Association between metformin use and the risk of developing open-angle glaucoma among patients with diabetes: a retrospective cohort study and meta-analysis

Recent studies examining the neuroprotective effects of metformin on open-angle glaucoma (OAG) have failed to provide consistent results. In this study, we investigated the association between metformin use and OAG.

Data were obtained from a sample cohort of the Korean National Health Insurance database. Patients diagnosed with type-2 diabetes (T2DM) between 2004 and 2013 were included. We performed propensity score-matched analysis in a matched cohort (N = 20,646). The risk of the newly developed OAG was estimated using a Cox proportional hazards model. Including the present study, the meta-analysis included five studies to calculate the pooled risk for OAG based on metformin use.

In the adjusted model, the analysis revealed no statistical association between metformin use and OAG incidence (hazard ratio [HR] 1.05; 95% confidence interval [CI] 0.79–1.40; P = 0.738). The highest tercile of metformin use demonstrated no statistical significance (HR 0.93 [95% CI 0.63–1.37]; P = 0.703). No significant dose-dependent association was observed between the cumulative dose and incidence of OAG (P-value for trend = 0.336). In a meta-analysis of four published articles and the present study, the common-effects and random-effects models indicated conflicting results in terms of significance. The random effects model demonstrated no significant association (pooled risk ratio 0.53; 95% CI 0.24–1.19; P = 0.123).

We found no significant association between metformin use and OAG incidence in patients with T2DM in this population-based cohort study and meta-analysis. Further studies are needed to investigate the association between metformin use and the risk of OAG among patients with T2DM.