Light-induced changes in the retina of albino rat. Structural Immunohistochemical and quantitive studies.

Abstract

BACKGOUND and OBJECTIVES: Exposure to the lights seems to be at the basis of some age-related retinal deseases, especially macular degenerations, probably inducing cell-death, oxidative stress, or inducing the expression of several genes. Nevertheless, it remains to be clarified the part of the visual spectrum responsible for those changes. The present study was designed to investigate the role of continuous exposure to white-light, and to white-light filtered to eliminate the yellow (blue light) or blue (yellow light) segments of the visual spectrum on the retina MATERIAL AND METHODS: Adult albino rats were exposed to continuous white, yellow or blue lights for 15 days. The animals were sacrificed, the eyes removed and fiex in appropiate fixatives in order to perform structural, immunohistochemical (for detection PGP 9.5, calterinin, rodopsin, opsin and GFAP antigens) and quantitative techniques. RESULTS: Exposure to continuous white light do not modifies the structure of the retina. The retina of the rats exposed to continuous yellow light shows a reduction of the external plexiform layer, reduced cell number in the inner and outer granular layers, and occasionally lack of the external segments of the photoreceptors. All these changes were still more evident inthe retina of the rats exposed to blue light. In these animals the retina was reduced in thickness, the external segment of the photoreceptors was absent, and the density of cells severely reduced. Furthermore, most of the animals showed enlaged an dilated coroidal blood vassels. The results were confirmed by immunohistochemistry and quantitative techniques. CONCLUSION: Continuous light exposure induces several retinal changes being the blue segment of the visual spectrum that inducing streaking changes.