[Light-induced retinal damage in pigmented rabbits--1. Histopathological observations of the natural course of...

Pigmented rabbits were exposed for 2 hours to xenon light to evaluate the light induced retinal damage clinicopathologically. The xenon light was passed through a heat filter to avoid the influence of long waves, and through the fundus contact lens on the cornea to avoid focusing the light on the retina. No abnormal findings were detected in the retina in fluorescein angiography immediately after the light exposure. Three hours later, hyperfluorescence was found in the center of the exposed area and gradually grew worse. This was most marked twelve hours later. After 6 days, granular hyperfluorescence appeared at the edge of the damaged area and in 2 weeks the whole damaged area showed granular hyperfluorescence. Histopathologically, immediately after the light exposure, slight changes appeared in the retinal pigment epithelium (RPE). Twelve hours later, the cytoplasm of the RPE was edematous, and in 24 hours the RPE became necrotic, but the outer segments of the photoreceptor cells appeared intact. After 6 days, the RPE showed double layering, many macrophages were found in the subretinal space, and the outer segments of the photoreceptor cells were severely damaged. The RPE was primarily damaged and photoreceptor cells were damaged subsequently by xenon light without long waves.