Transient monocular blindness

Alternative names
Amaurosis fugax

Definition
Amaurosis fugax involves loss of vision in one eye caused by a temporary lack of blood flow to the retina.

Causes, incidence, and risk factors

Amaurosis fugax is thought to result from a clot of plaque in the carotid artery breaking off and traveling to the retinal artery in the eye. This blocks the artery for a time and causes loss of vision in that eye for as long as its blood supply is cut off.

Atherosclerosis of the carotid arteries (in the neck) is the main risk factor for this condition. Risk factors for atherosclerosis include Heart disease, High Cholesterol, Smoking, Diabetes, and high blood pressure.

Symptoms
Symptoms include the sudden loss of vision in one eye. This usually only lasts seconds but may last several minutes. Some patients describe the loss of vision as a gray or black shade coming down over their eye.

Signs and tests

Tests include a thorough ophthalmological and neurological examination. Subsequently, a carotid ultrasound or an MRA (magnetic resonance angiography) should be done to evaluate the amount of blockage in the carotid artery.

Routine blood tests such as cholesterol and glucose should be done to assess risk of atherosclerosis, which increases with elevated cholesterol and Diabetes.

Treatment

Treatment depends on the results of the evaluation. If there is evidence of blockage of more than 70% of the carotid artery, the patient may be considered for surgery to remove the blockage.

The decision to do surgery will also be based on the presence and severity of other medical problems and the general health of the patient. If the patient is not a surgical candidate, treatment with aspirin or another blood thinning agent may be warranted.

Lowering cholesterol, reducing high blood pressure and cessation of Smoking can help decrease the risk of atherosclerosis.

New techniques include stenting of the carotid artery and balloon Angioplasty of the stenosis (blockage) in the carotid artery. Both techniques aim to open up the region of the carotid artery that is being blocked by plaque. These techniques are promising, especially for patients who are not well enough to undergo major surgery.

Expectations (prognosis)
Amaurosis fugax may be a sign of impending Stroke . The attack itself does not result in any permanent disability.

Complications
Though this condition does not result in any permanent damage, it is a sign of atherosclerotic disease and therefore implies a serious risk for Stroke .

Calling your health care provider
Call your health care provider if any loss of vision occurs. If symptoms last for longer than a few minutes, or if there are any other symptoms accompanying the visual loss, it is important to seek immediate medical attention.

Prevention
Prevention of Stroke  includes eating a healthy diet low in fat, controlling high blood cholesterol and high blood sugar as well as lowering Blood pressure, doing regular exercise, and not Smoking.

Johns Hopkins patient information

Last revised: December 6, 2012
by Dave R. Roger, M.D.

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