The relationship between metformin administration and age-related macular degeneration; a systematic review and meta-analysis of observational studies

Abstract

Introduction: Vision loss due to age-related macular degeneration (AMD) is a major and growing health issue. Given that no definitive treatment is available for AMD, this study aims to evaluate the association between metformin use and AMD risk using a systematic review and meta-analysis approach. Materials and Methods: In this study, databases including ProQuest, PubMed, Web of Science, Cochrane, and Google Scholar search engines were searched without time restriction until April 20, 2024, based on PRISMA statement guidelines. Data were analyzed using STATA 14 software at a significance level of P < 0.05. Results: Overall, metformin administration reduced the risk of AMD (OR: 0.86, 95% CI: 0.80, 0.94). Concerning the dosage, a metformin dose of 1-270 g per 2 years (OR: 0.93, 95% CI: 0.90, 0.96) and 271-600 g per 2 years (OR: 0.91, 95% CI: 0.89, 0.94) mitigated the risk of AMD. Metformin use in women increased the risk of AMD (OR: 1.14, 95% CI: 1.09, 1.18). However, no significant relationship was noticed between metformin use and AMD risk in men (OR: 0.86, 95% CI: 0.73, 1.01). In addition, metformin was associated with a lower risk of AMD in case-control (OR: 0.93, 95% CI: 0.89, 0.97) and cohort (OR: 0.69, 95% CI: 0.51, 0.95) studies. Likewise, metformin use was associated with a lower risk of AMD in the age groups of 50-59 years (OR: 0.54, 95% CI: 0.50, 0.58) and 70-79 years (OR: 0.90, 95% CI: 0.84, 0.97). Conclusion: Metformin administration lowered the risk of AMD by 14%. Moreover, female gender was identified as a risk factor for AMD development. However, further studies are required on this subject to reach a definite conclusion. Registration: This study has been compiled based on the PRISMA checklist, and its protocol was registered on the PROSPERO (ID: CRD42024539904) and Research Registry (UIN: reviewregistry1824) website.