Fellow Eye as a Predictor for Keratoconus Progression Following Accelerated Corneal Cross-linking

PURPOSE: To assess the fellow eye as a predictor for keratoconus progression following bilateral same-day accelerated corneal cross-linking (A-CXL). METHODS: This was a post-hoc analysis of data from a prospective study of bilateral A-CXL for progressive keratoconus between 2013 and 2015. The primary outcome measures were absolute change in maximum keratometry (Kmax) (diopters [D]), relative change in Kmax (%), and A-CXL progression (increase in Kmax > 2.00 D). Responses in both eyes were measured by the change in Kmax, with the right eye serving as the "predictor" of progression for the left eye. RESULTS: Three-hundred ninety-two eyes (196 patients) with a mean age of 26.8 +/- 7.7 years were included. There was a significant correlation in absolute and relative Kmax change (r = 0.26, P < .001 and r = 0.32, P < .001, respectively) between right and left eyes. In regression analysis, the only significant predictors of change in Kmax in the left eye were preoperative Kmax of the left eye (P < .02) and change in Kmax of the right eye (P < .001). Eyes that progressed in the right eye were more likely to progress in the left eye (29.4% versus 4.5%, odds ratio = 8.85, P < .001). In multiple regression, right eye progression of greater than 2.00 D was the significant predictor of left eye progression of greater than 2.00 D (odds ratio = 15.15, P < .007). CONCLUSIONS: This large-scale study of keratoconus following A-CXL indicates that patients with progression in the right eye were 15.5 times more likely to have progression in the left eye. Patients with progression following A-CXL in one eye should be closely observed due to increased risk of progression in the fellow eye.