Vision Loss, Temporary (Amaurosis Fugax)

What is amaurosis fugax?

Episodic blindness, or 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.

Episodes of blindness may be very short, from under a minute to 30 minutes. The episodes may happen rarely. If the cause is treated, the temporary vision loss may stop.

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

What is the cause?

There are 3 common causes of episodic blindness:

• Carotid artery narrowing (called stenosis) or disease can reduce the blood flow to the eye. This is the most common cause of episodic blindness. 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. Plaques can build up along the inside walls of the arteries and slow the flow of blood. These plaques can break off and block the blood flow to the eyes. Diabetes, smoking, high blood pressure, and high cholesterol can cause problems in your carotid arteries and lead to episodic blindness
• Small blood clots or plaques may break off from heart valves or the inner walls of the heart. Pieces of the clot or plaque may float to the arteries of the eye. This can block blood flow to the eye and cause temporary blindness.
• Migraine headaches can cause spasms and narrowing in arteries leading to the eye.

Less common causes of episodic blindness are:

• sickle cell disease (an inherited blood disorder)
• acute angle-closure glaucoma (a sudden rise in the pressure 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, 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. You can usually see fine out of the other eye.

How is it diagnosed?

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

• an ultrasound exam of your carotid arteries to look for narrowing or blockages
• an MRI or CT scan 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
• a check of your blood pressure

Referral to an eye specialist is sometimes necessary.

How is it treated?

Treatment of temporary blindness depends on the cause. 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, you may need surgery to remove the blockage (called a carotid endarterectomy).

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 new or worsening symptoms to your healthcare provider right away.