Evaluation of retinal susceptibility to light damage in pigmented rats supplemented with beta-carotene

The present study evaluated the influence of beta-carotene supplementation on the susceptibility of the retina to light damage. Long-Evans pigmented rats were supplemented with betacarotene by either dietary or intraperitoneal administration, and beta-carotene levels in plasma, liver and retina were determined by high performance liquid chromatography Other animals from each group were exposed to ultraviolet-A light at a dose of 8.1 J/cm² in their right eye only, and photoreceptor cell losses determined by light microscopic morphometry. In supplemented animals, beta-carotene levels increased markedly in the liver, and were elevated from non-detectable to detectable in the plasma and retina, relative to nonsupplemented controls. In each tissue, beta-carotene levels were found to be higher in animals receiving intraperitoneal supplementation as compared to dietary. Betacarotene supplementation by either route did not protect the retina against photoreceptor cell loss measured at two weeks following UVA exposure. Preliminary observations indicated that betacarotene supplementation decreased the incidence of light-induced retinal pigment epithelium destruction.