Retinal Artery Occlusion

Most people know high blood pressure and other vascular diseases pose risks to overall health, but many may not know that high blood pressure can affect vision by damaging arteries in the eye.

Branch retinal artery occlusion (BRAO) blocks the small arteries in the retina, the light- sensing nerve layer lining the back of the eye. The most common cause of BRAO is a thrombosis, the formation of a blood clot. Sometimes the blockage is caused by an embolus, an obstruction such as cholesterol or calcium carried by the blood from another part of the body.

Visual loss from retinal artery occlusion is equivalent to loss of function in other parts of the body from stroke. Unfortunately, unlike other strokes, visual loss is not reversible, even with rehabilitation therapy.

Central vision is lost suddenly if the blocked retinal artery is one that nourishes the macula, the part of the retina responsible for fine sharp vision. Following BRAO, vision can range from normal (20/20) to barely detecting hand movement.

BRAO poses significant risks to vision. If you have had a branch retinal artery occlusion or have high blood pressure, regular visits to your eye doctor are essential.

Central retinal artery occlusion (CRAO) blocks the central artery in your retina (See Photo). 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.

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. Sometimes CRAO is caused by an embolus, a clot that breaks off from another area of the body and is carried to the retina by the bloodstream.

Loss of vision can be permanent without immediate treatment. Irreversible retinal damage occurs after 90 minutes, but even 24 hours after symptoms begin, vision may still be saved. The goal of emergency treatment is to restore retinal blood flow. After emergency treatment, you should have a thorough medical evaluation to determine the underlying cause of your arterial occlusion.