Retinal artery occlusion is when one or more arteries that supply blood to the retina become blocked resulting in sudden painless loss of vision. A central retinal artery occlusion (CRAO) is a blockage that affects the entire retinal arterial circulation, while a branch retinal artery occlusion (BRAO) affects only a portion of the retina. Retinal artery occlusion is often referred to as a stroke in the retina.  

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What causes a retinal artery occlusion?
The retina is fed by a system of blood vessels (arteries and veins) like a tree, with one large central artery branching into smaller arteries in the periphery of the retina.  A central retinal artery occlusion (CRAO) is blockage of blood flow to the retina in the main artery causing complete loss of blood flow to the eye and resulting in sudden, severe vision loss.  A branch retinal artery occlusion (BRAO) is blockage along a smaller, distal artery and often causes a visual field defect but relatively preserved central vision.  

 

An artery becomes blocked by am embolus, which is a piece of debris such as a cholesterol plaque that can break off in a larger artery in the neck and clog the smaller retinal arteries.  Risk factors for an embolus are age, atherosclerosis, hypertension, and diabetes.  

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Evaluation of retinal artery occlusion

Your retinal surgeon may order diagnostic tests in the office to determine the degree of damage caused  by the artery occlusion. Fluorescein angiography evaluates blood flow in the retina with a series of photographs taken after intravenous injection of a synthetic dye (fluorescein).  A full physical and stroke evaluation is also recommended including carotid studies to check for blockage in the neck arteries, echocardiogram to asses for blood clots in the heart, and blood tests.

 

Treatment of retinal artery occlusion
No proven treatment for retinal artery occlusion exists.  It is still important to identify and treat the underlying cause of a retinal arterial occlusion in order to help prevent other vascular events (heart attack, stroke).  

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Separate from the vision loss caused directly by the artery occlusion, secondary complications may occur months or even years later. New abnormal blood vessels (neovascularization) may grow in the front of the eye, causing glaucoma and elevated eye pressure, sometimes with pain and further loss of vision. Neovascularization requires treatment with laser and anti-VEGF injections of medicine into the eye, but these treatments do not restore vision.