EyeWorld India March 2019 Issue

41 March 2019 EWAP CATARACT / IOL Surgical remedy for negative dysphotopsia by Maxine Lipner EyeWorld Senior Contributing Writer F or patients with complaints of negative dysphotopsia (ND), a surgical strategy of secondary reverse (anterior) optic capture can remedy the situation, according to Samuel Masket, MD, Los Angeles. Dr. Masket reported on study results 1 in remedying negative dysphotopsia in the Journal of Cataract and Refractive Surgery . In all but one case of secondary reverse optic capture, this technique was successful. In cases of negative dysphotopsia, the typical complaint centers around a dark temporal crescent or line in the periphery of patients’ vision. One of the ironies with the condition is its association with a well-centered posterior chamber lens in the capsule bag with an overlapping anterior capsulotomy for 360 degrees. “We only see it under what we consider to be anatomically perfect postoperative circumstances,” Dr. Masket said, adding that if there’s significant decentration, significant tilt from capsule damage, ND tends not to occur. Shifting theories Theories on the condition have abounded over the years. “Negative dysphotopsia was first reported in 2000 by Jim Davison, MD , ” Dr. Masket said. “It corresponded to the same time that acrylic IOLs became popular in the market.” The assumption was that the chief cause of ND was the single- or multi-piece acrylic IOL with a high index of refraction and a square edge; these characteristics were already associated with positive dysphotopsia (PD). With the assumption of a particular lens style being responsible, many practitioners, including Dr. Masket, exchanged (bag to bag) such acrylic IOLs for round, silicone IOLs with a low index of refraction for symptomatic patients. “In our experience, we had no success with this strategy,” Dr. Masket said. Meanwhile, an investigation 2 done by Peter Vamosi, MD, helped to enhance Dr. Masket’s understanding. Dr. Vamosi reported that if he exchanged the lens in the bag for one made of a different lens material, he had no success. However, if he exchanged the in the bag lens for one in the sulcus, he was successful. In his study, position of the IOL was paramount, not the material or the design. Another theory was based on the expanded space between the back of the iris and the front of the lens implant (posterior chamber) in the pseudophakic eye. Surgeons filled this gap with a piggyback IOL, with moderate success. “It’s about 70% successful,” Dr. Masket said. However, in a case where he attempted to shallow the posterior chamber by fixating the lens bag to the iris, he found that this failed to help. In addition, the Vamosi study indicated that the depth of the posterior chamber was identical in both the symptomatic patient group and the controls, disproving the theory that the expanded posterior chamber was causal for ND. Dr. Masket noted that during the late 1980s surgeons not only changed the lenses they were implanting but also began incorporating capsulorhexis into their surgeries. “Prior to that we used can-opener capsulotomies,” he said, adding that with this early approach the majority of lenses ended up with one loop in and one loop out of the bag. “We started to look at the relationship of the anterior capsulotomy to the anterior surface of the IOL as being one potential site for induction of negative dysphotopsia.” Dr. Masket decided that he would try a new approach by placing the optic in front of the capsule, rather than behind the capsule while leaving the loops in the bag for support. “That strategy worked extremely well,” he said. Studying treatments That method, as well as other approaches, were considered in the recent consecutive surgical case series of 37 patients with chronic ND. Investigators looked at how Secondary reverse optic capture in a symptomatic patient. Source: Samuel Masket, MD Continued on page 42