edged optic and the adhesion of the posterior side of the lens to the posterior capsule are aimed at providing both PCO prevention and stability. Recent trials have proven that the Acrysof Toric lens offers excellent rotational stability in the capsular bag with an average lens rotation of less than 4º from the lens’ initial placement at 6 months after surgery [16]. Currently, the IOL is available in powers of +1.50D (SN60T3), +2.25D (SN60T4), and +3.00D (SN60T5) which are supposed to correct 1.03, 1.55 and 2.06 dioptres respectively at the corneal plane. Greater magnitude of astigmatism can be corrected with SN60T6, SN60T7, SN60T8 and SN60T9 (which would correct 3.75, 4.5, 5.25, and 6 D at the plane of the IOL and thus 2.57, 3.08, 3.60 and 4.11 respectively at the corneal plane), these models available outside of the USA but are still pending FDA approval. The AcrySof® IQ Toric IOL (SN6AT series) has an aspherical profile aiming to improve the quality of sight. The toric component is corrected on the posterior optical surface, while the aspheric component on the anterior optical surface. AcrySof® IQ Restor® toric IOL is also available outside of the USA. For selecting the appropriate Acrysof Toric IOL for a particular patient, the surgeon must determine the required spherical lens power, which can be done using the surgeon’s preferred method and formulae for conventional monofocal IOLs. The

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online Acrysof Toric IOL Calculator (http://www.acrysoftoriccalculator.com) can assist surgeons in selecting the correct model and optimal axis location within the capsular bag. The Calculator allows for precise surgical planning by compensating for expected surgically induced astigmatism resulting from the cataract incision [11].

Figure 2: The Acrysof Toric IOL.

B. TORIC CUSTOMIZED IOLs These toric IOLs are available or are currently under study in Europe and are an alternative for the correction of high corneal astigmatism. Most of them offer both standard stocks for usual spherocylindrical combinations and customized fabrications for special ones. 1) MicroSil Toric IOL (HumanOptics AG) A) MS6116TU and The MS6116T-Y This three-piece, foldable, toric IOL has been developed by Dr Schmidt Intraocularlinsen GmbH (St. Agustin, Germany), a company of the HumanOptics AG (Erlangen, Germany) group. There are two models of MicroSil toric IOL available (MS6116TU and the MS6116T-Y), both having identical features except for the blue light protection of the MS6116T-Y, (Fig. 3).

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Technical Features The optic of the lens is made of foldable silicone and is marked in the peripheral part with two radial lines for alienating them with the steepest axis. The lens has stable PMMA haptics in a z-design, as well as a 6-mm optic made of silicone. The z-design of the haptics have been created to increase the IOL’s rotational stability compared with conventional C-loop haptics, helping as well to balance mechanical forces during postoperative capsular bag shrinkage [17, 18]. The IOL has been designed to be implanted in the capsular bag and is available in a wide power range: from -3.00 to 31.00D (spherical power) and 2.00 to 12D (cylindrical). Surgical Technique The IOL’s overall diameter is 11.6 mm and can be implanted through an incision of 3.2 to 3.4 mm. However, careful attention must be paid during implantation of the extended Z-haptics of this toric IOL. Due to the shape of its haptics, implanting the MicroSil Toric lens is more difficult than inserting a conventional PCIOL. In a study of 36 eyes implanted with MicroSil 6116 TU by Fox et al. they proposed to create an oval-shaped capsulorhexis to avoid difficulties in implanting these lenses and thereby help to prevent complications [19].

A Fig. 3: contd….

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B Figure 3: The MicroSil toric IOL a) MS6116TU and b) MS6116T-Y.

B) MS 614 T and the MS614 T-Y (Blue Light Protection) Humanoptics has also developed these two models of toric IOLs to be implanted in the ciliary sulcus in special cases: the MS 614 T and the MS614 T-Y. The main design difference regarding MS6116TU and MS6116T-Y is the shape of the haptics: C-loop modified for sulcus fixation. As can be seen in (Fig. 4), the silicone made optic is 6 mm diameter and is marked in the steepest axis. Maximum size of the haptics is 14 mm allowing the surgeon to locate them in sulcus in special cases such as aphakia or capsular breaks. They are available in cylindrical powers of +2 to +12D, in increments of 1D.

A Fig. 4: contd….

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B Figure 4: The MS toric IOL. a) MS 614T and b) MS 614T-Y.

C) MS 714 TPB – MS 714 TPB-Y Blue Light Protection Finally, the company has marketed these two lenses for piggyback to be used for correcting spherocylindrical refractive errors after implanting them in the ciliary sulcus. The design of the haptics is C-loop modified undulated and the silicone made optics are available in cylindrical powers from +1.0 D to +6.0 D and in increments of 1.0D with spherical equivalent power of 0D, with special powers available on request, (Fig. 5) [19].

A Fig. 5: contd….

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B Figure 5: The MS 714 a) MS 714 TPB and b) MS 714 TPB-Y.

2) LENTIS Unico (LU) Oculentis The company Oculentis: Oculentis GmbH (Berlin) and Oculentis BV (Eerbeek, NL), together with its distribution partner Topcon Medical Europe, offer 3 different toric IOLs, one standard IOL and two other models with customized ranges. These foldable acrylic intraocular lenses (IOL’s) are manufactured with sharp, square edges for preventing cell migration in the posterior capsule and therefore delaying the formation of PCO. The acrylic material used for the Oculentis IOLs is called Hydrosmart, and has the following main technical features: -

Refractive index 1, 46.

-

~25% water content.

-

Hydrophobic surface.

The company has called its line of toric IOLs LENTIS Unico (LU) aiming at offering a customized compensation of virtually any corneal astigmatism, (Fig. 6).

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A

B

C

D

E Figure 6: The Oculentis designs: (a-b) Lentis LU 312 T and (c-d) Lentis LU 313 T. e) Lentis LS.

An IOL calculator form is provided for the surgeon in order to identify the right IOL parameters for the individual patient. Then the lens is manufactured to order. The LENTIS Unico is available in the plate (LENTIS LU -313 T) and the one piece open loop design (LENTIS LU -313 T). The former can be inserted through sub 2.0 mm incisions (MICS) and be implanted after making astigmatism-neutral incisions. Finally, apart from the astigmatism compensation on the anterior surface, these toric IOLs have been designed with an aspheric posterior surface.

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3) Toric IOLs of Rayner ™ This British company offers a wide range of toric IOL models with different features: A) T-flex® Toric IOLs (573 T and 623T) The main technical features are: -

Rayacryl® hydrophilic acrylic co-polymer.

-

One piece injectable design with C-haptics, (Fig. 7).

-

Square edge on the posterior side of the lens for avoiding posterior capsule opacities.

-

Customized toric power implemented on the anterior surface of the optic and radial marks along the steepest axis.

-

Designed to provide torsional stability thanks to an “anti-vaulting” haptic system (AVH technology®).

-

The model 623T is especially suitable for myopic eyes and designed for low and medium power lenses. The model 573T on the other hand, is used for normal and hyperopic eyes and for higher power lenses [20].

Figure 7: The T-flex® IOL.

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B) M-flex® Multifocal IOL Description: As refractive cylinders greater than 1.5 D create important postoperative UCVA reduction and decrease visual quality if multifocal IOLs are implanted, this lens has been marketed in 2006 to allow such multifocal implants in eyes suffering significant corneal astigmatism. This permits surgeons to increase the range of patients who can receive presbyopia correction with similar visual quality outcomes to those previously reported for lenses with similar characteristics even if an excimer laser is not available [20]. Technical Features: -

Same Rayacryl® hydrophilic acrylic co-polymer in a single piece injectable design with C-haptics and square edge on the posterior side of the lens.

-

Multifocal refractive aspheric technology with 4 or 5 annular zones depending of the IOL power to provide +2.25 or +3 D of additional refractive power at the spectacle plane, (Fig. 8).

-

Toric power on the anterior surface of the optic and radial marks along the steepest axis.

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Two different marketed models (Rayner M-flex® 588F and 638F) with a 5.75 mm optic or a 6.25 mm optic respectively.

Figure 8: The M-flex® toric IOLs.

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C) Sulcoflex® Toric 653T Conceived for correcting post-surgical or residual ametropia, Rayner has designed one of its Sulcoflex® pseudophakic supplementary IOLs for correcting refractive cylinders using piggy-back techniques. Technical Features: -

Same Rayacryl® hydrophilic acrylic co-polymer.

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One piece foldable design with modified undulated C haptics, (Fig. 9).

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Large optical zone designed to reduce the contact between lenses with round optic edge to decrease disphotopsia.

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Customized cylinder range of +1.00D to +6.00 D in 0.5D increments.

Figure 9: The Sulcoflex 653T.

4) Toric IOLs of Carl Zeiss Meditec Since 2007 the company has commercialized the IOLs of Acri.Tec AG, which manufactures two main models of toric IOLS: Acri.Comfort 646TLC and Acri.LISA toric 466TD.

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A) Acri.Comfort 646TLC Description: This aspherical bitoric IOL was the first designed to be inserted through incisions smaller than 2 mm and thus, thought to minimize the SIA. Technical Features: -

Hydrophilic acrylic polymer containing 25% water.

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Hydrophobic surface.

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Plate design with square edges in haptic and optic, (Fig. 10).

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Total diameter 11 mm.

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Optic diameter 6.0 mm.

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A-constant of 118.0.

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Spherical powers available from -10.0 to +32.0D and a cylinder powers from +1.00 to +12D (cylinder values outside the standard range are manufactured individually).

Figure 10: The Acri.Comfort 646TLC.

B) Acri.LISA Toric 466TD Description: This monotoric bifocal IOL can also be used for MICS, being injected through less than 2 mm clear corneal incisions, (Fig. 11).

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Technical Features: -

Same hydrophilic acrylic polymer with hydrophobic surface.

-

Similar plate haptics design and the same size as Acri.Comfort 646TLC.

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Monotoric aspheric correction on the anterior side.

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Bifocal aspheric correctionoin the posterior side: diffractive technology with asymmetric light distribution (far focus 65% and near focus 35%) and +3.75D of addition.

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Cylindrical correction from +1.0D to +12.0D in 0.5D increments.

Figure 11: The Acri.LISA toric 466TD.

5) Toric IOL of PysIOL The Ankoris IOL is a new design aiming to increase stability and reduce rotation of the IOL. It base on a platform that is available since 2008. The implant is a monofocal aspheric intraocular lens, made from 26% hydrophilic yellow acrylic. It is characterized by 2 symmetrical bifid C-loop haptics with open handles, which allows 4 support points inside the capsular bag, (Fig. 12). According to the company the rotational stability has been clinically investigated on 117 consecutive eyes 3 and 12 months after implantation. The absolute rotation of the lens averaged 2.5 ± 2.6°. The position of the center of the implant relative to the pupillary center expressed by a vector was 0.01 mm at 70°. Currently there is no

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peer review information regarding this IOL. The IOL received CE labeled since 2011 but do not have an FDA approval. -

Dioptric range (SE): 10 to 30 D by 0.5 D increments.

-

Cylinders at the IOL plane: 1.5, 2.25, 3, 3.75, 4.5, 5.25 and 6.0 D.

Figure 12: The Ankoris IOL.

SURGERY A) Surgical Technique Apart from the standard procedures of modern cataract surgery, the following specific actions should be taken when implanting toric IOLs: 1.

Cataract surgery must be immediately preceded by marking the horizontal axis with the patient in the seated position. Torsional movements of the eye when the patient lies down can significantly affect the accuracy of the procedure. Several external corneal or limbar markers have been designed for such purposes (Figs. 13 and 14), and recently a special electronic toric marker was developed by Dr Akahoshi, although the slit lamp can be simply used by rotating the beam light to the horizontal position (Fig. 15). Later, a corneal marker for radial keratotomy can be used for painting the axis of the toric IOL alignment. The major incision location should also be marked especially when larger incision is being used.

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2.

Non-astigmatic cataract surgery must be performed. We recommend MICS (bimanual cataract surgeries using incisions smaller than 2 mm) [4] as the technique of excellence inducing a minimum and predictable amount of SIA.

3.

The use of a cohesive OVD for implanting the toric IOL will facilitate the full aspiration of the viscoelastic material making an earlier rotation of the IOL axis difficult. For completely removing the OVD, the aspiration port must be directed over and later under the IOL in the capsular bag.

4.

A fine realignment of the toric IOL axis must be done at the end of the surgery.

Proper IOL alignment is still considered the major challenge of this technology. Several instruments were developed for correct IOL alignment such as the ORA System Intraoperative wavefront Aberometer (Wavetec Vision) based on real time intraoperative wavefront aberometry measurements after the IOL implantation to ensure correct alignment, or the SMI surgery guidance technology which reflects real time overlay marks on the patients' cornea using the surgical microscope based on the patient preoperative cornea images that were acquired while the patient was in a seating position. The system comes with an eye tracker. Preoperative high definition image of the eye with marks of the proper angle can also serve as an alternative.

Figures 13 and 14: The Codman’s marker.

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B)

Figure 15: A) The electronic toric marker, B) The CALLISTO System.

B) Trascendence of Rotational Stability The rotational stability is crucial for successful surgery. It has been estimated that approximately 1 degree of off-axis rotation results in a loss of up to 3.3% of the lens cylinder power. When the toric lens rotates 30 degrees, the cylinder power is completely lost, (Fig. 16). Different studies regarding rotational stability and its evaluation have also been reported [15, 21-24].

Figure 16: The percentage of variation in the corrected astigmatism for each degree of misalignment of the toric IOL.

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As most of the rotations occur during the first postoperative days, a careful exam including mydriasis should be performed during the earlier postoperative period. A realignment of the axis is easy to do at this time [21]. Recently Flipe et al. [25]. using a mathematical model showed encouraging results that toric IOL rotations of less than 10 degrees will induce a changed the eye's refraction of less than 0.50 diopter. METHODS OF EVALUATION OF THE RESULTS: VECTOR ANALYSIS There are several ways of analyzing astigmatic data [21, 26-30]. Descriptive statistics cannot be applied to polar coordinates because the cylinder is not an independent (orthogonal) parameter in magnitude and axis. Therefore, the polar values should be converted to Cartesian values (each data point must be converted into an x–y coordinate system). This has been taken into account by many authors such as Holladay, Naeser and Hjotdal, Thibos and Horner, Alpins among others [27, 31-34]. The Alpins method of vector analysis has been described extensively in many studies and peer review articles. We recommend this method because it considers two aspects. First, the vertex adjustment for the refractions performed at the spectacle plane or in the phoropter avoiding measurement errors when working with keratometric data. Secondly, the angles of astigmatism are doubled so that 0º and 180º are equivalent [21, 31, 35-37]. The Alpins method allows a reliable analysis of the results of astigmatic treatment by both refractive and corneal measurements, represented as vectors [21]. Each data point is converted into an x-y coordinate system, which allows the application of standard descriptive statistics. This method uses three fundamental vectors, namely, target induced astigmatism vector (TIA), surgically induced astigmatism (SIA) and difference vector (DV). The following are definitions of astigmatism vectors used in this chapter [21]: 1.

Target induced astigmatism vector (TIA). The astigmatism change, by magnitude and axis, the surgery intended to induce.

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2.

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Surgically induced astigmatism vector (SIA). The amount and axis of astigmatism change that the surgery actually induced. Correction index (CI). Calculated by the ratio of SIA to the TIA by dividing SIA by TIA. The CI is preferably 1.0. It is greater than 1.0 if overcorrection has occurred and less than 1.0 if there is undercorrection. Magnitude of error (ME). The arithmetic difference between the magnitudes of the SIA and TIA. The ME is positive for overcorrections and negative for undercorrections. Angle of error (AE). The angle described by the vectors of the achieved correction (SIA) versus the intended correction (TIA). The AE is positive if the SIA is on an axis counterclockwise (CCW) to where the TIA is and negative if the SIA is clockwise (CW) to the TIA.

3.

Difference vector (DV). The induced astigmatic change (by magnitude and axis) that would enable the initial surgery to achieve its intended target. It is the absolute measure of success. The ideal DV score is 0.

4.

Index of success (IOS). Calculated by dividing the DV by the TIA. The IOS is a relative measure of success and is preferably 0.

5.

Percentage of astigmatism corrected. It is CI multiplied by 100.

6.

Percentage success of astigmatism surgery. Calculated by multiplying 1.00-IOS by 100.

The method is marketed in a software package called ASSORT (Alpins Statistical System for Ophthalmic Refractive Surgery Techniques) allows the surgeon to perform the vectorial analysis of individual cases. RESULTS Although a wide choice of different models of toric IOLs is available today on the market, a relatively short list of indexed papers compare the efficacy, safety and predictability of these models.

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Perhaps due to their FDA acceptance, the Toric IOLs with fixed torus (Staar Toric IOL and Acrysof Toric IOL) constitute most of the information reported. The first model of Staar Toric IOL was analyzed in 1994 suffering almost 40% of the implant rotations greater than 6º [38]. On the other hand, the current model of this lens has proven to reach a rotational stability between 0º and 10º for 90% of cases and displacements smaller than 5º in 72% of implants [39]. Even when the first models of Staar Toric IOLs were uesd, efficacy and predictability of their implantation demonstrated to be greater than conventional implants associated to incisional surgical techniques [40]. The FDA approved Acrysof Toric IOL (Alcon Laboratories, Inc., Fort Worth, Texas) has undergone a sizeable proportion of comparative and controlled trials [41-45]. This toric IOL has proven to be accurate for correcting low to moderate degrees of astigmatism, with the vector analysis of attempted versus achieved correction showing that 100% of eyes were within +/-1.00 D and 80% and 93.9% were within +/-0.50 D for J(0) and J(45), respectively [41]. Rotational stability has been demonstrated for the different models of Acrysof Toric IOL with the mean IOL misalignment being estimated at 2.5 +/- 2.1 degrees after implanting SN60T3, 3.5 +/- 2.3 degrees for SN60T4, and 4.1 +/- 3.5 degrees for SN60T5 [42]. Furthermore, it has been reported that this rotational stability is greater for Acrysof Toric IOL than when such parameter is analyzed for retrospective series of Staar Toric IOL implants [43]. A later study of the same Alcon IOLs showed up to 5 degrees misalignment of the IOL axis from the target axis in 90.8% of the eyes and up to 10 degrees misalignment in 99.1% of the eyes. 90.2% of the eyes had 1.00 D or less residual refractive astigmatism, 85.4% had 0.75 D or less, 70.7% had 0.50D or less and 45.7% had 0.25 D or less [46]. A study of the Acrysof Toric IOL SA60T3-5, showed mean IOL rotation of 3.8 degrees (range 0-20 degrees). One year after the surgeries 78% of the IOLs were found to rotate 5 degrees or less and 93.4% of the eyes rotated 10 degrees or less. The mean residual refractive cylinder was 0.59 D. 97.5% of the eyes had 1.5 D or less residual refractive astigmatism, 88.0% had 1.0 D or less, 53.35% had 0.5 D or less, and 25.6% had no residual refractive astigmatism. Six months after the surgery 61.0% of the patients reported spectacle independence for distant vision in comparison with 36.4% of a control non toric IOL group [47].

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A study using the whole Alcon toric IOLs range (SN60T3-T9) demonstrated mean errors in reference axis marking of 2.4 +/- 0.8 degrees, alignment axis marking of 3.3 +/- 2.0 degrees, and IOL alignment of 2.6+/-2.6 degrees, which result in a total error of 4.9 +/- 2.1 degrees [48]. Two other studies using the higher range of the Alcon toric IOLs (SN60T6-9) found residual cylinder of less than 0.75 D in 62% of the eyes and less than 1.00 D in 81% of the eyes. The mean IOL misalignment was found to be 3.2+/-2.8 degrees in this series [49], and residual cylinder of less than 1.00 D in 92.5% of the eyes with 100% of the eyes within 1.50 D. Median IOL misalignment was found to be 2.0 degrees (range 0 to 12 degrees). The alignment was found to be 0 to 4 degrees in 77.5% of the eyes, between 5 and 9 degrees in 20% of the eyes, and 12 degrees in 2.5% of the eyes [50]. A study compared the effectiveness of paired opposite clear corneal incisions versus Acrysof Toric IOL for managing pre-existent astigmatism. In the toric IOL group, 95% and 100% of eyes were within +/-0.50 D for J(0) and J(45), respectively. In the OCCI group, the percentages were 70% and 100%, respectively [44]. The majority of the reports about results of the use of customized toric IOLs correspond to communications in congresses or references in tabloids either web page of the companies which market the IOLs. After implanting the MicroSil MS 6116 TU it has been reported a rotation of the lenses about 2.6º on average, which decreased the astigmatic correction by approximately 9% [51]. Regarding predictability, it has been communicated a percentage of correction in the astigmatism of 73% being the cylinder in the postoperative refraction 0.75D or less in 86% of cases [19]. Cases presenting high astigmatism has been treated by implanting MicroSil MS 6116 TU, So, Schipper likewise reported two cases with 12.00D and 18.00D of preexisting corneal astigmatism who underwent cataract surgery [17]. After implanting the MicroSil toric IOL, their refractive astigmatism was reduced to values of between zero and 1.00D. After two years follow-up, no rotation or decentration was observed [51]. Descriptive series about the predictability of the Rayner T-flex® toric IOL have been communicated during recent meetings. Rotational stability was always

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inferior to 10º in all communicated series and the mean residual refractive cylinder varied from 0.3 to 0.95 D in a wide range of preoperative astigmatic defects [52, 53]. A recent study of the T-flex® 623T showed a reduction of the mean preoperative cylinder from 3.35+/-1.20 D to 0.95+/-0.66 D 4 months after the surgery. The mean difference between the intended axis and the achieved cylinder axis was found to be 3.4 degrees (range 0 to 12 degrees). All the eyes were found to be within 15 degrees of the intended axis, and 91% were within10 degrees [54]. Our investigational team conducted a study which involved 21 eyes suffering astigmatism between 2 and 8.5 D which were operated by employing microincision cataratact surgery and lately implanted Acri.Comfort 646TLC IOL. The percentage of astigmatism corrected was 91% and the residual refractive cylinder was -0.45 ± 0.63D. The mean keratometric changes before surgery and after surgery were not statistically significant due to the no-astigmatic surgical technique [55]. Shah et al. showed a strong correlation between axial length and IOL rotation 6 months after the surgery with a greater rotation in eyes with longer axial length. The alignment of the IOL in the capsular bag (vertical, horizontal, or oblique) had no influence on rotation [56]. CONCLUSIONS Pseudophakic toric IOLs appear today as effective, safe, quite predictive and efficient (in terms of cost/benefit ratio) tools for managing pre-existing astigmatism during cataract surgery. As postoperative astigmatism has a deep impact in the visual function of the operated patient, it seems reasonable to ask how adaptative optics, optical aberration control, management of presbyopia or other complex techniques have been developed before these kinds of lenses. The answer to this question is clear: until today, we have not been able to control the surgically induced astigmatism. The unpredictable effect of long incisions over the refractive cylinder made illogical thinking in fabricate lenses able to correct both, spherical and cylindrical refractions. The implantation of minimal or microincision cataract surgery techniques as the usual practice have promoted the development and marketing of pseudophakic toric IOLs. The combination of this technology with

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others aimed at avoiding presbyopia, optical aberrations or refining postoperative defects (adjustable IOLs) is currently avialble only outside of the USA. ACKNOWLEDGEMENTS Declared none. CONFLICT OF INTEREST The authors declare no proprietary or financial interest about any of the products used in the study. REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15]

Hoffer KJ. Biometry of 7, 500 cataractous eyes. Am J Ophthalmol 1980;90:360-368. Kershner RM. Refractive cataract surgery. Curr Opin Ophthalmol 1998;9:46-54. Koch MJ, Kohnen T. Refractive cataract surgery. Curr Opin Ophthalmol 1999;10:10-15. Elkady B, Pinero D, Alio JL. Corneal incision quality: microincision cataract surgery versus microcoaxial phacoemulsification. J Cataract Refract Surg 2009;35:466-474. Elkady B, Alio JL, Ortiz D, Montalban R. Corneal aberrations after microincision cataract surgery. J Cataract Refract Surg 2008;34:40-45. Gills JP. Treating astigmatism at the time of cataract surgery. Curr Opin Ophthalmol 2002;13:2-6. De Silva DJ, Ramkissoon YD, Bloom PA. Evaluation of a toric intraocular lens with a Zhaptic. J Cataract Refract Surg 2006;32:1492-1498. Till JS, Yoder PR, Jr., Wilcox TK, Spielman JL. Toric intraocular lens implantation: 100 consecutive cases. J Cataract Refract Surg 2002;28:295-301. Gills JP. Cataract surgery with a single relaxing incision at the steep meridian. J Cataract Refract Surg 1994;20:368-369. Muller-Jensen K, Fischer P, Siepe U. Limbal relaxing incisions to correct astigmatism in clear corneal cataract surgery. J Refract Surg 1999;15:586-589. Horn JD. Status of toric intraocular lenses. Curr Opin Ophthalmol 2007;18:58-61. Nichamin LD. Treating astigmatism at the time of cataract surgery. Curr Opin Ophthalmol 2003;14:35-38. Mingo-Botin D, Munoz-Negrete FJ, Won Kim HR, Morcillo-Laiz R, Rebolleda G, Oblanca N. Comparison of toric intraocular lenses and peripheral corneal relaxing incisions to treat astigmatism during cataract surgery. J Cataract Refract Surg 2010;36:1700-1708. Poll JT, Wang L, Koch DD, Weikert MP. Correction of astigmarism during cataract surgery: toric intraocular lens compared to peripheral corneal relaxing incisions. J Cataract Refract Surg 2011;27:165-171. Weinand F, Jung A, Stein A, Pfutzner A, Becker R, Pavlovic S. Rotational stability of a single-piece hydrophobic acrylic intraocular lens: new method for high-precision rotation control. J Cataract Refract Surg 2007;33:800-803.

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[16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32] [33] [34] [35] [36] [37] [38] [39]

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Lane SS, Ernest P, Miller KM, Hileman KS, Harris B, Waycaster CR. Comparison of clinical and patient-reported outcomes with bilateral AcrySof toric or spherical control intraocular lenses. J Refract Surg 2009;25:899-901. Gerten G, Michels A, Olmes A. [Toric intraocular lenses. Clinical results and rotational stability]. Ophthalmologe 2001;98:715-720. Gerten G. Foldable toric IOL. Paper presented at: The ESCRS XIV Congress; September 2001; Amsterdam, The Netherlands. 2001. Fox P. Lens Results Promising for Astigmatism Reduction. Cataract and Refractive Surgery Today Europe. Becker KA, Martin M, Rabsilber TM, Entz BB, Reuland AJ, Auffarth GU. Prospective, non-randomised, long term clinical evaluation of a foldable hydrophilic single piece intraocular lens: results of the Centerflex FDA study. Br J Ophthalmol 2006;90:971-974. Alpins N. Astigmatism analysis by the Alpins method. J Cataract Refract Surg 2001;27:3149. Nichamin LD. Astigmatism control. Ophthalmol Clin North Am 2006;19:485-493. Novis C. Astigmatism and toric intraocular lenses. Curr Opin Ophthalmol 2000;11:47-50. Shimizu K, Misawa A, Suzuki Y. Toric intraocular lenses: correcting astigmatism while controlling axis shift. J Cataract Refract Surg 1994;20:523-526. Felipe A, Artigas JM, Diez-Ajenjo A, Garcia-Domene C, Alcocer P. Residual astigmatism produced by toric intraocular lens rotation. J Cataract Refract Surg 2011;37:1895-1901. Huang D, Stulting RD, Carr JD, Thompson KP, Waring GO, III. Multiple regression and vector analyses of laser in situ keratomileusis for myopia and astigmatism. J Refract Surg 1999;15:538-549. Thibos LN, Horner D. Power vector analysis of the optical outcome of refractive surgery. J Cataract Refract Surg 2001;27:80-85. Harris WF. Analysis of astigmatism in anterior segment surgery. J Cataract Refract Surg 2001;27:107-128. Kaye SB, Patterson A. Analyzing refractive changes after anterior segment surgery. J Cataract Refract Surg 2001;27:50-60. Naeser K, Hjortdal J. Multivariate analysis of refractive data: mathematics and statistics of spherocylinders. J Cataract Refract Surg 2001;27:129-142. Alpins NA. A new method of analyzing vectors for changes in astigmatism. J Cataract Refract Surg 1993;19:524-533. Holladay JT, Cravy TV, Koch DD. Calculating the surgically induced refractive change following ocular surgery. J Cataract Refract Surg 1992;18:429-443. Holladay JT, Moran JR, Kezirian GM. Analysis of aggregate surgically induced refractive change, prediction error, and intraocular astigmatism. J Cataract Refract Surg 2001;27:6179. Naeser K. Assessment of surgically induced astigmatism; call for an international standard. J Cataract Refract Surg 1997;23:1278-1280. Alpins NA. Vector analysis of astigmatism changes by flattening, steepening, and torque. J Cataract Refract Surg 1997;23:1503-1514. Alpins NA. New method of targeting vectors to treat astigmatism. J Cataract Refract Surg 1997;23:65-75. Alpins NA, Goggin M. Practical astigmatism analysis for refractive outcomes in cataract and refractive surgery. Surv Ophthalmol 2004;49:109-122. Sanders DR, Kraff MC, Shepherd J, Grabow B. Clinical investigation of a toric IOL: FDA study update. In: Slak Inc, ed. Surgical treatmen of astigmatism. 1994;159-164. Chang DF. Early rotational stability of the longer Staar toric intraocular lens: fifty consecutive cases. J Cataract Refract Surg 2003;29:935-940.

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[40] [41] [42] [43] [44] [45] [46] [47] [48] [49] [50] [51] [52] [53] [54] [55] [56]

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Sun XY, Vicary D, Montgomery P, Griffiths M. Toric intraocular lenses for correcting astigmatism in 130 eyes. Ophthalmology 2000;107:1776-1781. Mendicute J, Irigoyen C, Aramberri J, Ondarra A, Montes-Mico R. Foldable toric intraocular lens for astigmatism correction in cataract patients. J Cataract Refract Surg 2008;34:601-607. Bauer NJ, de Vries NE, Webers CA, Hendrikse F, Nuijts RM. Astigmatism management in cataract surgery with the AcrySof toric intraocular lens. J Cataract Refract Surg 2008;34:1483-1488. Chang DF. Comparative rotational stability of single-piece open-loop acrylic and platehaptic silicone toric intraocular lenses. J Cataract Refract Surg 2008;34:1842-1847. Mendicute J, Irigoyen C, Ruiz M, Illarramendi I, Ferrer-Blasco T, Montes-Mico R. Toric intraocular lens versus opposite clear corneal incisions to correct astigmatism in eyes having cataract surgery. J Cataract Refract Surg 2009;35:451-458. Ruiz-Mesa R, Carrasco-Sanchez D, Diaz-Alvarez SB, Ruiz-Mateos MA, Ferrer-Blasco T, Montes-Mico R. Refractive lens exchange with foldable toric intraocular lens. Am J Ophthalmol 2009;147:990-6, 996. Ahmed II, Rocha G, Slomovic A, et al. Visual function and patient experiance after bilateral implantation of toric intraocular lenses. J Cataract Refract Surg 2010;36:609-616. Holland E, Lane S, Hoen JD, Ernest P, Arleo R, MIller KM. The Acrysof toric intraocular lens in dubjects with cataracts and corneal astigmatism A randomized, subjective-masked, parallel-group, 1 year study. Ophthalmology 2011;117:2104-2111. Visser N, Berendschot TTJM, Bauer NJC, Jurich J, Kersting O, Nuijts RMMA. Accuracy of toric intraocular lens implantation in cataract and refractive surgery. J Cataract Refract Surg 2011;37:1394-1402. Visser N, Ruiz-Mesa R, Pastor F, Bauer NJC, Nuijts RMMA, Montes-Mico R. Cataract surgery with toric intraocular lens implantation in patients with high corneal astigmatism. J Cataract Refract Surg 2011;37:1403-1410. Hoffmann P, Auel S, Hutz W. Results of higher power toric intraocular lens implantation. J Cataract Refract Surg 2011;37:1411-1418. Gerten G, Schipper I. Toric correction of high astigmatism. Available http://www.crstodayarchive.com/03_archive/0303/211.html. Peckar C. Rayner Centreflex Toric IOL shows stability in astigmatic eyes. Black D. The emerging importance of the toric IOLs. Eurotimes educational symposium.The rol of premium IOLs in modern Lens surgery.XXVI Congress of the ESCRS, Berlin, Germany.September 2008. Entabi M, Harman F, Lee N, Bloom P. Injectable 1-piece hydrophilic acrylic toric intaocular lens for cataract surgery: efficacy and stability. J Cataract Refract Surg 2011;37:235-240. Pongo V, Alió JL, El Kady B. Microinsicion Cataract Surgery – MICS (sub 2 mm) with toric intraocular lens ACRI.COMFORT 646 for the management of astigmatism. J Cataract Refract Surg 2010;36:44-52. Shah GD, Praveen MR, Vasavada AR, Vasavada VA, Rampal G, Shastry LR. Rotational stability of a toric intraocular lens: influence of axial length and alignment in the capsular bag. J Cataract Refract Surg 2012;38:54-59.

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CHAPTER 5 Multifocal IOLs – Clinical Indication and Pearls for Successful Application and Clinical Results Gerd U. Auffarth1,* Adi Abulafia2 and Guy Kleinmann2,3 1

International Vision Correction Research Centre (IVCRC), Dept. of Ophthalmology, Univ. of Heidelberg, INF 400, 69120 Heidelberg, Germany; 2 Ein-Tal Eye Center, Tel Aviv, Israel and 3Ophthalmology Department, Kaplan Medical Center, Rehovot, Israel Abstract: Cataract surgery has undergone dramatic improvements, rehabilitation is quick, the complication rate is decreasing, IOL material and calculations have improved, and excellent uncorrected distance visual acuity can be expected in most cases where the eye is healthy. Currently, one of the major challenges of cataract surgery is presbyopia correction. Patients expect excellent distance vision, as well as spectacle freedom for near vision. Multifocal IOLs, better termed bifocal IOLs, and recently trifocal IOLs, create 2 or 3 foci. These IOLs have improved in recent years and can provide a good solution for those who seek to reduce spectacle dependency. However, the downside to these IOLs includes halo, glare and reduced distance vision contrast sensitivity. In this chapter, we will review the basic principles of multifocal IOLs and their clinical results. It is worthy to note that currently only the Alcon AcrySof ReSTOR (Fort Worth, TX, USA) MIOL and the Tecnis ZMB00 (Abbott Laboratories, Inc., Abbott Park, IL, USA) MIOL have FDA approval and a large database of detailed clinical results.

Keywords: Presbyopia, near vision, intermediate vision, multifocal IOL, bifocal IOL, trifocal IOL, range of vision, complication, halo, glare. INTRODUCTION Due to the development of special intraocular lenses (IOL), so-called Premium IOLs, and improved calculation formulas, modern cataract and refractive surgery have made postoperative independence from eyeglasses possible. The demand for *Address correspondence to Gerd U. Auffarth: International Vision Correction Research Centre (IVCRC), Dept. of Ophthalmology, Univ. of Heidelberg, INF 400, 69120 Heidelberg, Germany; Tel: +49-6221-566604; Fax: +49-6221-562254; E-mails: [email protected]; [email protected] Guy Kleinmann, Ehud I. Assia and David J. Apple (Eds) All rights reserved-© 2014 Bentham Science Publishers

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personalized procedures are high, particularly in the field of refractive lens exchange. In particular, the field of presbyopia correction, is gaining increasing importance [1-8]. Multifocal intraocular lenses (MIOL) have been developed since the 1980s by 3M Corporation, IOLAB, Storz, and Pharmacia. For these IOLs, the near zones of both designs are central and the distance portions are peripheral. In recent years, significant advances in the design of multifocal IOLs have resulted in corresponding improvements in clinical results. These IOLs are rotationally symmetric and are based on the principles of diffraction and/or refraction of light or on a combination of these two principles. The Array lens (AMO, Abbott Laboratories, Inc.) was the first to receive FDA approval. The optical design of this distance-dominant lens was zonal-progressive, with five concentric zones. The addition for near vision is +3.5 D. Near segment and trifocal technology have been recently introduced. DIFFRACTIVE OPTICAL PRINCIPLES Light travels in a straight line, but when it encounters the edge of an obstruction, it slows and spreads out slightly. This effect is called diffraction. Diffractive MIOLs [1, 2, 4-14] distribute incoming light rays to two principal focal points, distance and near vision, and are pupil-size independent. Diffractive IOLs consist of a refractive anterior lens surface and a diffractive posterior surface with concentric rings/steps. The speed of light is faster in the aqueous than in the lens material. The slower speed of light at the lens material side of the step delays the light about ½ wavelength in comparison to the aqueous side of the step. Steps of 2 µm create a grid that diffracts and separates incoming light rays into two foci – one for near and one for distance vision. Due to physics, 41% of the incoming light is distributed to each of the foci and 18% is lost due to light scatter. The step height and the distance between the steps essentially determine how much light goes to each image and the amount of the near addition. In diffractive bifocal IOLs, far focus is defined by the curvature of the lens as well as by the refractive index of the material. The steps of the diffractive gratings determine how much light goes into the far and near foci and their construction determines

Multifocal IOLs – Clinical Indication

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how strongly the light rays are bent. The step width determines the addition power, the larger the step, the lower the addition power. The step height determines the energy distribution between near and far vision. Therefore, with high steps, more light goes into the near focus and with low steps, more light goes into the far focus. Decreasing the step height from the center of the lens to the periphery providing dominant near distance vision with small pupil and dominant far distance vision with large pupil. Examples of diffractive MIOLs include the three-piece Tecnis ZMA00 and the single-piece version ZMB00 (Abbott Medical Optics, Santa Ana, CA, USA) and the three-piece, silicone model Diffractiva-s (HumanOptics AG, Erlangen, Germany) (Table 1). Tecnis ZMB00 The most complete data on the Tecnis Multifocal lens comes from two clinical studies that were conducted in the United States with the parent lens, the silicone version of the TECNIS® multifocal IOL, Model ZM900 [15]. The diffractive multifocal optic design of the silicone lens is the same as that of the TECNIS® multifocal 1-piece acrylic IOL, Model ZMB00. The mean UDVA was 0.13 logMAR, mean CDVA was 0.0 logMAR, and mean UNVA was 0.18 logMAR (see later Table 5). Spectacle independence, mean reading speed (wpm) and main unwanted visual phenomena data are presented later in Table 6. REFRACTIVE OPTICAL PRINCIPLES The first optic principle that was used for multifocal IOL was Refractive MIOLs which consist of different refractive zones of the IOL optical component, creating several foci dependant on the pupil diameter, with the advantage that intermediate distances have better coverage (Fig. 1). However, the ability to read very small print at 30-40 cm distance can be limited. John Pearce implanted the first MIOL in 1986 [1, 2, 16-19]. Due to relative sharp transition between the different refractive zones photopic phenomena like halo and glare are more common and more severe. The postoperative results depend on a good centration and pupil diameter [1, 2, 11, 12]. Major representative of this group of IOL include the ReZoom NXG1 model which is a three-piece IOL made of hydrophobic acrylate,

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an nd the Rayn ner M-flex 630F 6 model which is a hydrophilicc acrylic, sinngle-piece IO OL (Table 1)). Table 1: Curren nt diffractive an nd refractive multifocal m IOLss

Multifocal IOLs – Clinical Indication

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M-flex 630F (Rayner, England) In a prospective study evaluating 32 eyes of 22 patients after implantation of the Rayner M-flex 630F, the mean UDVA was 0.09 logMAR, mean CDVA was 0.03 logMAR, mean UIVA was 0.15 logMAR and the mean UNVA was 0.28 logMAR (see later Table 5). Contrast sensitivity values were found to be within the standard function under photopic and mesopic conditions. One month after surgery, 78.2% complained of halos (graded as low to moderate) and 71.9% complained about glare (graded as low); both resolved completely after one year. Among patients who had bilateral implants 70% reported never using spectacles for near vision, 80% for intermediate vision and 90% for far vision, one year after surgery [16].

Figure 1: Demonstration of the effect of a refractive MIOL on green light passing through the IOL (M-flex, Rayner). Notice that although there are 2 major foci for the light there is a lot of “background noise” around these foci which translate clinically as halo and glare.

COMBINATION OF BOTH PRINCIPLES Modern MIOL models consist of a combination of both optical principles. The Alcon AcrySof ReSTOR MIOL has an apodized diffractive/refractive optic design. The first model had a +4 D near addition (3.2 D at corneal plane, focal point at 31 cm). The later model had +3 D near addition (2.4 D at corneal plane, focal point at 41 cm) [4, 7] and recently, a +2.5 D near addition was introduced with less diffractive rings on a smaller area of the optical component of the IOL in order to reduce the disturbing photopic phenomena, improve contrast sensitivity of the far vision and improve the intermediate vision (Fig. 2). Previous diffractive lenses used the same step height for the entire zone, which also made the zone curvatures similar to one another. For the ReSTOR lens, the

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ph hase delay at a the centraal steps is ap pproximatelyy one half w wavelength w with small pu upils, which h divides thee light energ gy fairly equually betweenn the base ppower and ad dd power. As A the pupilss enlarge, ad dditional zonnes are used, with the steep heights beecoming pro ogressively smaller and d the zones less steeplyy curved. T The phase deelay at the steps is reducced, becausee the step heeights get shorter and thee distance beetween them m enlarge, which w resultts in less ligght going too the add ppower and co orresponding gly more light being useed for far vision. The T ReSTOR R IOLs havee been design ned so that the anteriorr diffractive grating is prresent only in the centraal 3.6 mm of o the optic (in the +3.00 model). Thhe highest diiffractive steep is at the lens center, which w sends half of the uusable light energy to th he near focuss. Progressiv ve peripheraal steps graduually decreaase in height,, blending in nto the perip phery, thereb by sending a decreasingg proportion of energy too the near fo ocus and a greater g propo ortion to thee distance foocus. Beyonnd the centraal 3.6 mm diiameter to th he periphery y, the optic is i refractive only and dedicated sollely to the diistance focu us. As a resu ult of this deesign, there iis equal poteential for goood vision fo or both distance and neear focus with w small ppupil situatioons, such ass distance viision in daylight or duriing near task ks, when thee accommoddative reflexx creates a sm mall pupil an nd in larger pupil situatiions, such ass during disttance focus, when the acccommodatiive reflex iss not active. In dim m mesopic condditions suchh as night drriving, the ReSTOR R lens becomes, depending d oon the patient nt's ability to dilate the pu upil, more of a distantt-dominant lens, providding good ddistance visiion while minimizing m unwanted u vissual phenom mena becausee of the relaatively smalll amounts off energy con ntributing to the near foccus point. The T Zeiss AT A LISA MIIOL (Carl Zeiss Z Medittec Group, Jena, Germ many) also co onsists of a refractive--diffractive optic surfacce profile w with a +3.755 D near ad ddition (Tab ble 2).

Fiigure 2: Demo onstration of the t effect of a diffractive MIIOL on green light passing through the IO OL (ReStor, Allcon, Hünenberg, Switzerland d). Notice thatt the 2 foci are more distinctivve with less “n noise” at the tw wo light focuss in comparison n with the refr fractive IOL inn Fig. 1. This ttranslates to leess photopic ph henomena like halo and glare.

Multifocal M IOLs – Clinical Indica ation

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Table 2: Curren nt combined difffractive and reefractive multiifocal IOLs

ReSTOR R SN N6AD1 The T most com mplete data on o the ReSTOR SN6AD D1 lens comees from a ranndomized, prrospective, multicenter clinical stu udy conductted on catarractous subjjects who were w implantted bilaterallly with eith her the AcrrySoR IQ R ReSTOR IO OL Model SN6AD3 or Model M SN6A AD1. The stu udy compareed the cliniccal outcomess achieved with w these IO OLs that diffeer only in thee amount of near add poower (+4.0 D and +3.0 D, D respectiveely) [20]. Comparable C clinical peerformance relative to near and diistance visuaal acuity werre observed for both Moodel SN6AD D1 and SN6A AD3, with beetter interm mediate visuaal acuity no oted for Mo del SN6AD D1. Patients receiving Model M SN6A AD3 (+4.0 D near add po ower) exhibi ted best neaar vision at aan average diistance of 31 cm, whilee those receiiving the M Model SN6AD D1 (+3.0 D near add po ower) exhib bited best neaar vision at an average distance of 37 cm. The SN6AD1

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model provided one Snellen line or more improvement in mean distance corrected binocular intermediate visual acuity compared to Model SN6AD3 [20]. Comparisons of contrast sensitivity measures demonstrated clinical equivalence between Model SN6AD1 and Model SN6AD3 under the lighting conditions and spatial frequencies tested. For binocular contrast sensitivity testing, at least 76.3% of patients in both models were able to see at least one grating, with the exception of mesopic with glare testing at 12 cpd (69.8%) [20]. No statistically significant differences were found in contrast or glare visual acuity under photopic or mesopic conditions in comparison to a monofocal group [21]. Spectacle independence rates between Models SN6AD1 and SN6AD3 were similar, with better than 78% of patients in both groups reporting “never” having to use glasses at any time. There was no clinically relevant increase in severe visual disturbances when implanting Model SN6AD1 compared to the Model SN6AD3. In the patient satisfaction survey, the majority of patients implanted with Model SN6AD1 (93.5%) and the control Model SN6AD3 (92.0%) indicated that they would have the lenses implanted again [20]. In the study of Alfonso et al., no patient reported severe visual phenomena; patients rated halos and glare as none to moderate [22]. Spectacle independence and main visual disturbance data are presented later in Table 6. Summary of the literature for Model SN6AD1: The mean UCDVA was -0.03 to 0.1 logMAR, mean CDVA was -0.064 to 0.02 logMAR, mean UCIVA was 0.165 to 0.27 and mean UCNVA was 0.022 to 0.2 logMAR (see later in Table 5) Recently Alcon introduced a +2.5 version aiming to reduce halos and glare. AcryLisa 366D Summary of the literature: the mean UDVA was 0.1 to 0.11 logMAR, mean CDVA was 0.01 to 0.02 logMAR and mean UNVA was 0.12 to 0.19 logMAR (Table 5). Postoperative photopic contrast sensitivity was significantly reduced at spatial frequencies of 3, 6, and 18 cpd in comparison to a monofocal IOL group [23]. MIX & MATCH OR CUSTOM MATCH PROCEDURES A further concept favors the implantation of two different MIOLs, the so-called Mix & Match or Custom Match procedure. These combine the strengths and

Multifocal IOLs – Clinical Indication

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reduce the weaknesses of optical principles in order to optimize visual acuity at all distances. A prerequisite is that the distant dominant eye is determined before surgery. Refractive and diffractive designs (e.g. AMO ReZoom and AMO Tecnis), as well as +3 D and +4 D near additions of the same MIOL type (Alcon ReSTOR, Rayner M-flex) are combined. SEGMENT MIOL TECHNOLOGY The LENTIS Mplus multifocal intraocular lens (Oculentis GmbH, Berlin, Germany) features a new approach in multifocal lens technology. An aspheric, asymmetric distance-vision zone is combined with a sector-shaped near-vision zone of + 3.0 diopters, avoiding the center of the optic, allowing for seamless transition between the zones (Table 2, Figs. 3 and 4).

Figure 3: Slit lamp photo of the Mplus multifocal IOL (Oculentis, Germany).

The lens combines two spherical surfaces with different radii: one main surface with a radius R1 and an embedded surface with a radius R2, creating two defined focal points. The design principle of the surface-embedded sector segment makes the MIOL independent of the pupil size. This embedded sector segment ensures optimum adjustment of near and distance vision acuity. Another distinctive feature of the lens is that when the light hits the transition area to the embedded sector element, it is reflected away from the optical axis. This prevents any superposition of interference/diffraction normally caused by curvature variations

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on optical surfaces. Although it will result in a minor loss of light intensity, the segmental design claim to significantly improves contrast sensitivity, as well as decreases glare and/or halo effects (Fig. 5). A prerequisite for the best possible effect of the LENTIS Mplus lens is the positioning of its optical axis in the line of sight of the eye, as well as inferior positioning of the sector-shaped reading zone. The well-proven HydroSmart acrylic material, in use since 1996, already guarantees excellent biocompatibility. Moreover, the LENTIS design ensures high stability in the capsular bag. Another important feature is the 360-degree continuous square optic and haptic edge to reduce the risk of posterior capsule opacification. The LENTIS Mplus IOL is currently being evaluated in a multicenter clinical trial (Heidelberg, Pardubice, Poznan) [24]. Results of 134 eyes of 79 patients (54 binocular, 25 monocular) are presented. The mean age of the study participants was 68 ± 12 years. The average power of the implanted MIOLs was 20.9 +/- 2.1 D. The study parameters evaluated one and three months after surgery included visual acuity, contrast perception, glare and halos, postoperative use of spectacles, refraction, patient satisfaction, positioning and handling, complications and side effects, as well as postoperative visual acuity.

Figure 4: Mplus Surface design.

Multifocal IOLs – Clinical Indication

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Three months after surgery, the postoperative results were excellent, with a mean best corrected distance visual acuity of 0.01 logMAR and an average uncorrected near visual acuity of 0.08 logMAR. The mean spherical equivalent was -0.11 ± 0.60 D (n=110 eyes). The defocus examination clearly revealed two peaks at 0 and about -2.5 diopters, which are explained by the two foci. Good visual results are also obtained in the intermediate area of -1.0 diopters. On average, over a range of +0.75 to -3.0 diopters, a visual acuity value of more than 0.3 logMAR or more than 0.5 decimal visual acuity can be achieved. Regarding contrast perception, the results obtained with LENTIS Mplus are very good and are equivalent to those of a 20-year-old person with healthy eyes. Patient satisfaction was analyzed with a questionnaire. Only 10% of the patients reported halos and 3% mentioned glare effects. Ninety percent of the patients would choose a LENTIS Mplus lens again, 5% were undecided and another 5% decided against the lens. Interestingly, this high patient satisfaction with the novel MIOL was seen very early after surgery (3 months postoperatively). This indicates a very short adaption period. The described clinical outcomes maintained at the 6 month postoperative follow-up. In summary, the multi-center clinical trial showed very good results with the MIOL LENTIS Mplus. It can be centered stable in the capsular bag. As early as three months after implantation, near and distance visual acuity, as well as contrast sensitivity were excellent; halo and glare effects were rarely reported and the patient satisfaction rate was very high. A summary of the literature for the LENTIS Mplus, indicates that the mean UDVA was 0.04 to 0.25 logMAR, mean CDVA was -0.08 to 0.09 logMAR, mean UIVA was 0.35 and mean UNVA was 0.08 to 0.3 logMAR (see later in Table 5). In a study published by Alio et al., contrast sensitivity test showed a trend toward better contrast sensitivity outcomes at 12 cpd and 18 cpd in comparison to a monofocal IOL group. Aberrometric parameters, higher-order and coma-like RMS values, as well as primary coma and tilt were significantly larger in the multifocal IOL group in comparison to a monofocal IOL (Acri.Smart 48) [25]. In

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another study by McAlinden et al., 2 of 22 study patients voluntarily reported photopic symptoms that affected their night vision; the other patients who indicated similar symptoms did so after direct questioning. Symptoms ranged from mild to moderate night-vision problems. Two patients indicated that they had no abnormal visual symptoms [26]. The company changed the IOL from a C-loop design to a plate haptic design which was purported to improve the lens stability in the capsular bag and by that, lens performance.

Figure 5: Demonstration of the effect of a Refractive MIOL on green light passing through the Segmental MIOL (Mplus, Oculentis).

Recently, Oculentis launched the LENTIS Comfort, a new design with a +1.5 D addition for intermediate vision. This IOL was designed for patients with cataract who wish to become more independent from spectacles in everyday situations, such as computer work, shopping or driving a car. A peer review report on this IOL is still lacking. COMBINATION MULTIFOCAL AND TORIC IOLs Toric multifocal IOLs are a good option for presbyopic patients with astigmatism of more than 1.0 diopter. The first worldwide model was the Rayner M-flex T IOL, which is based on a multi-zone refractive aspheric optic technology with either four or five annular zones, depending on the IOL base power (Table 3). The lens was first implanted at the Department of Ophthalmology, University of Heidelberg, in June 2006. Like the monofocal T-flex, it is made of hydrophilic acrylic and features a 360° sharp optic edge to prevent secondary cataract.

Multifocal IOLs – Clinical Indication

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Table 3: Current multifocal toric IOLs

Results of 10 M-Flex T IOLs that were implanted at the University of Heidelberg in 10 eyes (including six refractive lens exchange and four cataract eyes) of six patients, with a median age of 55.5 years (range 17 to 60 years) (Fig. 6). Two patients received a Custom Match procedure due to anisometropia and mild ambylopia, combining a standard multifocal lens and an M-flex T in the fellow eye. Four to eleven months after surgery (n=9 eyes), the median spherical equivalent ranged between -0.5 and +0.75 D. Median uncorrected distance visual acuity was 0.15 logMAR and best corrected distance visual acuity was 0.1 logMAR. Near visual acuity results at 40 cm were also satisfactory in terms of the amblyopic cases. This included uncorrected and distance corrected median visual acuity of 0.3 logMAR, and best corrected even slightly better, at 0.22 logMAR with almost no further near addition accepted (median: 0 D; range 0 to 1.5 D). IOL power calculation was also very predictable with a median difference between target and achieved spherical equivalent of only -0.18 D.

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Fiigure 6: Slit laamp photo of th he M-flex T mu ultifocal and tooric IOL (Raynner, UK).

In n the meantiime, three additional a mu ultifocal torric IOL moddels are avaiilable, the AT.Lisatoric A 466TD (Z Zeiss), the Mplus M toricc (Oculentiss) and the AcrySof ReSTOR R Multifocal Toric IOL (Alco on). ADDITIVE A MULTIFOC M CAL IOLs Currently, C Raayner (Sulco oflex modell) and Dr. S Schmidt/Hum man Optics (Add-On model) m provide lenses th hat can be im mplanted in the sulcus oof pseudophhakic eyes (T Table 4). Th hese are also available ass multifocal versions and offer the ppossibility off correcting residual refrractive errorrs after cataraact or refracctive surgeryy and are a go ood option in cases with changes in dynamic refraction, e.g. after perforating keeratoplasty, because they y can be exp planted or exxchanged eassily [2, 27]. Table 4: Curren nt multifocal ad dd-on/supplem mentary IOLs

Multifocal IOLs – Clinical Indication

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TRIFOCAL IOL Trifocal Optical Principle Trifocal IOLs are another new advance in the field of multifocal IOLs. As previously mentioned, most multifocal IOLs are actually bifocal, with one focus for distance and one for near. The trifocal IOL combine two optics, one diffractive optic that has a far focus and a grating that is narrow enough to create a near focus of 3.50 D and another diffractive optic that has the same far focus, but a near focus that is precisely half of the first near focus (1.75 D) or 3.33 and 1.66 D. This combination creates three foci, for near, intermediate, and far vision. With a bifocal lens, the second order of diffraction (about 7.00 D) is lost; however, when combining two optics, the second order of the 1.75 D diffraction grating is 3.50 D and the 1.66 D diffraction grating is 3.33 D. This resultant diffraction is useful for near vision. Instead of losing up to 20% of light through a diffractive bifocal lens, there is a 14% loss with the trifocal IOL. This concept enhances near vision and provides intermediate vision, which has always been the weak point of the bifocal lenses. Fine Vision The FineVision (PhysIOL, Liége, Belgium) is the first diffractive IOL to improve intermediate vision while maintaining good near and far vision. This is a hydrophilic Acrylic (25% water content) aspheric IOL with a blue and UV blocker. The optic diameter is 6.15 mm and the overall length is 10.75 mm, with a 5 degree angulation. The power range is 10.00 to 30.00 D in 0.50 D steps. The lens can be implanted trough a 1.8 mm incision (Fig. 7).

Figure 7: The micro F FineVision IOL.

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Initial experience with this lens is promising. Voskresnskaya et al. [34] reported their experience with 36 eyes. Six months after surgery, monocular uncorrected and corrected distance visual acuity were 0.74+/-0.21 and 0.86+/-0.23, respectively. Uncorrected and best distance corrected near visual acuity were 0.85+/-0.13 and 0.89+/-0.12, respectively. Uncorrected and best distance corrected intermediate visual acuity at 50 cm were 0.58+/-0.16 and 0.6+/-0.2, respectively. Spectacle freedom was achieved in 94% of patients. Using a questionnaire, 25% of the patients reported nighttime halos, 16.7% reported glare difficulty and 22.3% reported persistent difficulties with night vision. Cochener et al. [35] reported the results of 94 eyes of 47 patients operated by 6 different surgeons. Far and near visual acuity were comparable to previous reports of bifocal IOLs, with an improvement in intermediate vision. AT LISA tri 839MP The AT LISA tri 839MP (Carl Zeiss Meditec), is also a trifocal IOL with a unique, asymmetrical light distribution of 50%, 20%, and 30% for far, intermediate, and near foci, respectively. This is a plate haptic IOL using the platform of the AT LISA (mentioned above) with a trifocal design over the 4.34 mm central optic and bifocal design from 4.34 to 6.00 mm of the optic. Early personal experience reports described better intermediate vision with fewer visual disturbances, high resolution in all lighting conditions, and better pupil independence. However, peer review information is still lacking and required for evaluation of this IOL. UNWANTED PHENOMENA OF BIFOCAL IOLs This advanced technology is not free from undesirable effects. Major concerns include problems with night vision, halo and glare, which usually improve with time, and reduced contrast sensitivity (Table 6). Recent models possess fewer unwanted phenomena, but patient selection remains a crucial step before surgery, together with expectation management. PREOPERATIVE EVALUATION, REALISTIC PATIENT EXPECTATIONS AND CONCLUSION A variety of very sophisticated Premium MIOLs currently available, allow individualized refraction correction and for the most part, spectacle independence.

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Nevertheless, due to the MIOL principle of separating light into two or three different foci, patients need to adapt to the new visual perception, as well as to the possibility of reduced contrast and induced photopic phenomena, especially at night. Thus, detailed informed consent prior to surgery is imperative. Recent developments in this field, such as foldable, multizonal, progressive, refractive MIOLs or new Table 5: Clinical results of multifocal IOLs

IOL

Intermediate No. Distance VA Near VA Binocular Vision No. of VA (70cm) of Patients Eyes UDVA CDVA UIVA DCIVA UNVA DCNVA CNVA UDVA CDVA UIVA

Ref. DCIVA UNVA DCNVA

ReSTOR 268 SN6AD3

134

-0.05

0.35

0.1***

[20]

ReSTOR 276 SN6AD1

138

-0.05

0.19

0.07

[20]

ReSTOR 64 SN6AD1

32

-0.02

0.15

ReSTOR SN6AD1 40

20

ReSTOR SN6AD1 294

147

ReSTOR SN6AD1 186

93

ReSTOR SN6AD1 20

10

ReSTOR SN6AD1 32

16

ReSTOR SN6AD1 24

12

Tecnis

632

335

32

22

AcryLisa 48 366D

24

AcryLisa 42 366D

21

AcryLisa 20 366D

10

Lentis Mplus

24

N/S

Lentis Mplus

44

22

Lentis Mplus

134

79

ZM900 M-Flex 630F

0.1

0.02

0.27

0.2

0.19

0.001

-0.064

0.165

-0.035

-0.041

(±0.1)

(±0.05) (±0.11)

(±0.06)

(±0.06)

[21] [22]

0.04

0.17

0.1

(±0.13)

(±0.14)

(±0.16)

-0.03

0.2

0.04

-0.03

0.2

0.04

(±0.13)

(±0.14)

(±0.11)

(±0.13)

(±0.14)

(±0.11)

-0.06

0.11

-0.08

(±0.05)

(±0.13)

(±0.04)

0.032

-0.006

(±0.07) (±0.07) 0.2*

0.022

0.003

(±0.08)

(±0.08)

0.0

0.2

0.1

(±0.1)

(±0.05) (±0.13) (±0.14)

(±0.12)

(±0.08) (±0.05) (±0.06) (±0.1)

0.13

0.0

0.18*** 0.15***

0.09

0.03

0.15^

0.28*** 0.28 (±0.11) (±0.25)

0.04

0.11

0.12

0.08

0.17

(±0.11)

(±0.01)

(±0.3)

0.1

0.19

0.15

(±0.08)

(±0.01)

0.01

0.25

0.09

(±0.33) (±0.18) 0.04

-0.08

(±0.25) (±0.07) 0.01

0.35

0.34

0.3

0.17

0.12

(±0.21)

(±0.19)

(±0.18)

0.28*** 0.27*** 0.08

[30]

-0.1

0.1

-0.05

0.1

0.1

0.0

(±0.1)

(±0.1)

(±0.08)

0.1***

0.08***

[31]

[15]

[16]

(±0.05)

(±0.11) (±0.06)

(±0.11) (±0.03)

0.0

0.04

(±0.09) (±0.05) (±0.05) (±0.05) 0.02

[29]

[7]

0.1

0.15^

0.2*

[13]

[32]

[23] -0.08

0.16

-0.02

(±0.08)

(±0.14)

(±0.08)

[30]

[25]

0.17

0.14

[26] [33]

^ 65 cm, * 60 cm, ** 50 cm *** 33 cm VA = visual acuity; UDVA = uncorrected VA; CDVA = corrected VA; UIVA = uncorrected intermediate VA; DCIVA = distance corrected intermediate VA; UNVA = uncorrected near VA; DCNVA = distance corrected near VA; CNVA = corrected near VA; N/S – not specified.

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aspheric diffractive MIOL models, together with improved surgical techniques have minimized initial problems, such as decentration, reduced contrast sensitivity or glare and halos. To determine which MIOL type best fits individual needs, distance preferences have to be clarified preoperatively, especially since individual’s differ in defining “near” vision as 30, 40 or even 70 centimeters distance. Moreover, the patient should be informed before surgery that there is no absolute guarantee of spectacle freedom [1, 2, 28]. Furthermore, it is paramount to carefully evaluate patients for any eye pathology that can lead to dissatisfaction with postoperative results, and to have the tools and knowledge to hit the target refraction; the result in these cases is much more sensitive to lack of emmetropia and IOL decantation (Table 6). Patient selection and informed consent, as well as realistic expectations remain important parameters for achieving successful postoperative results. Table 6: Side effects and performance of multifocal IOLs

IOL

Spectacle Independence (None of the Time) Far

Inter

Near

Mean Glare Halos Problems with Night Vision Max reading Refs. speed Overall None/Mild Moderate Severe None/Mild Moderate Severe None/Mild Moderate Severe (wpm)

ReSTOR 96% SN6AD3

81%

81%

72.4%

20.9%

6.7%

63.4%

26.9%

9.7%

83.6%

10.4%

6.0%

[20]

ReSTOR 94% SN6AD1

76%

78%

70.3%

24.6%

5.1%

65.9%

27.5%

6.5%

88.4%

9.4%

2.2%

[20]

89%

88%

83%

5%

83%

8%

83%

7%

[29]

0%

0%

[22]

43.6%

12.1%

[15]

ReSTOR 99% SN6AD1

94%

ReSTOR SN6AD1

369.7 (±32.3)

Tecnis ZM900

94.9%

M-Flex 630F

90%

AcryLisa 366D Lentis Mplus

93.8% 88% 80%

148

0% 33.6%

41.4%

25.0%

100% 30.1%

34.6%

70%

35.3%

44.3%

[16] 182.25 (±36.5)

[32] 22%

10%

[24]

MANAGING THE UNHAPPY PATIENT Careful management of the dissatisfied patient is required. Dr Eric Donnefeld defined few common problems that could result in an unhappy patient and should be treated: 1. Small refractive errors including cylinder (Laser vision correction should be considered), 2. The IOL is not well centered over the pupil (argon laser iridoplasty was suggested), 3. Dry eye should be aggressively treated, 4. Early

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treatment of posterior capsule opacification, and 5. Diagnosis and early treatment of cystoid macular edema. ACKNOWLEDGEMENTS Declared none. CONFLICT OF INTEREST The authors confirm that this chapter content has no conflicts of interest. REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14]

Auffarth GU, D.H., Multifokale Intraokularlinsen: Eine Übersicht. Der Ophthalmologe 2001; 98: p. 127-137. Auffarth GU, et al. Design and optical principles of multifocal lenses. Ophthalmologe 2008; 105(6): p. 522-6. Holzer MP, R.T., Auffarth GU, Presbyopia correction using intraocular lenses. Ophthalmologe 2006; 103(8): p. 661-6. Kohnen T, K.D., Auffarth GU, Derhartunian V. Use of multifocal intraocular lenses and criteria for patient selection. Ophthalmologe 2008; 105(6): p. 527.32Mester, U., et al. Functional results with two multifocal intraocular lenses (MIOL). Array SA40 versus Acri.Twin. Ophthalmologe 2005; 102(11): p. 1051-6. Mester, U., et al. Functional vision training after MIOL implantation. Ophthalmologe 2008; 105(6): p. 533-7. Santhiago, M.R., et al. Comparison of reading performance after bilateral implantation of multifocal intraocular lenses with +3.00 or +4.00 diopter addition. J Cataract Refract Surg 2010; 36(11): p. 1874-9. Steinert RF. Visual outcomes with multifocal intraocular lenses. Curr Opin Ophthalmol 2000; 11(1): p. 12-21. Akaishi, L., et al. Visual Performance of Tecnis ZM900 Diffractive Multifocal IOL after 2500 Implants: A 3-Year Followup. J Ophthalmol 2010. 2010. Brydon KW, AC Tokarewicz, and BD Nichols. AMO array multifocal lens versus monofocal correction in cataract surgery. J Cataract Refract Surg 2000; 26(1): p. 96-100. Hayashi K. et al. Effect of astigmatism on visual acuity in eyes with a diffractive multifocal intraocular lens. J Cataract Refract Surg 2010; 36(8): p. 1323-9. Hutz WW, R. Jackel, and P.C. Hoffman. Comparison of visual performance of silicone and acrylic multifocal IOLs utilizing the same diffractive design. Acta Ophthalmol 2010; Lane SS, et al. Improvements in patient-reported outcomes and visual acuity after bilateral implantation of multifocal intraocular lenses with +3.0 diopter addition: multicenter clinical trial. J Cataract Refract Surg 2010; 36(11): p.96-1887 . Yoshino M, et al. Two-year follow-up after implantation of diffractive aspheric silicone multifocal intraocular lenses. Acta Ophthalmol 2010.

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[15] [16] [17] [18] [19] [20] [21] [22] [23] [24] [25] [26] [27] [28] [29] [30] [31] [32]

Auffarth et al.

Summary of Safety and Effectiveness Data (SSED), Tecnis Multifocal Intraocular Lens, FDA ,Editor. 2009: http://www.accessdata.fda.gov/cdrh_docs/pdf8/P080010b.pdf. Cezon Prieto, J. and M.J. Bautista. Visual outcomes after implantation of a refractive multifocal intraocular lens with a +3.00 D addition. J Cataract Refract Surg 2010; 36(9 :(p. 1508-16. de Vries, N.E., et al. Visual outcome and patient satisfaction after multifocal intraocular lens implantation: aspheric versus spherical design. J Cataract Refract Surg 2010; 36(11): p. 1897-904. Featherstone, K.A., et al. Driving simulation study: bilateral array multifocal versus bilateral AMO monofocal intraocular lenses. J Cataract Refract Surg 1999; 25(9): p. 125462. Ferrer-Blasco, T., et al. Stereopsis in bilaterally multifocal pseudophakic patients. Graefes Arch Clin Exp Ophthalmol 2011; 249(2): p. 245-51. Alcon Laboratories, I., DFU - Product Information, 6 Month Direction for use - AcrySof IQ ReSTOR Multifocal IOL. 2009. Hayashi, K., S. Manabe, and H. Hayashi. Visual acuity from far to near and contrast sensitivity in eyes with a diffractive multifocal intraocular lens with a low addition power. J Cataract Refract Surg 2009; 35(12): p. 2070-6. Alfonso, J.F., et al. Visual function after implantation of an aspheric bifocal intraocular lens. J Cataract Refract Surg 2009; 35(5): p. 885-92. Alio, J.L., et al. Quality of life evaluation after implantation of 2 multifocal intraocular lens models and a monofocal model. J Cataract Refract Surg 2011; 37(4): p. 638-48. Auffarth GU, R.T., Philips R, Novák J, Oculentis LENTIS Mplus: A new concept of multifocal intraocular lens technology (12-month results). Unpublished results, 2010. Alio, J.L., et al. Visual outcomes and optical performance of a monofocal intraocular lens and a new-generation multifocal intraocular lens. J Cataract Refract Surg 2011; 37(2): p. 241-50. McAlinden, C. and J.E. Moore. Multifocal intraocular lens with a surface-embedded near section: Short-term clinical outcomes. J Cataract Refract Surg 2011; 37(3): p. 441-5. Wolter-Roessler, M. and M. Kuchle. Implantation of multifocal add-on IOLs simultaneously with cataract surgery: results of a prospective study. Klin Monbl Augenheilkd 2010; 227(8): p. 653-6. Javitt, J., et al. Cataract extraction with multifocal intraocular lens implantation: clinical, functional, and quality-of-life outcomes. Multicenter clinical trial in Germany and Austria. J Cataract Refract Surg 2000; 26(9): p. 1356-66. Kohnen, T., et al. Visual function after bilateral implantation of apodized diffractive aspheric multifocal intraocular lenses with a +3.0 D addition. J Cataract Refract Surg 2009; 35(12): p. 2062-9. Alfonso, J.F., et al. Intermediate visual function with different multifocal intraocular lens models. J Cataract Refract Surg 2010; 36(5): p. 733-9. Petermeier, K., et al. Effect of +3.00 diopter and +4.00 diopter additions in multifocal intraocular lenses on defocus profiles, patient satisfaction, and contrast sensitivity. J Cataract Refract Surg 2011; 37(4 :(p. 720-6. Alio, J.L., et al. Optical analysis, reading performance, and quality-of-life evaluation after implantation of a diffractive multifocal intraocular lens. J Cataract Refract Surg 2011; 37(1): p. 27-37.

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[33] [34] [35]

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Auffarth GU, R.T., Philips R, Novák J, Oculentis LENTIS Mplus: A new concept of multifocal intraocular lens technology (12-month results). Unpublished results, 2011. Voskresenskaya A, Pozdeyeva N, Pashtaev N, Batkov Y, Treushnicov V, Cherednik V. Initial results of trifocal diffractive IOL implantation. Graefes Arch Clin Exp Ophthalmol, 2010. 248(9):1299-306. Cochener B, Vryghem J, Lesieur G, Heireman S, Blanckaet JA, Van Acker E, Ghekiere S. Visual and refractive outcomes after implantation of a fully diffractive trifocal lens. Clin Ophthalmol 2012. 6:1421-7.

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CHAPTER 6 Accommodative and Dual Optic Intraocular Lenses Mark Packer1,*, H. Burkhard Dick2 and George Beiko3 1

Clinical Associate Professor, Oregon Health & Science University, 4075 Southpointe Dr. Eugene, OR 97405, USA; 2Center of Visual Sciences and Department of Ophthalmology, Ruhr University Eye Hospital, In der Schornau 23 – 25, Bochum, Germany 44892 and 3McMaster University, 180 Vine St., Suite 103, St. Catharines, Ontarios, Canada L2R 7P3 Abstract: The purpose of this chapter is to provide perspective on intraocular lens technology designed to achieve accommodative function in the pseudophakic state. We briefly introduce the fundamental physiologic optics of accommodation and presbyopia, and then review the achievements and limitations of multifocal intraocular lens technology. We detail the historical development and current status of three single optic accommodative designs, the crystalens, the 1CU and the Tetraflex. Summaries of published and presented clinical studies demonstrate the range of accommodative amplitude expected with each lens, while imaging and biometric data provide conflicting evidence regarding the mechanism of action of these devices. We then examine the Synchrony dual optic accommodative IOL in detail, providing summaries of all available clinical data along with supportive imaging results. In a final section we discuss a couple of novel technologies that lie on the horizon of accommodative IOL implementation, the NuLens and the FluidVision lens.

Keywords: Accommodative intraocular lens, accommodation, presbyopia correction, pseudophakia, dual optic. INTRODUCTION Accommodation in the youthful, phakic human eye is accomplished by contraction of the ciliary body and subsequent release in the resting tension of the zonular fibers by which the crystalline lens is suspended, resulting in increased lens curvature. Presbyopia is defined by the progressive loss of accommodation amplitude producing compromised near function, and has been attributed to *Address correspondence to Mark Packer: Clinical Associate Professor, Oregon Health & Science University, 4075 Southpointe Dr. Eugene, OR 97405, USA; Fax 888-840-9392; Email: [email protected] Guy Kleinmann, Ehud I. Assia and David J. Apple (Eds) All rights reserved-© 2014 Bentham Science Publishers

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mechanical changes in the lens and capsule including changes in elastic property and progressive circumferential enlargement of the crystalline lens, weakening of the ciliary muscle, and loss of zonular and ciliary body effectiveness and elasticity [1]. This chapter will provide perspective on intraocular lens technology designed to achieve accommodative function in the pseudophakic state. PSEUDOPHAKIC ACCOMMODATION AND PSEUDOPHAKIC PSEUDOACCOMMODATION Although the mechanisms of accommodation and presbyopia remains incompletely understood, the weight of current evidence seems to suggest that although some loss of ciliary body action might contribute to reduced accommodation [2] significant ciliary body function persists into advanced maturity, and that loss of lens and capsule elasticity in concert with changes in the geometry of zonular attachments are probably most culpable in producing the distress of presbyopia [3]. If so, then replacement of the crystalline lens with a lens that responds to ciliary body contraction should restore accommodative function. An alternative to engineering the restoration of true accommodation is the manufacture of pseudo-accommodation through the use of multifocal optics. Although multifocal IOLs provide good uncorrected distance and near vision, their drawback is the reduction of quality of vision [4]. For example, of subjects who received the Tecnis Multifocal IOL (Abbott Medical Optics, Inc., Santa Ana, CA) in both eyes, 88% reported never wearing glasses 4 to 6 months after surgery [5]. In the FDA-monitored clinical investigation of the Tecnis Multifocal IOL, these 292 subjects were compared with 118 in the control arm who received monofocal IOLs (only 5% of these subjects never wore glasses). With the Multifocal, 94.9% never needed glasses for distance activities such as driving, while 93.8% never needed glasses for near activities such as reading (for the control subjects, 83.1% did not wear glasses for driving, while only 5.1% did not need glasses for reading). With one year follow up (N = 112), 96.4% of subjects implanted bilaterally with the Tecnis Multifocal reported being able to function comfortably without glasses for distance and near activities, while 93.8% said they could function comfortably at intermediate range without glasses.

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These results give the Tecnis Multifocal the highest rate of spectacle independence, or freedom from glasses, of any intraocular lens studied so far in the United States. For example, comparable studies of the ReSTOR 3 and 4 Diopter Add IOLs (Alcon Surgical, Ft. Worth, TX) demonstrated that 76% of subjects with either lens implanted in both eyes never wore glasses [6]. Multifocality by its intrinsic optical properties diminishes image quality to some extent. Diffractive IOLs such as the Tecnis Multifocal and the ReSTOR rely on constructive and destructive interference of light waves to create two distinct focal points. In the process, some light never reaches the retinal photoreceptors (about 20% is lost to destructive interference) and the blurred image of the near focal point may produce halos around distant lights at night. The Tecnis Multifocal IOL, partly as a result of its aspheric anterior optical surface and partly as a result of the quality and material of its manufacture, results in fewer unwanted optical side effects than other multifocal IOLs. For example, by 4 to 6 months, 24.3% of subjects (n = 292) implanted bilaterally with the Tecnis Multifocal IOL experienced moderate (15.3%) or severe (9.0%) halos. This percentage compares favorably with 31.1% moderate (21.0%) or severe (10.1%) halos for subjects at 3 months implanted with the ReSTOR +3 D (n = 151) and 34.3% moderate (20.6%) or severe (13.7%) halos with the ReSTOR +4 D (n = 143). By 1 year, only 5.2% of subjects (n = 116) implanted with the Tecnis Multifocal experienced moderate and 6.2% severe halos. Slightly over 11% described blurred vision or difficulty with vision. The improvement in vision over time demonstrates the effect of neural adaptation, which has been recognized to enhance the outcomes of multifocal IOL implantation [7]. Nevertheless, the desire for accommodation and aberration-free vision has driven the further pursuit of pseudophakic designs that do not require a multifocal optic to achieve distance, intermediate and near range acuity without loss of contrast sensitivity. For example, attempts have been made to replace the crystalline lens by refilling the capsular bag with appropriately deformable polymers and gels. However, this approach is limited by the intrinsic mechanical instability of such materials that at the moment cannot be expected to retain a specific shape (and thus optical power) over time while sustaining a rapid, constant, and predictable

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response to equatorial tension as demanded by the dynamics of accommodation. Nishi has recently concluded that experiments “with lens refilling from the last 3 decades have shown lens shape changes to be attainable in the early postoperative period. Thereafter, after-cataract remains the main obstacle, resulting in both a decrease in lens elasticity and a loss of optical clarity of the capsule. Attempts to eradicate lens epithelial cells during surgery have not yet been fully successful and a depletion of all lens epithelial cells may also result in long-term decay in lens capsule integrity” [8]. SINGLE OPTIC ACCOMMODATIVE IOLs The principle of axial lens movement has been adopted by recent accommodating IOL designs. It has been calculated that the amount of accommodative effect in IOLs with single optics is dependent on IOL power, with less effect per millimetre of displacement being noted in myopic patients compared to hyperopic patients. Based on the Gullstrand formula, the pseudophakic accommodation per millimetre focus shift is 1.00 D with an IOL power of +16.00; 1.37 D with +21.00; and 2.20 D with +31.00. Thus, a forward movement of 1.00 mm can equate to an increase in the effective lens power of 0.8 to 2.3 D [9]. This observation underscores the necessity to have the average IOL power implanted reported in any study. In the 1980s, Cumming made the observation that patients with silicone plate haptic intraocular lenses were able in some instances to read well through their distance correction [10]. Using A scan ultrasonography, he demonstrated optic movement of 0.7 mm, which was later confirmed by Thornton [11]. This realization has generated much interest in this mechanism for achieving accommodation, and several lens designs have been investigated. The Crystalens The first FDA approved accommodative IOL, the crystalens AT-45, was the 7th in a series of design changes, and became commercially available in the US in 2003. The crystalens 5-0, featuring a 5.0 mm optic diameter and sturdier haptics, subsequently became available and was then superseded by the crystalens HD. The surface of the Crystalens HD was shaped to enhance the depth of focus with a

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proprietary optical modification. In a study of the HD design modification, a total of 125 primary eyes were implanted with the crystalens HD in patients who had a visually significant cataract, less than 1 diopter of corneal astigmatism, and the potential for best corrected visual acuity (BCVA) of 20/25 or better in both eyes. Of these patients, 80% reported vision at J2 or better at four (4) months [12, 13]. The crystalens is constructed as a multipiece, third generation silicone, posterior chamber, modified plate-haptic IOL with polyimide loops. The hinges are grooves, which are 50 % of the thickness, across the surface of the plates adjacent to the optic. The biconvex, square-edged optic is 4.5 mm in diameter for the AT-45, and 5.0 mm in diameter for the crystalens 5-0 and HD500. The overall length is 10.5 mm, with a diagonal length of 11.5 mm. The refractive index is 1.43 (Fig. 1).

Figure 1: The crystalens AT-45 seen in retroillumination 3 years after implantation. Note that the round, centered capsulorhexis is slightly smaller than the 4.5 mm diameter IOL optic. There is mild capsular fibrosis overlying the arms of the haptics; the remained of the capsule is clear. There is a small patch of iris transillumination due to pigment lost during phacoemulsification.

The overall diameter being greater than the capsular bag is designed to make the optic assume a posterior position after implantation in the bag. The small optic and relatively long haptics are design features, which are meant to optimize the amount of anterior displacement for a given angle of deflection. The mechanism of action was thought to be due to the contraction of the ciliary muscle, producing

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changes in the pressure of the vitreous body, and causing the lens to be displaced forward. In fact, studies had confirmed an increase in the vitreous cavity length of 0.7 mm after pilocarpine instillation [14]. However, more recent data has left unsettled the mechanism by which the crystalens provides the 1 diopter of accommodation recognized in the FDA study of the AT-45. Using ultrasound biomicroscopy with the patient in the supine position and fixating the non-study eye at distance and then near, it has been shown that the lens is displaced forward 0.33 ± 0.25 mm (or about 0.5 D of accommodative power) at 6 months. This same study found that the patients required a mean of 1.18 ± 0.3 D of add to read J1. An indirect measure of accommodative amplitude by of 1.08 ± 0.54 D was reported [15]. In a study comparing binocular crystalens against binocular standard monofocal IOLs, it has been reported that the crystalens group had better near vision, attaining J3 vision in 100% of patients versus 29% in the control group. Dynamic retinoscopy in the study group was found to be 2.42 ± 0.38 D compared to 0.91 ± 0.24 D in the control group. Similarly, subjective measures of accommodation in the Crystalens were also greater; monocular defocus was reported as being 1.74 ± 0.48 D versus 0.75 ± 0.25 D and monocular near point of accommodation as being 9.5 ± 3.1 inches (4.78 D) versus 34.7 ± 9.8 inches (1.23 D) [16]. In contradistinction to these studies, Koeppl et al. found neither an accommodative forward shift nor an improvement in near visual acuity with the crystalens. They studied fifty-four eyes of 28 patients with age-related cataract. Each patient received an AT-45 accommodating IOL after standardized cataract surgery. In a subgroup of 24 eyes, capsular bag fibrosis was reduced by extensive polishing of the anterior capsule with a slit cannula. Assessment included measurements of anterior chamber depth, assessed with partial coherence interferometry, before and after application of pilocarpine 2% and evaluation of near visual acuity 1 month and 3 months postoperatively. The authors detected a slight backward shift of the IOL of 151 µm in the standard group (P 2500 cells/mm2 if >21 years old, > 2000 if >40 years old).  No anomaly of the iris or pupil function.  Mesopic pupil size < 5-6 mm.

       

Background of active disease in the anterior segment. Recurrent or chronic uveitis. Any form of clinically significant cataract. Previous corneal or intraocular surgery (to be evaluated). IOP > 21 mmHg or glaucoma. Preexisting macular degeneration or macular pathology. Abnormal retinal condition. Systemic diseases (e.g., autoimmune disorder, connective tissue disease, atopia, diabetes mellitus).

Table 3: Anterior chamber depth requirements for phakic IOL implantation ACD Requirements (Measured from Endothelium)    

Acrysof phakic: >2.7 mm. Artisan-Verisyse/Artiflex-Veriflex:  2.7 mm. ICL:  2.8 mm for myopia,  3 mm for hyperopic lenses. PRL:  2.5 mm.

Surgical Technique IOL Power Calculation and Diameter Selection Van der Heijde proposed the theoretical basis of the calculation of the power of refractive phakic iris-claw implants. These principles are totally transferable to

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angle-supported implants. For calculation of the lens’ power, patient’s refraction, corneal keratometric dioptric power at its apex and adjusted ultrasound central ACD are implemented. Based on this formula, the manufacturers provide nomograms or software to calculate the PIOL required power. The implant’s overall diameter depends on the anterior chamber diameter, and should provide perfect stability with no excess of compression forces to the angle, so as not to damage angle structures or induce pupil ovalization. Before development of anterior segment imaging techniques no system allowed determination of the internal diameter of the anterior chamber, the angle-to-angle (ATA) distance. Evaluation was approximate and based on white-to-white (WTW) measurement. WTW distance can be measured either manually or using automated technology (Zeiss IOLMaster, and Orbscan II topography system (Bausch & Lomb)). Automated measurement provides more precise results than measurements using manual methods. Angle-supported implant’s diameter is oversized 0.5 to 1 mm from the WTW measurement. Currently, with the advent of anterior segment OCT and UBM, the ATA distance and the anterior chamber angle can be measured precisely. Implantation of Non-Foldable Angle-Fixated PIOL With PMMA lenses, the incision may be created via a corneal or corneoscleral approach. Care must be taken so as to minimize SIA. Incision size depends upon size of the IOL optic from 4.5 to 6 mm. A viscoelastic substance (OVD) is injected through a paracentesis prior to the insertion of the lens in order to form the anterior chamber, to protect the corneal endothelium and to protect the crystalline lens during manipulation of the PIOL. Pupil constriction either using 1 % pilocarpine preoperatively, or acetylcholine intracamerally is mandatory. The PIOL is inserted into the anterior chamber with a forceps and repositioned with a Sinskey hook, avoiding any pupil ovalization. The corneoscleral incision is then sutured and OVD is removed. Iridotomy/Iridectiomy should be performed before or during the surgery. Implantation of Foldable Angle-Fixated PIOLs Kelman Duet The Kelman Duet PIOL is not actually foldable but consists of two separate components, the optic and the haptic. These are sequentially inserted through a

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small incision and assembled in the anterior chamber. Two 1-mm clear cornea incisions are created at 3 and 9 o’clock that facilitate the manipulation of the components. The haptic is first inserted through one of the incisions and repositioned in the angle. The optic is then injected into the anterior chamber through a 3-mm incision. Two diametrically opposed tabs on the optic are then fastened to corresponding clips on the haptic. An iridotomy/Iridectiomy should be performed before or during the surgery. AcrySof CACHET AcrySof PIOL implantation may be performed under topical anesthesia. Some surgeons recommend preoperative instillation of 1 % pilocarpine, others prefer intracameral injection of acetylcholine, intraoperatively. After intracameral injection of OVD, the PIOL is introduced with a Monarch II or III IOL Delivery System (Alcon Laboratories, Inc., Fort Worth, TX) and a B or P cartridge through a 3.2 or 2.6 mm incision. Placement of the haptic’s footplates can be confirmed by intraoperative gonioscopy. No peripheral iridotomy is required. However, some surgeons may prefer to perform the iridotomy to avoid pupillary block glaucoma. Although the incision usually is watertight, incisions larger than 3.0 mm may be sutured with a single 10-0 nylon. Suture may be removed 1 or 2 weeks postoperatively (Fig. 2).

Figure 2: (A and B) After intracameral injection of viscoelastic material, the PIOL is introduced with a Monarch II IOL Delivery System (Alcon Laboratories, Inc., Fort Worth, TX) through a 2.75 mm incision usually centered at 10:30 o’clock. (C and D) Placement of the haptics’ footplates in the anterior chamber angle is performed using a blunt spatula.

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Iris-Fixated Anterior Chamber Phakic Intraocular Lenses Historical Overview The iris-claw IOL was initially used in aphakic eyes after intracapsular cataract extraction. Starting in 1953, the first-generation models, such as the Binkhorst lens and the Medallion lens, were associated with cystoid macular edema and corneal decompensation [8-10]. Also, due to its fixation at the mobile iris sphincter near the pupil margin, there was progressive erosion of the iris stroma and breakage of the blood/aqueous barrier, eventually leading to lens dislocation, uveitis and glaucoma [11]. In 1978, Jan Worst designed the iris-claw or ’lobsterclaw’ IOL, a co-planar, one-piece, PMMA IOL, which was enclavated in a fold of mid-peripheral iris stroma, a relatively immobile portion of the iris. Many surgeons have used the iris-claw lens after intracapsular cataract extraction or as secondary implantation in aphakia. In 1980, Worst implanted an opaque iris-claw lens in a phakic eye to solve untreatable diplopia. In 1986, Fechner implanted the first sighted myopic phakic eye, which showed good predictability but progressive corneal endothelial cell (CEC) loss. The currently available iris-claw model is basically the original IOL with few changes. CURRENT MODELS PMMA Iris-Claw Anterior Chamber PIOL The iris-claw Artisan (Ophtec B.V., Groningen, The Netherlands) – Verisyse (Abbott Laboratories, Abbott Park, Illinois, US) IOL is a single-piece, non-foldable PMMA lens, which is available for the correction of myopia, hyperopia and astigmatism, as well as for aphakia (Fig. 1B and 1D). The optic vaults approximately 0.87 mm anterior to the iris, allowing for important clearance from both the anterior lens capsule and the corneal endothelium. The distance from the optic edge to the endothelium ranges from 1.5 to 2 mm depending on the dioptric power, the anterior chamber anatomy and the diameter of the optic. There are two models available to correct myopia: model 206 has a 5.0-mm optic with power ranging from -3 to -23.5 diopters (D) in 0.5 D increments; model 204 has a larger 6.0-mm optic and is consequently limited to a smaller range of powers because of its greater proximity to the endothelium in the periphery of the IOL: -3 to -15.5 D in 0.5 D increments. For the correction of hyperopia, model 203 incorporates a 5 mm optic, and it is available

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in dioptric powers ranging from +1 to + 12 D in 0.5 D increments. Myopic lenses require more clearance than hyperopic due to thicker peripheral edges. The thickest part of the hyperopic IOL on the other hand is central, where the anterior chamber depth is greater. The toric model has a 5-mm optical zone and is available in powers ranging from +12 D to -23.5 D in 0.5 D increments, with additional cylinder from +1.0 D to +7.0 D, also in 0.5-D increments, and oriented either at 0º and at 90º. The lens has an overall length of 8.5 mm (or 7.5 mm for pediatric implantations or small eyes), which is a great advantage for the surgeon who does not wish to deal with sizing measurements. Another major advantage of these lenses is that they can always be properly centered over the pupil, even when it is off-center, a relatively common situation among people with high ametropias. Off-center pupils cannot be used as a reference for centration of symmetrical implants like angle-supported and sulcus-fixated IOL (Fig. 3A and 3C). Foldable Iris-Claw Anterior Chamber PIOL The foldable model of the iris-claw lens is the Artiflex (Ophtec, Groningen, The Netherlands). It is a hydrophobic polysiloxane foldable design with a 6.0-mm optic and powers ranging from –2 D to –14.5 D in 0.5 D steps (Fig. 3B and 3D). The toric model of the Artiflexis available with powers ranging from - 2 D to -14.5 D in 0.5 D steps, and cylinder correction ranging from +1.0 D to + 5.0 D, also in 0.5 D steps. By the end of 2013, a new acrylic Artiflex for myopia and aphakia will be available.

Figure 3: (A) Pharmacological midriasis after Veriflex phakic IOL implantation. (B) Pharmacological midriasis after Verisyse phakic IOL implantation. In both cases, exploration of the retina can be easily performed. (C) Verisyse toric PIOL implantation to correct residual myopic astigmatism after penetrating keratoplasty. (D) Veriflex PIOL 2 years after implantation. Notice the superior slit iridotomy. No pupil ovalization is seen.

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Surgical Technique PIOL Power Calculation Regarding selection criteria for iris-claw anterior chamber PIOL see Table 2 and 3. The most commonly used method to calculate PIOL power is the Van der Heijde formula, which includes patient’s refraction, keratometry and adjusted ultrasound central ACD. The measurements are independent of the axial length. Moreover, the position in the anterior chamber defines the distance between the IOL and the retina. Based on this formula, the manufacturers provide nomograms or software to calculate the required power. The “one-size-fits-all” overall diameter of 8.5 mm prevents complications due to sizing errors that may occur with angle-supported or sulcus-supported PIOLs. PMMA Iris-Claw PIOL For Verisyse PIOL implantation, retrobulbar or peribulbar anesthesia is generally recommended. According to our recommended technique, a two-plane, 5.2 or 6.2mm posterior corneal incision is centered at 12 O’clock, and two vertical paracenteses directed to the enclavation site are performed at 2 and 10 O’clock. Alternatively, a scleral incision may be used. Wound construction is important to minimize induced astigmatism or wound leaks. Some surgeons locate the incision on the steep corneal meridian. The pupil should be constricted so as to protect the crystalline lens from contact with the PIOL or instruments during surgery. This can be achieved by either instilling 1 % pilocarpine preoperatively or injecting acetylcholine in the anterior chamber at the beginning of the procedure. Taking advantage of the capability to locate this type of implant over the center of the pupil, it should be marked at the cornea (entrance pupil) preoperatively if using 1 % pilocarpine, or at the beginning of the surgery if using intracameral acetylcholine, so as to enable proper centration of the PIOL. After the anterior chamber is filled with a cohesive viscoelastic material, the lens is introduced and rotated 90 degrees into horizontal position. The PIOL is fixed with an enclavation needle that has a bent shaft and a bent tip that pushes the iris into both claws. The needle is introduced through one of the paracentesis and holds the fold of iris while the lens is slightly depressed with the implantation forceps so that the claws will automatically grasp

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the iris. Then, hands are switched and the same maneuver is performed through the other paracentesis. Both fixation of the iris claws and proper centration of the PIOL over the pupil should be checked before the next step, which is one of the main advantages of this PIOL style. It is not unusual to have mild ovalization of the pupil at the end of the surgery because of the effect of the miotic agent. If the lens is not well centered, enclavation can be released by pushing in the central portion of the claw with the enclavation needle. A peripheral iridectomy should be performed to prevent pupillary block situation. Alternatively, Nd:YAG laser can be applied preoperatively to create one or two small iridotomies 90º apart. The corneal wound is then sutured with five interrupted 10-0 nylon stitches, the scleral incison with one running suture. Proper tension of the sutures is checked with a standard qualitative Maloney keratoscope. Beginning at week 4, and over a period of 3 months, sutures are selectively removed, depending on the patient’s refractive and topographic astigmatism. Toric Verisyse implantation requires careful preoperative marking of implantation axis. There are two models of toric Verisyse: one with torus at 0º, and the other with torus at 90º. Therefore, implantation is always performed close to the horizontal or vertical axis, depending on the individual surgeon’s preference (Fig. 4).

Figure 4: Toric Verisyse PIOL implantation. (A) Preoperative marcation of the axis of implantation. (B) Surgical caliper measuring 5.2-mm incision. (C) Two vertical paracentesis directed towards the site of enclavation are performed. (D) A two-plane, 5.2-mm posterior corneal incision is centered 90º apart the axis of implantation. (E) Pupil constriction is achieved by injecting acetilcholine (Myochol, Ciba Vision) in the anterior chamber. The anterior chamber is filled with a cohesive viscoelastic material, the lens is introduced by means of a special forceps and rotated 90 degrees into a horizontal position. (F) Enclavation process. The enclavation needle is introduced through one of the paracentesis and holds the fold of iris and the claws automatically grasp the iris. (G) Peripheral iridectomy using scissors is performed to prevent pupil block. (H) The wound is sutured with five interrupted 10-0 nylon stitches.

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In cases of aphakia it is possible to implant the lens upsidedown and to fixate it to the posterior side of the iris so the distance between the IOL and the cornea will increase. Different A constant should be used for those cases. Foldable Iris-Claw PIOL Implantation of the foldable model requires a 3.1 mm incision, which corresponds to the width of the PMMA haptics (3.0 mm). The Artiflex lens is inserted using a spatula, process of enclavation is the same as for the PMMA lens. The only difference is, that the lens is grasped with the implantation forceps at the base of the haptic instead of at the edge of the optic. The incision is usually watertight, but a 10/0 Nylon suture may be preferred by some surgeons (Fig. 5). The issues to take into account for the toric foldable model are the same as for the toric PMMA implant.

Figure 5: Implantation of the Artiflex/Veriflex PIOL. (A) A 3.1-mm incision is required. (B and C) The Artiflex lens is inserted using a specially designed spatula. (D) The enclavation needle is introduced through one of the paracentesis and holds the fold of iris while the lens is grasped with the implantation forceps by the base of the haptic. (E) Hands are switched and the same maneouver is repeated to enclavate the other claw. (F) The incision is sutured with a 10-0 Nylon suture.

Posterior Chamber Phakic Intraocular Lenses Historical Overview Posterior chamber position theoretically provides fewer incidences of halos and glare as the margins of the pupil cover the border of the optical zones. Additionally, the risk of corneal endothelial damage is also theoretically minimized, due to greater distance between implant and corneal endothelium. However, higher rate of cataract formation and pigment dispersion remain as clear disadvantages of posterior PIOL.

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One of the first posterior chamber PIOL designs, the ’collar-button’ or ’mushroom’ configuration, is attributed to Fyodorov. He developed a one-piece silicone PIOL, with a 3.2-mm optic and a concave anterior surface that projected anteriorly through the pupil. The lens was fixated behind the iris plane by two haptics, and had a total length of 8.0 mm. Initial complications included corneal touch, decentration, pupillary block glaucoma, iridocyclitis and cataract formation [11]. Since then, evolution in design and materials has led to the emergence of several different models, including the Adatomed lens (Chiron, Claremont, USA). It was a 5.5-mm optic ellastomer model, with an overall length up to 12.5 mm, and dioptric range up to -25 D. However, cortical opacities and decentration frequently occurred after surgery and this lens fell into disuse. Currently, there are two posterior chamber PIOLs available on the market: the “Implantable Contact Lens” (ICL, STAAR Surgical, Monrovia, USA), and the “Phakic Refractive Lens” (PRL, Carl Zeiss Meditec, Jena, Germany). Current Models Implantable Contact Lens (ICL) The ICL is currently the most widespread used posterior chamber PIOL. This lens incorporates material with increased biocompatibility known as Collamer. This material attracts deposition of a monolayer of fibronectin on the lens surface that inhibits aqueous protein binding and makes the lens invisible to the immune system. ICL’s design and materials were refined through a series of prototypes in different clinical trials. For models V (Version) 2 and V3, complications reported were pupillary block and pigment dispersion glaucoma. However, late anterior subcapsular opacities of the crystalline lens occurred and may be attributed to an intermittent contact between the ICL and the crystalline lens. The current model, the Visian ICL V4, is a rectangular single-piece lens, 7.5-8 mm wide, available in four overall lengths: 11.5 to 13.0 mm in 0.5-mm steps for myopic, and 11.0 to 12.5 mm in 0.5mm steps for hyperopic lenses. Optic diameter ranges from 4.65 to 5.5 mm in myopic IOL, depending on the dioptric power. In hyperopic ICLs, optic diameter is always 5.5 mm. Available powers for myopic lenses range from -3.0 to -23.0 D, for hyperopic lenses from +3.0 to +22.0 D, and for toric ICLs correcting myopia with added positive cylinder of +1.0 to +6.0 D (Fig. 6B). The ICL can be inserted through a 3.0 mm incision using a microinjector. The ICL has orientation markings on its

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haptics, allowing control during the unfolding maneuver. ICL thickness is less than 50 μm at the optic zone, 500 to 600 μm at the haptic zone, and 100 μm at the haptic footplates, which are theoretically positioned in the cilliary sulcus by means of a spatula specially designed for it (Fig. 7G and 7H). The basic design change of the ICL V4 addresses the vaulting. It has an additional 0.13 to 0.21 mm anterior vault. The higher vault provides a greater space between the posterior surface of the ICL and the anterior surface of the crystalline lens, which allows for a fluid change of nutrients and prevents contact between the ICL and the crystalline lens. Numerous studies have proved that ICL are predictable, stable and safe for the correction of refractive errors. However, the risk of cataractogenesis, pigment dispersion and glaucoma should not be overlooked (Fig. 6).

Figure 6: (A) Clinical photograph of ICL PIOL. Notice the two superior laser iridotomies 90º apart, to prevent pupillary block. (B) The Toric ICL has two orientation marks that have to fit with the selected axis of implantation (C) Slightly insufficient vaulting (< 250 µm) probably due to a too short ICL. (D) Excessive vaulting (> 750 µm) due to a too long ICL. Both lenses were selected according to the white-to-white distance plus 0.5 mm rule. Sizing errors highlight the need for more accurate measurements of the sulcus diameter.

Figure 7: (A-D) Loading of the ICL in the cartridge. (A) Using a modified McPherson forceps, the lens is checked under the operating microscope. The two tiny holes on the footplates must be oriented distal-right and proximal-left. (B and C) The lens is loaded with the dome up. (D) Piece of soft

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material, the Staar Foam-tip, is positioned to protect the ICL from contact with the plunger of the shooter. (E) Broad pharmacological mydriasis is essential for implantation. The anterior chamber is filled with a cohesive viscoelastic, and the cartridge is inserted bevel-down. (F) The lens is carefully injected. (G and H) The haptics are gently pushed under the iris with a blunt spatula.

Phakic Refractive Lens (PRL) The “Phakic Refractive Lens” (PRL) for the correction of myopia and hyperopia is made of ultra-thin highly purified, optically clear silicone, and has a concave posterior base curve of 10 mm radius that mimics the anterior curvature of the crystalline lens. Central thickness is less than 0.5 mm and is constant for myopic lenses but varies with hyperopic lenses. Edge thickness is always less than 0.2 mm, and it is constant in hyperopic lenses and varies in myopic ones. There are two models of myopic lenses available: overall diameter of 10.8 mm (PRL 100) and 11.3 mm (PRL 101). The diameter of the optic of the lens is 4.5-5.5 mm, depending on the lens power, which ranges from -3.0 to -20.0 D (maximum correction at the spectacle plane of -28 D). Hyperopic lenses (PRL 200) have an overall diameter of 10.6 mm, a4.5 mm optic, and power ranges from +3.0 to +15.0 D. This foldable lens can be inserted through a 3.2-mm incision, and theoretically floats on a layer of aqueous humor inside the posterior chamber, exerting no pressure on the ciliary structures without any contact to the anterior capsule of the crystalline lens. Because this type of PIOL lacks fixation, stability of centration and rotation are concerns. Thus, this PIOL is not suitable for correction of astigmatism. Spontaneous dislocation lens into the vitreous cavity were also reported probably due to damage to the zonules fibres. Selection Criteria Selection criteria are displayed in Tables 2 and 3. For the PRL, the company suggests an ECC of  2000 cells/mm2, and a central ACD of  2.5 mm. For the ICL, an ACD, measured from the endothelium to the anterior surface of the crystalline lens, of  2.8 mm for myopia, and of  3.0 mm for hyperopia is required. Surgical Technique IOL Power Calculation and Diameter Selection For calculation of the lens power, the majority of users employ the formula proposed by Feingold and Olsen, which uses patient’s refraction from the 12 mm spectacle plane or the vertex refraction, the corneal keratometric dioptric power at its apex, and

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adjusted ultrasound central ACD, also known as the Effective Lens Position (ELP) [12]. ELP is calculated as the difference between the ACD and the distance between the IOL and the crystalline lens. Based on this formula, the manufacturers provide nomograms or software to calculate the required IOL power at the ciliary sulcus plane. ICL overall diameter depends on the ciliary sulcus diameter, and should provide perfect stability with no excess of compression forces to the sulcus, and allows for a correct ‘vaulting’ (Fig. 6 C and 6 D). Excessive vaulting (> 750 µm) due to too long ICL may cause angle-closure, pupillary block glaucoma, or pigment dispersion glaucoma. On the other hand, insufficient vaulting (< 250 µm) due to a too short ICL increases the risk of cataractogenesis due to the contact between the posterior surface of the ICL and the anterior surface of the crystalline lens. Before the development UBM, evaluation of the inner diameter of the ciliary sulcus was approximated and depended on a WTW measurement. ICL’s diameter is oversized 0.5 to 1 mm from the WTW measurement in myopic eyes, and same-length or oversizing 0.5 mm in hyperopic eyes. However, recent studies demonstrate that there is no anatomical correspondence between external measurements and internal dimensions [13]. Therefore, WTW distance alone may not predict either angle or sulcus size, causing some of the problems with anterior chamber angle-supported or posterior chamber PIOL. Surgical Technique for ICL Correct loading of the ICL in the cartridge and the injector is essential for a correct and easy implantation. The ICL has two tiny holes on the footplates (distal-right and proximal-left) that allow a correct anterior-posterior orientation of the lens. The cartridge is filled with viscoelastic substance. The lens is loaded with dome up, taking special care of a correct haptic position avoiding their rupturing. A piece of soft material, the Staar Foam-tip, is positioned to protect the ICL from contact with the plunger of the shooter. Additionally, some surgeons recommend inserting the tip of a wet surgical microsponge between the foam-tip and the ICL to further protect the optic and the haptics. Broad pharmacological mydriasis is essential for uneventful implantation. Although the ICL can be inserted through an under-3-mm incision, some surgeons use incisions up to 3.5 mm, located on the steeper corneal axis, so as to compensate for previously existing corneal astigmatism (up to 1.5 D). This approach may be used for any type of foldable PIOL. If there is no corneal astigmatism, a

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temporal incision is generally preferred. One side-port incision of about 1 mm and 90º separated from the main incision is created. Some surgeons prefer two paracentesis to enable an easier implantation of the haptics in the ciliary sulcus. The anterior chamber is filled with a cohesive, low-viscous viscoelastic to protect corneal endothelium and crystalline lens from surgical trauma. The cartridge is inserted bevel-down, and the ICL is carefully injected. It is essential to control unfolding of the lens, so as to twist the bevel right or left to assure a correct orientation of the lens. Finally, the haptics are gently pushed under the iris with a blunt spatula. As correct centration of the ICL and position of the haptics in the ciliary sulcus is checked, acetylcholine is injected in the anterior chamber to induce pupil constriction. Complete extraction of viscoelastic substance, as in any intraocular surgery, is mandatory to avoid postoperative ocular hypertension. Peripheral iridectomy should be performed to prevent pupillary block situation (Fig. 7). Alternatively, two Nd:YAG laser iridotomies are performed in the peripheral iris one week preoperatively. These generally measure 250 to 500 μm and are located superiorly, 90º apart, thus being covered by the upper eyelid (Fig. 6A). Finally, the wound is hydrated. Surgical Technique for PRL The implantation procedure for the PRL is almost the same as for the ICL. Two opposed paracentesis ports are created on either side of a 3.2-mm clear cornea incision. The PRL is inserted with a specially designed forceps or with an injector system. Once the lens unfolds slowly in the anterior chamber, its haptics initially lie anterior to the dilated iris. Each haptic corner then is gently placed behind the iris through the pupil with a long spatula or an intraocular hook. When proper horizontal lens orientation is verified, a miotic agent is injected. spontaneous postoperative year [43,47,48]. At two rotation of the PRL may easily occur, two peripheral iridotomies, 90º apart, are mandatory to prevent pupillary block situation. BIOPTICS, ADJUSTABLE REFRACTIVE SURGERY AND ENHANCEMENTS Zaldivar et al. introduced the term “Bioptics” to describe the combination of LASIK following PIOL implantation in patients with SE ≥ -18.0 D, patients with high levels of astigmatism and in patients for whom lens power availability was a problem [14]. Similarly, with the aim to improve the quality of vision and to diminish glare, halos,

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and other common complaints under dim illumination in highly myopic subjects (greater than -15.0 D), Guell et al. developed the idea of “Adjustable Refractive Surgery” (ARS), in which implantation of a 6-mm optic Verisyse PIOL and a 6.5mm optical zone LASIK procedure were combined [15]. Later on, several other investigators used this combined approach that allows for fine-tuning refractive results, especially in patients with high refractive errors and/or astigmatism. Anterior Segment Imaging and Phakic Intraocular Lenses Until the recent development of new anterior segment imaging techniques, monitoring of the anatomic relationship of these lenses with anterior chamber structures was mostly carried out at the slit-lamp. This limited accuracy of the measurement of distances between the IOL and the corneal endothelium or the anterior capsule of the crystalline lens, as well as internal diameters of the anterior chamber or the sulcus. In addition, the dynamic relations during accommodation or pupil light reflex were difficult to assess. UBM, anterior segment optical coherence tomography (AS OCT) and Scheimpflug photography have already been used to provide measurements and verify the intraocular position of PIOLs within the anterior chamber. Table 4 summarizes the main features of each anterior segment imaging technique. Table 4: Main features of new anterior segment imaging techniques AS OCT

UBM

Scheimpflug

Image source

Optical

Ultrasound

Optical

Axial resolution

18 µm

25 µm (50 MHz)

N/A

Contact

-

Immersion fluid

-

Operator skills

+

++++

++

Topography

-

-

+

Pachymetry

+

+

+

Angle visualization

+

+

-

ATA distance measurement

+ direct

+ image reconstruction

-

Ciliary sulcus visualization

-

+

-

Opaque media

+

+

-

AS OCT: anterior segment optical coherence tomography; UBM: Ultrasound Biomicroscopy; +: Yes; -: No; N/A: Not applicable; ATA: angle-to angle distance. *Accommodation studies performed using miotic agents or contralateral eye stimulation.

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Measuring Angle-to–Angle Distance The overall diameter of angle-supported PIOLs should be selected according to the anterior chamber diameter. One of the main source of complications with anterior chamber angle-supported PIOLs is the sizing error of the lens. A too short lens will be unstable, and may move freely in the anterior chamber, thus contacting with the corneal endothelium. On the other side, a too long lens will have a high vault that will approximate the optic of the lens to the endothelium, increasing the risk of corneal decompensation. Additionally, it may cause an excess of compression forces to the angle, thereby damaging angle structures and provocing pupil ovalization. Before development of anterior imaging techniques the evaluation of anterior chamber diameter depended on WTW measurement. WTW distance can be measured either manually or using automated technology. Automated measurement provides more precise results than measurements using manual methods. Anglesupported implant diameter is oversized 0.5 to 1 mm with WTW measurement. However, WTW distance does not always correspond to anterior chamber diameter. The internal horizontal diameter of the AC is usually larger than the horizontal corneal diameter determined by automated WTW measurements [16]. Currently, with the advent of AS OCT, anterior chamber angle can be precisely measured. UBM may also be useful, but it requires image reconstruction to allow for angle-toangle measurement. In addition, it requires immersion of the eye in a water bath solution, which can lead to slight anterior segment distortion through external compression. Moreover, use of miotic eyedrops or stimulation of the fellow eye is required to perform dynamic studies of accommodation. Although Scheimpflug imaging allows for a fast non-contact acquisition of data, it requires clear optical media, iris tissue is imprecisely depicted due to light scattering, and anterior chamber angle structures cannot be properly captured. Anterior Segment Optical Coherence Tomography: Anterior Chamber Biometry Anterior Segment Optical Coherence Tomography (Visante™ OCT, Carl Zeiss Meditec Inc., Dublin, CA) is a noncontact, high resolution, cross-sectional imaging technique that uses low-coherence interferometry to provide in vivo cross-sectional images of ocular structures with a spatial resolution of 10 to 20 μm. Using1310-nm infrared wavelength allows for increased penetration in

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scattering tissues, such as the sclera and iris, while simultaneously permits sufficient illumination power to be used to enable high-speed imaging [17]. The Visante™ OCT is designed to image the shape, size and position of the structures of the anterior segment and make precise measurements of the distances between them, including corneal thickness and surface profile, anterior segment biometry (ACD, ATA distance, angle size in degrees), pupil diameter, and thickness and radii of curvature of the crystalline lens. It has also proved useful in determining PIOL position and relation to the crystalline lens (Fig. 8). The equipment has a target that can be defocused with positive or negative lenses. By focusing and defocusing the target with positive or negative lenses, it is possible either to relax or stimulate the subject’s accommodation in a natural way. Accommodation studies in PIOL implantation show, that with every diopter of accommodation,

Figure 8: The Visante™ OCT is capable of making precise measurements of anterior chamber structures, including corneal thickness, anterior chamber depth-ACD-, angle-to-angle distance, and angle size in degrees. It can also determine PIOLs’ location and its relation with the corneal endothelium and the crystalline lens.

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anterior pole of the crystalline lens moves 30 μm forward [18]. This could affect the relationship between intraocular structures and the PIOL. There may be intermittent contact between the ICL and the crystalline lens, which can cause cataract formation. In case of iris-claw phakic lenses, the distance between the phakic lens and the crystalline lens remains stable during accommodation. Morphologic changes of the crystalline lens with aging may also affect its relationship with PIOLs. Baikoff’s observations with aging showed that along with a thickening of the crystalline lens, there is also a forward movement of the crystalline lens’ anterior pole even when the eye is at rest. This is accompanied by a reduction in ACD. Considering that the crystalline lens thickens with age, with 18 μm to 20 μm movements of its anterior pole forwards each year, the remaining distance allows calculating how long PIOL can theoretically remain safely in the eye [19]. The distance between anterior PIOL surface and corneal endothelium is also modified during the accommodation process. A decrease of the PIOL to endothelium distance was found in some studies [20]. This is especially important in case of anterior chamber angle-supported and iris-claw PIOL, as this may be a factor for endothelial cell loss with age, and points out the importance of monitoring the ECC of these patients throughout their life time. Regarding the corneal endothelium, security criteria for iris-claw anterior chamber phakic intraocular lenses are as follows: (1) Preoperative distance between the corneal endothelium and the anterior surface of the crystalline lens should be greater than 2.8 mm; (2) Postoperatively, the distance between the center of the optic of the lens and the corneal endothelium should be at least of 2 mm; (3) Postoperatively, the distance between the periphery of the optic of the lens and the corneal endothelium should be at least of 1.5 mm. AS OCT allows for close monitoring of these distances during accommodation and ageing. Rotating Scheimpflug Imaging The Pentacam Scheimpflug is a non-contact optical system that has specifically been designed to image the anterior segment of the eye. It has a rotating Scheimpflug camera that takes up to 50 slit images of the anterior segment in less than 2 seconds. Software is then used to construct a 3-dimensional image. It calculates data for corneal topography (anterior and posterior surface), corneal

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thickness, and corneal wavefront, ACD, lens opacification and lens thickness. ACD is an important parameter to consider prior to PIOL implantation. A newer version has recently become available, the Pentacam HR. In addition to a higher resolution camera, it has software that simulates the position of the proposed lens. However, this device has certain limitations for evaluation of PIOLs, as neither anterior chamber angle structures nor the sulcus can be captured. Measuring Sulcus-to-Sulcus Distance As with angle-supported lenses and anterior chamber diameter, posterior chamber sulcus-supported PIOLs’ overall length should be selected according to sulcus-tosulcus distance. Sizing error is the main source of complications after ICL implantation, increasing the risk of angle-closure and pigmentary dispersion glaucoma if ICL is too long or increasing the risk of cataract if ICL is too short. Before development of UBM, there was no system that allowed determination of the internal diameter of the ciliary sulcus. This evaluation was approximated and depended on WTW measurement. ICL’s diameter is oversized 0.5 to 1 mm from the WTW measurement in myopic eyes, and same-length or oversized 0.5 mm in hyperopic eyes. However, recent studies demonstrate that there is no anatomical correspondence between external measurements and internal dimensons. The posterior chamber appears to have a vertically oval shape, and the white-to-white technique is thus inaccurate in predicting the horizontal diameter of the ciliary sulcus, as sulcus-to-sulcus distance is generally smaller than the anterior chamber diameter. In the ICL FDA study, which adopted the WTW measurement protocol, replacement rate due to symptomatic over-undersizing issues was 1.5 %. Moreover, ICL length determined by the UBM method achieved significantly a more ideal ICL vault than with the conventional WTW method. The UBM method is superior to the conventional method in terms of predicting sulcus-tosulcus horizontal diameter for ICL length determination. High Resolution Ultrasound Biomicroscopy: The Artemis and The Paradigm P60 Images of ciliary sulcus can only be obtained with high-resolution ultrasound devices that use very high frequency waves in the 50-MHz range. Ophthalmic ultrasound imaging is based on the emission of an acoustic pulse and reception of the

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pulse after it has been reflected by ocular tissues. The Paradigm P60 (Paradigm Medical Industries Inc, Salt Lake City, Utah, USA) offers flexibility in its clinical use by incorporating four different probes with different frequencies of 12.5, 20, 35, and 50 MHz. The best image quality and resolution is obtained by the 50 MHz probe, but the scan field is limited to a 5x5 mm square. Therefore, angle and sulcus dimensions cannot be measured in one scan sweep. UBM provides high-resolution images with an axial resolution of about 25 µm and transverse resolution of about 50 µm. In contrast to optical systems, UBM is able to scan through opaque media. However, image acquisition requires the eye to be immersed in a fluid with an eyecup, which is uncomfortable for either patient and examiner and may potentially distort the eye anatomy and angle configuration. The Artemis 2 system (Ultralink, St Petersburg, FL, USA) uses a 50 MHz transducer that is swept in an arc matching the curvature of the anterior surface of the eye. In addition, the Artemis uses a more sophisticated system for data acquisition, storing the actual echo data (from which images are formed) instead of the image itself. An optical system for eye fixation and alignment allows direct visualization to confirm the exact position where measurements are taken. Then a computer-controlled scan along multiple clock hours permits a three-dimensional biometric mapping of the eye. FUNCTIONAL RESULTS OF PIOL To provide better overview particular results of published data regarding the different types of PIOL are displayed in Tables 5-7. Refractive results in terms of visual acuity, predictability, efficacy and safety of current commercially available AC PIOL models, Baikoff ZB 5M, Duet Kelman ZSAL-4, Phakic 6, I-CARE and Vivarte are demonstrated in Table 5. Regarding the Vivarte PIOL, Table 5 only displays results of the refractive bifocal Vivarte PIOL [21]. At the time of composing this review, no published, peer-reviewed studies existed for the ThinPhAc and the Vision Membrane Lens. Of note, despite the long period in which AC PIOL are available on the market now, only few long-term studies exist [22,23]. In general, AC PIOL demonstrate good predictability, efficacy and safety. However, summing up the results of Table 5, one can notice a tendency for undercorrection of refractive errors for AC PIOL.

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Table 5: Summary of outcomes, efficacy and safety of angle-supported, anterior chamber phakic intraocular lenses.

Mean postoperative spherical equivalent in D

Postoperative ±0,5 D [%]

Postoperative ±1,0 D [%]

Postoperative UCVA ≥ 1.0 [%]

Postoperative UCVA ≥ 0.5 [%]

Efficacy

Loss of BCVA 2 or more lines (%)

Loss of BCVA 1 line (%)

No change of BCVA

Gain of BCVA 1 line (%)

Gain of BCVA 2 or more lines (%)

Saftey index

133

–12.5

–1.3

40

65

no data

no data

no data

no data

no data

no data

no data

no data

no data

Utine et al. (JRS, 2006)

37

-17.45

-1.76

no data

no data

no data

no data

0.79

3.2

no data

no data

no data

29.8

1.45

Javaloy et al. (JRS, 2007)

225

-17.23

-1.80

no data

39.28

no data

34.69

1.26

3.5

~7

~23

~21

~25

1.50

Perez-Santoja et al. (JCRS, 2000)

23

–19.56

–0.55

56.5

82.6

0

54.5

1.12

0

no data

82.6

no data

no data

1.45

Leccisotti et al. (JCRS, 2003)

12

-10.23 (keratokonus)

-1.31

67

100

0

100

0.77

0

0

40

50

10

1.18

Leccisotti et al. (JCRS, 2005)

190

-14.37

1.55

19

40

~7

~60

0.78

0

0

~25

~25

~40

1.25

Kelman Duet

Alio et al. (JRS, 2007)

169

-14.26

-0.15

57.72

81.30

28.68

83.72

1.19

0

~5

~27

~11

56.20

1.37

20

-15.76

no data

85

100

no data

85

1.58

0

0

5

25

70

no data

I-CARE

GierekCiacura et al. (Graefes Arch Clin Exp Ophthalmol, 2007)

Baikoff et al. Vivarte Presbyop (JCRS, 2004) ic

55

+1.8 (-5 to +5)

-0.12

no data

no data

no data

84 (³ 0.6)

0.80

no data

no data

no data

no data

no data

0.94

Kohnen et al. (Ophthalmology, 2009)

190

-10.38

-0.23

72.7

95.7

85.7

no data

1.04

0

1.2

44.7

31.1

23.0

1.25

Knorz et al. (JCRS 2011)

104

-10.41

-0.24

78.8

91.3

46.2

97.1

0.87

1.8

1.8

38.5

40.4

19.2

1.15

ZB5M

ZSAL-4

AcrySof

Index

Mean preoperative spherical equivalent in D

Baikoff et al. (JRS, 1998)

Type of PIOL

Number of eyes

Safety

Reference (journal, year)

Efficacy

Phakic Intraocular Lenses

Premium and Specialized Intraocular Lenses 155

Table 6: Summary of outcomes, efficacy and safety of iris-claw, anterior chamber phakic intraocular lenses.

Artisan/Verisyse

34

76.8

no data

40.9

Landesz et al. (JRS, 2001)

78

–17.00

–2.0

50

68

30

73

Maloney et al. (Ophthalmology 2002)

155

–12.69

–0.54

55

90

26

83

Malecaze et al. (Ophthalmology 2002)

25

–10.19

–0.95

60

137

–16.17

–0.78

4

81

Lifshitz et al. (Int Ophthalmol, 2004) Benedetti et al. (JRS, 2005) Benedetti et al. (JRS, 2005)

31 68 25

-11.25 -11.8 -18.9

93.5 25 8

no data 83.8 68

Senthil et al. (Indian J Ophthalmol, 2006)

60

-12.5

-0.50 -0.91 -1.20 no data

60 no data 96.8 69.1 52

no data

Menezo et al. (JCRS, 2004)

24 no data 67.8 44.1 32 73.3

90

5

75

no data

58

no data

Coullet et al. (AJO, 2006)

31

-10.3

Moshirfar et al. (JCRS, 2007)

85

-12.2

Gierek-Ciacura et al. (Graefes Arch Clin Exp Ophthalmol, 2007)

20

-15.73

Stulting et al. (Ophthalmology, 2008)

-1.01 -0.50 no data no data

63

28

78.5

12

0

12

64

0

0

14

23

62

0 0 0

0 0 0

35.5 35 3

64.5 11 4

41.9 22 18

0.93

0

11.6

51.6

0.60

6.4

6.4

29.0

19.4

25.8

0

7

31

43

19

0

5

20

10

65

1.8

6.6

38.6

40.4

13.6

10

84

65

95

no data

80

1.71

Silva et al. (Arch Ophthalmol, 2008)

26

-12.30

-0.44

74

95

74

95

Guell et al. (Ophthalmology, 2008)

101

-19.8

-0.50

9.9

22.8

no data

14.8

0.86

Guell et al. (Ophthalmology, 2008)

173

-11.27

-0.64

37.6

57.2

2.9

42.8

0.74

no data 79.3

no data 96.6

+9.98

0.07

Alio et al. (JRS, 2002)

29

+6.06

0.1

88

no data no data

-12.3

67

44

9.5

662

Fechner et al. (JCRS, 2002)

53 97.5

6.4

84

34.6

2

2.5

22

0

55

94.7

1.2

72

2.6

no data

71.7

6

~1.5

~35

6.9

65.5

no data 0.83

24

88.3

Safety index

Gain of BCVA 2 or more lines ( %)

Postoperative ±1,0 D [ %] 67

Gain of BCVA 1 line ( %)

Postoperative ±0,5 D [ %]

–0.6 no data

no data 1.03 no data no data no data 0.71 no data 0.95 0.84 0.90

No change of BCVA

–14.70

100

Loss of BCVA 1 line ( %)

–12.95

67

no data

Loss of BCVA 2 or more lines ( %)

249

no data 79

Efficacy index

Budo et al. (JCRS, 2000) Landesz et al. (JRS, 2000)

no data 57 no data

Postoperative UCVA

–0.35

0.5 [ %]

–12.76

Postoperative UCVA

264

Safety

1.0 [ %]

Mean preoperative spherical equivalent in D

Alexander et al. (Optometry, 2000)

Mean postoperative spherical equivalent in D

Reference (journal, year)

Number of eyes

Type of PIOL

Efficacy

no data 1.31 no data no data no data 1.12 no data 1.29 1.12 1.39 1.19

0

~4

~23

~56

~17

no data no data

no data no data

no data no data

no data no data

no data no data

0

~10

~73

~9

~8

0

3.4

55.1

27.5

13.7

1.13 no data no data no data no data 1.30 1.04 no data 1.1

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Güell et al.

Table 6: contd…. Alio et al. (JRS, 2002)

28

+5.88

0.55

50

71.4

3.6

46.4

Dick et al.(Ophthalmology, 2003)

22

+3.25

–0.24

50

100

18

96

Saxena et al. (Ophthalmology, 2003)

17

+6.8

–0.03

59

81

58.8

94

Pop et al. (JRS, 2004)

19

+5.89

–0.03

50

78

no data

89

41

+4.92

-0.02

Boxler Wachler et al. (JRS, 2009)

31

-12.31

-0.78

Coullet et al. (AJO, 2006)

31

-9.50

-0.58

Dick et al. (Ophthalmology, 2009)

290

-7.33

-0.15

Tehrani et al. (JCRS, 2003)

29

–1.9

–0.56

Dick et al. (Ophthalmology, 2003)

70

–3.74

Guell et al. (Am J Ophthalmol, 2003)

27

–3.43

–0.7 no data

Alio et al. (JRS, 2005)

8

no data 75.2 no data 72

0

0

32.1 86

39.3

7.2 14

0

17.6

82.4

0

1.05 no data no data no data

0

0

73.6

21

5.2

no data

no data

no data

no data

1.25

42.8

0.9

no data 3

3

66

16

6

no data

68

55

90

no data

83.9

no data

77.4

0.79

9.7

0

29.0

22.6

25.8

1.12

94.3

no data

97.2

95

no data

~85

1.00 no data 1.03 no data

0 no data 0

9 no data 0

51 no data 35

33 no data 65

7 no data 0

1.09 no data 1.25

0

11

19

70

0

1.40

100

10

88.6

62.9

96.2

no data

no data

+0.40

75

87.5

12.5

87.5

1.0

0

0

4

2

2

1.3

-1.1

62.5

75

12.5

62.5

1.2

0

1

0

1

6

1.6

Alio et al. (JRS, 2005)

9

+0.50

44.4

77.8

33.3

66.6

1.0

2

1

3

1

2

1.3

Guell et al. (Ophthalmology, 2008)

84

-0.09

no data

66.6

81.3

7.1

65.4

0.93

no data

no data

no data

no data

no data

1.17

Toric Artisan/Verisyse post kerato-plasty

8

58

64.2

14.3

0

Nujits et al. (Ophthalmology, 2004)

16

–6.6

–1.42

0

31.25

0

50

no data

0

0

31.25

18.25

50

no data

Toric Artisan in kerato-konus

Alio et al. (JRS, 2005)

Astigmatis-mus mixtus +3.6 Astigamtis-mus myopicus -8.6 Astigmatis-mus hyperopicus +5.9

34.8

7.2

Venter et al. (JRS, 2009)

18

-4.64

-0.46

no data

78

22

100

no data

0

0

28

39

33

no data

Toric Artiflex

Toric Artisan/Verisyse

Artiflex/ Veriflex

Guell et al. (Ophthalmology, 2008)

0.70 no data no data no data

Interim results (unpublished)

125

-7.66

-0.04

77

97.3

no data

no data

1.05

2.5

5

42.5

33.7

16.3

1.15

Phakic Intraocular Lenses

Premium and Specialized Intraocular Lenses 157

Regarding the Acrysof PIOL, Knorz et al. reported favorable 3-year results with 80.8 % of the 104 patients achiving 20/20 or better vision with annualized percentage loss in central ECD and peripheral ECD from 6 months to 3 years of 0.41 % and 1.11 %, respectively. No pupil ovalization, pupillary block, or retinal detachment was reported [24]. Kohnen and Klaproth reported maintained adequate central clearance distances to the corneal endothelium and the natural crystalline lens over 3 years follow-up [25]. Refractive results in terms of visual acuity, predictability, efficacy and safety of current commercially available IF PIOL models, Artisan/Verisyse, toric Artisan/Verisyse and Artiflex/Veriflex are demonstrated in Table 6. Published data comprise several studies with longer follow-up. IF PIOLs demonstrate very good predictability, efficacy and safety both for non-toric and toric models. With the toric PIOL models, larger amount of preoperative astigmatism can be managed successfully. As shown in Table 6, several reports addressed clinical outcomes after implantation of toric PIOL [26-30]. In 2008, Guell et al. reported the results of a series of 84 cases with a mean follow-up of 2.9 years after toric Artisan PIOL implantation [29]. Recently, reports on the clinical outcomes and complications of the toric Artiflex PIOL have been published [31]. The European Multicenter Study reported 99.0 % of eyes with UCVA of ≥20/40, and 81.8 % of eyes ±0.5 D of the intended refraction at 6 months. Moreover, toric Artiflex combined with corneal collagen cross-linking has proved effective to correct myopic astigmatism in patients with progressive keratoconus, with 94 % of eyes with UCVA of ≥20/40, and 82 % of eyes within ± 0.50 D of the attempted SE [32]. Refractive results in terms of visual acuity, predictability, efficacy and safety of current commercially available PC PIOL models are demonstrated in Table 7 for the Implantable Contact Lens (ICL) and the Phakic Refractive Lens (PRL). Published studies demonstrate a good safety and efficacy of these two PIOL types. Especially the ICL PC PIOL, that has been investigated in scope of an FDA study shows good functional results with a low complication rate [33]. In a prospective study comparing matched populations of LASIK and Visian ICL, the ICL performed better than LASIK in almost all measures of safety, efficacy, predictability and stability [34]. In few case reports, results of toric PC PIOL have also been demonstrated. Gimbel and Ziemba report about implantation of a toric ICL for correction of myopic astigmatism of 2.25 D with outcome of 1.2 VA and

158 Premium and Specialized Intraocular Lenses

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residual astigmatism of only 0.25 [35]. Schallhorn et al. found a better performance of toric ICL compared to conventional photorefractive keratectomy in a randomized prospective comparison in all measures of safety, efficacy, predictability and stability [36]. Mertens et al. demonstrated a case of bilateral custom-designed toric ICL with stable results 19 months, postoperatively [37]. A recent report by Park et al. also showed good clinical outcomes after toric ICL implantation [38]. PIOL types Fyodorov and Chiron Adatomed were withdrawn from the market because of their complication spectrum, results are therefore not displayed in Table 7. COMPLICATIONS OF PIOL B1. General Complications of Intraocular Surgery With today’s increasing use of topical or parabulbar instead of retrobulbar anaesthesia complications due to anaesthesia like retrobulbar hemorrhage, penetration of the globe or life threatening systemic side effects due to accidental injection in the optic nerve are very rare. Due to the fact, that implantation of PIOL is an intraocular procedure it certainly bears a potential risk of developing postoperative endophthalmitis. The risk for this event in general cataract surgery with implantation of a posterior chamber IOL has been reported to be 0.1-0.7 % with an optimal antiseptic perioperative treatment regimen [39]. Recently, a prospective, randomized multicenter study of the European Society of Cataract and Refractive Surgeons (ESCRS) demonstrated that an additional intracameral application of cefuroxime after cataract surgery significantly reduced the rate of postoperative endophthalmitis [40]. So far, only one case of postoperative endophthalmitis after PIOL implantation has been reported in the literature [41]. In this case, endophthalmitis developed on the first postoperative day after AC PIOL implantation and was caused by beta-hemolytic streptococci. Intraoperative sterility and meticulous postoperative follow-up examinations may help to prevent this severe complication or to treat it as early and aggressively as possible.

Phakic Intraocular Lenses

Premium and Specialized Intraocular Lenses 159

Table 7: Summary of outcomes, efficacy and safety of posterior chamber phakic intraocular lenses.

Sanders et al. (Ophthalmology, 2004)

369

–10.06

Uusitalo et al. (JCRS, 2002)

38

Jimenez-Alfaro et al. (JRS, 2001)

0.5 [ %]

no data

0

76.2

no data

0

0

9.5

19

71.4

no data

57.4

80.2

50.9

93.3

no data

1.6

7.8

41.2

38.5

10.9

no data

no data

67.5

88.8

40.8

81.3

no data

0.8

no data

no data

no data

10.8

no data

–15.1

–2.0

71.1

81.6

39.5

94.7

no data

0

6.3

18.8

31.3

40.6

no data

20

–14.1

–1.62

no data

20

no data

60

no data

0

0

0

0

100

no data

Gonvers et al. (JCRS, 2001)

22

–11.5

–1.19

32

45

18

68

no data

0

0

9.1

Arne et al. (JCRS, 2000)

58

–13.85

–1.22

no data

56.9

no data

no data

0.84

3

5

19

35

38

Jan46

Zaldivar et al.(JRS, 1998)

124

–13.38

–0.78

44

69

2

68

no data

0.8

7

29

28

36

no data

Rosen et al. (JCRS, 1998)

16

–9.28

–0.83

56.25

no data

25

56.25

no data

0

6.25

50

37.5

6.25

no data

Rosen et al. (JCRS, 1998)

9

-15.4

0.3

88

no data

44.4

88.9

no data

0

11.1

44.4

22.2

22.2

no data

Pineda-Fernandez et al. (JCRS, 2004)

18

-15.27

-0.62

no data

no data

5.5

44.4

no data

5.5

0

55.5

5.5

33.3

no data

Lackner et al. (Ophthalmology, 2003)

65

-16.23

-1.77

no data

42

no data

no data

no data

Pesando et al. (JRS, 1999)

15

+7.77

0.02

69.25

92.3

0

46.15

no data

7.7

0

76.9

0

15.4

no data

Davidorf et al. (JRS, 1998)

24

+6.51

–0.39

58

79

8

63

no data

4

0

33

29

8

no data

Postoperative ±1,0 D [ %]

1.0 [ %]

Number of eyes

Safety index

–0.56

Gain of BCVA 2 or more lines ( %)

–10.05

Gain of BCVA 1 line ( %)

258

No change of BCVA

Sanders et al. (Ophthalmology, 2003)

Loss of BCVA 1 line ( %)

no data

Loss of BCVA 2 or more lines ( %)

Postoperative ±0,5 D [ %]

–1.60

Efficacy index

Mean postoperative spherical equivalent in D

–16.0

Postoperative UCVA

Mean preoperative spherical equivalent in D

21

Safety

Postoperative UCVA

ICL

Menezo et al. (JCRS, 2004)

Reference (journal, year)

Type of PIOL

Efficacy

13.8

no data

90.9

1.5

84.6

1.31

160 Premium and Specialized Intraocular Lenses

Güell et al.

Table 7: contd…

Toric ICL

PRL

Lackner et al. (Ophthalmology, 2003)

10

+7.88

0.44

no data

73

no data

no data

no data

Chang et al. (JRS, 2007)

61

-14.53

-0.10

72.5

88.2

75

100

no data

0

~3

~27

~62

~8

no data

Kamiya et al. (Arch Ophthalmol, 2009)

56

-9.83

-0,38

79

93

70

95

0.83

0

9

32

46

13

1.19

Sanders (JRS, 2007)

164

-6.01

-0.09

85

97

63

99

no data

0

4

52

41

3

no data

Boxer Wachler et al. (JRS, 2009)

30

-11.48

-0.40

88

100

67

100

no data

0

0

50

40

10

no data

Schallhorn et al. (JRS, 2007)

38

-8.04

-0.17

76

100

97

100

no data

0

0

5

92

3

no data

Alfonso et al. (JCRS 2009)

15

-7.08

-0.95

66.6

80

no data

46.6

1.02

0

0

54

13

33

1.58

0

0

no data

no data

no data

no data

60

0

40

0.98

Park et al. (JRS, 2009)

30

-10.63

0.04

70

94

67

100

no data

Pallikaris et al. (JCRS, 2004)

34

–14.7

–0.61

44

79

no data

no data

no data

2.9

0

23.5

29.4

44.1

no data

Hoyos et al. (JCRS, 2002)

17

–18.46

–0.22

53

82

no data

no data

no data

0

0

35

47

18

no data

Verde et al. (JRS, 2007)

90

-11.90

+0.04

68

80

~16

~92

0.98

0

0

35

33

32

1.22

Donoso et al. (JCRS, 2006)

53

-17.27

-0.23

no data

71.2

60

no data

1.0

5.7

1.9

15.1

41.5

35.8

1.40

0

2

40

10

14

no data

Jongsareejit (JRS, 2006)

50

-12.54

-0.23

88

96

44

82

no data

Koivula et al. (JRS, 2008)

14

-10.28

-0.38

79

100

50

100

0.98

0

no data

no data

no data

no data

1.18

0

7

86

7

0

no data

Hoyos et al. (JCRS, 2002)

14

+7.77

–0.38

50

79

no data

no data

no data

Gil-Cazorla et al. (JRS, 2008)

16

+5.65

+0.07

93.75

100

12.5

100

0.8

0

31.25

68.75

0

0

0.9

Koivula et al. (JRS, 2008)

6

+5.67

-0.85

67

100

17

83

0.89

0

no data

no data

no data

no data

0.98

Koivula et al. (JCRS, 2009)

40

+5.90

-0.46

87.5

100

17.5

82.5

0.70

5.0

no data

no data

no data

0

0.89

Phakic Intraocular Lenses

Premium and Specialized Intraocular Lenses 161

AC PIOL COMPLICATIONS Optical Quality, Glare, Halos One of the disadvantages of AC PIOL is that they are positioned in front of the pupil, with edge effects being a potential source of optical aberrations. Furthermore, relation of pupil size and center to the optic of the lens is a crucial factor which should be evaluated and discussed preoperatively. Sometimes AC PIOL optic center and the pupil center are not coincident. If the scotopic pupil size is significantly larger than the optic of the lens, one should be very cautious with implantation of PIOL since this will probably result in postoperative glare and subjective discomfort. Incidence of glare is dependent on the size and position of the optic, which varies in different lens designs and generations. The acceptable relationship between AC PIOL optic and scotopic pupil size remains to be determined. In the literature, incidence of glare and halos is reported to be between 10 % at 7 years follow-up [42] and 80 % as observed by Allemann and coworkers [43]. However, in the last study the NuVita IOL had a special optic edge design to prevent glare. A study performed by Maroccos et al. showed that all tested types of PIOL (AC (NuVita), IF (Artisan) and PC (ICL), in particular PC PIOL and AC PIOL lead to a decreased visual performance during night time due to glare and halos [44]. Topical use of miotic agents like brimonidine should be considered in the early postoperative phase if the patient feels disturbed by these phenomena. A study analyzing the effects of PIOL implantation on contrast sensitivity demonstrated that in comparison to PC PIOL (PRL), AC PIOL (Phakic 6) and IF PIOL (Verisyse) led to improved contrast sensitivity [45]. Surgically Induced Astigmatism (SIA) SIA is of significance since patients request acceptable unaided postoperative visual acuity. The surgeon needs to consider the preoperative amount and axis of astigmatism in order to decide whether to use a 5-6 mm incision size with a PMMA lens (e.g. Phakic 6) or to implant a foldable PIOL (e.g. Vivarte) through a small incision. If significant SIA is noted, further refractive surgical procedures (e.g. suture revision or removal, limbal relaxing incisions or excimer laser surgery) may be required. Irregular astigmatism due to too large and incision to close to the corneal center should be avoided [46].

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Loss of Corneal Endothelial Cells (CEC) The main concern about AC PIOL is loss of CEC or damage to the endothelial integrity. Exact preoperative examination should exclude patients with low CEC count or with shallow anterior chambers since the risk of CEC increases as the distance between PIOL and the endothelium decreases. CEC loss was the major reason for withdrawn of AC PIOLs. In a 7-year follow-up study, Alió et al. report on an early postoperative loss of CEC of 3.8 %, gradually decreasing to about 0.5 % per year after the second postoperative year [42]. In this study the ZB5M/ZB5MF was investigated over the whole period of time and the ZSAL-4 only for 4 years. The total percentage of CEC loss over 7 years was 8.4 %. Other studies have confirmed the initial significant CEC loss and reduction of this tendency in the second postoperative year [43,47,48]. At two years Alleman found 12 % for the B&L NuVita, Perez-Santonja 4.2 % with the ZSAL-4, and at three years Baikoff found a 4.8 % loss at 3 years with the ZB5M. In a series of PIOL explanations due to different reasons CEC loss was the cause for PIOL explanation in 24 % in a report of Alio et al. [49]. Explanted PIOL were Baikoff ZB and ZB5M and Phakic 6 AC PIOL. In the study with the longest follow-up (up to 12 years) after PIOL implantation, Javaloy et al. report an initial reduction of CEC of 10.6 % in the first year followed by a mean annual decrease rate of 1.8 % after ZB5M PIOL implantation [22]. Mean CEC loss after implantation of I-CARE PIOL was 6.1 % after 1 year reported by Gierek-Ciaciura et al. [50]. All these AC except the I-CARE PIOL were PMMA rigid lenses. One report of the new flexible AC PIOL by Baikoff et al. showed that one year after implantation of the Vivarte PIOL, CEC loss was less than 5 %, but there was a difference between myopes (2.3 %) and hyperopes (5.4 %) [21]. For the AcrySof CACHET AC PIOL CEC loss was 4.8 % after one year follow-up [51]. However, meticulous long-term follow-up of each patient is necessary for any AC PIOL to detect those individuals with significant damage to the endothelium and to explant AC PIOL whenever clinically necessary, as noticed recently by several reports of severe CEC loss with the AcrySof CACHET that led to a safety notice letter that the company have sent to the users of the IOL [52].

Phakic Intraocular Lenses

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Pigment Dispersion / Lens Deposits Although no definite incidence for these conditions is reported in the literature, in clinical practice these conditions are seen (Fig. 9) which normally do not negatively affect the visual acuity and thus no further procedure – except for regular clinical observation – is necessary. Surgical intervention might be necessary in individual cases. Besides pigment dispersion, intraoperative hemorrhage (Fig. 10) may lead to erythrocyte deposits on the PIOL and IOP elevation. Bleeding originate either from vessels in the scleral tunnel or from the intraoperative iridectomy.

Figure 9: Protein deposits on AC PIOL, one month postoperatively in a 34year (y) female (f).

Figure 10: Anterior chamber hemorrhage after AC PIOL implantation (courtesy of E. Rosen, Manchester, Great Britain).

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Chronic Inflammation / Uveitis As AC PIOL is positioned directly in front of the iris, chronic inflammation and development of pigment dispersion is possible as pupil movement can induce some friction with the PIOL. Perez-Santonja et al. report a rate of 8.7 % of eyes presenting with slight chronic inflammation during the first 6 months after ZSAL4 lens implantation [48]. Allemann et al. removed one of the 21 implanted PIOL due to a chronic postoperative inflammatory response associated with ocular hypertension [43]. Alió et al. observed acute postoperative iritis in 4.56 % of 263 AC PIOL (ZSAL-4 and ZB5M) [42]. Leccisotti et al. found an incidence of 3.1 % of clinically significant iridocyclitis that appeared within a range of 1 to 31 months after ZSAL-4 implantation [53]. Van Cleynenbreugel reported one case of late intrapupillary membrane formation and chronic uveitis associated with CEC loss years after backward implantation of Vivarte AC PIOL [54]. Removal of the PIOL led to recovery of visual acuity. Like with other complications, if conservative topical treatment does not succeed, removal of PIOL should be considered to avoid any long-term risks. However, surgical intervention is rarely needed to control this type of complication. Pupil Ovalization / Iris Retraction Ovalization of the pupil is a specific complication of AC PIOL (Fig. 11). The position of haptics in the sclero-corneal angle and their size might lead to mild deformation of the irido-sclero-corneal architecture resulting in iris retraction and pupil ovalization. Mild deformation of pupil shape as reported by Alió et al. in 10.3 % of their large series of 263 eyes did not affect refractive, cosmetic or optical results of the surgery [42]. Severe ovalization causes glare. Alió et al. observed this condition in 5.9 %, which led to lens explantation in two cases. Allemann et al. reported 8 oval pupils in a series of 21 eyes [43]. Perez-Santonja et al. observed 4 cases in a series of 23 eyes [48]. Leccisotti et al. found pupil ovalization not associated with any photic phenomena in 11 % of eyes after ZSAL-4 AC PIOL implantation [55]. Javaloy et al. even found a cumulative incidence of 34.7 % of pupil ovalization after ZB5M implantation within 12 years follow-up [22]. In an analysis of a series of AC PIOL explantations (ZB5M PIOL) by Alio et al. marked pupil ovalization extending beyond edges of PIOL was the reason for PIOL removal in 10 % of cases [49]. For the novel AcrySof CACHET

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AC PIOL implanted in 190 eyes no case of pupil ovalization was reported [51]. Iris retraction with oval pupil deformation remains mainly a concern of AC PIOL. This matter together with potential damage to endothelial cells, are the major objections to this type of lens design. Topical use of miotic agents should be considered in the early postoperative phase if pupil ovalization associated with glare is detected. Minor pupillary ovalization requires observation only, but gross ovalization indicates entrapment of the iris root and ovalization may become irreversible if PIOL is not explanted promptly.

Figure 11: Severe cat-pupil ovalization following AC PIOL implantation.

Intraocular Pressure (IOP) Elevation/ Pupillary Block Glaucoma The risk of acute angle glaucoma is well known from aphakic AC IOL. Therefore a peripheral iridectomy is recommended for this type of lenses. Despite the recommendations of some companies that consider that a peripheral iridotomy is not required, the responsibility always relies on the surgeon. With AC PIOL the risk should not be less, particularly because the continuously growing crystalline lens is still in the eye. Ardjomand et al. observed one case of pupillary block after implantation of an AC PIOL which was successfully treated with Nd:YAG iridotomy [56]. Lecisotti et al. found a 3.0 % rate of pupillary block 6 hours postoperatively after AC PIOL implantation caused by incomplete iridectomy with uninterrupted pigment layer [55]. Kohnen et al. demonstrating results of the AcrySof CACHET PIOL found no case of pupillary block and in only 3.2 % increased IOP for a period of at least one month after surgery that required treatment was noted. Of note in 190 cases, iridotomy was performed in only 5 surgeries [51]. We recommend two very important steps to prevent the potential

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complication of acute angle glaucoma for angle-supported and the other types of PIOL. All viscoelastic substance from the anterior segment must be removed at the end of surgery. In addition, preoperative iridotomy by means of laser or intraoperative iridectomy with scissors or vitrector cutters to forestall acute pupillary block glaucoma is mandatory. Particularly with foldable AC PIOL the need for a peripheral iridectomy has been discussed amongst experienced refractive intraocular surgeons. For the latest PIOL, the AcrySof CACHET PIOL however, periperal iridectomy seems not to be mandatory [51]. Javaloy et al. found a mean difference between preoperative and 12 years postoperative IOP of only 1.9 mm Hg after ZB5M IOL implantation [22]. Prolonged therapy with antiglaucomatous medication was only used in 5 out of 225 eyes during the complete follow-up in this study. Other factors of postoperative elevated IOP may be due to the steroid medication. Leccisotti et al. found steroid-related IOP elevation in 14 % after ZSAL-4 implantation [55]. IOP elevation should be carefully observed and treated with conversion to non-steroidal anti-inflammatory drugs, if still necessary, and topical antiglaucomatous medication If chronic IOP elevation develops otherwise, the anterior chamber angle should be examined to rule out synechia formation and other pathologies and removal of PIOL should be considered if necessary. PIOL Rotation Rotation of AC PIOL might occur due to undersizing. In fact, Allemann et al. report that 80 % of eyes showed greater than 15° of rotation by two years, and 60 % had rotated between year 1 and 2 implying some instability in the anterior chamber [43]. Perez-Santonja observed rotation in 43.5 % of 23 treated eyes [48]. Baumeister et al. showed a marked rotation of the NuVita AC PIOL in 4 of 10 lenses despite following the recommended IOL size [57]. The authors postulate that this was due to the fact that the corneal diameter had been measured by caliper, which has been demonstrated to be less accurate than automated measurement models [58]. For the AcrySof CACHET PIOL, most eyes (71 %) did not show IOL rotation of >15 degrees, and 29 % had IOL rotations >15 degrees. However, intraocular lens rotation was not associated with any clinical sequelae in these cases [51].

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Incorrect Power and Upside-Down Placement One possible complication is implantation of a PIOL with an incorrect power. Given that the aim of the surgery is correcting ametropia as precisely as possible, this complication should be very rare using current formulas. Upside-down placement is another possible complication that might cause secondary complications like cataract formation. This complication was reported in 2 out of 190 cases in the study by Kohnen et al. after implantation of the novel AcrySof CACHET PIOL [51]. Cataractogenesis As position of AC PIOL is away from the lens, the formation of cataract is of less significance compared to PC PIOL (Fig. 12). Since cataract formation in high myopes, which represent the vast majority of the treated patients, is more frequent than in the general population, discriminating between myopia-associated cataract formation and surgically triggered or hastened cataract is difficult. Alió et al. reported on 9 cataract removals during the 7-year follow-up of 263 eyes (3.4 %) [42].

Figure 12: Nuclear cataract in an eye with an AC PIOL (courtesy of J. Alió, Spain).

All cataracts were nuclear and the calculated Kaplan-Meier survival curves for cataract development shows that more than 90 % of subjects would be expected to remain free from cataract after 98 months. A meta-analysis of cataract development after PIOL surgery found that 15 of 1161 eyes developed new-onset cataract [59]. Of these, 9 were nuclear sclerotic, 3 were nonprogressive posterior subcapsular cataract, 2 were nonprogressive anterior subcaspular cataract and 1 was both anterior and posterior subcapsular cataract. Total incidence of cataract formation for AC PIOL

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was 1.3 %. Incidence was 2.6 % for the ZB5M and 0.6 % for the ZSAL-4 AC PIOL and no cataracts were reported in eyes with the ZB, NuVita, Phakic 6H, the Newlife/Vivarte Presbyopic or AMO multifocal prototype PIOL [59]. For the novel AcrySof CACHET foldable PIOL incidence of cataract formation was 2.6 % (1 % secondary to concurrent ophthalmic disease) [51]. Excessive postoperative use of steroids should be avoided due to its potential risk of long-term cataract formation [11]. Retinal Detachment (RD) Ruiz-Moreno et al. found a RD rate of 4.8 % 1-44 months after AC PIOL implantation (ZB5M and ZB5MF) [60]. In this study, no correlation was found between axial length and incidence of RD. Mean preoperative refraction of the 166 eyes in the study was -18.6 D and mean axial length was 29.5 mm. Patients in this myopic range have been shown to have a 15 to 110 times higher risk in general for spontaneous RD than emmetropes [61]. Ruiz-Moreno et al. also state, that the time lapse between PIOL implantation and RD (mean 17.4 months) makes it difficult to imply that intraoperative hypotony with imbalance in premature degenerated vitreous structures played a role in development of RD [60]. In the study of Alio et al. analyzing causes of AC PIOL explantation, one case of RD was noted and PIOL had to be removed to enhance fundus visualization for retinal surgery [49]. In a study by Javaloy et al. reporting outcomes up to 12 years after ZB5M implantation, no case of RD was noted [22]. Also, no case of RD has been reported for the novel AcrySof CACHET PIOL [51]. Oddities Urrets-Zavalia syndrome, a fixed, dilated pupil, iris ischemia and IOP of 60 mm Hg despite an open surgical iridectomy after AC PIOL implantation was reported as a single case report by Yuzbasioglu et al. in a 26 year old high myopic one day after surgery [62]. Spontaneous macular hemorrhage has been reported in two eyes. In these cases, repeat fluoresceine and indocyanine angiography did not show a neovascular membrane and spontaneous improvement occurred [55].

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Iris Fixated PIOL COMPLICATIONS Optical Quality, Glare, Halos PIOL are often implanted in eyes with large scotopic pupil diameter due to mean age of mostly preponderant young patients. This can result in glare phenomena if the pupil is larger than the IOL optic. Glare and halos affect night vision and driving and are therefore important considerations in PIOL implantation. A study conducted by Maroccos et al. showed significantly less glare and halos for the Artisan PIOL than for other PIOL, especially for the 6.0 mm optic [44]. This was attributed to the larger IOL optic (6.0 mm vs. 5.0 mm) and the fixation of the IOL to the iris which causes less dilatation of the pupil. Therefore, the 6.0 mm optic iris-fixated PIOL seems to be preferable over the 5.0 mm optic. However, this is not always possible due to a greater thickness of these optics and possible damage to the corneal endothelium in a given anterior chamber depth (see later Fig. 21 A, B). The power of the 6.0 mm optic has an upper limit of –15.5 D for myopia. For hyperopia the range is +1.0 to +12.0 for both optic types. Menezo et al. describe 1 case of permanent wide dilation of the pupil causing decreased postoperative visual acuity because of glare [63]. Landesz et al. report 2 of 38 patients that required pilocarpine eye drops because of halos after implantation of the 5.0 mm optic Artisan lens [64]. Maloney et al. recorded mild to moderate glare in 18 eyes (13.8 %) and severe glare in one eye (0.8 %) of 130. In 3 eyes, a lens with 5.0 mm optic was exchanged for a lens with 6.0 mm optic with no further glare noticed afterwards [65]. Senthil et al. report no glare and halos after implantation of Artisan PIOL in 60 myopic eyes, probably because Indian eyes have smaller pupils compared to Caucasians in general [66]. Moshirfar et al. found an incidence of 6.0 % of glare and halos 1 month after Artisan/Verisyse implantation which decreased to 2.7 % at 2 years follow-up [67]. In a study by Stulting et al., analyzing 3-year results of Artisan/Verisyse PIOL, no contrast sensitivity decrease was seen [68]. In this prospective study, patients with a mesopic pupil size greater than PIOL optic size were not included and 80 % of PIOL implants had a 6.0 mm optic and only 20 % had a 5.0 mm optic. A study by Chung et al. demonstrated, that Artisan PIOL do not alter higher order aberrations (HOA) significantly, a finding comparable to findings of Chandhrasri et al., who showed a small increase in HOA under photopic conditions after Verisyse PIOL implantation [69]. One study investigating HOA showed, that after Artiflex PIOL implantation,

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postoperatively trefoil increased and spherical aberration decreased. The authors found a significant correlation between PIOL decentration and postoperative spherical aberration and coma. In the same study, after Artisan PIOL group, postoperatively, trefoil and spherical aberration increased. These differences are explained by differences in incision size in relation to trefoil and differences in the different optic design of the two PIOL in relation to spherical aberration [70,71]. Guell et al. compared the optical quality one month after Verisyse and Veriflex phakic IOL implantation and Zeiss MEL 80 LASIK for myopia from -5.00 to 16.50 diopters. They observed that the optical quality worsened noticeably 1 day after surgery with the Verisyse IOL with a 50 % to 60 % loss, most likely due to the large incision and the presence of sutures in most eyes. The LASIK technique and Veriflex IOL implant did not cause as remarkable a decrease in optical quality (20 % to 25 % loss). One month after surgery, the optical quality of patients with IOL implants was high, although some surgically induced astigmatism remained, especially in the Verisyse patients. Conversely, LASIK patients had slightly lower optical quality, with optical parameters that represented 90 % of their initial value [72]. Additionally, Malecaze et al. showed that although LASIK and Artisan phakic intraocular lenses seemed to produce a similar predictability in cases of moderately high myopia, best-corrected visual acuity and subjective evaluation of quality of vision were better for Artisan [1]. Cisneros-Lanuza et al. reported some degree of lenticular glistenings in 20 % after Artiflex lens implantation, that were noted from 6 days to 6 months after surgery and did not decrease over time and did not affect visual acuity or cause any complaints [73]. Surgically Induced Astigmatism (SIA) As the PMMA iris claw lens (Artisan/Verisyse) is not foldable it requires an incision that approximately equals the optic diameter (5.0 or 6.0 mm). This likely induces postoperative SIA (Fig. 13 A, B). There are several ways to influence postoperative astigmatism. Incision on the steep corneal meridian, use of clear corneal, posterior limbal or scleral tunnel incisions, adjustment of sutures during

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Figure 13: Induction of corneal surgically induced astigmatism due to a 6 mm superior limbal incision (35y m). (A) preoperative topography. (B) corneal topography one week postoperatively.

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surgery or selective suture removal after surgery. According to literature, SIA is less than one might expected. Menezo et al. found no significant increase of postoperative astigmatism [63]. Alió et al. found a mean SIA of 1.5 ± 0.9 D for the hyperopic Artisan IOL with correction of primary hyperopia and 1.9 ± 1.2 D with correction of secondary hyperopia after corneal refractive surgery [74]. Maloney et al. reported a mean decrease in astigmatism of 0.3 D after 6 months [65]. Stulting et al. found a change of more than 2 D of cylinder in 3.5 % of eyes 3 years after Artisan/Verisyse implantation and secondary refractive procedures had to be performed in 6.9 % of eyes during follow-up [68]. The foldable model of the iris claw lens, the Artiflex/Veriflex seems to further reduce SIA. In a prospective, randomized study by Coullet et al., comparing Artisan PIOL implanted in one eye and Artiflex PIOL implanted in the other eye, the mean refractive cylinder power at one year follow-up was significant lower for Artiflex with -0.6 ± 0.5 D than for Artisan with -1.0 ± 0.6 D [75]. Mean SIA was 0.3 ± 1.7 D in the Artiflex group and 0.7 ± 2.9 D in the Artisan group being close to statistical significance (p = 0.072). In another study by Coullet et al., SIA after Artiflex PIOL implantation was 0.4 D [76]. In a latest report by Dick et al., mean SIA at 2 years after Artiflex PIOL implantation was only 0.3 D [77]. Loss of Corneal Endothelial Cells (CEC) Damage to the corneal endothelium can occur mostly because of direct contact of PIOL to the inner surface of the cornea, either during implantation or by postoperative changes in PIOL position. Another possibility for postoperative endothelial damage may be subclinical inflammation with direct toxicity to the endothelium. In 1991, Fechner et al. described first results of this type of PIOL with a follow-up of more than 12 months: 5 of 109 eyes suffered from CEC loss (Fig. 14) by surgical trauma and 5 eyes showed progressive CEC loss that caused corneal edema in 1 eye [78]. Menezo et al. examined influence on corneal endothelium of 111 eyes over 4 years in a prospective study [8]. The authors found the largest percentage of CEC in the first 6 months after implantation and concluded that the main cause for CEC loss is surgical trauma. CEC pleomorphism and polymegathism did not change significantly after surgery. One PIOL that was placed too superiorly caused corneal edema and had to be removed. Other studies yielded similar results [9, 10, 64, 74]. Maloney et al. found no difference in CEC

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between preoperative state and 6 months postoperatively [65]. Budo et al. reported CEC loss of 0.7 % at 3 years follow-up after implantation of Artisan/Verisyse PIOL [79]. In a clinical trial for the FDA, Pop and Payette found even no significant change of CEC 2 years after Artisan PIOL implantation [80]. Also, Senthil et al. could not find any significant CEC loss after follow-up of at least 24 months after Artisan PIOL surgery [66]. Moshirfar et al. found 6.5 % CEC decrease 2 years after Artisan/Versisyse PIOL implantation [67]. A similar rate was found by Gierek-Ciacura et al. with 6.8 % CEC decrease 1 year after Verisyse implantation [50]. A study by Stulting et al. showed mean change of CEC of 4.8 % 3 years after surgery [68]. Another recent study by Guell et al. demonstrated significant decrease of CEC after myopic Verisyse PIOL implantation, whereas CEC loss was not significant in the hyperopic Verisyse and toric Verisyse group 3 years after implantation [29]. Overall CEC loss in this study was 5.1 % at 4 years follow-up. Of note, natural loss of CEC is about 0.6 % per year as reported by Bourne et al. [81]. Saxena et al. reported CEC loss of 8.3 % with mean follow-up of 35.3 months, which was higher than the series of Guell et al. with similar follow-up. This may be due to the fact that the minimum preoperative ACD required to implant an iris-claw lens was lower in the series of Saxena and may have affected the safety towards the corneal endothelium [82,83]. Saxena et al. found a significant negative correlation between ACD and CEC. One paper demonstrates, that CEC loss after cataract surgery and PIOL explantation in eyes after Artisan PIOL implantation was only 3.5 % 6 months after surgery [84]. In contrast to these findings, Perez-Santonja et al. reported continuous CEC loss with a decrease of 17.6 % 24 months after surgery. Benedetti et al. also found a continual decrease of CEC after Artisan PIOL implantation with 9.0 % at 5 years [85]. Silva et al. reported a decrease of 14.1 % CEC loss at 5 years follow-up after Artisan implantation [86]. In a study, investigating factors leading to CEC loss after PIOL implantation, the authors showed, that for a mean minimum distance between the edge of the PIOL and the corneal endothelium of 1.43 mm a yearly CEC loss of 1.0 % was noted, whereas a distance of 1.2 mm resulted in a yearly CEC loss of 1.7 % and 1.7 mm led to a yearly CEC loss of 0.2 %. In this study, according to a linear mixed model analysis, patients with preoperative CEC of 3000, 2500 or 2000 cells/mm2 and an edge-distance of 1.4 mm, a critical CEC of 1500 cells/mm2 would be reached 56, 37, and 18 years after Artisan/Artiflex PIOL

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implantation [87]. All authors agree that preoperative endothelial microscopy is mandatory. Patients with endothelial damage or CEC below 2000 per mm2 should therefore not receive a PIOL.

Figure 14: Confocal microscopic image of the endothelium reveals severe endothelial cell loss after implantation of AC PIOL (700 cells/mm2).

Dick et al. report CEC loss of only 1.1 % 2 years after Artiflex PIOL implantation [77]. The European Multicenter Study of the toric Artiflex have showed a significant decrease in ECD after 3 months (4.8 % ± 11.9 %), with no additional decline between 3 and 6 months, which is assumed to be related to surgery [31]. Height of the Artisan lens and therefore the potential closeness to the cornea increases with its dioptric power. On the other hand, the height of the Artiflex at the periphery of the cornea is independent of its dioptric power, increasing the preoperative predictability of the postoperative distance between the periphery of the optic and the corneal endothelium. Therefore a sufficient ACD for the calculated PIOL is necessary. Distance between PIOL implant and corneal endothelium should not be less than 1.5 mm [88,89]. Pigment Dispersion / Lens Deposits The optic of the iris-claw PIOL is vaulted anteriorly to prevent iris chafing. Pop et al. performed postoperative ultrasonic biomicroscopy of the haptics of myopic and hyperopic PIOL and found no evidence for irritation of the iris pigment

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epithelium by the PIOL haptics within a follow-up period of 24 to 371 days [90,91]. Occasionally pigment cells are visible on the PIOL optic in the early postoperative period due to surgical trauma (Fig. 15 A, B). Stulting et al. report iris pigment precipitates with an incidence of 6.9 % at 4-6 months follow-up and no case at all at 3 years follow-up [68]. Menezo et al. reported a long-term incidence of 6.6 % pigment dispersion with the longest mean follow-up of 10 years after Artisan implantation [92]. However, in phase III trial for the hyperopic iris-claw PIOL there were reports of 3 patients who had pigment dispersion or pupillary membrane formation due to iris touch [93]. Baikoff et al. consider crystalline lens rise as a risk factor for developing pigment dispersion after IF PIOL implantation [19]. The authors define crystalline lens rise as the distance between anterior pole of the crystalline lens and the horizontal plane joining opposite iridocorneal recesses measured with anterior chamber optical coherence tomography. In this study, 67 % of eyes with rise of  600 µm developed pupillary pigment dispersion after implantation of Artisan PIOL. Nearly all eyes were hyperopic, only one eye was myopic. For the Artiflex PIOL, pigment precipitates were reported in 4.8 %, nonpigment precipitates in 1.4 % and synechia formation in 1.4 % of 270 patients 2 years after surgery [77].

Figure 15: Inflammatory reaction after iris claw lens implantation. (A) dense fibrin coating of the PIOL one week postoperatively (34y f). (B) persistent deposits, three months after implantation (37y m).

Chronic Inflammation / Uveitis Chronic inflammation has always been a major concern with the iris-claw lens as this PIOL is fixated directly in the iris tissue and causes shear forces when the eye is

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moving or patient rubs his eyes (Fig. 16 A, B). This may lead to injury or increased permeability of iris vessels with breakdown of blood-aqueous barrier and chronic release of inflammatory mediators. This has been repeatedly examined using different technologies. Two studies which have been performed using iris angiography, showed no leakage of the iris vessels [63,78]. Studies conducted using a laser-flare cell meter came to diverging results. Fechner et al. found no elevated flare levels with at least 12 months follow-up [78]. Perez-Santonja et al. found elevated flare level compared to a normal population within 24 months after surgery [94]. Gross et al. also found no significantly elevated flare after 6 months [10]. In all studies, clinically relevant inflammation could only be detected in individual cases. In a case report by Koss et al., posterior synechias developed 2 weeks after Artiflex implantation, which led to surgical re-enclavation. However, 2 years after surgery posterior synechias did not change [95]. A similar case report was published by Tahzib et al. with development of severe cell deposition 1 week after Artiflex implantation [96]. After PIOL exchange, inflammation in the anterior chamber disappeared completely. Postoperative iritis was noted in 3 % of eyes after Artisan implantation in a study by Senthil et al. [66]. Moshirfar et al. only found an incidence of 1.2 % of cells and flare for one month postoperatively after Artisan/Verisyse surgery [67]. Toxic anterior segment syndrome (TASS) also known as sterile endophthalmitis has also been described in a case report by Moshirfar et al. [97]. This patient presented with severe corneal edema one day after Verisyse PIOL surgery that resolved with topical treatment over the course of 2 months. However, CEC decreased by 69 % 1 year after surgery. In general, careful postoperative monitoring of inflammatory signs is necessary. If persistent intraocular inflammation occurs that is not sufficiently treatable with drugs, removal of the PIOL has to be taken into consideration.

Figure 16: Iris pigment defects at the site of enclavation may be one source for dispersed iris pigment: (A) 30y male (m); (B) 47y f, both three months postoperatively.

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Pupil Ovalization / Iris Retraction Pupil ovalization or irregularity can occur if fixation of PIOL haptics is performed asymmetrically. However, no progressive pupil ovalization has been reported so far. Maloney et al. reports pupil irregularities in 14.0 % on the first day after surgery and 1.2 % after 6 months [65]. Moshirfar et al. showed an incidence of 2.4 % pupil ovalization after Artisan/Verisyse surgery [67]. Stulting et al. found an incidence of 13.0 % of an asymptomatic oval pupil at day 1 after Artisan/Verisyse PIOL implantation and this incidence decreased to 0.4 % at 3 years follow-up [68]. As enclavation is performed in the peripheral iris, pupil dilatation is limited after implantation of the PIOL. Artisan/Verisyse PIOL is centered on the middle of the pupil. This can lead to difficulties if the pupil itself is decentered and the optical axis is not in the middle of the pupil (Fig. 17). Postoperative decentration is possible if the enclavation is not sufficient. Menezo et al. reported an incidence of 13.5 % decentration, but only one case in which a second intervention was necessary due to double vision [63]. Perez-Santonja found a decentration greater than 0.5 mm in 43 % of the examined eyes [82]. Perez-Torregrosa found a mean decentration of 0.47 with respect to the pupil center in 22 eyes using a digital imaging system [98]. If the PIOL is fixated properly, no postoperative decentration or rotation should occur.

Figure 17: First generation Iris claw lens (Worst-Fechner), 11 years after implantation (61y f), note slight decentration.

IOP Elevation Generally, the anterior chamber angle is not believed to be affected by the haptics of the iris-claw PIOL. Coullet et al. demonstrated that within 1 year after surgery, IOP

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did not change significantly either after Artisan and Artiflex PIOL implantation [75]. However, a study by Yamaguchi et al. showed that after implantation of an Artisan/Verisyse PIOL, partial narrowing of the anterior chamber angle of more than 5 degrees occurred in the area where the PIOL haptics pinch the iris [99]. Of note, this did not affect IOP one month after surgery. A peripheral iridectomy or iridotomy is necessary for the prevention of acute pupillary block glaucoma. In several studies there were some cases of elevated IOP in the early postoperative period that resolved without further damage and were probably related to retained viscoelastics or steroid medication [65,66,68,100-102]. PIOL Rotation Photographic analysis after implantation of toric Artisan PIOL showed no rotation >2 degrees at 6 months follow-up in a report of Tehrani et al. [103]. Using Scheimpflug photography, Baumeister et al. examined the postoperative stability of PIOL and found that the IF PIOL had the best positional stability compared to AC and PC PIOL [57]. Therefore this design is particularly interesting for toric PIOL designs. However, spontaneous postoperative dislocations or dislocations due to blunt ocular trauma have been described (Fig. 18) [63,65,82,104].

Figure 18: Traumatic dislocation of an iris claw AC PIOL (courtesy of D. Annen, Switzerland).

Incorrect Power Due to the aim of the surgery, correcting ametropia as precisely as possible, this complication should not happen using current formulas. In one article, Kohnen

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et al. report about a myopic shift of -4 D after implantation of an Artisan PIOL ten days after surgery. The authors postulate that this event was probably related to either a secondary movement of the ciliary body inwardly or forwardly or an irritation of iris nerves of vessels with induction of ciliary body contraction [105]. However, this complication was not due to preoperative miscalculation of PIOL lens power. Cataractogenesis Formation of cataract due to the iris claw lens is unlikely because it is inserted over a miotic pupil without contact with the crystalline lens. Menezo et al. reported a nuclear cataract rate of 3 % after implantation [106]. Of note, in this study, implanted lens type was the older Worst-Fechner PIOL. In this study, age older than 40 years and axial length greater than 30 mm were factors related to nuclear cataract formation. However, new-onset nuclear cataracts were not ascribed to PIOL surgery. Clinically relevant cataract formation has also been reported by Stulting et al. [58]. Most lens opacities were nuclear and unlikely to be related to the implanted IOL. Significant lens opacities that required cataract extraction developed in 0.25 % of subjects. Very few were anterior subcapsular opacities that were expected to be caused by surgical trauma. Perez-Santoja et al. only detected a loss of lens transmittance of 1 % after 18 months by fluorophotometry that had no influence on visual acuity [82]. A meta-analysis of cataract development after PIOL surgery found that 20 out of 2781 eyes developed new-onset cataract [59]. Of these, 10 were nuclear sclerotic, 8 were cortical vacuoles and 1 was anterior subcapsular cataract (data for one eye was not clear). Total incidence of cataract formation for IF PIOL was 1.1 %. Incidence was 2.2 % for the Worst-Fechner biconcave PIOL, 1.1 % for the myopic Artisan/Verisyse PIOL and 0.3 % for the hyperopic Artisan/Verisyse PIOL. No cataracts have been reported with the Artiflex model so far [59]. Excessive postoperative use of steroids should be avoided due to its potential risk of longterm cataract formation [11]. Retinal Detachment (RD) Thorough examination of the posterior segment to rule out vitreoretinal pathologies is mandatory, although there have been no vitreoretinal complications

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that have shown to be causally related to IF PIOL implantation so far. In the European multicenter study of the Artisan lens over 8 years, Budo et al. reported RD in two eyes [79]. Stulting et al. found RD rate of 0.3 % per year after implantation of Artisan/Verisyse PIOL, that all developed in eyes with mean spherical equivalent between -11.50 and -18.6 D [68]. This incidence is similar to RD rates, that have been reported for highly myopic population who do not undergo refractive surgery [107-109]. Guell et al. reported a case of RD in a series of 399 eyes with Artisan/Verisyse implant [29]. In this patient RD was not believed to be in any relation to the PIOL implantation either. A recent report by Georgalas et al. describes a case of bilateral giant tear RD following Artisan PIOL implantation in a 39 year old male patient with an axial length of OD 25.5 mm and OS 25.8 mm [110]. In this report however, the authors attribute the RD to a combination of an inflammatory response and perioperative IOP fluctuations as a causative pathophysiological mechanism according to temporal proximity of the RD to PIOL implantation. In none of those reported cases, special difficulties on visualization during surgery were reported by the vitreoretinal surgeon. Oddities Other complications reported in the literature are Urrets-Zavalia syndrome, early postoperative hyphema and ischemic optic neuropathy [111]. Hyphema in the early postoperative phase due to iris trauma is occasionally described [63-65]. Iris bleeding can also be caused by preoperative Argon or Nd: YAG laser treatment of the iris to mark fixation points for the IOL enclavation. Iris perforation by the haptic claw of a PIOL has been reported by Benedetti et al. [112]. PC IOL COMPLICATIONS Complication spectrum is similar for ICL and PRL and is a result of the position of the IOL between the rear surface of the iris and the front surface of the crystalline lens. Differences in the incidence of most common complications like cataractogenesis, pupillary block and glaucoma are due to the different PIOL design and material.

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Optical Quality, Glare, Halos Consequences of a small optical diameter (ICL up to 5.5 mm; PRL up to 5.0 mm) and decentration of PC PIOL in relation to pupil size are complaints of glare and halos, especially at night. Menezo et al. reported high incidence after implantation of ICL [102]. For these complaints there are two explanations: decentration and/or a too small optical diameter in relationship to pupil size. Several studies report about glare and diplopia in eyes with decentration of the ICL greater than 1 mm [113,114]. Maroccos et al. observed a high increase of postoperative glare and halos after ICL implantation compared to Artisan implantation in the anterior chamber [44]. They explained these findings due to the edge effects of the small diameter of the whole ICL and the small optical diameter in relationship to pupil size. After PRL implantation, 25 % of 31 patients reported halos and night glare [100]. Because the PRL has an optical zone size of 4.5 to 5.0 mm, it has the same etiology of glare and halos as after ICL implantation. In a study investigating 3 years results after ICL implantation, patients were interviewed regarding their optical quality of vision. Improvement of glare and halos was reported in 11.9 % and 9.6 %, respectively and worsening in 9.6 % and 11.5 %, respectively [33]. After PRL implantation, 26-28 % of patients complained about glare and halos at night [100,115]. Some of these patients had scotopic pupil size of 6–7 mm, so that the discrepancy to the optic zone of the PRL (5.0 mm) seemed responsible for these problems [115]. A report by Koivula et al. showed incidence of glare and halos after hyperopic PRL implantation in 2 out of 40 eyes, in these cases PRL explantation had to be performed [116]. Surgically Induced Astigmatism (SIA) SIA has not been reported to be a major issue of concern in PC PIOL. Mertens et al. demonstrated a case of a custom-designed PC PIOL. In this case, a 40 yearold woman with high astigmatism of 5 D underwent successful bilateral toric ICL custom-designed PC PIOL [37]. The authors did not notice any change in corneal astigmatism 19 months postoperatively. In another study, SIA after ICL implantation in 73 eyes through a 3.0 mm horizontal clear cornea inzision was 0.45 D at an axis of 93.3 degrees using the keratometer and 0.49 D at an axis of 98.0 degrees using corneal topography [117].

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Loss of Corneal Endothelial Cells (CEC) Loss of CEC can be divided into direct trauma loss caused by surgery and longterm loss. In various studies for the ICL, immediate CEC loss of 5.2 – 5.5 % was documented after a follow-up of 12 months. However, the pace of CEC loss slowed down substantially by the time at the two-year follow-up [118,119]. Researchers therefore considered surgery to be the cause of the early CEC loss. Four years postoperatively, CEC counts revealed further decrease in cell density, a fact that can be explained with the implanted ICL, a learning curve of the surgeon or by natural cell loss, which is in the range of 0.5 % in the normal population [119]. A report by Kamiya et al. found CEC loss of 3.7 % 4 years after ICL implantation [120]. Another study showed accumulating CEC loss of 8.5 % three years and of 8.4 % four years after PC PIOL surgery [33,113]. These figures also suggest that CEC density stabilizes over a longer period of time. Alfonso et al. showed CEC loss of 8.1 % two years after toric ICL implantation, of note in eyes after penetrating keratoplasty [121]. In a report by Koivula et al. no significant CEC loss was noted after implantation of hyperopic PRL between 1 week and 1 or 2 years postoperatively [122]. In another report by the same author, CEC loss was 3.8 % one year after hyperopic PRL implantation [116]. Also Verde et al. did not find a significant reduction in CEC 12 months after PRL implantation in 90 myopic eyes [123]. Jongsareejit et al. found CEC loss of 5.36 % after a short follow-up of 6 months postoperatively [124]. Pigment Dispersion / Lens Deposits / IOP Elevation By means of UBM examination, contact between PC PIOL (ICL, PRL) and the posterior surface of the iris has been proven [118,125-128]. Pigment dispersion and consecutive pigment accumulation in the anterior chamber angle is one of the possible consequences while development of secondary glaucoma has not been observed (Fig. 19) [100,102,128,129]. However, eyes with pigment dispersion after implantation of PC PIOL must be kept under observation not to miss any increase in IOP. Menezo et al. observed a statistically not significant increase of IOP of 1.5 mm Hg after implantation of ICL over a follow-up of up to 3 years [92]. Also Park et al. did not find an increase of IOP after toric ICL implantation over a follow-up of 1-18 months [38]. In contrast, other studies with ICL or PRL only found significantly increased IOP in rare cases one month after ICL

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implantation. Kamiya et al. did not find an increase of IOP 4 years after ICL implantation [120]. Zaldivar et al. reported 2 of 124 eyes which showed IOLrelated IOP spikes [130]. One of these eyes with a decentered ICL had excessive pigment deposition on the PIOL surface. It remained unclear whether the pigment dispersion was related to the decentration or to the PIOL itself. In both eyes the ICL had to be removed and phacoemulsification with implantation of PIOL in the capsular bag was performed. Subsequently, IOP was well controlled without medication. Sanchez-Galeana et al. reported one case of refractory IOP increase due to pigment dispersion after ICL implantation. Despite medical therapy and ICL removal, this patient needed trabeculotomy to control IOP [131]. Although, Jiménez-Alfaro et al. observed contact of ICL and posterior iris with UBM in all cases, they did not find any pigment dispersion [118]. The authors suggested that the similarity between ICL-Collamer and the anterior capsule of the crystalline lens could prevent mechanical loss of pigment. Davidorf et al. found pigment deposition on the PIOL surface appeared stable over time in all eyes and no pigment dispersion glaucoma occurred, so the authors suggest that pigment dispersion was probably surgically related [129]. Hoyos et al. observed one case of window defects of the iris and increased angular pigmentation without raised IOP after PRL implantation in a hyperope [100]. As an explanation the authors propose a too shallow ACD of 2.8 mm and demand a minimum ACD of 3.0 mm for implantation of PC PIOL. Donoso et al. found no change in IOP with a mean follow-up of 8 months after PRL implantation [132]. Also, Koivula et al. found no change in IOP one year after PRL implantation [116]. Verde et al. found an increase in mean postoperative IOP compared with preoperative values, mean IOP was within normal levels (˂ 20 mm Hg) at each follow-up [123]. Only one of 90 eyes required antiglaucomatous medication for 3 months. Some authors reported incidents of secondary induced glaucoma due to use of topical steroids. However, in all eyes IOP normalized after postoperative treatment regimen with steroids was stopped [100,118,130,133]. Davidorf et al. observed increasing vascularization of the anterior chamber angle and development of secondary glaucoma after implantation of ICL into a hyperopic eye [129]. Rosen et al. also observed development of secondary glaucoma after implantation of a hyperopic ICL [134]. In both cases IOL had to be explanted as IOP could not be controlled by means of repeated iridotomy and topical medication.

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Figure 19: Pigment dispersion in the anterior chamber angle after implantation of ICL PC PIOL, gonioscopic view, three months after implantation (53y m).

Chronic Inflammation To detect intraocular inflammation, laser flare photometry was performed in a study by Uusitalo et al. 6 months after ICL implantation. In this study all eyes showed normal aqueous flare values [135]. Sanders et al. also did not detect any long-term inflammation 2-3 years after ICL implantation [136]. Pupil Ovalization / Iris Retraction In contrast to AC PIOL no cases of pupil ovalization or iris retraction have been reported so far with PC PIOL. Pupillary Block / Malignant Glaucoma Due to position of the PC PIOL, the iris may be pushed forward and cause acute glaucoma through pupillary block, especially in hyperopic eyes [118,129,130,137,138]. Diameter of PC PIOL is implemented in this pathophysiologic process. To prevent this problem, pre- or intraoperative iridotomy or iridectomy should be performed [129,130,134]. In some cases preoperative iridotomy close itself over time because it is too small or blocked by the haptic of the PC PIOL. This may cause acute papillary block glaucoma. A second iridotomy has to be performed in these cases [113,139,140]. In one case, pupillary block appeared 1.5 years after PRL implantation because of obstruction

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of the iridectomy with the haptic of the PRL. After treatment with a second iridectomy, IOP normalized. Especially the PRL, that can rotate and thereby occlude the iridotomy, requires an application of 2 iridotomies in an angle of 90 degrees [100]. Also for hyperopic treatment, preoperative iridotomy is even more important to prevent early pupillary block situation. Here it is necessary to make two peripheral and sufficient sized iridotomies either with the laser or within a surgical procedure [129]. In a report by Koivula et al. 7 out of 40 eyes developed pupillary block by a mean of 6 days after hyperopic PRL implantation [116]. All eyes were treated successfully with laser iridotomy. Malignant glaucoma after PC PIOL implantation is very rare and has only been described in one patient by Kodjikian et al. with IOP of 54 mmHg 3 days after ICL implantation in a myope [101]. Both preoperatively performed laser iridotomies were patent and seemed large enough. The iris was not bowed forward and posterior segment did not show any pathology. Despite medical treatment IOP still remained high, so that explantation of the ICL had to be performed. Thereafter, IOP normalized and BCVA was 20/25. Decentration / Incorrect Size / PIOL-Rotation Preoperatively it is mandatory to properly measure the white to white distance (WTW) with its known limitations regarding its relation with the sulcus diameter for choosing PIOL with sufficient length in order to prevent any decentration or rotation [102,114]. Although in few cases, Menezo et al. reported decentration with an adequate IOL length in relationship to corneal diameter [102]. The consequences of decentration are diplopia, glare and perhaps pigment dispersion syndrome because of mechanical trauma [129,130]. Trindade et al. report exchange of an ICL because of oversized length of the lens [131]. Malpositioning with a very great vault and undercorrection occurred because ICL was too long. Ten months after primary surgery the ICL was exchanged for a smaller ICL with higher power. This procedure was uneventful and patient was satisfied with the final visual outcome. In a study with 12 months follow-up, Garcia-Feijoó et al. measured rotation of ICL with UBM in 2 of 18 cases [125]. Although there was no decentration of the optic, the authors suggested that the diameter of the ICL was too small. Also, after PRL implantation decentration occurred after a too small PIOL-diameter was chosen [100]. After exchanging the small PRL for a

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newer generation into PRL with a greater diameter, no more decentration was observed. A recent study by Koivula et al. demonstrated a median rotation of PRL of 18.5 degrees during the first year after implantation and 0 degrees during the second year [122]. Centration of implanted PRL (n=20) was good in all eyes in this report up to one year follow-up. Minor decentration of PRL was observed in 5 out of 90 eyes in a study by Verde et al. [123]. None required secondary surgery. Length of the ICL has to be calculated from this diameter (addition of 0.5 mm to the horizontal WTW diameter). The study of Baumeister et al. showed, that most accurate value of horizontal WTW diameter can be determined by IOL master® (Zeiss, Jena, Germany) [58]. Mean rotation of the ICL was 0.9 degrees after 3-12 months follow-up in this study. A recent study by Park et al. showed, that postoperative rotation after toric ICL implantation was less than 5 degrees in 74 % and less than 11 % in all patients (n=30) 8 months (mean) postoperatively [38]. Incorrect Power One possible complication is implantation of a PIOL with an incorrect power. Due to the aim of the surgery, correcting ametropia as precisely as possible, this complication should not happen using current formulas. Cataractogenesis A meta-analysis of cataract development after PC PIOL surgery found that of at least 1210 eyes 223 eyes developed new-onset cataract most of them (195) were anterior subcapsular (Fig. 20 A-D) [59]. Total incidence of cataract formation for PC PIOL was 9.6 %, significantly higher than incidences for AC and IF PIOL. Incidence was 25.7 % for the Adatomed PIOL, 8.5 % for the ICL PIOL and 3.6 % for the PRL [59]. Cataracts after ICL and PRL implantation often remain stable over a long period of time and rarely lead to reduction of VA. Typical type after PC PIOL implantation is anterior subcapsular cataract [141-143]. Possible reasons are operative trauma, contact of the PC PIOL with the crystalline lens, insufficient nutrition through anterior chamber flow between PIOL and crystalline lens or chronic subclinical inflammation with disruption of blood-aqueous barrier due to friction between the PIOL and posterior iris or it’s haptic on the ciliary sulcus [142,144,145]. Studies with UBM and Scheimpflug-Imaging technique (Fig. 21 AC) could show a central gap between ICL and crystalline lens, but a contact in the

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mid periphery [58,118,125,128]. Moreover, antero-posterior movement of the ICL during iris contraction or accommodation led to intermittent central contact [118,125]. However, if distance between the crystalline lens and PC PIOL is increased, the PC PIOL is then closer to the iris with the consequent risk of pigment dispersion and development of pigment induced secondary glaucoma. In a study by Zaldivar, none of 124 eyes developed any lens opacities due to ICL implantation [130]. Nevertheless, one eye developed subscribed peripheral lens opacification at the position where laser iridotomy was performed preoperatively. Also Zadok et al. reported one case of focal lens opacification under the laser iridotomy site which did not enlarge after implantation of ICL [146]. Another study showed 2 eyes in one patient with anterior subcapsular cataractogenesis 1.5 years after ICL implantation [135]. In both eyes ICL were removed and phacoemulsification with capsular bag implantation of an IOL was performed. Also, Trindade observed anterior subcapsular cataract formation in the eye of a 59year-old patient 6 months after implantation of an ICL [128]. The surgery was uneventful and a-traumatic. With UBM, he was able to measure a central vault between the ICL and the natural lens whereas in the mid-periphery, contact was present. Anterior subcapsular lens opacities developed in the non-contact area. Therefore, he surmised that the proximity of the ICL to the natural lens could lead to metabolic disturbances and pressure from the PC PIOL on the anterior surface could both trigger cataract formation. Sanders et al. found a cumulative probability estimate of 6-7 % of anterior subcapsular opacities at 7+ years after implantation of the Visian ICL based on a FDA trial with mean follow-up of 4.7 years [147]. However, the authors found, that only 1-2 % progressed to clinically significant cataract. With various generations of the ICL, appearance of cataract formation is different. The less vaulted model V3 of the ICL caused a higher incidence of cataract formation than the newer models V4 and V5 [102]. With the V4 model the recently published FDA study showed an incidence of 2.1 % anterior subcapsular opacities, which were 11 in 523 eyes [158]. To prevent cataract formation it seems to be important to have a vault between the PC PIOL and the lens. With UBM, it was possible to measure central vault after implantation of ICL, while in the mid periphery mostly a lens-IOL contact existed [118,125,128]. Also, size changes and even loss of the central vault as well as changes of the location and extension of the contact zone were measured (Fig. 21 A-C) [118,125]. These findings would

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indicate anterior-posterior-shifts in position of the ICL. Such shifts may be due to the flexibility of the PIOL-material that would allow the ICL to become deformed, perhaps while iris movements or accommodation occurred. Nevertheless, in none of the examined eyes did lens opacities influence visual acuity. A recent study by Koivula et al. evaluated the dynamics of PRL in myopic and hyperopic eyes during accommodation with Visante OCT [148, 149]. PRL moved forward during accommodation in all eyes, with preserved distance between anterior crystalline lens surface and the smaller PRL 100 model. However, with other PRL models, 101 for myopes and 200 for hyperopes, this distance decreased significantly. The authors conclude that this finding combined with the floating design of the PRL could permit aqueous humor circulation to the anterior surface of the crystalline lens, resulting in less cataractogenic effect than with the ICL.

Figure 20: Cataract formation after implantation of PC PIOL. (A) faint anterior subcapsular opacities, twelve months after implantation (45y f). (B) same eye, retroillumination. (C) distinct anterior subcapsular cataract in an eye with PC PIOL. (D) retroillumination of anterior subcapsular cataract in an eye with PC PIOL with courtesy of E. Rosen, England (C) and J. Alió, Spain (D)).

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Figure 21: Contact between PC PIOL and crystalline lens. (A) myopic ICL, slit lamp image). Note delicate opacities in the lower hemisphere. (40y m). (B) myopic ICL, Scheimpflug image. c, hyperopic ICL, Scheimpflug image).

After implantation of PRL, Hoyos et al. observed anterior cortical opacification in the immediate postoperative examination in one eye. This opacification remained stable until 2 years follow up. Therefore, the authors suspected natural lens touch during surgery as trigger [100]. Koivula et al. report no case of cataract formation one year after hyperopic PRL implantation [116]. Other, IOL-independent risk factors are inexperience of the surgeon, progressed patient`s age and preexisting lens opacities [145]. As a differential diagnosis of lens opacities, residues of viscoelastic substances (Fig. 22) should be considered, in particular if the opacity is seen in the early postoperative period. If cataract formation progresses and leads to decrease in VA, PC PIOL explantation, phacoemulsification and implantation of PC IOL is indicated [128,150]. One should be careful with administration of pilocarpine in eyes with PC PIOL since a case report demonstrated a 46 year old hyperopic patient after ICL implantation with posterior chamber flattening and resulting crystalline lens opacification after instillation of pilocarpine eye drops [151]. Like for all PIOL one should also take into account, that an excessive use of steroids postoperatively is a potential cause of cataract formation [11].

Figure 22: Residual viscoelastic substance between a hyperopic ICL and the crystalline lens, one week postoperatively (23y f).

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Retinal Detachment (RD) As for all intraocular surgeries, also for implantation of PC PIOL there is a possible risk for vitreoretinal complications and development of RD. Most implantations of PC PIOL are performed in patients with high myopia and high axial length, who already have a predisposition for spontaneous RD in general as discussed previously. One case report has been published by Zaldivar et al. after implantation of a PC PIOL in 124 consecutive eyes RD developed in one eye. In this myopic patient, no causal relationship to PIOL surgery was noted [130]. Panazzo and Parolini described 4 cases of RD after PC PIOL implantation in a consecutive series. Noteworthy was that 2 of these 4 cases had giant retinal tears [152]. Navarro et al. demonstrated a case of bilateral giant retinal tear 4 months after PC PIOL implantation. Of note this patient had a history of previous RD [153]. Another case of RD as a late postoperative complication was reported by Donoso et al. after implantation of PRL PIOL [132]. In a prospective study comprising 61 Chinese eyes one eye developed RD 15 months after Visian ICL implantation [154]. This case was attributed to the pre-existing axial length of 31 mm and not to PIOL surgery. The largest clinical trial reporting results of 526 eyes after Vision PIOL implantation by Sanders et al. only found 3 RD [33]. The largest series of RD after PC PIOL surgery was published by Martinez-Castillo et al. with 16 eyes after ICL implantation (ICMV2, ICMV3 and ICMV4) [155]. In this retrospective study, RD occurred from 1 to 70 months after lens surgery (mean 29.1 months) and no giant retinal tear or retinal dialysis was noted. As mean axial length of these 16 eyes was 30.1 mm the authors also concluded that these RD were part of the natural history of RD in high degree myopia. Oddities There are some reports of serious complication with PRL luxation into the vitreous cavity. Eleftheriadis et al. found spontaneous dislocation of PRL two months after uneventful implantation into the vitreous cavity [155]. Luxation was attributed to preexsisting zonular defect in the high myopic eye and unrecognized ocular trauma. In a case report by Martinez-Castillo et al. two patients had PRL luxation into the vitreous cavity after normal surgery, 4 and 22 months postoperatively [154]. Also, Hoyos et al. reported two cases of zonular dehiscence two years after PRL implantation in high myopia [99]. Donoso et al. found 2

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cases of subluxation of PRL inferotemporally through the zonules with no predisposing factors [132]. The authors speculate that an altered position and rotation of the PRL and/or preoperative or undetected intraoperative trauma might contribute to this rare but potentially severe complication. .

SUMMARY Main complications in AC PIOL are glare and halos, pupil ovalization and CEC loss, main complications in IF PIOL are chronic subclinical inflammation, CEC loss, dislocation or pupillary block glaucoma and main complications in PC PIOL are anterior subcapsular cataract formation, pigment dispersion, pupillary block glaucoma or luxation of PIOL (PRL). For all types of PIOL there is no established direct relationship between PIOL and retinal detachment. CONCLUSIONS Depending on the site of implantation, there are three types of PIOLs: anglesupported anterior chamber, iris-fixated anterior chamber, and posterior chamber PIOLs that are usually fixated in the ciliary sulcus. Implantation of PIOLs has been demonstrated as an effective, safe, predictable and stable procedure to correct moderate and high refractive errors. Complications are rare and are mostly related to the site of implantation. However, longer follow-up studies are needed to establish long-term safety of these lenses. Development of new anterior segment imaging devices is changing preoperative and postoperative management of PIOLs, increasing safety profiles and allowing for a more accurate follow-up. Moreover, exact measurements of anterior chamber diameter, anterior chamber depth, and ciliary sulcus diameter are improving the PIOLs selection and thus decreasing the risk of unwanted complications. According to Charles Kelman learning from complications of former and current PIOL models, PIOL must be developed, that should fit all the following requirements: the haptics should not contact the anterior chamber angle, the haptics should not be in touch with peripheral corneal endothelium, the PIOL should not be in contact with any part of the iris that moves during pupillomotoric, PIOL should be as flexible to accommodate an internal diameter smaller than diameter of the PIOL, PIOL should be placed in the largest diameter of the eye to avoid rotation and edges of PIOL should be smooth.

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ACKNOWLEDGEMENTS Declared none. CONFLICT OF INTEREST Dr. Güell is consultant of and Visiometrics SL Carl Zeiss Inc., and OPHTEC BV, and owner of Calhoun Vision Inc; Dr. Kohnen is consultant of and receives travel reimbursment, lecture fees, and grant support from Alcon Labs, Abbot, B+L, Carl Zeiss Inc, Diomed Developments Ltd, Hoya Corp, Neoptics AG, Oculus Surgical Inc, Rayner Inc; Dr. Morral and Dr. Kook have no financial interest to disclose. REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13]

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Zaldivar R, Davidorf JM, Oscherow S, et al. Combined posterior chamber phakic intraocular lens and laser in situ keratomileusis: bioptics for extreme myopia. J Refract Surg 1999;15(3):299-308. Guell J. The adjustable refractive surgery concept (ARS). J Refract Surg 1998;14(3):271. Kohnen T, Thomala MC, Cichocki M, Strenger A. Internal anterior chamber diameter using optical coherence tomography compared with white-to-white distances using automated measurements. J Cataract Refract Surg 2006;32(11):1809-13. Radhakrishnan S, Rollins AM, Roth JE, et al. Real-Time Optical Coherence Tomography of the Anterior Segment at 1310 nm. Arch Ophthalmol 2001;119:1179-1185 Baikoff G, Lutun E, Wei J, Ferraz C. Anterior chamber optical coherence tomography study of human natural accommodation in a 19-year-old albino. J Cataract Refract Surg 2004;30:696-701. Baikoff G, Bourgeon G, Jitsuo H, et al. Pigment dispersion and Artisan phakic intraocular lenses. Crystalline lens rise as a safety criterion. J Cataract Refract Surg 2005; 31:674-680. Guell JL, Morral M, Gris O, et al. Evaluation of Verisyse and Artiflex phakic intraocular lenses during accommodation using Visante optical coherence tomography. J Cataract Refract Surg 2007;33:1398-1404 Baikoff G, Matach G, Fontaine A, et al. Correction of presbyopia with refractive multifocal phakic intraocular lenses.J Cataract Refract Surg 2004;30:1454-60. Javaloy J, Alio JL, Iradier MT, et al. Outcomes of ZB5M angle-supported anterior chamber phakic intraocular lenses at 12 years. J Refract Surg 2007;23(2):147-58. Utine CA, Bayraktar S, Kaya V, et al. ZB5M anterior chamber and Fyodorov's posterior chamber phakic intraocular lenses: long-term follow-up. J Refract Surg 2006;22(9):90610.Knorz MC, Lane SS, Holland SP. Angle-supported phakic intraocular lens for correction of moderate to high myopia: Three-year interim results in international multicenter studies. J Cataract Refract Surg. 2011 Mar;37(3):469-80) Kohnen T, Klaproth OK. Three-year stability of an angle-supported foldable hydrophobic acrylic phakic intraocular lens evaluated by Scheimpflug photography. J Cataract Refract Surg. 2010 Jul;36(7):1120-6. Dick HB, Alio J, Bianchetti M, et al. Toric phakic intraocular lens: European multicenter study. Ophthalmology 2003;110(1):150-62. Guell JL, Vazquez M, Malecaze F, et al. Artisan toric phakic intraocular lens for the correction of high astigmatism. Am J Ophthalmol 2003;136(3):442-7. Alio JL, Mulet ME, Gutierrez R, Galal A. Artisan toric phakic intraocular lens for correction of astigmatism. J Refract Surg 2005;21(4):324-31. Guell JL, Morral M, Gris O, et al. Five-year follow-up of 399 phakic Artisan-Verisyse implantation for myopia, hyperopia, and/or astigmatism. Ophthalmology 2008;115(6):1002-12. Venter J. Artisan phakic intraocular lens in patients with keratoconus. J Refract Surg 2009;25(9):759-64. Doors M, Budo CJ, Christiaans BJ, et al. Artiflex Toric foldable phakic intraocular lens: short-term results of a prospective European multicenter study. Am J Ophthalmol. 2012 Oct;154(4):730-73 Güell JL, Morral M, Malecaze F, et al. Collagen crosslinking and toric iris-claw phakic intraocular lens for myopic astigmatism in progressive mild to moderate keratoconus. J Cataract Refract Surg. 2012 Mar;38(3):475-84. Sanders DR, Doney K, Poco M. United States Food and Drug Administration clinical trial of the Implantable Collamer Lens (ICL) for moderate to high myopia: three-year follow-up. Ophthalmology 2004;111(9):1683-92.

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[146] Sanders DR. Anterior subcapsular opacities and cataracts 5 years after surgery in the visian implantable collamer lens FDA trial. J Refract Surg 2008;24(6):566-70. [147] Sanders DR, Vukich JA, Doney K, Gaston M. U.S. Food and Drug Administration clinical trial of the Implantable Contact Lens for moderate to high myopia. Ophthalmology 2003;110(2):255-66. [148] Koivula A, Kugelberg M. Optical coherence tomography of the anterior segment in eyes with phakic refractive lenses. Ophthalmology 2007;114(11):2031-7. [149] Wiechens B, Winter M, Haigis W, et al. Bilateral cataract after phakic posterior chamber top hat-style silicone intraocular lens. J Refract Surg 1997;13(4):392-7. [150] Maldonado MJ, Garcia-Feijoo J, Benitez Del Castillo JM, Teutsch P. Cataractous changes due to posterior chamber flattening with a posterior chamber phakic intraocular lens secondary to the administration of pilocarpine. Ophthalmology 2006;113(8):1283-8. [151] Panozzo G, Parolini B. Relationships between vitreoretinal and refractive surgery. Ophthalmology 2001;108(9):1663-8; discussion 8-9. [152] Navarro R, Gris O, Broc L, Corcostegui B. Bilateral giant retinal tear following posterior chamber phakic intraocular lens implantation. J Refract Surg 2005;21(3):298-300. [153] Chang JS, Meau AY. Visian Collamer phakic intraocular lens in high myopic Asian eyes. J Refract Surg 2007;23(1):17-25. [154] Martinez-Castillo V, Boixadera A, Verdugo A, et al. Rhegmatogenous retinal detachment in phakic eyes after posterior chamber phakic intraocular lens implantation for severe myopia. Ophthalmology 2005;112(4):580-5. [155] Eleftheriadis H, Amoros S, Bilbao R, Teijeiro MA. Spontaneous dislocation of a phakic refractive lens into the vitreous cavity. J Cataract Refract Surg 2004;30(9):2013-6.

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CHAPTER 8 Supplementary IOLs for Pseudophakic Refractive Error Correction Guenal Kahraman* and Michael Amon** Academic Teaching Hospital of St. John Vienna, Austria Abstract: In this chapter we will describe the rational for supplementary IOL that were developed mainly for the correction of post-surgery refractive error. We will describe the alternative and the advantages of the supplementary IOLs. Supplementary IOLs are also available for astigmatism correction and as a multifocal version with or without a blue light protection. We will describe and discusses the clinical results of the available IOL.

Keywords: Supplementary IOL, sulcoflex, add on intraocular lens, piggyback, add-on, polypseudophakie, ciliary sulcus, refractive error, polypseudophakia, multifocal intraocular lens, toric IOL, biocompatibility, capsular reaction, IOL exchange, iris chafing, refractive surprise. INTRODUCTION Refractive surprise after cataract surgery is an unpleasant and frustrating situation for both the surgeon and the patient. Despite advances in IOL power calculation formula and accurate biometry techniques, pseudophakic refractive errors are unavoidable in some cases. Certainly, the advent of optical coherence biometry (OCB), which uses partially coherent light to measure the axial length of the eye along its visual axis and also provides the surgeon with keratometry readings and anterior chamber depth measurements, has significantly increased refractive accuracy during cataract surgery. However, since a post-operative refractive surprise can still occur albeit less frequently, a secondary surgical intervention can often be indicated. Several options are available for the subsequent correction of refractive surprises. These include prescription of spectacles or contact lenses, IOL exchange, *Address correspondence to Guenal Kahraman: Barmherzige Brüder Wien, Department of Ophthalmology, Johannes von Gott-Platz 1; 1020 Vienna, Austria; Tel: +43 1 21121 1140; Fax: +43 1 211 21 1144; E-mail: [email protected] ** Prof. Dr. Michael Amon is a paid consultant to Rayner Intraocular Lenses Ltd. Guy Kleinmann, Ehud I. Assia and David J. Apple (Eds) All rights reserved-© 2014 Bentham Science Publishers

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keratorefractive surgery or implantation of a supplementary IOL (polypseudophakia) [1, 2]. Prescribing of spectacles may not be the best option, especially with the younger more self-aware patient. Similarly, contact lenses are often inappropriate for the elderly infirm. Keratorefractive surgery may also not be the solution because of the inherent risks associated with further corneal surgery and additionally, in many instances; such an option may not be possible or available. Instead of the option of IOL exchange, the implanting of a supplementary IOL in the ciliary sulcus, anterior to the primary implant, is a much easier and safer surgical option, especially when capsular changes may have firmly fixated the primary implant within the capsular bag. Furthermore, since an IOL exchange may be associated with an increased risk of retinal tears, cystoid macular oedema or capsular rupture with vitreous loss, the implantation of a supplementary IOL can be a much more acceptable option. The piggyback technique, first described by Gayton in 1993 to provide adequate power in highly hyperopic patients, has been extended to secondary cases in which additional power is added or subtracted to an underpowered or overpowered pseudophakic eye. As a +46 dioptres (D) IOL was not available, two IOLs were used with the first planoconvex lens implanted within the capsular bag (Plano side facing anteriorly) and the second implanted in the ciliary sulcus (Plano side facing posteriorly) [1]. Many surgeons have, since then, used this technique for less extreme cases of hypermetropia, where a single IOL power was out of the range. Piggyback optical systems induce less spherical aberration and provide superior image quality when the optical centers of the two IOLs are aligned, than a single high power IOL of the same power [3, 4]. Implanting two IOLs in the capsular bag raises concerns about the possibility of the formation of with in Elschnig Pearl proliferation in the peripheral Interface between two IOLs. Interlenticular opacification (ILO) may lead to decreased vision secondary to a postoperative hyperopic shift as well as opacification. Several methods to help prevent ILO with piggyback IOLs have been discussed in the literature [5]. One is to place the primary IOL in the capsular bag and the secondary IOL in the ciliary sulcus. The first intraocular lens placed in the bag posterior to the continuous curvilinear capsulorhexis edge will help isolate the lens equatorial cells from the interlenticular space.

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Currently C therre 2 modelss designed ass an add onn lens on thee market: Prrof. Amon to ogether with Rayner intrraocular lensses Ltd deveeloped the Suulcoflex® IO OLs which esspecially deesigned for implantatio on in the cciliary sulcuus for corrrection of psseudophakicc refractive errors e in the pseudophakiic eye (Raynner Intraocullar Lenses Limited, L Hovee, East Susseex, BN3 7AN N, U.K.). HuumanOptics A AG developeed its own deesign, the Ad dd-On IOL (H HumanOpticcs Ag, Erlanggen, Germanny). SULCOFLE EX®, RAYNE ER INTRAOCULAR L LENSES Lttd. Design D of Sulcoflex® Inttraocular Leens The T 653L Sullcoflex® Asp pheric is a siingle-piece, foldable, hyydrophilic accrylic IOL with w an overaall size of 14 4 mm and optic size of 6..5 mm (Fig. 1).

Fiigure 1: The Rayner R Sulcofllex® Aspheric. IOL has a largge optic body D Diameter of 6..50 mm and ov verall length off 14.0 mm. Thee haptics are un ndulated.

The T IOL iss designed for ciliary y sulcus fiixation. Thee Rayner Sulcoflex Pseudophakicc Supplemen ntary IOL is manufacturred from Rayyacryl®, a hyydrophilic accrylic co-pollymer noted d for its high uveal biocoompatibility, a factor so important fo or IOLs speecifically deesigned for ciliary c sulcuus placemennt [6]. The Sulcoflex material m has FDA F approv val. The optiic has roundd edge, anteriior convex / posterior co oncave conffiguration fo or a perfect fit with thee anterior convex surfaace of the prrimary IOL.. The haptics have a 10 degrees possterior anguulation with uundulated ed dges to preeclude IOL rotation, a factor partiicularly impportant for the postop perative refr fractive accu uracy of the toric desiggn. The hapttic angulatioon is also efffective in maintaining g distance from f the iriis, thereby further reduucing the

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occurrence of pigment dispersion syndrome (PDS) and optic capture. As posterior capsular opacification is not a consideration with this design, the haptic and optic edges are rounded to reduce dysphotopsia. As Sulcoflex Pseudophakic Supplementary IOLs are intended solely for ciliary sulcus placement, interlenticular opacification, seen when both IOLs are implanted in the bag is not a characteristic of this design [7]. The Sulcoflex IOL can only be used at pseudophakic eyes with the first IOL in the capsular bag. The Sulcoflex® Aspheric is available from – 10.0 D to +10.0D. The toric version of Sulcoflex® 653T is available from +1.0 to +6.0 cylinder power (Fig. 2).

Figure 2: Slit lamp photo of a Sulcoflex toric IOL 12 months after Implantation. Arrows demonstrate the cylinder axis of the supplementary IOL. First IOL Implantation was on January 2007.

There is also a multifocal version of Sulcoflex (model 653F) available which ranges -3.0D to +3.0D in 0.5D increments with +3.5D addition (equivalent to +3.0D at the spectacle plane) (Fig. 3).

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Figure 3: Slit lamp photo of the multifocal Sulcoflex (model 653F). The addition refractive rings on the IOL anterior surface can easily noticed.

Clinical Experience Data on a group of 340 pseudophakic patients who had unsatisfactory far distance correction with spectacles has been evaluated [8]. 68 eyes had received multifocal version of Sulcoflex and 36 eyes received Sulcoflex toric. The median age of the patients was 51 years (range 32 to 74 years). Patients with pre-existing ocular pathology, other than previous cataract surgery with capsular bag IOL implantation were excluded. Before surgery, a complete eye examination was performed including uncorrected and corrected visual acuity as well as Goldmann applanation tonometry and fundoscopy. Additionally, axial length, anterior chamber length (IOL Master, Carl Zeiss Meditec, Germany), back vertex distance and keratometry values were determined. These measurements were used to calculate the power of the supplementary IOL, using the Haigis formula, based on anterior chamber depth and lens power effectiveness. Additionally, Sulcoflex® power can be calculated online [9]. Pentacam rotating Scheimpflug camera (Oculus, Inc.) was used to determine corneal topography, pseudophakic anterior chamber depth (ACD), the distance between both intraocular lenses. Inflammation was measured with the

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laser flare/cell meter (KOWA Japan), and position and rotational stability of the IOL were regularly documented. On each visit, digital retro illumination images of the IOLs were obtained. Surgery All surgery was carried out in a standardized fashion. For the pupillary dilatation tropicamide and cyclopentolate eye drops were used. Secondary piggyback IOL implantations were performed through a self-sealing clear corneal incision (2.75 mm) under topical and intracameral anaesthesia. The anterior chamber and the retro-iridial space were filled with an ophthalmic viscoelastic device (OVD) (sodium hyaluronate 1% [Healon]). Sulcoflex IOLs were implanted in the ciliary sulcus, using the supplied single-piece single-use injector. The OVD was washed out, and a miotic (acetylcholine 1% -Miochol E®) was injected intracamerally. Additionally 1.0 mg Cefuroxime (Curocef 0.3 ml) was administered. After the surgery, all patients received topical gentamicin–dexamethasone (DexagentaPOS) and diclofenac sodium 0.1% (Voltaren Optha) eye drops, three times daily for four weeks. Results Post operatively emmetropia (within +/- 0.25D) was achieved in all cases, with stable refractions. In those cases with the multifocal Sulcoflex® version and in cases with multifocal primary IOL all eyes achieved spectacle independence. Except for one eye all the surgeries were uneventful. In one case during the implantation, IOL haptic was detached from the optic body by the injector, which required Sulcoflex® explantation. The IOL was easily removed from the anterior chamber using a forceps via clear corneal incision. A new supplementary IOL was implanted. In most cases, no postoperative complications were noted. One eye had an intraocular pressure (IOP) increase on day-1 of post-surgery (IOP 28 mmHg). This was treated with topical drops and resolved within 1 week. The IOP remained stable (IOP max 16 mmHg) through the follow up period (26 months). The rest of the 33 eyes (97.06 %) had no IOP increase at any visit.

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No N signs off iris chafin ng, pigment dispersion or iris bullging were observed th hroughout th he follow-up period. A good g distancee was observved betweenn the IOLs ® an nd between the iris and the Sulcofleex Pseudopphakic Suppplementary IOL (Figs. 4 and 5). No foreign body y giant cell formation orr ILO was oobserved. Flaare values were w lower th han the valuees measured after standaard cataract pprocedures.

Fiigure 4: Penttacam image of o both IOLs.. The small w white arrows demonstrate thhe distance beetween the IOL Ls.

Fiigure 5: UBM M Picture show ws good distancce between iriss and the suppplementary IOL L located in ciiliary sulcus.

Rotational R staability and centration c were w excellennt. With the exception oof 3 eyes, alll the lenses were well centered. Decentratioon was less than 0.5 m mm when ob bserved at day-1 d post-su urgery and remained r staable throughh the follow up period (4 48 months). The patient was follow wed up with S Scheimpflugg images andd the lens to o lens distancce remained d the same on n all occasioons.

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One eye showed an IOL rotation of 48 degrees after 16 months of implantation. The IOL had power of 2.50D / +3.0 C. Although the IOL rotation may cause ciliary body irritation, the eye showed no signs of pigment dispersion or IOP increase. The IOL was fixated with a 10.0 prolene transscleral suture (unpublished data). Smaller Series Falzon and Stewart [10] described their results with 15 eyes (13 patients) with a mean follow-up of 20 months experience. They implanted 3 Sulcoflex aspheric (653L) and 12 toric (653T) IOLS. Preoperative mean spherical and astigmatic errors were 1.07+/-0.83 D and 1.45+/-0.98 D. Postoperative mean sphere and astigmatism at months were -0.25+/-0.38 D and 0.50+/-0.57 D respectively. All patients were within 1.00 D and 93% within 0.50 D. They report no significant intra or postoperative complications. Khan and Muhtaseb [11] describe their experience with 3 Sulcoflex IOLs 2 multifocal Sulcuflex IOLs. All the patients achieved uncorrected distance visual acuity of 20/25 and the eyes with the multifocal Sulcoflex IOLs achieved J4 or better. ADD-ON IOL, HUMANOPTICS AG Design and Models The Add-On IOL is a 3 piece modified C-loop foldable silicone IOL with a high molecular PMMA haptics designed for implantation in the sulcus with Convexconcave with round anterior optic edge to prevent iris irritation. The lens over all diameter is 14.0 mm and the optic diameter is 7.0 mm. The lens designed with and without blue light blocker (sPBY and sPB, respectively). Fig. 6 shows an HumanOptics Add-On IOL design.

Figure 6: A Toric Add-On IOL. Haptics are undulated in order to increase the rotational stability.

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The Secura model designed for refractive error correction. The dioptre range is 6.0 to -0.5 and 0.5 to 6.0 D with 0.5 steps. There is no haptic angulation for this model. The toric IOL design (Torica) designed with a toric anterior surface and aspheric posterior concave surface. The sphere range is -6.0 to 3.0 D with 0.5 D steps and -30.0 to -7.0 and 4.0 to 6.0 D in 1.0 D steps. The cylinder range is 1.0 to 30.0 in 1.0 D steps. There is no haptic angulation also for this model. The multifocal design (Diffractive) designed with a diffractive anterior surface and spheric posterior surface. The dioptric range is -6.0 to 6.0 D in 0.5 steps. The near addition is +3.5 D in the IOL plane. There is 10 degree haptic angulation in this model. The IOL power calculations can be done by the company. Clinical Experience Gerten et al. [12] reported their experience with sulcus implantation of the MS 714 PB multifocal model with a +3.50 D diffractive element for near and zero refractive power for distance during cataract surgery with posterior chamber IOL implantation. They reported the results of 56 eyes of 30 patients. Three months after the surgery mean monocular uncorrected distance visual acuity was 0.10+/-0.11 logMAR with a remaining mean postoperative spherical equivalent of 0.01+/-0.51 D. the mean uncorrected intermediate visua acuity was 0.20+/-0.15 logMAR, and the uncorrected near visual acuity was 0.16+/-0.13 logMAR. No major complications were reported. Wolter and Kuchle [13] reported similar results with secondary implantation of the same IOL in 50 eyes of 25 patients. Basarir et al. [14] reported results of 10 eyes with implantation of the Add-On IOL due to residual refractive error ranged from -12.0 to + 9.0 D. All the patients were within the targeted refractive range of -0.50 to +0.50 D. No complications were observed during the operation or during the postoperative follow up period (mean 10.5+/-1.36 months, range 6-15 months).

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Prof Auffarth [15] described his non-peer-reviewed experience with 2 monofocal Add-On IOL for refractive error correction post PKP and IOL surgery (spherical power ranged between -14.0 to -2.0 D), with the toric Add-On IOL (11 eyes) for residual astigmatism correction after refractive lens exchange (toric power ranged from 2.0 to 26.0 D), and 2 multifocal Add-On IOLs. At 2 months the spherical equivalent for all the eyes was -0.05+/-0.51 D, and the residual astigmatism was 1.22+/-1.04. In 2 cases of toric Add-On IOLs with very high astigmatism post PKP IOL rotation required in the early days after the surgery. No other complication observed. Discussions With advanced IOL designs and modern surgical techniques, an exact refractive result following cataract surgery with implantation of an IOL is a reasonable expectation - indeed, with patients being increasingly informed and in cases with refractive lens exchange, there is a higher patient demand for a near-perfect visual outcome. One major advantage of polypseudophakia is predictability. When a post-operative refractive surprise suggests a secondary intervention may be necessary, with an IOL exchange, there can often be an underlying uncertainty as to whether the correct implant power was used in the primary procedure. This could obviously affect the refractive result of the IOL exchange, especially if an original power miscalculation was repeated – that is, assuming that the primary implant was not miss-labelled. Importantly, the power calculation for the supplementary IOL depends solely on the patient’s current refraction. Similarly, the surgeon cannot be confident that the replacement IOL would be implanted in exactly the same plane as the original IOL. IOL power calculations for cataract patients having had previous keratorefractive surgery can be especially less accurate than would otherwise be expected. This is largely due to the difficulties, which can be encountered during the predetermination of corneal refractive powers, particularly after myopic keratorefractive surgery, as they can easily be overestimated leading, in many cases, to a hyperopic shift in the post-operative refractive outcome.

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A further advantage of polypseudophakia is reversibility. Unlike the option of corrective laser treatment, supplementary IOL exchange is reversible. Implanting a second IOL is a procedure that does not require special settings such as are needed for laser refractive surgery. Thus, patients are offered immediate treatment. With a supplementary IOL, care must be exercised in the choice of which lens to use. Lenses designed primarily for in-the-bag placement definitely are not the best for use in supplementary procedures, as the performance dynamics differ considerably [16, 17]. Conventional uniplanar IOLs, i.e. those having no posterior haptic angulation and in particular, those with relatively steep anterior surfaces, can cause iris chafing and pigment dispersion when implanted as piggy-back lenses in the ciliary sulcus, as contact with the iris can easily occur [18]. In addition to any unwanted pigment adhesion to the implant surface, pigment dispersion can also result in higher intraocular pressures with an increased risk of the development of glaucoma. This disadvantage is further compounded when conventional IOL designs are used in conjunction with higher power primary implants as their relatively steeper anterior surfaces can cause both IOLs to be in physical contact, thereby increasing the likelihood of anterior vaulting of the secondary lens to the detriment of the polypseudophakic refractive outcome. A further disadvantage of any physical contact, especially with foldable or injectable designs, is the deformation of the optic surfaces at the point of contact, which causes a hyperopic shift and may result in unwanted photopic effects. Paul H. Ernest illustrates that inserting a second lens into the sulcus can successfully treat severe positive dysphotopsia [19]. The supplementary IOL can be inserted regardless of the primary IOL used, and the second IOL can be any type of lens suitable for sulcus implantation. In the case by Ernest, the severe positive dysphotopsia was completely eliminated by piggybacking a lens in the sulcus. The treatment was successful in both eyes of this patient. Later on it was also reported to be beneficial for negative dysphotopsia. Consideration should be given to performing this procedure in cases of severe dysphotopsia. The

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procedure does not have the same potentially inherent risks associated with an IOL exchange. The new supplementary IOLs by Rayner Sulcoflex® and by HumanOptics AG are an exciting new development in IOL design, allowing secondary implantation in pseudophakic eyes and offering exact refractive results after cataract surgery or refractive lens exchange. Unlike conventional IOLs, those IOLs were specifically designed for polypseudophakia with design and biomaterial attributes calculated to overcome the disadvantages of using conventional IOLs. The IOLs can be used at the same time with the primary implant (Duet implantation), or as secondary implant and are available with an aspheric monofocal, aspheric toric or aspheric multifocal (refractive type) design. Indications for the implantation are the correction of post-surgical pseudophakic and post-keratorefractive surgical ametropia, the correction of higher order aberrations [HOAs] (Aspheric), the correction of supplementary residual pseudophakic astigmatism (Toric) and for the correction of pseudophakic presbyopia (Multifocal). Especially in eyes with “dynamic refraction” (paediatric cases, keratoconus, silicone oil, keratoplasty) the use of this IOL may be advantageous. Another suggested indication for primary use can be during a cataract surgery of a high myopic patient with unilateral cataract. Another indication can be to induce myopia in the operated eye to avoid post-operative anisometropia which will be able to easily corrected after cataract surgery in the other eye by explanting the add on lens. Theoretically pseudophakic dysphotopsia should be minimised by a second implant too. CONCLUSION The correction of pseudophakic ametropia, or the enhancement of post-surgical refractive results with supplementary IOLs offers a safer and less traumatic option than IOL exchange. ACKNOWLEDGEMENTS Declared none.

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CONFLICT OF INTEREST Prof. Amon is a paid consultant to Rayner Intraocular lenses, Ltd. REFERENCES [1] [2] [3] [4] [5] [6] [7] [8] [9] [10] [11] [12] [13] [14] [15] [16]

Gayton JL, Sanders VN. Implanting two posterior chamber intraocular lenses in a case of microphthalmos.J Cataract Refract Surg. 1993 Nov;19(6):776-7. J.P. Gills, J.L. Gayton and M. Raanan, Multiple intraocular lens implantation. In: J.P. Gills, R. Fenzel and R.G. Martin, Editors, Cataract Surgery: The State of the Art, Slack, Thorofare, NJ (1998), pp. 183–195. Eleftheriadis H., Sciscio A., Ismail A. et al. Primary polypseudophakia for cataract surgery in hypermetropic eyes: refractive results and long term stability of the implants within the capsular bag. Br. J. Ophthalmol. 2001;85;1198-1202. Hull CC, Liu CSC, Sciscio A. Image quality in polypseudophakia for extremely short eyes. Br. J. Ophthalmol. 1999;83: 656–63. 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 Mar; 26(3):330-6. Abela-Formanek C, Amon M, Schild G et al. Uveal and capsular biocompatibility of hydrophilic acrylic, hydrophobic acrylic, and silicone intraocular lenses. J Cataract Refract Surg. 2002 Jan;28(1):50-61. Terrence S.,Mamalis N., Lane S. Interlenticular opacification of piggyback acrylic intraocular lenses J Cataract Refract Surg 2002; 28:1287–1290 © 2002 ASCRS and ESCRS Kahraman G,Amon M.New supplementary intraocular lens for refractive enhancement in pseudophakic patients. J Cataract Refract Surg. 2010;36(7):1090-1094. www.rayner.com Falzon K, Stewart OG. Correction of undesirable pseudophkic refractive error with the Sulcoflex intraocular lens. J Refeact Surg. 2012; 28:614-9. Khan MI, Muhtaseb M. Performance of the Sulcoflex piggyback intraocular lens in pseudophakic patients. J Refract Surg. 2011;27(9):693-6. Gerten G, Kermari O, Schmiedt K, Farvili E, Foerster A, Oberheide U. Dual intraocular lens implantation: Monofocal lens in the bag and additional diffractive multifocal lens in the sulcus. J Cataract Refract Surg. 2009; 35:2136-43. Wolter-Roessler M, Küchle M. Implantation of multifocal add-on IOLs simultaneously with cataract surgery: results of a prospective study. Klin Monbl Augenheilkd. 2010;227:653-6. Basarir B, Kaya V, Altan C, Karakus S, Pinarci EY, Demirok A. The use of a supplemental sulcus fixated IOL (HumanOptics Add-On IOL) to correct pseudophakic refractive errors. Eur J Ophthalmol. 2012 19;22(6):898-903. Auffarth G. Piggybacking with the Add-On IOL. Cataract and refractive surgery today. June 2010. Findl O, Menapace R, Georgopoulos M. et al. Morphological appearance and size of contact zones of piggyback intraocular lenses. J Cataract Refract Surg. 2001 Feb;27(2):21923.

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Werner L, Shugar JK, Apple DJ et al. Opacification of piggyback IOLs associated with an amorphous material attached to interlenticular surfaces. J Cataract Refract Surg. 2000 Nov;26(11):1612-9. Masket S.Pseudophakic posterior iris chafing syndrome. J Cataract Refract Surg. 1986 May; 12(3):252-6. Paul H. Ernest, MD. Severe photic phenomenon. J Cataract Refract Surg. 2006; 32:685– 686 Q 2006.

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CHAPTER 9 Special Intraocular Lenses For Small Incisions Irit Bahar1,*, Yoav Nahum1 and Guy Kleinmann2 1

Department of Ophthalmology, Rabin Medical Center, Petach Tikva, Israel, and Sackler Faculty of Medicine, Tel Aviv University, Tel Aviv, Israel and 2 Department of Ophthalmology, Kaplan Medical Center, Rehovot, Israel, and School of Medicine, Hebrew University of Jerusalem and Hadassah Medical Center, Jerusalem, Israel Abstract: The trend toward minimally invasive surgery has been introduced in many fields of medicine, including ophthalmology. Cataract surgery has evolved over the last few decades from very large incision intracapsular cataract extraction to mini- and recently microincision cataract surgery (MICS) with an incision size of less than 2 mm. Recent innovations in phacoemulsification and intraocular lens technology have enabled this concept. Although cataract surgery can be performed through an incision less than 1 mm long, most IOLs require an incision of more than 2.0 mm in length. Most MICS-IOLs are constructed of one-piece hydrophilic acrylic material. They used to have insufficiently sharp posterior optic edges and broad haptic-optic junctions that compromised the optic-edge barrier effect. Improvements in those designs have achieved better hydrophilic acrylic IOLs in terms of vision quality and prevention of posterior capsular opacity. Recently, a hydrophobic three-piece IOL, which features a slim haptic junction and a sharp optic edge, became available. This chapter reviews the characteristics of recently introduced microincision IOLs. Further investigation is needed to improve the IOL design to match the microincision platform, without compromising vision quality.

Keywords: Cataract surgery, phacoemulsification, small incision, IOL, astigmatism, SIA. INTRODUCTION Recent developments in cataract surgery have enabled surgeons to reduce the size

*Address correspondence to Irit Bahar: Department of Ophthalmology, Rabin Medical Center, Petach Tikva, Israel; Tel: 972-3-9376101; Fax: 972-3-9219084; E-mail: [email protected] Guy Kleinmann, Ehud I. Assia and David J. Apple (Eds) All rights reserved-© 2014 Bentham Science Publishers

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of the incision for phacoemulsification (phaco) and intraocular lens (IOL) implantation. Historically, incision size for intracapsular cataract extraction (ICCE) surgeries was larger than 10 mm. It was reduced to 3-4 mm during phaco surgeries, to 2.2- 2.4 mm during mini-incision phaco surgeries and to less than 1.8 mm in microincisional cataract surgery (MICS). In general, incision length has been dictated by the size of IOL to be inserted. In 2001, Alió introduced the concept of MICS, as the surgery is performed through incisions of 1.8 mm or less [1]. This concept permits smaller incisions, and makes a significant transformation toward minimally invasive surgery. Progress in instrument adaptation, machine construction, software programming and IOL design had to be achieved, as well. The advantages of reducing incision size during cataract surgery include higher stability of the eye during surgery, faster recovery of the wound, and possible decreases in postoperative wound leakage, risk of endophthalmitis and surgically induced astigmatism (SIA). Up to 80% of MICS patients have less than 0.5D SIA [1]. There is a mismatch between cataract surgery technology and IOL technology. Although cataract surgery can be performed through an incision less than 1 mm long, most IOLs require an incision of more than 2.0 mm. In general, a MICS IOL should be implanted through a sub-2 mm incision and it should not have any structural deformation or optical alteration after unfolding. In addition, the design should aim to prevent posterior capsular opacity, and the lens should not induce halos, glare or night vision problems. Two types of IOL for MICS have been developed in recent years. The first type was an acrylic, one-piece IOL. These lenses were designed for larger incisions (3-4 mm) and had to be changed in order to be implanted through smaller incisions. Using a cartridge with a smaller tip and performing a wound-assisted implantation, enabled the implantation of IOLs designed for 3 mm incisions through 2.2 - to 2.4 mm incisions [2,3]. Additionally, the aspheric design and the high refractive index of some IOL materials allowed some thinning of the optic center, enabling its implantation

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through a smaller diameter incision. However, these IOLs cannot be safely implanted through microincisions of 2 mm or less. Forcing an IOL through a smaller incision carries the risk of stress and damage to the incision, creating uncontrolled microtears, which eliminates all the advantages of small incisions. The second type of IOL for MICS is smaller and thinner and can be implanted through smaller than 2 mm incisions. However, some of the IOLs that were manufactured to reach this incision size compromised optical quality. This chapter reviews the characteristics of recently introduced microincision IOLs (Table 1). Table 1: Recently introduced microincision IOLs No

Name of Lens

Manufacturer

1.

UltraChoice 1.0 Rollable™ ThinLens

ThinOptX, USA

2.

Acri.Smart™ lens

Carl Zeiss Meditec, Germany

3.

Akreos MI60 IOL

Bausch & Lomb, USA

4.

Tetraflex KH-3500

Lenstec, USA

5.

HOYA Y-60H

HOYA, Japan

6.

Miniflex

Mediphacos, Brazil

7.

MicroSlim and SlimFlex

PhysIOL, Belgium

ULTRACHOICE ThinOptX MICS IOL One of the first attempts to develop a lens that can be inserted through an incision smaller than 2.0 mm (1.45 mm) was the UltraChoice 1.0 Rollable™ ThinLens (ThinOptX, Abingdon, VA, USA) lens (Fig. 1). This is an acrylic hydrophilic rollable IOL, with a plate-haptic design. The refractive index of the material is 1.47. The dioptric power of this lens ranges from +15 to +25 diopters. The optical thickness is 300-400 microns, with a biconvex optical configuration with a meniscus shape. The overall diameter of the lens is 11.2 mm and the optical diameter is 5.5 mm [4]. The ultrathin properties of the lens are attributable to its optical design. The optic features three to five concentric optical zones with steps of 50 microns (Fig. 1). Each Fresnel-like ring or segment of the lens has a small change in the radius to correct for spherical aberration. The difference in radii ensures that each ring of

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the lens focuses light at nearly the same point as the prime meridian. According to the manufacturer, by making the lens thinner, other aberrations such as coma, as well as the potential for distortion and glare may be reduced [5].

A

B Figure 1: The UltraChoice™ lens, manufactured by ThinOptX, USA. A. Schematic of overall design and dimensions. B. Profile of the optic of the UltraChoice™, showing optical steps designed to reduce the mass of the lens and aberrations (Courtesy: ThinOptX).

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The four tips of the haptic component have a thickness of 50 microns. They can roll once in the capsular bag, absorbing capsular contraction forces (Fig. 2). The edge of the lens is also 50 microns thick, which is purported to reduce the potential for halos and glare.

Figure 2: Schematic drawing showing an UltraChoice™ implanted in the capsular bag. The thin tips of the haptic component are intended to roll and absorb capsule forces, preventing lens decentration/tilt (Courtesy: ThinOptX).

During the first clinical studies involving this lens design, many patients presented with better than expected near vision. It has been hypothesized that the thin nature of this design provides increased amplitude of pseudoaccommodation, which planned to be investigated further. Another explanation could be that the thin lens is associated with increased field depth. An additional possibility is that the lens would move with the capsular bag during efforts for accommodation, as it is thin and light, and exerts little force against the equator. At first, the UltraChoiceTM was folded manually. Later, a specially designed roller/injector system with an autoclavable, reusable cartridge made of Teflon was developed. This IOL can be inserted through an incision length less than 1.5 mm and was shown to be implantable through incision as small as 1.1 mm. ThinOptX received CE Mark approval for the UltraChoice™ monofocal cataract lens on September 9, 2002. Cadaver eye studies conducted at the Laboratories for Ophthalmic Devices Research of Prof. David J. Apple demonstrated good centration of the UltraChoiceTM IOL (Fig. 3).

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A

B Fiigure 3: UltraaChoice™ lensses implanted in the capsulaar bag, showing excellent centration. A. Clinical picture obtained from m an anterior orr surgeon’s view w (courtesy: T ThinOptX). B. Posterior or Miyake-Apple M view v of the an nterior segmentt of a human eeye obtained ppostmortem (coourtesy: Dr. Nick N Mamalis, Salt S Lake City,, UT, USA).

CLINICAL C STUDIES S Results R of cliinical trials that t compareed this lens tto the Acryssof IOL (Alccon) vary. Dogru D et al. showed thaat BCVA forr near and ddistance visiion was nott different beetween the IOLs, I while Kaya et al. showed thee lens resultss to be inferiior to that off Acrysof in terms of vissual perform mance and PC CO rates [6, 7]. Prakash et al. examined the t results of o 50 patientts implantedd with the Ultrachoice IO OL. In all 50 0 cases, the IOL I was inseerted througgh 1.70 mm cclear corneal incision. The T mean besst-corrected visual acuity y was 0.02 ((6/6-1) at 6 w weeks and 0.17 (6/10)

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at the final follow-up. The mean surgically induced astigmatism at 6 weeks was 0.0106. Colored haloes around artificial lights were perceived by 69.2% of patients at 6 weeks and by 61.3% at the final follow-up. One patient underwent IOL exchange for this reason. Posterior capsular opacification was noticed in 31.3% at 6 weeks and in 64.5% at 15 months. Anterior capsular opacification was noticed in 5.3% at 6 weeks and in 16.1% at 15 months. In one patient, the IOL was exchanged because of tilt and displacement secondary to anterior capsular phimosis [8]. Cinhüseyinoglu et al. implanted 85 eyes with Ultrachoice IOL. At 6 months postoperatively, 1 patient had a best spectacle-corrected visual acuity (BSCVA) of 0.2, the patient had atrophic, senile macular degeneration. The rest of the eyes achieved a BSCVA of 0.63 or better. At 6 months postoperatively, 55 (61.1%) eyes had uncorrected visual acuity (UCVA) at least 0.8 and 83 (92.2%) eyes had a BSCVA equal of at least 0.8 according to the Snellen chart. The mean postoperative corneal astigmatisms at 1 week, 1 month, and 6 months were 0.69+/-0.43 D, 0.66 ± 0.46 D and 0.65 ± 0.48 D, respectively. Statistical analysis revealed a significant change in corneal astigmatisms at the 1-week post-operative visit (p0.05) compared with preoperative findings [9]. In spite of these encouraging results, the lens is not available today. ACRI.SMART™ Another recently developed lens for insertion through very small incisions is the Acri.Smart™ lens (Carl Zeiss Meditec) (Fig. 4).

Figure 4: Acri.SmartTM lens model 48S. Manufacturer’s Illustration. (Courtesy Carl Zeiss Meditec, Germany).

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This is a one-piece, plate, planar lens that has an optical diameter of 5.5 mm and a total length of 11.0 mm (model 48S). The first Acri.Smart™ lens was pre-folded as follows: after up to 27% dehydration, the optic of the lens was rolled onto itself to create a pre-folded lens that was shorter in diameter. A folded +19-diopter lens had a width of about 1.2 to 1.3 mm. Over the next few minutes after implantation in the capsular bag, the Acri.Smart™ unfolded gradually, completely unfolding after 23 to 30 minutes. The more recent models of the Acri.Smart™ lens (model 48S with a 5.5 mm optic and model 46S with a 6.0 mm optic) have been developed for implantation with a specially designed injector through a 1.4 to 1.5 mm incision. These are hydrophilic acrylic (25% water content) lenses with a hydrophobic coating. The overall design is that of plate haptic lenses with square edges, which are loaded into the injector in a hydrated state; thus, the unfolding is faster. Model 36A, with a special aspherical design has also been developed to compensate for the positive spherical aberration of the cornea, in a mechanism probably similar to that of the Tecnis® lens. Toric (Acri.Comfort 646 TLC) and multifocal (Acri.LISA 366D) models of this lens are available. The Acri.LISA Toric 466TD features a toric anterior surface and a diffractive design 3.75 D added to the posterior surface. The Acri.Smart was also demonstrated to be suitable for pediatric bimanual microincision cataract surgery [10]. Other MICS IOLS by this company include the CT Spheris 209M and the CT Asphina 409/509 preloaded lenses, both can be inserted through a 1.5 mm incision [11]. CLINICAL STUDIES Lubinski et al. implanted the Acri.Smart 48S lens in 22 eyes through a mean incision size of 1.56 ± 0.07 mm. One month after surgery the mean UCVA improved from 0.49 ± 0.33 preoperatively to 0.97 ± 0.11 postoperatively (p < 0.001) and BCVA improved from 0.68 ± 0.3 preoperatively to 1.0 postoperatively (p < 0.001). BCVA for near vision improved from 5.27 ± 3.30 preoperatively to 2.91 ± 1.48 postoperatively (p = 0.002). One month after surgery, there was no significant increase in astigmatism and the pseudo-accommodative ability of Acri.Smart 48S was not observed [12].

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Alió et al. implanted an Acri.Smart IOL 48S in 45 eyes. The lens was inserted through a mean incision size of 1.5 mm ± 0.3 (SD). The mean UCVA improved significantly from 20/100 (0.2 ± 0.2 decimal value) preoperatively to 20/32 (0.7 ± 0.3) by 6 months postoperatively (p