Eyeworld Daily News

EW SHOW DAILY 6 Sunday, May 8, 2016 by Ellen Stodola EyeWorld Senior Staff Writer ASCRS News Today D oyle Stulting, MD, Atlanta, presented this year's Binkhorst Lec- ture on "Predicting and Treating Corneal Ectasia." In 1998, Theo Seiler, MD, Zurich, Switzerland, published the first case of corneal ectasia after LASIK, Dr. Stulting said, and he postulated that forme fruste keratoconus (FFKC) was a risk factor. Meanwhile from 1996 to 2001, Dr. Stulting said 17 cases of ectasia presented to the Emory Contact Lens Service. They found 10 eyes of 7 patients with adequate data for analysis of risk factors and did an analysis. Preoperative refraction, preoperative pachymetry, residual stromal bed, and forme fruste kera- toconus were significant risk factors, with FFKC seemingly the strongest predictor. Further study indicated that age could be another risk factor. Dr. Stulting developed an ectasia risk score system (ERSS) that "placed patients at low, medium, and high risk for corneal ectasia." Advantages of the ERSS, Dr. Stulting said, are that it measures multiple risk factors simultaneously, it utilizes common- ly measured parameters, and it was evaluated on a second population. Meanwhile, some of the shortcom- ings are the percentages of false positive and false negative rates, its subjective classification of topogra- phies, it does not consider thickness profiles, it does not utilize all diag- nostic technologies, and it does not perform as well in recent published clinical studies. The sensitivity of the risk score system over time falls, he noted. So why does the risk score system seem to be failing today? The incidence of FFKC has been falling in ectatic eyes in published case reports. The residual stromal bed is going up. The mean preoperative corneal thickness is going up as well. These reflect implementation of the risk score system even if not done consciously or formally, Dr. Stulting said. "The ERSS appears to be failing because it's working," Dr. Stulting said. "Physicians avoid surgery on patients with previously publicized risk factors, so new analyses will not identify risk factors that cur- rently prevent patients from being treated," he said. Future screening methodologies must recognize all risk factors, Dr. Stulting added. Comprehensive ectasia screen- ing should include early cases in future analyses. It should also utilize a 2-step screening process using the original ERSS and newly derived screening methods. "The lower inci- dence of ectasia makes the scientific comparison of predictors difficult," Dr. Stulting said. Dr. Stulting then discussed crosslinking, introduced by Dr. Seiler, and remembered his first crosslinking case on January 5, 2008 using the classic Dresden protocol and his involvement in a multi- center clinical trial. Dr. Stulting noted that he began to see com- plications of crosslinking in print literature, which included corneal haze, sterile infiltrates, bacterial ker- atitis, and perforation, among other complications. Most complications are a result of epithelial removal, he said, but the epithelium is a barrier to riboflavin absorption. So why try epi-on crosslinking? Dr. Stulting said it's much safer and could possibly be "good enough." It can also be repeated with minimal risk if it's not good enough or could be followed by epi-off, he added. Dr. Stulting noted that he pre- viously was a great proponent for epi-off over epi-on but has recently been looking more at the latter. He also detailed his involvement with CXLUSA (Bethesda, Maryland) to study crosslinking, which offered the opportunity to explore a new technique. CXLUSA used a novel riboflavin formulation; there was no riboflavin applied during UVA exposure to prevent blockage of ultraviolet light, and the technique used pulsed UVA to allow oxygen to enter the cornea. Conclusions from studies with CXLUSA found that at 1–2 years, the technique achieves visual results better than some epi-off procedures. There is also less risk compared to the epi-off technique, BSCVA im- proved by decreased K and reduction in HOA, and retreatment is possible with minimal risk. "Future refine- ments may improve the outcomes of epi-on crosslinking even further," Dr. Stulting said. On the horizon, he sees non-toxic absorption enhancers and direct measurement of corneal biomechanics to identify patients at risk and access the effects of treat- ment. "Treating ectasia in the future is probably going to be different from what we have today," Dr. Stulting said. This could include routine topographic screening, baseline biomechanical testing, riboflavin drops with non-toxic absorption enhancers, exposure to natural UVA from the environment, and moni- toring biomechanical changes. "I hope in the future that there will be a transition to a safer epi-on procedure that avoids the complica- tions of epithelial removal that we all know so well now," Dr. Stulting said. EW Editors' note: Dr. Stulting has no finan- cial interests related to his comments. Binkhorst Lecture highlights ectasia Dr. Stulting accepts the Binkhorst Medal from Dr. Solomon.

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