[Ornithine induced retinopathy in the rat--1. Histopathological study on the retinal pigment epithelium]

An intravitreal injection of a small amount of 1-ornithine hydrochloride damages the retinal pigment epithelium (RPE) selectively in monkey eyes. In this paper, we examined the rat eye and observed similar results. Clinically, retinal edema appeared immediately after injection and showed hyperfluorescence on a fluorescein angiograph after 3 days. Histopathologically, RPE showed marked swelling 3 hours after injection, then became necrotic and disappeared gradually. One month after injection, retinal structure was maintained in the area where RPE regenerated to cover Bruch's membrane, but in the area where RPE cells disappeared, the photoreceptor cells and choriocapillaris degenerated and finally disappeared. In the eyes injected intravitreally with NaCl solution of equivalent osmosis microvacuoles were seen but no necrotic change in RPE. Thus, a small amount of ornithine damaged RPE selectively, and induced disappearance of the photoreceptors and choriocapillaris secondarily.