A retinal artery occlusion is a blockage in one of the blood vessels that supplies your retina with blood. It usually occurs suddenly and can cause vision loss without causing pain.

A retinal artery occlusion is a medical emergency that requires a prompt evaluation. No treatment has yet been proven to improve vision after an artery occlusion, but an evaluation is still important because the risk of developing a stroke is very high after this event.

Read on to learn more about retinal artery occlusion, including its symptoms, treatments, and outlook.

According to the American Academy of Ophthalmology, the most common symptom of retinal artery occlusion is sudden painless vision loss in one eye. Your vision loss may occur in part or all of your eye.

Other symptoms can include:

Symptoms may only last seconds to minutes, or you may have permanent vision loss.

A retinal artery occlusion results from a blockage in the blood vessels that supply your retina. A blood clot is the most common underlying cause, but other substances — like cholesterol or calcium — can also cause the blockage.

Most blood clots originate from the carotid artery in your neck.

There are two types of retinal artery occlusion. Doctors classify these based on which blood vessel is blocked.

Branch retinal artery occlusion

A branch retinal artery occlusion occurs when one of the small arteries in your retina is blocked. A blockage in one of these blood vessels might cause the loss of a section of your visual field, such as your peripheral vision.

Central retinal artery occlusion

A central retinal artery occlusion occurs when the central retinal artery becomes blocked. Doctors consider it a type of stroke, and it’s a major risk factor for developing a stroke in your brain.

High blood pressure and increasing age are the main risk factors for retinal artery occlusion. It most commonly occurs in males in their 60s. About 1 in 100,000 people develop central retinal artery occlusion each year.

Other risk factors include:

Retinal artery occlusion can cause permanent vision loss. Vision loss can be severe in people with central retinal artery occlusion.

Some people with retinal artery occlusion develop new blood vessels in their iris or retina that can bleed. These blood vessels can cause further vision loss by causing vitreous hemorrhage or glaucoma.

Medical emergency

A retinal artery occlusion is a medical emergency that requires immediate medical attention. Go to the nearest emergency room or your eye doctor right away if you develop symptoms such as:

  • sudden vision loss
  • blurry vision
  • distorted vision

The main test that doctors use to diagnose retinal artery occlusion is a fundoscopic exam. During this test, a doctor shines a light in your eye and uses a special magnifying lens to examine your retina and optic nerve. A central retinal artery occlusion appears as a pale area with a cherry red central spot.

You may have blood tests, and if your symptoms started within the previous 6 hours, you may need a CT scan to rule out intracranial hemorrhage.

You may also undergo fluorescein angiography or electroretinography if they’re available. A fluorescein angiography involves injecting a fluid into a vein, usually in your arm, and then using a special camera to take a picture of the blood vessels in your eye. Electroretinography involves measuring the responsiveness of your retina cells to light.

Medical experts haven’t established any standard treatment guidelines for retinal artery occlusion. Treatment usually revolves around restoring oxygen and blood flow to your eye.

Treatment may include:

  • hyperbaric oxygen, which involves breathing in concentrated oxygen with some carbon dioxide to widen the blood vessels in your eye
  • removing some liquid from your eye
  • massaging your eye
  • infusing a drug through one of your veins to break up a blood clot, which is most effective when administered within several hours

Most people have some degree of vision loss following retinal artery occlusion. Vision loss in people with a branch retinal artery occlusion is usually permanent, but about 80% of people recover to at least 20/40 visual acuity.

Fewer than 20% of people with a central retinal artery occlusion regain functional visual acuity.

Up to about 50% of eyes have an anatomical variation called the cilioretinal artery. About 80% of people with this variation recover to at least 20/50 vision.

You may be able to prevent retinal artery occlusion by taking steps to prevent strokes, such as:

Here are answers to some frequently asked questions people have about retinal artery occlusion.

Is retinal artery occlusion a stroke?

Retinal artery occlusion is a form of acute ischemic stroke. This occurs when a blood clot or another substance blocks a blood vessel in your brain.

Can you recover from retinal artery occlusion?

Some people recover fully from retinal artery occlusion, but most people have some degree of vision loss.

What’s the life expectancy of a person with retinal artery occlusion?

People with a central retinal artery occlusion have an average survival of 5.5 years, compared with 15.4 years for people without retinal artery occlusion.

What’s the difference between retinal artery occlusion and retinal vein occlusion?

Retinal vein occlusion is a blockage in the blood vessel that carries blood away from your eye. Retinal artery occlusion is a blockage in a blood vessel that supplies your retina with blood.

Retinal artery occlusion is a blockage in the blood vessel that supplies your retina, usually due to a blood clot. It can cause severe vision loss in one of your eyes.

Retinal artery occlusion needs immediate evaluation due to the associated high risk of stroke. Go to the nearest emergency room if you have potential symptoms, such as sudden vision loss or distortion.