Amaurosis Fugax (Episodic Blindness)

What is amaurosis fugax?

Amaurosis fugax is temporary blindness caused by a lack of blood flow to the eye. The loss of vision is usually in just one eye and lasts from seconds to minutes.

Amaurosis fugax may be a warning of something more serious, such as decreased blood flow to the brain, which could cause a stroke.

How does it occur?

There are 3 common causes of amaurosis fugax:

• Carotid artery narrowing (called stenosis) or disease can reduce the blood flow to the eye. This is the most common cause of amaurosis fugax. You have 2 carotid arteries, one on each side of the neck. They bring blood from the heart to the eyes and brain. Smaller arteries branch off from the carotid arteries to bring blood to the eyes. Debris from deposits on the walls of the diseased carotid arteries can break off and travel into these branches. The debris may then block the blood flow to the eyes. Diabetes, smoking, high blood pressure, and high cholesterol can cause problems in your carotid arteries.
• Small blood clots or pieces of debris may break off from heart valves or the inner walls of the heart and travel to the arteries of the eye, blocking the blood flow to the eye.
• Problems in smaller vessels bringing blood to the eyes and brain can cause amaurosis fugax. For example, migraine headaches can cause spasms and narrowing in arteries leading to the eye.

Less common causes of amaurosis fugax are:

• sickle cell disease (an inherited blood disorder)
• acute angle-closure glaucoma (a sudden rise in the pressure of fluid in the eye)

Sudden blindness in one eye is an emergency that you should report to your healthcare provider right away. If you cannot reach your provider, you should go to the nearest emergency room to be checked.

What are the symptoms?

The most common symptom is sudden blindness in one eye that goes away within seconds or minutes. It is often described as feeling like the pulling of a curtain or a shade over one eye. It is not painful. The other eye is usually not affected.

How is it diagnosed?

Your healthcare provider will ask about your symptoms, examine your eyes, and perform tests to identify the cause. Tests you may have are:

• an ultrasound exam of your carotid arteries to look for blockages
• an MRI to check the blood vessels of the brain and to see if you may have had a stroke
• an echocardiogram to check your heart
• a blood test to check your cholesterol level
• a blood test to check your blood sugar if you are a diabetic

Referral to an eye specialist is sometimes necessary.

How is it treated?

Treatment depends on the cause, and it is the underlying cause, not the temporary blindness, that is treated. Aspirin or blood thinners may be prescribed to help prevent blood clots. High cholesterol levels, high blood pressure, and diabetes may be treated with diet and medicine. If you smoke, it is very important to stop. If there is a serious blockage of a carotid artery, surgery to remove the blockage (called a carotid endarterectomy) may be considered.

What can I do to help myself?

• Follow your treatment plan.
• Maintain normal blood pressure, blood sugar, and cholesterol levels with diet, exercise, and medicine, if prescribed.
• Do not smoke.
• Report any symptoms to your healthcare provider right away.

Reviewed for medical accuracy by faculty at the Wilmer Eye Institute at Johns Hopkins. Web site: http://www.hopkinsmedicine.org/wilmer/

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