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Retinal Artery Occlusion (RAO) occurs when an abrupt blockage of blood flow to the retina halts proper retinal functioning. Depending on the extent of the blockage and area of the retina affected, the loss of vision may be relatively mild or very severe. This problem is analogous to a “stroke” of the eye.
Central Retinal Artery Occlusion (CRAO) occurs when the central retinal artery, the main blood supply to the eye, is blocked. This blockage results in severe vision loss. About 25 percent of people who develop CRAO have an extra artery in their eye, which can greatly lessen the chances of damage to central vision.
Branch Retinal Artery Occlusion (BRAO) occurs from a blockage in a smaller artery. This blockage may result in partial vision loss.
RAO is usually associated with sudden painless loss of vision in one eye. The location of the blockage within the retina determines the extent of vision loss. In CRAO, vision loss is severe. In BRAO, vision loss is only partial and may go unnoticed.
The sudden vision loss may only last for a few seconds or minutes if the blockage breaks up and restores blood flow to the retina. It may also be permanent.
Common risk factors include:
Most RAO patients are men 60 years and older. Only a very small percentage of cases involve both eyes.
A comprehensive eye examination is important to assess RAO, including vision testing, eye drops to dilate the pupils, and a complete examination of the front and back of the eye. It is best if a driver accompanies the patient during their eye exam as pupillary dilation may create near-vision blurring.
People with RAO may undergo several tests to evaluate their condition including:
Unfortunately, there is no treatment that has been clinically proven to restore blood flow and improve vision. Sometimes there will be a limited, spontaneous improvement in vision.
Sometimes patients with RAO develop neovascular glaucoma that can cause complete loss of vision and a painful, red eye. Although uncommon, this glaucoma is often very severe. The warning signs for neovascular glaucoma can only be monitored with follow-up examinations.
If the warning signs should develop, treatment is recommended. Treatment does not improve vision; it is intended to reduce the risk of developing neovascular glaucoma.
In general, patients with RAO require medical evaluation by an internist or cardiologist to identify a source for the blockage. Your doctor may prescribe a blood thinning medication such as aspirin, Plavix, or Coumadin to reduce the risk of new clots and blockages. These medications will not help improve sight in the affected eye.