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Branch Retinal Artery Occlusion (BRAO)

Other names:

Retinal artery occlusion, retinal arterial occlusion, central retinal artery occlusion.

What is a retinal artery occlusion?

A retinal artery occlusion is a blockage of the blood supply in the arteries to the retina, the light-sensitive tissue in the back of the eye, leading to sudden complete or partial loss of vision. This is typically caused by a tiny embolus (clot) in the blood stream.

macular hole


What causes retinal artery occlusion?

Retinal arteries may become blocked by a blood clot, or substances such as fat or plaque, that get stuck in the arteries. These blockages may occur due to hardening of the arteries in the eye.

Also, clots may travel from other parts of the body, and block an artery in the retina. A common source of a clot would be from the carotid artery in the neck, or from the heart lining.

Most clots are caused by conditions such as:

If a branch of the retinal artery is blocked, part of the artery will not have enough blood and oxygen delivered to the eye. If this happens, you may loose part of your vision. Retinal artery blockage or occlusions may last from only a few seconds, to a few minutes. They also may cause permanent vision loss. The amount of vision loss is partly related to the location of the blockage.

Who is at risk for retinal artery occlusion?

Retinal vessel occlusion more often affects older people. Risk factors include smoking, hypertension, hypercholesterolemia, diabeties, coronary artery disease, or history of stroke or transient ischemic attack (TIA).

What are the symptoms of retinal artery occlusion?

Sudden, painless, loss of vision, in all or part of the eye. Call your eye care professional immediately, if you experience these symptoms.

What tests are performed to diagnose retinal artery occlusion?

Some of the tests to evaluate the retina may include:

dilated exam

Dilated Eye Exam - Drops are placed in your eyes to widen (dilate) the pupils. This allows the eye care professional to see more of the inside of your eyes to check for signs of the disease. Your eye care professional uses a special magnifying lens to examine your retina for signs of damage.

Fluorescein angiography - Performed to evaluate the blood vessels in your eyes for retinal disease. This requires a small injection of vegetable dye into a vein in your arm. Serial photos are taken of your retina through a dilated pupil.

eye pressure

Tonometry - An instrument measures the pressure inside the eye. Numbing drops may be applied to your eye for this test.

Retinal Photography - High resolution images of the retina are taken, to help document changes in the retina.

Slit Lamp Exam - A microscope is used for examining the eye; allowing for the cornea, lens and otherwise clear fluids and membranes to be seen in layer-by-layer detail.


What can I do to prevent retinal artery occlusion?

Measures used to prevent other blood vessel (vascular) diseases, such as coronary artery disease, may decrease the risk of retinal artery occlusion. These include:

Aspirin is commonly used to prevent the artery from becoming blocked again. Never take any medication without first consulting with your physician.


Vortmann M, Schneider JI. Acute monocular vision loss. Emerg Med Clin North Am 2008;26:73-96.

Pokhrel PK, Loftus SA. Ocular emergencies. Am Fam Physician 2007;76:829-836.

Disclaimer: The information contained in this website does not substitute for the advice of a qualified eye care professional and is not intended to constitute medical advice.