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Abstract
The results of a long-term study (3 to 9 months) of chorioretinal vascular occlusions resulting from injection of latex microspheres of known sizes are reported. Isolated occlusions of small retinal vessels (capillaries and precapillary arterioles) resulted in no histologic changes in the retina. Occlusion of large retinal vessels (arterioles) caused atrophic changes in the inner retinal layers (ganglion and bipolar cells). Flat preparations of the retina revealed no evidence of neovascularization or formation of new anastomotic vessels. Multiple occlusions of the choriocapillaris created atrophic changes in the external retinal layers (receptor cells and their nuclei). Occlusions of large choroidal vessels resulted in diffuse atrophy of all overlying retinal layers. Such occlusions also caused migration of pigment into the retina and formation of giant retinal cysts.