Early cellular disruption and phagocytosis in photically-induced retinal degeneration.

Abstract

AbstractAlbino rats kept at normal body and room temperature develop a progressive retinal degeneration when exposed to ordinary animal room intensities of fluorescent light. Early changes at the light microscope level include stratification of the inner and outer segments of the receptor cells, followed by rapid fragmentation of these elements. Concurrently, cells not usually seen in control retinas invade the outer plexiform and receptor cell layers. These cells, which are first seen after 60 hours of light exposure, resemble microglia and are apparently phagocytic in function, since cytoplasmic inclusions can be detected. Attempts to mark these cells with intraocular India ink or with intraperitoneal trypan blue were unsuccessful. Removal of cellular debris after degeneration of the receptor cells was followed by gliosis in the area of the retina between the bipolar nuclei and the remnants of the pigment cell layer. The extensive retinal damage occurring after fragmentation and removal of the outer segments was irreversible when animals were removed from continuous light and placed into cyclic lighting.