Itagaki T

Choroidal Neovascularization and the Retinal Pigment Epithelium

Senile disciform macular degeneration is increasing as a cause of blindness in elderly aged people. It is well known senile disciform macular degeneration is caused by development of choroidal neovascularization.

[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 Bruchs 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.

[Ornithine induced retinopathy in rat--2. Process of disappearance of choriocapillaris].

We observed the process of disappearance of the choriocapillaris after loss of the retinal pigment epithelium (RPE) induced by intravitreal injection or ornithine. Three hours after administration of ornithine, the RPE cells swelled remarkably in the posterior pole, but, the endothelial cells of the choriocapillaris remained intact. At 3 days, the RPE cells became necrotic, but the choriocapillaris still preserved its in normal appearance. At 7 days, RPE disappeared completely in the posterior pole and the choriocapillaris displayed evidence of atrophy; the swollen lumen of the choriocapillaris became narrow the cytoplasm of the endothelium was swollen, and the number of fenestrae was reduced. On the other hand, these changes were not seen where the RPE remained. At 14 days, in the posterior pole, the lumen of the choriocapillaris occluded by the swollen endothelial cells. At 28 days, the choriocapillaris completely disappeared and the large choroidal vessel was directly in contact with Bruchs membrane. These results showed that the RPE is correlated with the presence of the choriocapillaris.