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 beta-carotene 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. Beta-carotene supplementation by either route did not protect the retina against photoreceptor cell loss measured at two weeks following UVA exposure. Preliminary observations indicated that beta-carotene supplementation decreased the incidence of light-induced retinal pigment epithelium destruction.