Retinitis pigmentosa (RP) affects over a million people worldwide, characterized by photoreceptor cell death, progressive retinal degeneration, and visual loss. Metformin is demonstrated as a potential therapeutic approach for preventing light-induced retinal degeneration by decreasing apoptosis and oxidative stress. This work aimed to investigate the effect of metformin on the retina of the N-Ethyl-N-nitrosourea (ENU) induced rat model of RP. Eighteen adult male Wistar rats were divided into two groups. Group I: normal vehicle control (N = 6). Group II: ENU-induced photoreceptor degeneration (N = 12) received a single intraperitoneal injection of ENU at a 600 mg/kg dose. Rats in group II were equally divided into two subgroups: IIa: photoreceptor degeneration-induced group and IIb: metformin-treated group (200 mg/kg) for seven days. Specimens from the retina were processed for light and electron microscopy …