Influence of metformin on age-related macular degeneration

Metformin is the most commonly prescribed antihyperglycemic drug as first-line therapy in type II diabetic patients. In recent years, evidence is increasing that metformin has beneficial effects beyond its classical antihyperglycemic way of action. Those effects include anti-inflammation, anti-oxidation, anti-aging, anti-angiogenesis, anti-neoplasia, anti-apoptosis, and neuroprotection. The complex pathophysiology of age-related macular degeneration (AMD) includes age-related changes in the retinal pigment epithelium (RPE) and Bruch’s membrane. An inflammatory and oxidative damage component has also been described. The dry form of late AMD is especially characterized by degeneration of the RPE, Bruch’s membrane, the choriocapillaris and finally, loss of the photoreceptors (geographic atrophy), and the wet form of late AMD is characterized by pathological neovascularization. An increasing number of reports about the beneficial effects of metformin on AMD have been published in the last few years. Several effects of metformin could be linked to the AMPK pathway. A first prospective trial investigating the effect of metformin on dry AMD is ongoing with estimated results by the end of 2024. In this review, the current knowledge about the association between metformin and AMD is summarized.