retinal artery occlusion

blockage of an artery supplying blood to the retina, usually as a result of thrombosis or embolism. The central retinal artery enters the eye at the optic disc and then divides into branches to supply different parts of the retina. Blockage of the central retinal artery (central retinal artery occlusion) usually results in sudden painless loss of vision. Blockage of one of the branches of the central retinal artery (branch retinal artery occlusion), usually by emboli, results in ischaemia of the retina supplied by the occluded vessel and related visual field loss.