[The physiopathology of retinal circulation: consequences of acute retinal vascular occlusion]

A constant oxygen supply from the retinal and choroidal vascular system is essential for the maintenance of the retinal electrical activity. Arterial or venous retinal obstruction modifies the hemodynamics in the retinal circulation and produces hypoxia in the affected area. In the case of arterial obstruction, severe hypoxia (anoxia) rapidly (in less than 45 min) produces irreversible cell damage in the inner area of the retina. With venous obstruction, the hypoxia is moderate and the retinal damage is partial. In some cases, hypoxia regresses because the formation of collateral vessels most probably provides adequate perfusion. In cases of irreversible venous obstruction, insufficient formation of collateral vessels results in the development of ischemic regions in the retina and severe hypoxia. In these cases preretinal neovascularization may develop.