You probably know that high blood pressure and other vascular diseases pose risks to your overall health, but you may not know that they can affect your eyesight by damaging the arteries in your eye.

Central retinal artery occlusion (CRAO) usually occurs in people between the ages of 50 and 70. The most common medical problem associated with CRAO is arteriosclerosis (hardening of the arteries). Carotid artery disease is found in almost half the people with CRAO.

The most common cause of CRAO is a thrombosis (an abnormal blood clot formation). CRAO can also be caused by an embolus, a clot that breaks off from another area of the body and is carried to the retina by the bloodstream.

CRAO blocks the central artery in your retina, the light-sensitive nerve layer at the back of the eye. The first sign of CRAO is a sudden and painless loss of vision that leaves you barely able to count fingers or determine light from dark.

Loss of vision can be permanent without immediate treatment. Irreversible retinal damage occurs after 90 minutes, but even 24 hours after symptoms begin, vision can still be saved or partially restored. The goal of emergency treatment is to restore retinal blood flow. After emergency treatment, you should have a thorough medical evaluation.