Corneal Collagen Crosslinking for Ectasia After Refractive Surgery: A Systematic Review and Meta-Analysis

Introduction: Corneal ectasia leads to progressive irregular corneal curvature and reduced visual acuity. Objective: To assess the safety and effectiveness of corneal collagen cross-linking (CXL) for managing corneal ectasia resulting from refractive laser surgery (RSL). Methods: A systematic review and meta-analysis were realized according to PRISMA guidelines. We searched PubMed, EMBASE, Cochrane, and Web of Science databases for studies on CXL in patients with ectasia after RLS. The outcomes of interest included visual acuity, refractive outcomes, topographic parameters (Kmax, index surface variance (ISV), index of Vertical Asymmetry (IVA), keratoconus index (KI), central keratoconus index (CKI), index of height asymmetry (IHA), index of height decentration (IHD) and Rmin (minimum sagittal curvature)), central corneal thickness, endothelial cell count, and possible adverse events. Statistical analysis was performed using the R software (version 4.2.3, R Foundation for Statistical Computing, Vienna, Austria). Results: 15 studies encompassing 421 patients (512 eyes) were included. The mean age was 32.03 +/- 4.4 years. The pooled results showed a stable uncorrected visual acuity post -CXL, with a significant improvement in corrected distance visual acuity (SMD = 0.09; 95% CI: -0.07 to 0.26). The spherical equivalent decreased significantly (SMD = -0.09; 95% CI: -0.35, -0.02). The topographic parameter Kmax decreased significantly (SMD = 0.15; 95% CI:0.01 to 0.28); however, the other parameters, ISV, IVA, KI, CKI, IHA, IHD, and Rmin, did not change significantly. Central corneal thickness decreased significantly (SMD = 0.24; 95% CI:0.07 to 0.41), and the endothelial cell count remained stable The complications were rare. Conclusion: CXL is a safe and effective technique for managing corneal ectasia after RLS.