Probiotic Lactobacillus reuteri Y7 Protects Against Blue Light–Induced Retinal Degeneration via Antioxidant Defense, Anti-Inflammatory Action, and Gut–Retina Axis Modulation

Chronic exposure to short-wavelength blue light induces oxidative stress, inflammation, and apoptosis in retinal tissues, contributing to vision loss. This study investigated the protective effects of Lactobacillus reuteri Y7, a human-derived probiotic, against blue light–induced retinal damage in mice. Male C57BL/6 mice were exposed to 400 lux blue light for 35 days and received either low- or high-dose Y7, lutein, or no intervention. Retinal morphology, inflammatory gene expression, gut barrier integrity, and gut microbiota composition were assessed. Low-dose Y7 promoted microbial diversity and enrichment of short-chain fatty acid–producing taxa, while high-dose Y7 favored enrichment of Akkermansia, Parasutterella, and Bacteroides, enhancing mucosal barrier function and metabolic regulation. Both doses attenuated retinal inflammation, preserved retinal layers, and improved gut barrier integrity, with high-dose Y7 matching or exceeding lutein’s protective effects. Mechanistic insights suggest a gut–retina axis whereby microbial metabolites modulate oxidative stress, inflammation, and vascular homeostasis. These findings highlight L. reuteri Y7 as a potential non-invasive strategy for retinal degeneration prevention, with efficacy comparable to dietary antioxidants. Future studies should explore long-term safety, metabolite-mediated mechanisms, and comparative efficacy with other antioxidants.