Amaurosis fugax – Transient visual disturbance
Your vision suddenly decreased for a few minutes in one or both eyes and then returned to normal. These symptoms were either isolated or accompanied by dizziness, tingling, slurred speech, or paralysis. This is very likely a transient ischemic attack (TIA), also known as amaurosis fugax: a mini-stroke affecting the visual pathways or the eye. Be aware, this is a warning sign! Approximately 1 in 3 patients who have experienced a TIA will have a stroke at some point in their lives, and about half of these strokes will occur within a year. A TIA can serve both as a warning of a future stroke and as an opportunity to prevent it. Seek medical help!
What is amaurosis?
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Amaurosis is a sudden, profound and transient (a few seconds or minutes) decrease in vision, usually occurring in only one eye.
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It reflects a sudden suffering of the eye or brain.
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It is caused by a clot or spasm of an artery in the artery supplying your eye.
Symptoms
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Transient ischemic attacks (TIAs) usually last only a few minutes. Symptoms disappear spontaneously within an hour.
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The signs and symptoms of a TIA are similar to those found at the beginning of a stroke.
The ophthalmic symptoms of a TIA are transient blindness or diplopia (double vision). These symptoms may be associated with:
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Weakness, numbness, or paralysis of the face or a limb.
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A speech disorder.
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Dizziness or loss of balance.
You can have more than one TIA and the signs and symptoms may be similar with each episode or different depending on the area of the brain involved.
When to consult a doctor
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Since TIAs most often occur a few hours or days before a stroke, it is essential to seek urgent medical attention after a possible TIA.
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Call 15 immediately to be assessed by an emergency medical dispatcher if you experience symptoms consistent with a TIA. A rapid assessment will allow you to be directed to the appropriate emergency department.
What is the difference between a stroke and a TIA?
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A TIA is often called a mini stroke, because it corresponds to a cerebral arterial thrombosis that lasted a short enough time not to damage the brain.
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A TIA is therefore a stroke that spontaneously cleared itself before damaging neurons.
Causes
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A TIA has the same origins as an ischemic stroke, the most common type of stroke. In an ischemic stroke, a clot blocks the blood supply to a part of the brain or the artery supplying your eye.
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In the case of a TIA, unlike a stroke, the blockage is brief and there is no permanent damage.
The potential causes of the clot are:
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A cholesterol plaque – Usually found on a blood vessel in the neck. Also called an atheroma, a cholesterol plaque forms with age. If it ruptures, an embolus (clot) travels towards the brain and blocks a small blood vessel.
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A cardiac embolus – In the event of a heart rhythm disorder, particularly atrial fibrillation, a clot can form spontaneously. It can travel from the heart to the brain.
Diagnosis
The assessment of amaurosis or any other transient visual disturbance, if a TIA is suspected, is based on:
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A brain MRI (or failing that, a CT scan) to look for a previously undetected stroke.
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Ultrasound of the neck vessels (or scan of the supra-aortic trunks) to look for a cholesterol plaque.
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A blood test to look for clotting disorders or inflammation (CRP).
The examinations must be carried out urgently and followed by a neurological consultation.
Risk factors
Some risk factors for TIA and stroke are controllable. Others cannot be changed, but they help assess your cardiovascular risk:
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Heredity – Family history – Your risk may be higher if one of your family members has had a TIA or stroke.
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Age – Your risk increases with age, especially after 55.
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Sex – Men have a slightly higher risk of TIA and stroke. But as women age, their risk of stroke increases.
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History of ischemic stroke – If you have already had one or more TIAs, you are much more likely to suffer a stroke.
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High blood pressure – The risk of stroke begins to increase when blood pressure is above 140/90 millimeters of mercury (mmHg).
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Dyslipidemia – high cholesterol – Eating less cholesterol and fat, especially saturated fats and trans fats, can help reduce plaque buildup in your arteries. If you are unable to control your cholesterol by changing your diet alone, your doctor may prescribe a statin to artificially lower your cholesterol levels.
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Cardiovascular diseases – These can include a rhythm disorder, heart failure, a heart defect, or a heart infection.
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Carotid artery narrowing – In this condition, the blood vessels in the neck that lead to the brain become blocked. The risk is similar if other large arteries are affected: aorta, femoral artery, etc.
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Diabetes – Hyperglycemia increases the severity of atherosclerosis and accelerates the narrowing of arteries by accumulation of fatty deposits.
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Overweight or obesity, particularly overweight with increased abdominal circumference in men.
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Smoking – Quit smoking to reduce your risk of TIA and stroke. Smoking increases the risk of blood clots, raises blood pressure, and contributes to the development of fatty deposits containing cholesterol in the arteries (atheroma).
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Sedentary lifestyle – Doing 30 minutes of moderate-intensity exercise almost every day helps reduce the risk.
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An unbalanced diet – Reducing fat and salt intake decreases the risk of TIA and stroke.
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Excessive alcohol consumption – If you drink alcohol, limit yourself to two drinks per day if you are a man and one drink per day if you are a woman. Maintain at least one alcohol-free day per week.
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Drug use – Avoid cocaine and other illicit drugs.
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Migraines with aura – Migraines are a known risk factor for stroke. The vascular spasm responsible for headaches in migraines can also lead to thrombosis. In cases of unusual migraines or aura, a stroke or TIA should be suspected.
Covid-19 and the risk of transient visual disturbances.
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There is evidence that COVID-19 increases the risk of stroke during the infection period.
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This is probably a hypercoagulation mechanism related to the viral infection, immune response, or fever spike.
Prevention and treatment
Treating modifiable risk factors, living a healthy lifestyle and, if necessary, taking blood-thinning medication as a preventative measure can help prevent the recurrence of amaurosis, another TIA or a stroke.
The hygiene rules to be followed are:
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Don't smoke – Quitting smoking reduces your risk of TIA or stroke.
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Monitor and treat your cholesterol – Reducing cholesterol and fats, especially saturated and trans fats, in your diet can reduce plaque buildup in the arteries.
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Balance your diet – Eat 5 fruits and vegetables a day as recommended. These foods contain nutrients such as potassium, folate, and antioxidants, which can protect against a TIA or stroke.
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Balance your diabetes – Uncontrolled diabetes greatly increases the formation of atheroma and the risk of stroke.
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Take your preventative treatment – In cases of high cardiovascular risk, preventative treatment with antiplatelet drugs is generally prescribed. This significantly reduces the risk of blood clots.
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Limit your salt intake – especially if you have high blood pressure, avoid salty foods and don't add salt to your food. This can lower your blood pressure and reduce the stiffening of your arteries.
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Do some sport – Regular exercise works your heart and helps lower your blood pressure.
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Limit your alcohol consumption – Drink alcohol in moderation (or not at all). It is recommended not to exceed one drink per day for women and two per day for men, with one or two alcohol-free days per week.
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Control your weight – A BMI (body mass index) over 25 is a vascular risk factor.
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Do not use hard drugs – Cocaine in particular greatly increases the risk of stroke, including in young patients.
Complications
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Any transient amaurosis or visual disturbance is a transient ischemic event until proven otherwise.
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The danger is suffering a full-blown ischemic stroke, which is serious and leaves severe after-effects in the hours, days, or weeks that follow.
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An assessment, a neurological consultation and, if necessary, preventive treatment (low-dose aspirin) should be initiated.
Frequently Asked Questions
What are the causes of transient amaurosis?
The causes of amaurosis are the same as those of ischemic stroke: cholesterol plaque or cardiac embolism. Both are favored by cardiovascular risk factors: hypertension, smoking, obesity, etc.
What treatment is available for amaurosis?
Treatment for amaurosis fugax focuses on managing cardiovascular risk. The goal is not to eliminate the amaurosis, which is by definition transient and resolves on its own, but rather to prevent the occurrence of a stroke.