Comparison of standard and accelerated corneal cross-linking for the treatment of keratoconus: a meta-analysis.

Abstract

To compare results between standard and accelerated corneal collagen cross-linking (CXL) for the treatment of progressive keratoconus. We performed literature searches in PubMed, Cochrane Library, Web of Science, ISRCTN registry, ClinicalTrials.gov, and EMBASE for studies comparing conventional Dresden (C-CXL) and accelerated CXL (A-CXL). Outcomes were clinical results and changes in corneal properties. Weighted mean differences were used to evaluate the effects. Here, 22studies with 1158 eyes (C-CXL: 577eyes; A-CXL: 581eyes) were included. At the last follow-up, C-CXL was superior regarding minimum keratometry (p<0.00001) and demarcation line depth (p<0.00001), whereas A-CXL should be favoured when considering minimum corneal thickness (p=0.0005). No differences in uncorrected and corrected distance visual acuity (p=0.09 and 0.98), spherical equivalent (p=0.11), spherical and cylindrical error (p=0.29 and 0.32), maximal and average keratometry (p=0.05 and 0.65), central corneal thickness (p=0.15), corneal biomechanical properties (p≥0.21 respectively), time of reepithelialization (p=0.76), subbasal nerve density (p=0.69), endothelial cell density (p=0.30) and morphology (p≥0.40 respectively) were found among both groups. Consideration of less corneal thinning favours A-CXL, whereas the deeper demarcation line and greater changes in minimum keratometric values in C-CXL may indicate a higher treatment efficacy. Altogether, C-CXL, as well as A-CXL, provides successful results in the strengthening of corneal tissue.