Eyeworld

135 EW REFRACTIVE March 2018 eyes was more than 500," he said, adding that all but two of them had a residual stromal bed above 300 microns. "Some people may say that they had funny looking topography and should not have had the surgery to begin with," he said. "But we saw two eyes in this group that had normal thickness, a normal resid- ual stromal bed above 300, normal topography, and they still developed ectasia." Dr. Moshirfar asked what might be involved in developing a differ- ent metric specifically for SMILE. With LASIK flaps, one of the factors that is thought to be important in corneal strength is that the incision goes approximately 11 clock hours around. "We are doing a vertical cut, which is around 23 mm," he said. Meanwhile, a SMILE cap involves a superior incision, which is only about 5 mm, he continued, adding that this means with SMILE there should be about 70% less disruption in the anterior cornea. "The ratio is about 0.3," Dr. Moshirfar said. "If you implement that ratio, maybe the percent tissue altered in these eyes shouldn't be 40%." Had practi- tioners used a modified PTA of 20%, they would have realized that six of the eight eyes here should not have undergone the procedure. Others are looking into com- ing up with a new formula. Dr. Moshirfar hopes that those who are working on this take into account the vertical incision that is made as part of the SMILE process. "We can- not assume that this tiny vertical in- cision that we're making with SMILE is of no biomechanical impact," he said, adding that if someone wants to come up with a metric, they need to keep the procedure's vertical cut ratio to LASIK in mind in modifying the PTA factor. Overall, in ruling someone in or out for refractive surgery, abnor- mal topography is paramount, Dr. Moshirfar stressed. "If the cornea is otherwise normal but does have an asymmetric look to it, maybe we shouldn't be doing refractive surger- ies on these eyes," he said. EW Contact information Moshirfar: cornea2020@icloud.com Editors' note: Dr. Moshirfar has no financial interests related to his comments. Reference 1. Moshirfar M, et al. Ectasia following small-incision lenticule extraction (SMILE): a review of the literature. Clin Ophthalmol. 2017;11:1683–1688. (800) 367-8327 DuPont, WA 98327 info@lacrimedics.com • www.lacrimedics.com ©2018 Lacrimedics, Inc. 1 ASCRS Clinical Survey 2015. Global Trends in Ophthalmology and the American Society of Cataract and Refractive Surgery. Don't let 41% of your patients with OSD go untreated, especially when they need something more than artifi cial tears. Lacrimedics' VisiPlug® is FDA approved for the treatment of the Dry Eye components of varying Ocular Surface Diseases (OSD) and to enhance the effi cacy of topical medications. VisiPlug® – Provides approximately 180 days of occlusion so you can better manage your patient's treatment plan. Don't let 41% of your 41% of refractive or cataract surgery patients have ocular surface dysfunction levels requiring some treatment beyond artifi cial tears! 1 0.4mm 0.5mm

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