Retinal degeneration in animal models with a defective visual cycle

•The visual (retinoid) cycle is a critical enzymatic pathway that sustains vision.•Mutations in genes encoding visual cycle proteins cause retinal degeneration.•Animal models were generated with faulty visual cycles that mimic human pathologies.•These animals are instrumental for testing new therapies to prevent blindness.

Continuous generation of visual chromophore through the visual (retinoid) cycle is essential to maintain eyesight and retinal heath. Impairments in this cycle and related pathways adversely affect vision. In this review, we summarize the chemical reactions of vitamin A metabolites involved in the retinoid cycle and describe animal models of associated human diseases. Development of potential therapies for retinal disorders in these animal models is also introduced.