Eyeworld

EW FEATURE 38 by Vanessa Caceres EyeWorld Contributing Writer Treating, eliminating negative dysphotopsia Treatments linked to suspected causes; prevention remains under investigation T he best way to treat nega- tive dysphotopsia remains a hot topic among surgeons. Negative dysphotopsia that occurs right after cataract surgery is usually best left to resolve on its own. However, if the problem continues a few months after sur- gery, ophthalmologists must step in to provide a treatment. Their treat- ment approach usually depends on what they suspect is the cause. Looking at causes Negative dysphotopsia appears in patients as a temporal crescent- shaped shadow after in-the-bag IOL implantation following cataract sur- gery. It was first reported in 2000 by James Davison, MD, cataract and refractive specialist, Wolfe Eye Clinic, with locations throughout Iowa. 1 Dr. Davison said he observed the phenomenon with acrylic square-edge IOLs, which were intro- duced in the 1990s as a way to pre- vent posterior capsule opacification. "There's controversy with the exact mechanism of action," said David V. Folden, MD, North Subur- ban Eye Specialists, Minneapolis. "I think more physicians and data would support the fact that it's ultimately the sharp posterior optic edge design of the modern-day IOL that's likely the culprit." Other suggested factors include an IOL's high index of refraction, transparency of the peripheral nasal capsule, and type of incision used during surgery. The immediate postop inci- dence for negative dysphotopsia appears to be around 20%, said Samuel Masket, MD, in private practice in Los Angeles, and clinical professor of ophthalmology, Jules Stein Eye Institute, David Geffen School of Medicine, University of California, Los Angeles. However, long-term chronic dysphotopsia complaints are closer to 1.5% to 3%, Dr. Masket said. Surgeons cannot yet predict who will experience negative dys- photopsia, said Jack T. Holladay, MD, clinical professor of ophthal- mology, Baylor College of Medicine, Houston. Dr. Holladay wrote an article in 2011 that used ray tracing diagrams to explain negative dysphotopsia. 2 "The peripheral arcuate shadow that patients see is the result of square-edge optics causing a refrac- tion of the rays that pass through the edge of the lens that go in oppo- site directions (leaving a blind spot), and that creates a shadow. That al- ways happens. If that shadow falls anterior to the functional retina, then you can't see it. If it falls on the functional retina then you'll see it," he said. "Not everyone's peripheral retina is at the same point. People who have a functional retina ex- tending far anteriorly will have a higher chance of experiencing this than people who don't," Dr. Holladay said. "We have no clinical way of determining how far a patient's functional retina goes." However, Dr. Holladay added that if someone experiences negative dys- photopsia in one eye, it's more likely that he or she will experience it in the fellow eye as well. Available treatments for negative dysphotopsias The first recommended treatment for negative dysphotopsia is observa- tion. "Observation is a great first step. Ultimately, we think the capsule peripheral to the optic edge on the nasal side clouds over time, increasing light scatter into that shadow, and that eliminates the neg- ative dysphotopsia," Dr. Folden said. If the patient still has the prob- lem 3 to 4 months later, the use of thick-framed glasses or a trial dila- tion can take place, Dr. Folden said. However, not many patients want to use thicker frames, and dilation is good for diagnosis but not for treatment, he cautioned. Even if patients must wait a few months before treatment, Dr. Masket reassures them what they are experi- encing is a legitimate—and bother- some—visual phenomenon. A treatment approach published recently by Dr. Folden in one report and David L. Cooke, MD, February 2011 Pseudophakic dysphotopsia April 2014 AT A GLANCE • Negative dysphotopsia can occur after cataract surgery, even if the surgery was perfect. • Surgeons cannot predict who will experience negative dysphotopsia. • It's best to observe patients for a few months before providing treatment, as many cases will resolve on their own. • Treatment options include Nd:YAG laser capsulectomy, a piggyback lens, and lens exchange. Slit lamp image shows the nasal anterior capsule overlying the anterior surface of the IOL optic prior to Nd:YAG laser anterior capsulectomy. This shows the creation of an anterior capsule sector along the nasal aspect of the capsulorhexis following Nd:YAG laser anterior capsulectomy. Source (all): David Folden, MD; J Cataract Refract Surg. 2013;39:1110–1115 continued on page 40

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