amaurosis

Amaurosis: description

The term amaurosis refers to blindness, ie the complete inability of a sensation of light. This corresponds to the scientific definition of blindness. According to the Schwerbehindertengesetz (SchwbG), those persons who have an amaurosis are considered blind.

In addition, patients with a visual acuity (visual acuity) of less than 0.02 are also classified as better on the better eye and those with a greater degree of impairment than blind. The visual acuity describes visual acuity. Physicians describe the area of ​​the environment that can be seen without moving the head. When restricted to a mere 5 degrees, humans are considered blind because they can no longer focus on seeing in space.

Amaurosis: occurrence

The frequency of blindness varies by region of the world. In Europe, about every thousandth inhabitant is blind. In developing countries, the proportion is higher, because here several infectious diseases threaten the eyesight: For example, in trachoma areas (trachoma = bacterial eye infection) up to four percent of the population are blind, in areas with onchocerciasis (a parasitic disease) even more than 20 percent.

Two diseases that lead to an amaurosis should be considered in the following:

• Amaurosis fugax
• Liver congenital amaurosis (amaurosis congenita)

Amaurosis: symptoms

If a patient suffers from an amaurosis, he no longer sees anything on the affected eye. Depending on the cause of amaurosis, various other symptoms may occur.

Symptoms of Amaurosis fugax

With an Amaurosis fugax, someone suddenly becomes blind for a few minutes, almost always in one eye. No pain occurs. This temporary blindness may be the harbinger of a stroke and may be accompanied by other neurological deficits such as hemiplegia. Other possible underlying illnesses with Amaurosis fugax are for example heart problems, hypertension or overweight.

Symptoms of Leber’s Congenital Amaurosis

In Leber’s congenital amaurosis, blindness occurs in both eyes from birth or develops within the first year of life. In some cases, a small portion of the field of view is preserved, so that patients can see through appropriate aids for the blind.

Sometimes affected children press their fingers over the eyes, because they perceive at least light flashes. This is called the oculo-digital phenomenon. In addition, patients often suffer from nystagmus (“eye shivering”) and are hyperopia. Liver congenital amaurosis may also be associated with cataract (opacity of the eye lens) or keratoconus (protrusion of the cornea of ​​the eye).

Amaurosis: causes and risk factors

There are several diseases that may underlie amaurosis. The risk factors are accordingly variable. The most common causes of blindness in Europe are:

• Diabetes mellitus (diabetic retinal disease)
• Age-related macular degeneration (destruction of the point of sharpest vision on the retina)
• Green Star (glaucoma)
• injury
• Inflammation (uveitis)
• Retinal detachment (retinal detachment)

Apart from that, there are specific reasons that can lead to different types of amaurosis. These are described below.

Origin of Amaurosis fugax

If the blood supply to the retina (the retina) is disturbed for a short time, a fatal blindness develops. Reason for this circulatory disorder are often vascular diseases of the larger, feeding vessels. These include, in particular, the carotid artery (carotid artery). Arteriosclerosis causes plaques to form on its inner wall. These can come loose and be flushed with the bloodstream into the central retinal artery (Arteria centralis retinae). In the tiny ramifications of the vein, they impede blood flow and thus cause a temporary loss of function of the retina.

According to the cause of amaurosis fugax, the risk factors are those that favor vascular disease. These include:

• Smoke
• high blood pressure
• older age (over 40 years)
• Heart disease such as mitral valve calcifications or connections between the atria (persistent foramen ovale)
• Diseases of the rheumatic type

Genesis of congenital amaurosis

As the name implies, Leber’s congenital amaurosis is congenital (= congenital). It is inherited from the parents to the child. So far, several genes have been found, the change (mutation) are considered to be the cause of this type of amaurosis. In some cases, the genetic information of one parent is enough to cause amaurosis (autosomal dominant inheritance). In other cases, a child has to be inherited by both parents to get the genes (autosomal recessive inheritance).

Amaurosis: examinations and diagnosis

If you can not see anything on one or both eyes, consult an ophthalmologist. This first asks you in detail about your medical history (anamnesis). He will ask you the following questions:

• Since when can you not see anything anymore?
• Do you have pain?
• Are both eyes affected?
• Do you suffer from vascular disease?
• Are hereditary diseases known in your family?

The doctor then examines your eyes. On the one hand, the visual acuity (visual acuity) is determined. To do this you need to recognize certain letters or numbers at a given distance on the wall. Your doctor will then light your eyes with a slit lamp. So he can examine the different sections of the eye.

At a Amaurosis fugax Often small, bright shimmering deposits can be found in the vessels of the retina, which clog these. In order to confirm the suspicion of this kind of Amaurosis and to recognize possibly threatening bottlenecks in the blood supply of the brain in time, a neurologist and a vascular surgeon should be consulted. They examine the arteries that supply the brain with blood on the one hand with the stethoscope and on the other hand by means of ultrasound (sonography). So you can determine possible mixtures. Circulatory amaurosis should differentiate other possible conditions such as migraine or optic nerve inflammation.

In the congenital amaurosis the ophthalmologist may make the following findings during the examination:

• Nystagmus (eye shaking)
• Strabismus (strabismus)
• no reaction of the pupils to incident light
• initially an inconspicuous retina, later defects in pigmentation of the retina and its vessels

In this hereditary amaurosis, should be excluded by a pediatrician possible other diseases that often occur additionally. These include kidney disease, epilepsy and mental retardation.

Amaurosis: treatment

Being blind makes day-to-day life difficult. But with the help of various tools, blind people can find their way around their environment. These include:

• Computer programs that read the information out loud on the screen
• Household appliances that communicate with the person via sounds, for example, when a saucepan is filled to the brim
• a blind stick to recognize obstacles

In addition, guide dogs can increase safety on the move because they also recognize higher-level obstacles such as hanging mailboxes missed by a blind stick.

Therapy of Amaurosis fugax

Since the Amaurosis fugax usually lasts only a few minutes, it is acutely often not treated. It is important to ensure the long-term blood flow to the arteries supplying the brain. For this, a so-called blood thinning is often necessary: ​​The patient gets drugs such as acetylsalicylic acid, which prevent the blood from clotting, thus narrowing vessels. In addition, a healthy lifestyle is of great importance to avoid a possible impending stroke. These include:

• the abandonment of cigarettes
• regular sports
• a good glycemic control in diabetes mellitus
• the lowering of blood pressure in patients with hypertension
• a healthy diet

Amaurosis: disease course and prognosis

Depending on the cause of the amaurosis, it may remain permanent or disappear after a short time. The Amaurosis fugax usually lasts only one to ten minutes. In rare cases, it takes a few hours. Since it is often due to the narrowing of blood vessels supplying the brain, it can announce a stroke.

Of the amaurosis congenita affected children often come blind or die during their first year of life. In some cases, a small portion of the visual field remains, so that patients can even learn to read with appropriate visual aids.