Photorefractive keratectomy in patients with thin corneas: systematic review and meta-analysis of clinical outcomes and complications.

TOPIC: To systematically investigate the safety and efficacy of photorefractive keratectomy (PRK) or transepithelial PRK (transPRK) in patients with thin corneas.

CLINICAL RELEVANCE: Concerns exist regarding the outcomes of refractive surgeries including PRK/transPRK in patients with thin corneas.

METHODS

This study was registered prospectively in PROSPERO with an ID of CRD42023457156. It was conducted according to the Cochrane Handbook for Systematic Reviews of Interventions and reported in line with the PRISMA 2020 Consensus Statement. We searched 7 databases and 3 registries from January 1, 1985, until November 30, 2024: PubMed, Web of Science, Scopus, Google Scholar, Embase, ProQuest, Cochrane Central Register of Controlled Trials (CENTRAL), ClinicalTrials.gov , and International Clinical Trials Registry Platform. Our primary outcomes include the safety index (SI), efficacy index (EI), and corrected distance visual acuity (CDVA) changes, while our secondary outcomes include predictability and the rate of complications (including corneal ectasia and haze). We included any observational or interventional study reporting data on the primary or secondary outcomes of PRK or transPRK in patients with a mean central corneal thickness <500 μm, with no history of previous ocular pathology or surgery. The outcome estimates and 95% CIs were derived from a random-effects model meta-analysis to account for possible heterogeneity.

RESULTS

946 eyes from 10 studies were included. All included studies were case series, either retrospective (n = 4) or prospective (n = 6). 4 studies (n = 4) reported the SI and EI, with pooled estimates of 1.01 (95% CI 0.73-1.29) and 1.01 (95% CI 0.98-1.04) after sensitivity analysis, respectively. The mean postoperative change in CDVA was -0.01 (95% CI -0.07 to 0.05). Compared with baseline values, a mild yet non-significant improvement in CDVA was observed (standardized mean difference -0.20 95% CI -0.89 to 0.49). The pooled predictability within ±0.5 diopter of emmetropia, based on data from 6 studies, was 0.83 (95% CI: 0.98 to 1.04). No study reported any cases of corneal ectasia after surgery.

CONCLUSIONS

PRK/transPRK seems to be a safe and effective refractive surgery for thin corneas with simple or astigmatic myopia and without any other ocular pathologies/topographic abnormalities. However, the power analysis and insufficient follow-up call for future studies to draw definitive conclusions about safety and efficacy.