Amaurosis Fugax (Episodic Blindness)

What is amaurosis fugax?

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

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

How does it occur?

There are three common causes of amaurosis fugax.

• Carotid artery narrowing or disease can cause decreased blood flow to the eye. This is by far the most common cause of amaurosis fugax. There are two carotid arteries, one on each side of the neck. They bring blood from the heart to the eyes and brain. Smaller arteries that go to the eyes branch off from the carotid arteries. Debris from deposits on the walls of the diseased carotid arteries can break off and travel through these smaller branches to the eye. The debris blocks the blood flow within those smaller vessels.
• Small blood clots or pieces of debris can break off of heart valves or heart chambers and travel to the arteries of the eye, blocking the blood flow to the eye.
• The arteries of the eyes can be affected by increased pressure in the brain, which increases pressure on the optic nerve, or by migraine headaches, which can cause spasms and narrowing in arteries of the eye.

Less common causes of amaurosis fugax are:

• sickle cell disease (an inherited blood disorder)
• acute closed-angle glaucoma (a condition in which the pressure of the fluid in the eye rises suddenly)
• polycythemia (an increase in the number of blood cells in the arteries).

What are the symptoms?

The most common symptom is sudden blindness in one eye that goes away quickly. It is often compared to a curtain pulled down over one eye. It is not painful.

How is it diagnosed?

The doctor will ask about your symptoms, examine your eyes, and perform tests to identify the cause. Among these tests may be an ultrasound examination of your carotid arteries to look for blockages, and blood tests, including one to determine if your cholesterol level is too high. A high cholesterol level in the blood may cause deposits in your arteries that can block blood flow. 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 and high blood pressure may be treated with diet and medication. If you smoke, it is very important to stop. If there is a serious blockage of a carotid artery, surgery to remove the blockage may be considered.

What can I do to help myself?

• Follow your treatment plan.
• Maintain normal blood pressure and cholesterol levels with diet, exercise, and medication, if prescribed.
• Report any symptoms to your doctor immediately.