Amaurosis fugax (AF) is an eye disorder characterized by a momentary or temporary vision loss in one or both eyes. It occurs when there is insufficient blood flow to the light-sensitive inner lining at the back of the eyeball, i.e., the retina.
Also Known As
- Transient visual loss
- Transient vision loss
- Transient binocular visual loss
- Transient monocular blindness
- Transient monocular visual loss
- Transient monocular visual field loss
- Temporary visual loss - amaurosis fugax
Causes and Risk Factors
AF occurs when there is an obstruction or blockage in the central retinal artery supplying blood to the eyes. The anomaly itself is not a disease; it’s a symptom of other conditions and can arise from various causes.
A blood clot or a piece of plaque blocking an artery in the eye is the most common cause of AF. Plaque is a hard matter that forms when cholesterol, fat and other material accumulate on the inner lining of blood vessels. The plaque or blood clot usually comes from a more significant artery, for example, an artery in the heart or the carotid artery in the neck to a blood vessel in the eye.
Blood clot and plaque formation risk factors include:
- Cocaine use
- Alcohol abuse
- High cholesterol
- Family history of stroke
- Heart disease, especially irregular heartbeat
Other underlying AF causes include:
- Systemic lupus erythematosus, an autoimmune condition in which immune cells invade healthy tissues in the body
- Strenuous exercise, sexual intercourse and long-distance running, which can cause vasospasm
- Vasospasm, where the eye blood vessels suddenly tighten, restricting blood flow
- Polyarteritis nodosa, an abnormality that affects the blood vessels
- History of systemic lupus erythematosus
- Inflammation of the optic nerve
- Diseases of the nervous system
- History of multiple sclerosis
- Migraine headaches
- Head trauma
- Brain tumor
Signs & Symptoms
AF symptoms include an abrupt loss of vision that can last for several seconds or minutes, and thereafter sight returns to normal. It can affect one or both eyes. The sudden vision loss may appear as a generalized darkening, black curtain, or a shadow falling over the visual field in one eye.
In many instances, AF is a sign of an underlying condition, such as decreased blood flow to the eyeball’s blood vessels or a blood clot. Often, the disorder is a sign of a Transient Ischemic Attack (TIA), which is a forerunner to a stroke. TIAs lead to temporary stroke-like symptoms. Other symptoms linked to TIAs include:
- Sudden weakness on one side of the body
- A facial droop on one side of the face
- Difficulty speaking
It’s essential to see a doctor if one is experiencing AF symptoms. The doctor will take a medical history and inquire about the signs. They will conduct a physical assessment, including an eye examination, and consider the patient’s age, overall health and symptoms when making the diagnosis.
S/he can also order testing, including:
- An electrocardiogram (EKG) to determine heartbeat irregularities
- Blood tests to assess blood sugar levels and cholesterol levels as well as assess the probability of blood clotting
- Imaging scans such as Ultrasound or magnetic resonance angiography scan, to identify the damage or blockages in the eyes’ blood vessels
AF treatment depends on its cause and may involve:
The doctor seeks to identify and address the underlying medical problem. Where the anomaly is associated with blood clots or high cholesterol levels, it indicates that the patient is at an increased risk for a stroke. A blood clot can lodge in an artery in the brain and stop the flow of blood to the brain. The doctor will seek to prevent a stroke.
Stroke prevention therapy may include:
- Medications to lower blood pressure
- Blood thinners ,e.g., warfarin or aspirin
- Carotid endarterectomy, a surgical procedure in which the doctor removes blockage or plaque deposits that can potentially block the carotid arteries
The doctor may recommend at-home therapy, including:
- Stop smoking
- No more than two alcoholic drinks a day
- Managing chronic disorders like high cholesterol, high blood pressure, or diabetes
- Regular exercise: At least half an hour (30 minutes) a day for four to five days week
- A healthy, low-fat diet and avoiding high-fat foods, including fast foods, fried and processed foods
The doctor can also only recommend routine visits to monitor the health of the patient’s carotid arteries and heart.
AF is a fleeting condition that is often an indicator of an underlying medical condition. Ignoring the signs increases the risk of severe complications, including stroke. Therefore, one should contact a doctor as soon as they experience an episode of transient blindness.
For TIAs, early treatment of the disorder lowers the risk of severe complications.
One can reduce the risk of AF by maintaining an ideal weight and healthy habits.