• Experimental occlusion of both major temporal retinal veins simultaneously (in six eyes of cynomolgus monkeys) and of the central retinal vein (in one rhesus monkey) produced a fall in intraocular pressure (hypotensive effect) and neovascularization (NV) of the iris and, less frequently, of the optic disc (vasogenic effect). The retinal changes (severity and extent of retinopathy, retinal capillary leakage, and onset and extent of retinal capillary obliteration) were correlated with the pattern of ocular NV and hypotony. No direct correlation was seen between the retinal capillary obliteration and the hypotensive or vasogenic effect. However, a correlation was found between the retinal vascular leakage and the development of ocular NV and hypotony. The pathogeneses of ocular NV and hypotony in retinal vein occlusion are discussed in light of the findings of this study.