Accelerated corneal collagen cross-linking in progressive keratoconus: Five-year results and predictors of visual and topographic outcomes

Purpose: To analyze the 5-year results of accelerated corneal collagen crosslinking (CXL) for progressive keratoconus and identify preoperative characteristics predictive of visual and topographic outcomes. Methods: A prospective interventional case series. Nineteen eyes of 19 patients receiving accelerated CXL with settings of 18 mW/cm(2) for 5 min were included. Clinical and topographic parameters were assessed. Linear regression and logistic regression were used to compare the R-2 and odds ratio (OR), respectively, between baseline characteristics and postoperative outcomes. Results: Corrected distance visual acuity (CDVA) remained stable from 0.28 +/- 0.21 to 0.25 +/- 0.18 logMAR (P = 0.486). The mean cylindrical refraction was stable (P = 0.119). The maximal keratometry (Kmax) decreased from 61.99 +/- 10.37 to 59.25 +/- 7.75 D (P < 0.001), flattening in the flattest and steepest meridians and mean keratometry were also observed (P <= 0.040). The mean anterior elevation at the apex reduced from 21.42 +/- 16.69 to 18.53 +/- 12.74 mu m (P = 0.013) and changes in posterior elevation were non-significant (P = 0.629). Preoperative Kmax best predicted the postoperative change in Kmax (R-2 = 0.55, P < 0.001) compared to the other baseline characteristics (P < 0.028), whereas preoperative CDVA was the only significant predictor of postoperative change in CDVA (R-2 = 0.41, P = 0.003). Accelerated CXL is less likely to fail in eyes with a steeper preoperative Kmax (OR = 0.74, P = 0.040) or greater posterior elevation at the apex (OR = 0.91, P = 0.042). Conclusion: Kmax significantly decreased following accelerated CXL. Eyes with worse preoperative CDVA and higher Kmax were more likely to have an improvement in visual acuity and corneal flattening.