Central Retinal Artery Occlusion (CRAO) and Retinal Vein Occlusion (RVO)
The blood vessels of the retina are very fine and vulnerable to blockage, which can profoundly affect vision. The arteries and veins can both become blocked.
A central retinal artery occlusion is caused by arteriosclerosis, small emboli from cardiac arhythmias, temporal arteritis, and many other causes. The central vision can sometimes be maintained if there is an anomylous cilio-retinal artery, otherwise there is profound sudden loss of vision which is often unreversible unless treated within a short period of time.