Corneal collagen cross-linking in pediatric keratoconus with three protocols: a systematic review and meta-analysis

Keratoconus is a bilateral progressive noninflammatory degenerative disease of the cornea characterized by corneal thinning, irregular astigmatism, and subsequent visual impairment. It has an aggressive course in children. This systematic review evaluates the efficacy of available corneal collagen cross-linking (CXL) protocols for stabilizing the cornea in pediatric patients with keratoconus. We searched all peer-reviewed publications from 2000 to 2019 indexed in PubMed, Google Scholars, Web of Science, and Cochrane's Database for the terms keratoconus and cross-linking. The following data were extracted from eligible studies: study design, type of intervention, number of the eyes and mean age of patients for each study, duration of follow-up period, mean pre- and postoperative uncorrected and corrected visual acuity, keratometric and aberrometric indices, were analyzed with RevMan 5.3 software. Intra-and intergroup post hoc analyses of outcome variables were performed using t tests. A total of 28 studies, including 1,300 eyes, were reviewed. In conventional and accelerated epithelium-off techniques, there was a significant improvement in uncorrected and corrected visual acuities. Similarly, the keratometric indices improved significantly after CXL. Uncorrected visual acuity did not alter after CXL using transepithelial method. Both conventional and accelerated collagen CXL of the cornea are effective therapeutic options in management of keratoconus in children.