Shift in progression rate of keratoconus before and after epithelium-off accelerated corneal collagen crosslinking

Purpose: To evaluate the shift inkeratoconus progression rate after corneal collagen crosslinking (CXL). Setting: Chinese University of Hong Kong Eye Centre, Hong Kong, China. Design: Prospective case series. Method: Accelerated epithelium-off CXL was performed in patients with progressive keratoconus. Optical coherence tomography based corneal measurements were recorded. The data collected after the first postoperative month were used for analysis. The main outcome measure was the rate of progression of steep keratometry (K), flat K, average K, and best-fit sphere (BFS) using linear mixed-effects models. Progression was defined based on a significant slope against time in these models. Results: Forty-seven eyes (38 patients; mean age 27.6 years +/- 6.5 [SD]) were included. The median number of preoperative visits and postoperative visits was 3 and 5, respectively. A significant reduction in the progression rate of the anterior average K (0.063 +/- 0.138 diopter [D]/mo to -0.022 +/- 0.029 D/mo) and posterior average K (-0.011 +/- 0.025 D/mo to 0.000 +/- 0.009 D/mo) occurred (both P < .001). On univariate analysis, the baseline anterior average K had the strongest association with the progression rate of the anterior average K after CXL. On multivariate analysis, the preoperative progression rate of the posterior BFS was significantly associated with postoperative progression rate of the anterior (P < .001) and posterior average K (P <= .05). Conclusions: A significant reduction in the progression rate of average K occurred after accelerated epithelium-off CXL. The reduction was associated with the baseline anterior average K and preoperative progression of posterior BFS. (C) 2017 ASCRS and ESCRS