Retinal artery occlusions are caused by blockages in the retinal arteries. The blockage can occur in the form of a blood clot or thrombus but can also be caused by a piece of clot that breaks off (embolus) from another major artery in the body and lodges in a retinal artery.
One of the key risk factors for retinal artery blockage is arteriosclerosis (hardening of the arteries).
As soon as a retinal artery becomes blocked, there is rapid loss of vision in the area of retina served by the artery. In cases involving the central retinal artery (the main artery supplying the entire retina), severe and sudden vision loss occurs. Without treatment, irreversible vision loss occurs after about 90 minutes