Corneal collagen cross-linking in keratoconus: a systematic review and meta-analysis

Abstract

The aim of this study was to determine the effectiveness of corneal collagen cross-linking (CXL) for the treatment of progressive keratoconus (KC). Some of the published literature, including a few small, randomized controlled trials (RCTs), demonstrated good results after CXL, but large RCTs with long-term follow-up to establish a cause-effect relationship are lacking. Using PubMed, EMBASE, and the Cochrane Library database, we searched for relevant studies published between October 2007 and March 2014. A comprehensive literature search was performed using the Cochrane Collaboration methodology to identify the effectiveness of CXL for treating KC. The primary outcome parameters included uncorrected visual acuity (UCVA), best-corrected visual acuity (BCVA), refraction, corneal topography, and corneal thickness at baseline and at 1, 3, 6, 12, and 18 months after CXL. A total of 1171 participants (1557 eyes) were enrolled in this meta-analysis. CXL may be effective in halting the progress of KC for at least 12 months under certain conditions. However, further research from randomized trials is needed to confirm our findings.

Figure 1. Flow diagram of study selection.

Figure 2. The clinical results at 18 months post-CXL treatment.

UCVA = uncorrected visual acuity, BCVA = best-corrected visual acuity, MRSE = mean refractive spherical equivalent, Kmax, Kave, CCT = central corneal thickness, ECD = endothelial cell density.

Figure 3. Funnel plot of long-term results after CXL treatment.