Most people know that 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 the 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, a clot carried by the blood from another part of the body.

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 being barely able to detect hand movement.

BRAO poses significant risks to vision. If you have had a branch retinal artery occlusion, regular visits to your ophthalmologist are essential.

(c) 2007 The American Academy of Ophthalmology