Amaurosis fugax is the term used to describe sudden blindness in one eye, usually lasting only minutes and, in exceptional cases, several hours. The leading symptom of the disease is that the blindness, which begins suddenly and is completely painless, regenerates on its own. Amaurosis fugax is usually caused by a temporary disturbance of blood flow in the central retinal artery.
What is amaurosis fugax?
Short-term blindness is caused by temporary ischemia of the retina. Amaurosis fugax is a sudden onset of blindness in one eye that usually lasts only a few minutes and then resolves without permanent changes or damage. In exceptional cases, symptoms may last up to several hours. Characteristically, the onset of unilateral blindness is sudden and completely painless without any warning. It disappears again just as suddenly, usually after only a few minutes. The short-term blindness is caused by temporary ischemia of the retina. The very sensitive photoreceptors in the retina immediately lose their function when there is a lack of oxygen, so that no more messages are sent from the receptors (rods and cones) to the optic nerve. If the lack of oxygen is corrected within a period of no more than 60 to 90 minutes, the functionality of the photoreceptors will restore itself. If the “blackout” lasts longer, the light-sensitive cones and rods are irreversibly damaged, and there is a risk of permanent blindness in the affected eye.
Causes
The most common cause of amaurosis fugax is transient blockage of the central retinal artery. In principle, blockage of the central retinal artery can be caused by disease of the artery itself or by entrained plaques or thrombi (blood clots). In many cases, obstruction of the central retinal artery is caused by stenosis of the internal carotid artery. The internal carotid artery branches off from the carotid artery, as the carotid artery is also called, and supplies the eyes, among other organs. When the carotid artery is affected by arteriosclerosis, so-called plaques form, from which fragments can detach and be transported to the central artery of the retina. Here they trigger a temporary obstruction, so that the photoreceptors in the retina are temporarily no longer supplied with oxygen. However, amaurosis fugax can also be caused by introduced thrombi, which are responsible for a temporary blockage or embolism in the central retinal artery. If the central retinal artery itself is affected, it is usually the autoimmune disease arteritis temporalis, in which the immune system stimulates the formation of epithelial giant cells.
Symptoms, complaints, and signs
The chief complaint, which also serves as the main symptom of amaurosis fugax, is sudden onset of unilateral blindness, which is completely painless and usually resolves on its own after a few minutes. Typically, there are also no previous symptoms that could be interpreted as warning signs of the coming short-term blindness. However, the disease itself should be taken as a warning sign and indication of an impending stroke if, for example, the carotid arteries are the culprit for the temporary blindness. The fragments of the plaques that led to transient blockage of the central retinal artery could instead be washed into the CNS, triggering a stroke.
Diagnosis and Progression
After short-term unilateral blindness suggestive of amaurosis fugax, examination of the retina by ophthalmoscopy is recommended . If necessary, an examination of the retinal vessels by fluorescein angiography should also be considered to determine the possible site of blockage of the central retinal artery. If the arterial blockage is an entrained thrombus or a fragment of a plaque, sonographic examination of the carotid arteries is recommended. If arteriosclerosis of the carotid arteries has caused the amaurosis fugax, there is a high risk of stroke without treatment of the carotid arteries. The course of the disease is self-limiting by definition even without treatment.However, there is a high risk of recurrent unilateral blindness. Only after the causative underlying disease has been successfully treated does the risk of recurrent amaurosis fugax and stroke with unpredictable consequences decrease.
Complications
If the eye experiences short-term or partial blindness, this indicates amaurosis fugax. The symptom occurs because of circulatory problems in the retina. If too much plaque has accumulated on the artery of the eye and a piece of it detaches, it can block the central artery. Only when the blocked blood flow clears does the effect of temporary blindness disappear. In some cases, the symptom becomes noticeable with a gray or black haze in front of the eye. Affected persons should seek medical assistance immediately, because serious complications are imminent. Amaurosis fugax is the harbinger of arteriosclerosis developing in the neck region. This increases the risk of stroke for the patient. Furthermore, high blood pressure or latent swelling heart disease is suspected. High cholesterol levels and diabetes can also trigger the symptom and cause further problems. Smokers, in particular, belong to the group at risk. A magnetic resonance angiography can be used to diagnose the circulatory disorder in the eye. In addition, the patient needs regular checks of high blood pressure as well as cholesterol and blood sugar levels. As a therapeutic measure, an anticoagulant is administered to stimulate blood flow. As a complication, the patient temporarily becomes a hemophiliac. If the eye is too occluded by plaque, surgical intervention is performed depending on the patient’s health status.
When should you see a doctor?
Amaurosis fugax must always be examined by a physician. Since blindness usually occurs very suddenly and spontaneously, most patients also suffer from a panic attack or sweating. Furthermore, loss of consciousness may also occur. In this case, an emergency physician must be notified. Although amaurosis fugax usually disappears after a few minutes or hours, in any case a doctor should perform an examination and diagnose the cause of its occurrence. This may prevent recurrence if necessary. In some cases, amaurosis fugax indicates a stroke. In this case, urgent treatment is necessary so that the stroke can be prevented. In the worst case, this can lead to the death of the affected person. If the short-term blindness causes an accident, a hospital should be visited or an emergency doctor should be called. If the patient smokes, smoking should definitely be stopped or at least reduced.
Treatment and therapy
Direct treatment of amaurosis fugax is hardly possible because the phase of blindness usually lasts only a few minutes. Therefore, effective therapy is aimed at treating the underlying disease causing the condition. This can be, for example, the treatment of arteriosclerosis of the carotid arteries or the treatment of the autoimmune disease arteriitis temporale, if the retinal arteries themselves are affected. Regarding the treatment of arteriosclerosis, graded therapies are available, which can be applied depending on the severity and on the affected artery. In addition, preventive measures are often indicated, for example, to minimize the risk of thrombus formation and thus prevent not only amaurosis fugax but also stroke. Any occurrence of short-term unilateral blindness should be taken as a forewarning of stroke. As a first consequence, coagulation protection can be established. Anticoagulants provide good protection against stroke and similar problems related to freighted blood clots.
Outlook and prognosis
In most cases, only temporary blindness occurs with this disease. This blindness usually disappears after a few minutes or hours and does not cause further discomfort. However, it can lead to panic attacks or sweating in the patient and thus significantly reduce the patient’s quality of life. In most cases, amaurosis fugax does not cause any particular pain or pre-existing symptoms.However, the disease should be examined by a doctor in any case, as it can be associated with an increased risk of stroke. A stroke can be fatal for the person affected and for this reason should be prevented in any case. A direct treatment of this disease is usually not possible and also not necessary. The vision returns after a certain period of time. However, the affected person should lead a healthy lifestyle so that a possible stroke does not continue to occur. Medication can also be used against a stroke, which significantly reduces the risk.
Prevention
Direct preventive measures to avoid amaurosis fugax do not exist. However, a number of measures exist to help minimize the risk of developing atherosclerosis. Preventive measures therefore consist primarily of building up protection against coagulation of the blood. This includes both good blood sugar control in diabetes mellitus, sustained blood pressure reduction in arterial hypertension, and a healthy diet. It goes without saying to keep alcohol consumption and smoking at the lowest possible level. Moderate exercise in endurance disciplines can also be understood as a preventive measure.
Aftercare
The options for follow-up care are usually very limited in amaurosis fugax. The patient is primarily dependent on treatment by a physician to prevent further complications or discomfort and to fully treat the condition. Self-healing cannot occur. Since amaurosis fugax has not been fully researched, the options for treating this condition are also severely limited. Treatment of the affected arteries can be performed, but this does not lead to success in every case. In the first instance, therefore, a doctor must be consulted at the first symptoms of amaurosis fugax. Only early treatment can prevent further symptoms. In general, a healthy lifestyle with a balanced diet also has a positive effect on the course of amaurosis fugax. This also includes sports activities and abstaining from alcohol, tobacco or other drugs. A stroke can also promote the disease and should of course be avoided. Whether amaurosis fugax also limits the life expectancy of the affected person cannot be predicted in general. Often, contact with other sufferers of the disease is also useful, as there is an exchange of information.
Here’s what you can do yourself
The options for self-help with amaurosis fugax are very limited. Since the symptoms occur temporarily for a few minutes or hours, it is important that the affected person remains calm and does not become hectic or busy. Everyday life should be structured in such a way that the general risk of accidents in the event of sudden onset of blindness is minimized as far as possible. In case of feelings of fear or panic, it is helpful if the affected person basically seeks therapeutic help. There he learns behavioral strategies that he can implement independently in everyday life and use optimally. In order to be fully prepared for all symptoms and complications, it is advisable for the person affected to obtain detailed information about the disease. It is equally helpful if he also informs people in his immediate environment about the disease and its accompanying symptoms. The more stable and informed the social network is, the more professionally friends, colleagues and relatives can react to the affected person and the surprisingly appearing symptoms. In this way, the feeling of helplessness is minimized as far as possible for everyone involved. In addition, the affected person can be sure that he or she will receive the necessary support, as being overwhelmed by the situation is also reduced.
