Updated April 02, 2015.

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A specific type of 'eye stroke' called a retinal artery stroke can start suddenly and may cause blindness in one eye if isn't treated promptly. If you have already heard that you or one of your loved ones has had a retinal artery stroke or a retinal artery infarct, you might have some questions about it.

What is a Retinal Artery Infarct?

The retinal artery is a blood vessel that supplies oxygen and nutrients to part of the eye.

A retinal artery infarct is caused by a retinal artery occlusion, which is an interruption of blood flow in the retinal artery. Retinal artery ischemia, the blockage of blood flow to the eye through the retinal artery, results.  The interruption of blood flow results in damage to the eye due to a process called retinal artery infarction, which is the injury that occurs to the eye from chemical changes that happen during and after ischemia. Subsequently, the eye loses some of its functions. Most of the time, a retinal artery stroke causes loss of vision. Depending on whether the blockage affects a large part of the retinal artery or a small branch of the retinal artery, there may be a small section of vision loss, a large section of vision loss, or complete vision loss.

Recognizing a Retinal Artery Stroke

Sudden vision loss is an emergency. It can be a sign of stroke, serious brain injury, disease of the heart, or another medical emergency such as a retinal artery stroke. A retinal artery infarct usually affects only one eye at a time and it doesn't typically cause eye pain.

Will I Get My Vision Back?

Some people who experience retinal artery stroke regain some or all vision. However, a retinal artery stroke can cause permanent vision loss in one or more visual fields. A visual field describes the area in the upper or lower or right or left section of vision.
There is a better chance for recovery if you get medical attention right away.

Important Facts about Retinal Artery Infarcts

Retinal artery strokes are associated with the usual stroke risk factors, such as heart disease and hypertension. In these instances, a blood clot traveling from elsewhere in the body (usually from the heart) can obstruct the right or left retinal artery.
However, there are some other causes of retinal artery stroke. Disease or narrowing of one of the carotid arteries in the neck is a risk factor for stroke, but must be more thoroughly evaluated whenever there is a retinal artery occlusion because the carotid artery is a frequent source of retinal artery occlusion.
A relatively uncommon condition called giant cell arteritis is caused by inflammation of the blood vessels. The inflammation has a tendency to affect blood vessels near the forehead. This condition is associated with retinal artery stroke, but not usually with strokes in the brain. 

A detailed examination of the eye is necessary for evaluation of vision loss and to identify a retinal artery stroke. Once a diagnosis of retinal artery stroke is established, the extent of the stroke and the cause are investigated by vision examination, determination of which part of the retinal artery is blocked, imaging studies, blood studies and sometimes a biopsy.

Could I Have a Bigger Stroke in My Brain?

Because some of the risks of stroke in the brain and the risks for retinal artery stroke overlap, your doctors will evaluate you for stroke risk and start the necessary measures to get those risk factors under control. You will also need an evaluation to determine whether you have ever had any silent strokes.
However, many people with retinal artery occlusion do not experience strokes in the brain. Your health care team will be able to explain to you whether or not you are also at risk of stroke and to determine the best course of action.

Sources:

Retinal and optic nerve ischemia, Biousse V, Newman N, Continuum, August 2014

Systemic conditions associated with central and branch retinal artery occlusions, Coisy S, Leruez S, Ebran JM, Pisella PJ, Milea D, Arsene S, Journal Francais d’ophthalmologie, November 2013

Co-occurrence of acute retinal artery occlusion and acute ischemic stroke: diffusion-weighted magnetic resonance imaging study, Lee J, Kim SW, Lee SC, Kwon OW, Kim YD, Byeon SH, American Journal of Ophthalmology, June 2014