Retinal Artery Occlusion (Eye Stroke)

How an eye stroke happens

The central retinal artery enters the eye at the optic nerve and branches over the retina. If it is blocked, the retina loses its oxygen supply and the nerve cells begin to die within hours. Blockages are usually caused by:

• an embolus, such as a cholesterol plaque fragment from the carotid artery in the neck, or a clot from the heart
• atherosclerosis within the artery
• inflammation of the artery, as in giant cell arteritis

The eye is part of the central nervous system, so RAO is treated as a stroke.

Types

Retinal vein occlusion is a different condition with blocked veins, causing blurred vision and bleeding in the retina.

Symptoms

• sudden, painless loss of vision in one eye
• a curtain, shadow or dark area over part of the vision
• brief episodes of vision loss lasting minutes (amaurosis fugax) before a full occlusion
• no eye pain or redness, in most cases

Risk factors

• high blood pressure
• diabetes
• high cholesterol
• smoking
• carotid artery disease
• atrial fibrillation and heart valve disease
• older age, usually over 60
• giant cell arteritis
• clotting disorders, sickle cell disease and, in younger people, cocaine use or a patent foramen ovale

Diagnosis

• eye examination: a pale, swollen retina with a "cherry-red spot" at the center in CRAO, and sometimes a visible cholesterol fragment (Hollenhorst plaque) in a branch
• optical coherence tomography (OCT) and fluorescein angiography to confirm reduced blood flow
• urgent stroke workup: brain MRI, as many people also have silent brain strokes
• carotid ultrasound or CT angiography
• ECG, heart rhythm monitoring and echocardiogram to look for a heart source
• ESR and CRP blood tests in people over 50, to check for giant cell arteritis, which needs immediate steroids to protect the other eye

Treatment

There is no proven treatment that reliably restores vision, but time matters:

• Emergency stroke pathway: some stroke centers consider IV thrombolysis (clot-dissolving medicine) within about 4.5 hours of symptom onset, and clinical trials are ongoing. The AHA recommends treating CRAO as a stroke emergency
• Older measures such as eye massage, lowering eye pressure and breathing carbon dioxide mixtures have not been shown to help and are not routinely recommended
• Giant cell arteritis: high-dose steroids immediately to protect the other eye
• Secondary prevention: antiplatelet medicine, statins, blood pressure and diabetes control, stopping smoking, anticoagulation for atrial fibrillation, and carotid surgery or stenting for significant narrowing

Complications

• permanent vision loss in the affected eye
• stroke and heart attack: the risk of brain stroke is highest in the first weeks
• neovascular glaucoma: abnormal blood vessels growing in the eye weeks to months later, causing painful high pressure. Regular eye follow-up allows early treatment

Outlook

Most people with CRAO are left with poor vision in the affected eye, though some improve, especially when part of the retina is spared. Branch occlusions usually leave a permanent blind area but often preserve useful central vision. The most important goal is preventing a brain stroke.

Frequently asked questions

What is an eye stroke?

An eye stroke, or retinal artery occlusion, is a blockage of the artery that supplies the retina. It causes sudden, painless vision loss in one eye. It is a medical emergency and is linked to a high risk of stroke in the brain.

What are the symptoms of retinal artery occlusion?

The main symptom is sudden, painless loss of vision in one eye, either total or partial, such as a shadow over part of the vision. Some people have brief episodes of vision loss beforehand that return to normal.

Can vision come back after retinal artery occlusion?

Sometimes partially, especially with branch occlusions or if a small cilioretinal artery spares the center of vision. With a central occlusion, most people have significant permanent vision loss, which is why immediate emergency care is important.

Is retinal artery occlusion a stroke?

Yes. It is a type of ischemic stroke affecting the retina, which is part of the central nervous system. People with RAO should receive the same urgent evaluation as for a brain stroke, including tests of the heart and carotid arteries.

What causes retinal artery occlusion?

It is usually caused by a small clot or piece of cholesterol plaque traveling from the carotid artery or heart and lodging in the retinal artery. Risk factors include high blood pressure, diabetes, smoking, high cholesterol, atrial fibrillation and giant cell arteritis.