Due to poor blood flow to the eye(s), a person with amaurosis fugax is unable to see out of one or both eyes. An underlying issue, such as a blood clot or inadequate blood flow to the blood vessels supplying the eye, maybe the cause of the condition, which is a symptom. Amaurosis fugax is also referred to as transient monocular blindness, transient monocular visual loss, or transient visual loss.
Consider yourself reading the morning paper while seated at the kitchen table, sipping coffee. Your left eye's vision suddenly vanishes, leaving only blackness behind. But your vision has already started to return by the time the initial shock subsides. What just happened? What causes this type of temporary vision loss?
The condition known as amaurosis fugax, which is also referred to as transient monocular blindness, is one possibility. This is a brief loss of vision that happens in one eye only (rarely both at once) and lasts anywhere from a few seconds to a few minutes. The layer at the back of the eye, the retina, which transmits visual data to the brain for processing, receives insufficient blood flow, which is the cause of it. Lack of blood causes the retina to temporarily stop transmitting this information, which causes vision to vanish.
The most frequent cause of blood flow disruptions is some kind of blockage in an eye artery. This may be caused by a blood clot or, more frequently, by a piece of plaque becoming lodged in a constricted artery. 90% of amaurosis fugax cases are caused by plaque, which is composed of hardened fatty substances that build up inside arteries as part of the cardiovascular disease atherosclerosis.
Amaurosis fugax is much more prevalent in adults than in children, but in adults, it is typically a sign of another underlying condition that requires attention. When children have amaurosis fugax, it is usually caused by a migraine or seizure rather than a major medical problem such as cardiovascular disease.
The temporary reduction in blood flow to one or both eyes causes amaurosis fugax. This is brought on by illnesses that affect the blood vessels in charge of supplying the brain and eyes with blood. The retina, a component of the eye, can no longer function when that blood flow is reduced. This causes someone to lose their vision.
The following circumstances can result in decreased blood flow:
● Atherosclerosis: Plaques accumulate on the insides of blood vessels over time in this situation. These plaques can restrict or completely block blood arteries. This frequently happens in the carotid arteries, which are major arteries in the neck that deliver blood from the heart to the brain. The eyes, too, rely on this blood flow.
● Blood clots: A blood clot that forms in the heart or an artery might break off and migrate downstream, blocking the more narrow arteries near the eye. These blood clots may occur in the carotid arteries, particularly if they are clogged. People with atrial fibrillation, a cardiac disorder, can form blood clots inside the heart that can migrate to these arteries.
● Low blood pressure: Anything that reduces blood pressure throughout the body can affect blood flow to the eyes. This can occur with conditions such as orthostatic hypotension, which occurs when blood pressure lowers due to a change in position. It could also be caused by a sudden drop in blood pressure caused by drugs or acute dehydration. Amaurosis fugax is more prone to occur when the blood arteries in the neck and brain are already restricted for another reason.
A greater percentage of people over 50 are susceptible to amaurosis fugax.
Other risk factors include:
● High cholesterol
● Cerebrovascular disease
● Smoking
● Cocaine use
● High blood pressure
● Diabetes
● Heart disease
● Carotid artery disease
● Brain tumor
● Head injury
● Multiple sclerosis (MS)
● Migraine headaches
● Eye inflammation
● Significant carotid stenosis
Amaurosis fugax causes brief, painless loss of vision that typically lasts a few seconds or minutes before full vision spontaneously returns. Permanent vision loss is a rare consequence of the condition.
Amaurosis fugax symptoms have been described as follows:
● A heavy drape covering the eye(s)
● The loss of vision in one or both eyes for a brief period of time.
● Blurred vision
Those over the age of 60 who experience multiple episodes of amaurosis fugax are at risk for giant cell arteritis (inflammation of blood vessels in the scalp, neck, and arms).
Because amaurosis fugax is a symptom of other medical conditions, there is no specific test to identify it. If you are experiencing symptoms that are concerning for amaurosis fugax, you may still require some tests. These include:
● A fundoscopic exam: This allows your doctor to have a good look at the retina in the back of your eye. They use a special torch to conduct it, but it will feel like any other eye exam. This enables them to detect blood clots in the retina.
● Imaging of the carotid arteries: To screen for atherosclerosis, you may need an ultrasound or a CT scan of the carotid arteries. These tests may also reveal anything else impeding blood flow in these arteries.
● Imaging of the brain: The majority of people will have imaging examinations to examine the brain, such as a CT scan or an MRI. They can also search for other areas of the brain that may be impacted by a lack of blood supply.
Even though amaurosis fugax is a transient condition with symptoms that can last anywhere from a few minutes to an hour, it is frequently a worrying sign of a more serious medical condition.
A higher chance of stroke, which can be fatal, is one consequence of this. The risk of more serious complications increases if a person ignores these symptoms.
The initial goal of treatment is to manage and address the underlying vascular risk factors, including hypertension, diabetes, and hyperlipidemia. Most patients need conservative care, which includes anticoagulants like aspirin and clopidogrel (drugs that prevent blood from clotting).
It has been demonstrated that minimally invasive procedures, such as carotid stenting (i.e., enlarging a narrow point within the vessel), are beneficial for asymptomatic people with severe carotid stenosis.
The use of more invasive techniques, such as carotid endarterectomy (i.e., surgical removal of the vessel blockage), is usually restricted to people who have carotid stenosis levels greater than 70%.
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