Efficacy and safety of topical cysteamine in corneal cystinosis: a systematic review and meta- analysis.

Abstract Purpose To evaluate safety and efficacy of topical cysteamine ophthalmic solution for corneal cystinosis. Method We searched seven databases(PubMed, OVID, EMBASE, Web of Science, Cochrane CENTRAL, Google scholar and ClinicalTrials.gov ) for relevant studies using appropriate keywords. Comparative observational studies/ RCTs comparing cysteamine with control or other formulation for treatment of corneal/ophthalmic cystinosis were included. Outcome measures were improvement/response to therapy, change in Corneal Cystine Crystal Score(CCCS), In Vivo Confocal Microscopy score(IVCM), cystine crystal depth, contrast sensitivity(CS), photophobia score and safety. Study design Systematic review and meta-analysis Result 7 studies were included. Compared to placebo/control, cysteamine arm was better in terms of “improvement/response to therapy” (2 studies, RR 16, 2.30-111.37) and “crystal density score” [1 study, MD -0.80, -1.56 to -0.04). No significant difference observed in-terms of “improvement in CS” (1 study, RR 7.00, 0.47 to 103.27). Compared to cystamine, cysteamine showed benefit in terms of crystal density score (MD -0.94, -1.64 to -0.24). When compared to a newer formulation, the standard formulation(Cystaran; 0.55% CH + BAC 0.01%) performed better in terms of decreasing CCCS. Another newer viscous formulation “Cystadrops” performed better than the standard formulation in terms of change in CCCS, IVCM score, corneal crystal depth, and photophobia score, however, local adverse effects and blurring was higher in the Cystadrops group. Conclusion Conventional cysteamine (0.1% to 0.3%) performed better than placebo/control in terms of response to therapy. In terms of decreasing corneal cystine density, cysteamine (0.55%) was better than cystamine(0.55%) and the viscous Cystadrops(0.55%) was better than the standard formulation(0.1%).