Accelerated Versus Conventional Corneal Collagen Cross-Linking in the Treatment of Keratoconus: A Meta-analysis and Review of the Literature

Abstract

Our aim was to examine existing literature, and determine if there are outcome differences between accelerated corneal collagen cross-linking (A-CXL) and conventional corneal collagen cross-linking (C-CXL). A systematic review of the literature was conducted examining studies which compared A-CXL to C-CXL. Available studies were combined and the weighted mean difference (WMD) was calculated for range of outcome measures including maximal keratometry (Kmax), mean keratometry (Kmean) and minimum keratometry (Kmin), spherical equivalent, best corrected visual acuity (BCVA), and central corneal thickness (CCT). Seven eligible studies were included in our meta-analysis, with 283 eyes (135 in A-CXLand 148 in C-CXL). In the combined analysis, there was no statistically significant difference observed in Kmin or Kmax between A-CXL and C-CXL for at least 6months after the procedure. Kmean was statistically higher in the C-CXL group in comparison with the A-CXL group for at least 6months after the procedure (WMD - 3.15, 95% CI - 4.34 to - 1.97, p < 0.01).No statistically significant difference observed in spherical equivalent or central corneal thickness between the A-CXL group and C-CXL group for at least 6months after the operation. The BCVA was statistically higher in the A-CXL group in comparison with the C-CXL group for at least 6months after the procedure (WMD - 0.05, 95% CI 0.00-0.10, p < 0.05). No surgery complication was recorded in the researches. Our study demonstrated greater reductions of Kmean in the A-CXL group in comparison with the C-CXL group. Overall A-CXL is comparable to C-CXL from outcome basis.