Subretinal Neovascularization After Experimental Ocular Histoplasmosis in a Subhuman Primate

Abstract

Subretinal neovascularization was demonstrated in a subhuman primate eye (Macaca speciosa) one year after the internal carotid injection of yeast-phase Histoplasma capsulatum. In this animal model of ocular histoplasmosis, initial injection of viable H. capsulatum results in the development of self-limiting acute multifocal choroiditis. Acute lesions resolve within six months, forming chorioretinal scars that are clinically similar to human histo spots. Detailed ultrastructural study of a peripapillary scar 30 months after the injection showed the presence of subretinal neovascularization located between Bruch's membrane and degenerated retinal inner segments. These vessels appeared to be continuous, had tight junctional complexes, and a well-developed basal lamina with occasional pericytes. Failure of fluorescein angiography to demonstrate the presence of this neovascular net may be explained by the presence of tight junctions within the subretinal capillaries.