Description, Causes and Risk Factors:
Def: A transient blindness that may result from a transient ischemia due to carotid artery insufficiency, retinal artery embolus, or to centrifugal force (visual blackout in flight).
Amaurosis fugax is loss of vision in one eye due to a temporary lack of blood flow to the retina. The symptom usually develops suddenly, and many individuals describe the event as “it was as if a shade or curtain came over my eye.”
It is caused by a blockage or low blood flow within the main blood vessel supplying the eye. Blockages are usually due to a blood clot or plaque (small piece of cholesterol) that breaks off from a larger artery and travels upward to the brain or eye, becoming lodged in the main artery supplying the eye. Low blood flow to the eye may also result from a critical narrowing of one of the main blood vessels supplying blood to the brain and eye.
This condition can also occur in ruminants suffering from a vitamin B1 deficiency due to thiamine related cerebrocortical necrosis.
Vision loss occurs as long as the blood supply to the artery is blocked. Atherosclerosis of the arteries in the neck is the main risk factor for this condition.
Other risk factors may include:
Ocular: Dry eye syndrome, blepharitis, keratitis, intermittent angle closure glaucoma, optic disc drusen, vitreous detachment, retinal break, orbital tumor, intraocular hemorrhage, and angiospasm.
Neurologic: Optic neuritis, papilledema, multiple sclerosis, intracranial tumor, and lupus.
Circulatory: Carotid emboli, hypoperfusion, coagulation disorder, carotid stenosis, arrhythmia, increased blood viscosity, and migraine.
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.
The experience of amaurosis fugax is classically described as a transitory monocular imagination departure that appears as a "drape coming downward vertically into the area of imagination in one heart;" however, this altitudinal visual departure is comparatively rare.Other descriptions of this experience include a monocular blindness, dimming, fogging, or blurring. Total or sectorial imagination departure typically lasts simply a few seconds, but may live minutes or still hours. Duration depends on the etiology of the imagination departure.
Certainly, extra symptoms may be existing with the amaurosis fugax, and those findings will bet on the etiology of the transitory monocular imagination departure.
When interviewing a patient with amaurosis fugax, it is important to pay special attention to the medical history. The clinician should attempt to uncover the presence of hypertension, diabetes, previous myocardial infarction, prior cerebrovascular accidents, hypercholesterolemia, long standing migraine history, or peripheral vascular disease (PVD).
The eye care provider should perform biomicroscopy paying special attention to the lid margins, tear film, cornea, and anterior chamber. Conditions such as dry eyes, blepharitis, and iritis can all be ruled out from the differential diagnosis if the biomicroscopy is normal. Gonioscopy permits direct observation of the anterior chamber angle of the eye under high magnification. This clinician observation can rule out micro hemorrhage in the anterior chamber or evidence of angle closure glaucoma. Therefore, it should be performed for patient experiencing transient visual disturbance.
A dilated retinal examination is mandatory for patients presenting with amaurosis fugax. The retina, retinal vasculature, optic nerve and vitreous will all provide additional information forming a clinical diagnosis. A vitreous detachment, retinal tear, or retinal detachment should be observable once the patient's eyes are dilated.
Other tests may include an ultrasound of the carotid arteries in the neck, a study of the electrical system of the heart, a magnetic resonance angiography (MRA) scan of the blood vessels in the head and neck, an echocardiogram of the heart, or an angiogram (dye imaging of the blood vessels). If these studies reveal the source of the problem, medication and/or surgery may be necessary.
The treatment of amaurosis fugax depends upon identifying the source of the blood clots or cholesterol that have caused low blood flow or blocked the main artery to the eye. Blood clots may come from arteries inside the head, arteries in the neck, or from the heart. 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.
Surgery options include: Balloon angioplasty, stenting. Both techniques are used to open up the area of the carotid artery that is blocked by plaque. These methods are promising, especially for patients who are not well enough to undergo major surgery.
The decision to perform surgery will also be based on the severity and the patient's general health. If the patient does not need surgery, doctors usually recommend aspirin or blood thinners.
NOTE: The above information is educational purpose. The information provided herein should not be used during any medical emergency or for the diagnosis or treatment of any medical condition.
DISCLAIMER: This information should not substitute for seeking responsible, professional medical care.
A new study from the University of Granada, Spain, shows that contrary to the widespread belief, those who make self-deprecating jokes do not have low self-esteem, nor they are predisposed to depression. In fact, scientists suggest that this type of people may be...
Sometimes it is difficult to have a bowel movement. Bowel movements range is different for everyone. However, movements from three times per week up to three times per day are considered as healthy. There are some natural methods that can help a person poop. Below,...
Quiz about this article
0 of 2 questions completed
Please answer on few questions to make our service more useful
You have already completed the quiz before. Hence you can not start it again.
Quiz is loading...
You must sign in or sign up to start the quiz.
You have to finish following quiz, to start this quiz:
0 of 2 questions answered correctly
Time has elapsed
You have reached 0 of 0 points, (0)
Question 1 of 2
Was this article useful for you?Correct
Thanks for your feedback!Incorrect
Thanks for your feedback!
Question 2 of 2
What else information about this disease you want to know ?Correct
Thanks for feedback!Incorrect
Thanks for feedback!
Many people spontaneously decide starting to do sport, while others weigh all the pros and cons for a log time. But almost all of them make the same mistakes, listening to the advice of non experts. There are 10 anti-tips for those who want to do plan to do some sport...read more
Spring is not far off and very soon you will see many people riding a bike. It's worth to join them and now we will give you the 8 reasons why. Weight control Scientists of the University of Surrey (England) found that it's enough riding a bike for an hour, and, not...read more
We all want to get in shape and keep fit. But not everyone has time for visiting the gym. Give up the elevator. Give up lifts and climb the stairs. At work, at home, at the mall. This simple advice is a great benefit if you follow it daily. Climbing the stairs...read more