Amaurosis fugax

Amaurosis fugax (AF) is a severely discomforting eye disorder in which affected individuals suddenly and temporarily fail to see with one of their eyes. Read and find out all about the causes, symptoms, diagnosis and treatment of this ocular condition.

Amaurosis fugax Definition

It is a condition of temporary blindness in only one eye (monocular). The disease generally arises all of a sudden and is described as a “dark curtain falling before the eye” by patients.

It is also known as “Transient monocular blindness” or “Temporary monocular blindness”. The condition should not be confused with Amaurosis, which is marked by partial or total lack of vision.

Amaurosis fugax ICD 9 Code

The ICD 9 Code for this disease is 362.34.

Amaurosis fugax Incidence

The exact prevalence of this disorder is not known. However, it has been described as a rare disease by ORD (Office of Rare Diseases). This indicates that the condition, or its subtype, affects lower than 200,000 individuals in the U.S. Its incidence all over the world is unknown.

Amaurosis fugax Etymology

The name of this condition comes from a merger of the Greek term “Amaurosis” standing for “dark”, “obscure” or “darkening” and the Latin word “fugax” meaning “fleeting”. A fusion of the words simply indicates a fleeting or momentary darkness which obviously refers to the temporary absence of vision in one eye that characterizes this disorder.

Amaurosis fugax Symptoms

A short-lived absence of sight in one eye is the primary problem that an AF sufferer experiences. The condition generally persists for a short duration of a few seconds or a few minutes. The problem is also described by some patients as a gray or dark shade coming down over one eye, similar to dropping of a curtain on stage.

Picture 1 – Amaurosis fugax

Depending on the cause, the loss of vision may also last up to a few hours. In some cases, the loss of vision can be permanent if not properly addressed. However, it is only in rare cases that the disorder becomes permanent or lasts for a long time. In most cases, the darkness of vision lasts from anywhere between 5 to 30 minutes.

Generally, the condition itself causes little more problems than temporary loss of vision. In some cases, however, it may be a sign of a more severe impending disorder – such as an imminent stroke. It may also be a sign of carotid artery disease.

Transient Ischemic Attack (TIA) is a condition arising from insufficient supply of blood to the brain. Some of the common symptoms of TIA include:

• Changes in vision
• Blindness
• Loss of balance or coordination
• Dizziness
• Confusion
• Numbness or weakness on one side of the body or face
• Slurred speech
• Difficulties in swallowing
• Inability to talk

AF patients suffer from a few symptoms of this disease. Naturally, the condition reportedly qualifies for a Transient Ischemic Attack (TIA).

Amaurosis fugax Causes

AF is usually a result of a short-lived absence of blood flow to the retina. In case Cartoid Artery Disease leads to the disorder, AF is caused by a strip of plaque which snaps from a carotid artery and goes to the retinal artery located in the eye. The carotid arteries, located on either side of the neck and under the jaw, are the main source of blood for the brain. Plaques are hard substances formed by the deposition of fats, cholesterols and other organic materials in the arterial walls. Pieces of plaques may obstruct the flow of blood. In AF sufferers, loss of vision continues as long as there is obstruction of blood supply to the retinal artery.

AF may also arise due to any other neurological event other than stroke that interrupts the signals sent to the brain from the eye. It may also result from some eye disorders, such as Glaucoma. Exposure to centrifugal force may also cause this problem, which explains why sometimes vision in one eye gets blurry or darkened after carnival rides such as “Merry-Go-Round”.

In 1990, the Amaurosis fugax Study Group classified the causes of AF into five distinct categories. Of these, two are associated together:

Embolic and hemodynamic causes

It involves problems like Eosinophilic vasculitis, Hyperviscosity syndrome and Periarteritis nodosa.

Ocular causes

It involves disorders such as Blepharitis, Keratitis, Iritis and Optic disc drusen.

Neurological causes

It includes conditions like Migraine, Optic neuritis, Multiple Sclerosis and Intracranial tumor.

Idiopathic causes

It indicates that the causes of the problem have not been found.

Amaurosis fugax Diagnosis

The disease is diagnosed by a complete examination of the eye as well as a neurological test. A MRA (Magnetic Resonance Angiography) or Carotid Ultrasound should be performed to determine a possible obstruction in the carotid artery. In some patients, an examination of the eye helps reveal a bright spot which is actually the clot obstructing the flow of blood to the retinal artery.

Doctors should also perform routine tests to determine levels of sugar (glucose) and cholesterol in the bloodstream. This can help evaluate whether a particular patient is at risk of developing atherosclerosis, a phase of arteriosclerosis involving buildup of fatty substances within the walls of the arteries. The risk of developing this disorder increases if a patient suffers from diabetes (high blood sugar) or high blood cholesterol.

During diagnosis, the following factors need to be investigated and taken into account:

• Age of the patient
• Frequency of the symptoms
• Rate of development of the symptoms
• Duration of the symptoms
• Whether one or both eyes are affected
• Nature of visual disturbances
• Whether or not there is any pain associated with the vision problem
• Whether or not the symptoms worsen with ocular movement
• Whether or not exercise cause or change the visual abnormalities
• Whether there are associated symptoms like weight loss, malaise, fever and scalp tenderness
• Whether the patient has a history of headaches
• Whether or not he or she experiences motion sickness

Amaurosis fugax Misdiagnosis

AF being a signal of Atherosclerosis, any error in diagnosis may delay the treatment of this condition and even complicate it further. In some cases, the disorder is mistakenly diagnosed as retinal detachment or cardiac emboli. In such cases, physicians may use a wrong treatment. The actual condition would continue to exist and left untreated. This can be avoided by making a thorough study of case history, proper systemic testing and careful ocular and clinical examination.

Amaurosis fugax Differential Diagnosis

AF should be distinguished from other disorders that produce similar symptoms. Such conditions include:

• Retinal migraine
• Migraine, along with aura
• Retinal emboli
• Seizure
• Papilledema
• Vertebrobasilar insufficiency
• Amaurosis

Some of these result in monocular while others lead to binocular loss of vision. Conditions like Retinal migraine, Retinal emboli and Papilledema – which lead to monocular vision loss – are more often confused with AF than those that produce binocular loss of sight. It is essential for ophthalmologists to establish whether an individual is suffering from a monocular or binocular loss of eyesight. Even patients suffering from recurring cases of vision loss for a prolonged duration find it difficult to differentiate between the two cases.

Amaurosis fugax and Amaurosis

AF can be confused with Amaurosis, another ocular condition characterized by partial or complete lack of sight. AF is one of the four major types of Amaurosis, the others being:

• Quinine Amaurosis
• Leber’s Congenital Amaurosis (LCA)
• Thiamine-related cerebrocortical necrosis

These other types are usually characterized by headaches, cloudy or obscure vision and flickering of the upper eyelid. However, as has already been mentioned before, AF is marked by temporary darkness or obscure vision in one eye. While some of tests and treatment options for all types of Amaurosis may be similar, they also differ according to the form of the disorder that one suffers from.

Amaurosis fugax Treatment

Although an attack of AF lasts for only a short time, more than one episode of it needs prompt treatment. This is essential to avoid complications, such as stroke. The treatment of AF depends on the seriousness of the obstruction in the carotid artery. The aim of cure is to prevent occurrence of a stroke, which may result in brain damage.

Picture 2 – Amaurosis fugax Image

The medical cure for this disease involves dietary changes and medicines to help reduce blood pressure and level of cholesterol. Common medications used for this disease involve Warfarin, Aspirin (Coumadin) or other blood-thinning drugs that reduce the risk of stroke.

If a major section of the carotid artery appears to be obstructed, patients may be recommended surgery to get the blockage removed. The decision to use an operative technique should also depend on the overall health of sufferers. In some cases, a stent may be installed in an appropriate position to prevent recurrence of ocular blockages.

If AF is found to result from Glaucoma, it may be an indication that patients require more aggressive treatment or better management.

In some cases, patients may not require any treatment. Doctors may only recommend regular health check-ups to evaluate the health of the carotid artery of patients.

Amaurosis fugax Management

If caused by some circulatory problems, the management of this disorder should be done by a surgical or medical specialist. A vascular surgeon can be able to handle such cases. The management of the condition presents as quite a clinical challenge for sufferers. However, a systemic approach coupled with appropriate research and laboratory tests can help manage this disorder properly.

Amaurosis fugax Prognosis

In most cases, the disorder resolves gradually. Generally, AF does not lead to any type of permanent disability. However, the presence of the condition can indicate that patients are already suffering from Atherosclerosis and are at an elevated risk for stroke.

Amaurosis fugax Risk Factors

People who suffer from Atherosclerosis of the neck arteries are the ones who are most susceptible to this disease. This coronary artery disease may develop due to:

• High cholesterol
• Diabetes
• Smoking
• Heart disease
• High blood pressure

Amaurosis fugax Complications

The common complications of this disease include:

• Stroke
• Loss of vision
• Myocardial infarction

In some cases, certain serious ocular disorders may also develop in sufferers.

Amaurosis fugax Prevention

As aforesaid, AF is usually a sign of an impending stroke. This can be avoided by:

• Following a low-fat, healthy diet and non-intake of fatty foods
• Regular exercise
• Avoidance of smoking
• Not drinking alcohol or restricting it to not more than 1-2 alcoholic drinks every day
• Getting blood pressure checked after every 1-2 years, particularly if there is a family history of high blood pressure
• Going through regular check-ups, to monitor stroke, heart disease or high blood pressure
• Making sure that your LDL or “Bad Cholesterol” level is less than 70 mg/dL.
• Following treatment recommendations of doctor

If you are an adult and suffering from high cholesterol, you should often check its level to keep it within control. Even healthy individuals should check their cholesterol level after every 5 years and treat it, if found high.

Living with Amaurosis fugax

If you are suffering from AF, here are some measures you should try to follow.

Do not smoke

Smoking tobacco products leads to vascular disorders and can worsen this condition

Do not drive

Try not to drive and let some other person steer the wheels. A sudden attack of AF, while you are driving, may put yours as well as others’ life at serious risk.

Maintain blood sugar

If you have diabetes, it is necessary for you to control your blood glucose levels. Unmonitored diabetes can further complicate your condition and make you susceptible to these episodes in increasing frequency.

If you or anyone in your family is suffering from temporary vision loss for a few days, seeking medical attention is imperative. Report any other abnormalities, such as a very severe headache, that you are possibly experiencing along with short-lived loss of eyesight. Prompt diagnosis and treatment can help prevent complications, such as stroke, and cure the condition in time.

References:

http://www.ncbi.nlm.nih.gov/pubmedhealth/PMH0001788/

http://www.umm.edu/ency/article/000784.htm

http://www.medmerits.com/index.php/article/amaurosis_fugax/P8

http://www.rightdiagnosis.com/a/amaurosis_fugax/intro.htm