Mitomycin C for the prevention of corneal haze in photorefractive keratectomy: a meta-analysis and trial sequential analysis.

Purpose: To evaluate the anti-haze effect and visual outcome after intraoperative mitomycin C (MMC) use during photorefractive keratectomy (PRK) in myopia or myopic astigmatism patients.

Methods: We searched in PubMed, EMBASE, Cochrane Library and Google Scholar comprehensively to obtain studies comparing the clinical effects after PRK with and without MMC published until February 2020. Meta-analysis of primary outcome (corneal haze rate) and secondary outcomes [predictability, efficacy, safety and corneal endothelial cell density (ECD)] were conducted. We used trial sequential analysis (TSA) in an effort to collect firm evidence supporting our conclusion.

Results: Of the included 11 randomized controlled trials, five cohort and one case-control studies, 3536 eyes (2232 and 1304 in the MMC and control groups, respectively) were enrolled for meta-analysis. The TSA disclosed strong evidence of decline in corneal haze rate in the MMC group compared with that of the control group. In the subgroup analysis of duration, MMC seemed to reduce corneal haze rate in early-onset and late-onset haze. Predictability of refraction and visual acuity were greater in the MMC groups, not significantly though. The proportion of patients losing at least two lines of best corrected visual acuity postoperatively in the MMC groups was lower than that in the control groups. The corneal postoperative ECD showed no significant difference between the MMC and control groups.

Conclusion: Our meta-analysis revealed that MMC is an important anti-haze agent in PRK for reducing both early- and late-onset haze and can also help improving predictability of refraction and subjective postoperative visual acuity.