Circulatory dynamics and pathology of occlusion of the central retinal vein was compared at two sites in the owl monkey eye. In 17 eyes, neoprene occluded the central retinal vein at the disc and, in ten eyes, the central retinal vein was tied and cut as it emerged from the optic nerve. The first group of animals demonstrated rapid ischemic and hemorrhagic infarction of the retina and obstruction of the arterial flow by fluorescein angiography. The second group demonstrated a temporary and reversible increase in venous congestion without secondary damage to the eye. Collateral circulation in the region of the disc and posterior to it explains best the difference in the two groups. Partial obstruction of the central retinal vein by neoprene approximated the central vein occlusion in man, but neither model exactly reproduced it.