Metformin (MET), a first-line oral agent used to treat diabetes, exerts its function mainly by activating adenosine monophosphate-activated protein. The accumulation of oxidized phospholipids in the outer layer of the retina plays a key role in retinal pigment epithelium (RPE) cells death and the formation of choroidal neovascularization (CNV), which mean the development of age-related macular degeneration (AMD). Recent studies have shown that MET can regulate lipid metabolism, inhibit inflammation, and prohibit retinal cell death and CNV formation due to various pathological factors. Here, newly discovered functions of MET that may be used for the prevention and treatment of AMD were reviewed.