Experimental central serous chorioretinopathy. III: ultrastructural findings.

Experimental central serous chorioretinopathy was produced in a cynomolgus monkey. The sites of the outer blood retinal barrier coinciding with the spots of fluorescein leakage as confirmed by fluorescein angiography were examined by light and electron microscopy. Degeneration of a few retinal pigment epithelial cells was found, suggesting that the leakage of fluorescein into the subretinal space resulted from the disruption of the outer blood retinal barrier due to degeneration of the retinal pigment epithelial cells. Loss of the diaphragms or defects of damaged endothelial cells were observed in the inner surface of the choriocapillaris underneath these degenerated pigment epithelial cells. The region of these endothelial cell defects was covered with fibrin-platelet clots, and further, a considerable amount of fibrin existed within the Bruch's membrane. It is, thus, suggested that abnormal hyperpermeability of the choriocapillaris plays an important role in the pathogenetic development of this disease. Moreover, the results obtained in this study demonstrate that regional reparation of degenerated retinal pigment epithelial cells at the sites of fluorescein leakage will be initiated by rapid migration of surrounding normal retinal pigment epithelial cells in this experimental model.