Protection from light damage by ocular pigmentation: analysis using experimental chimeras and translocation mice.

Experimental mouse chimeras and Cattanach's translocation mice, both with alternating pigmented and non-pigmented cells of the retinal pigment epithelium (RPE), have been exposed to various periods of constant fluorescent light. Photoreceptor degeneration was always more severe in the central retina than in the peripheral retina, and it was independent of the pigmentation phenotype of the immediately overlying RPE. The findings suggest that although RPE melanosomes lower total retinal irradiance by absorption of light, they do not provide direct protection from light damage for the immediately underlying photoreceptor cells by a biochemical mechanism as previously suggested.