Definition of Retinal artery occlusion:

Retinal artery occlusion is a blockage in one of the small arteries that carry blood to the retina. The retina is a layer of tissue in the back of the eye that is able to sense light.

Causes, incidence, and risk factors:

Retinal arteries may become blocked by a blood clot or fat deposits that get stuck in the arteries. These blockages are more likely if there is hardening of the arteries (atherosclerosis) in the eye.

Clots may travel from other parts of the body and block an artery in the retina. The most common sources of clots are the carotid artery in the neck and the heart.

Most clots occur in people with conditions such as:

• Carotid artery disease, a condition in which the two large blood vessels in the neck become narrowed or blocked
• Diabetes
• Heart rhythm problem (atrial fibrillation)
• Heart valve problem
• High levels of fat in the blood (hyperlipidemia)
• High blood pressure
• Intravenous drug abuse
• Temporal arteritis (damage to arteries due to an immune response)

If a branch of the retinal artery is blocked, part of the retina will not receive enough blood and oxygen. If this happens, you may lose part of your vision.