Blindness: types of pathology and tests used to determine it

The problem of blindness today is particularly acute - in the world about 100 million will be counted. blind people, and this figure is increasing every year.The growth of patients is caused by poor organization of occupational safety at work and at home, the use of toxic substances in agriculture, environmental problems and other factors. More details on the types of blindness, the causes of its development, the main tests used to diagnose, and a possible outcome for patients with this pathology, read further.

Definition of blindness and types

Blindness implies the disruption of the normal functioning of the organs of vision, in which the person sees nothing.In some cases, visual perception is not complete, in others it is only about disturbed visual acuity (although, distortions will be strong enough) or changes in color perception.

Blindness is acquired, congenital and not always characterized by complete loss of vision - it can be about changes in the acuity of perception of objects or color distortions.

The main types of blindness:

• Complete (or absolute, amaurosis)- pathology is innate. There is no reaction of the pupil to the light, the visual function does not work.
• Scotoma - loss of individual fields of vision. That is, the visual function suffers in certain areas of space.
• Hemianopsia- in this case, only certain halves of the field fall in both eyes, and this manifests itself from time to time.
• Color blindness- problems with the perception of colors, which are expressed in a decrease in the ability to correctly distinguish certain color shades or its complete absence. They suffer from green, blue and red colors (only one or all at once).

• Peripheral blindness- a person can not distinguish objects in the peripheral, i.e. lateral review. It is diagnosed by perimetry and the main cause of the occurrence is peripheral dystrophy of the retina.

Blindness, which is expressed in the deterioration of the vision of objects in the dark, is called chicken, and as a result of prolonged work at the computer or strong fatigue - a false chicken.

If certain areas of the visual zone in the brain are damaged, selective blindness may develop. In this case, a person does not see such signs of an object as an exact shade or form.

Causes of development of blindness

Blindness can appear for a number of reasons.The main pathological disorders of the visual system that cause its appearance:

• Light rays do not reach the retina or do not focus on it as they should. It is characteristic for strong degrees of myopia and hypermetropia.
• The retina can not normally perceive light pulses. As a rule, arises against the background of severe retinal diseases.
• Due to pathologies in the structure of the brain, information coming from the organ of vision is not perceived as it should.
• Nerve impulses in the brain centers come in a distorted form.

According to official WHO data, cataracts cause loss of vision in 47.9% of all cases, and glaucoma - in 12.3%.

Blindness can also occur because of:

• age-related decrease in visual acuity - 8.7% of cases;
• Leber's amaurosis is a congenital disease that leads to a complete loss of vision;
• keratitis - inflammation in the cornea;
• Diabetic retinopathy is a serious complication of diabetes;
• onhoznekoza - damage to the organs of vision, skin by helminths;
• trachoma - infectious damage to the organs of vision.

To complete blindness can lead retinopathy of prematurity - a serious pathology that causes irreversible changes in the vitreous body, the retina of the eye.In children, the disease in some cases causes congenital rubella - it penetrates into the blood of the fetus from the infected mother.

Diagnostic Methods

To determine color blindness, loss of visual fields, the presence of cattle, special tests are used. About them further.

Definition of color blindness

If there is a suspicion of color blindness, an examination with the use of anomaloscopes is carried out.The principle of their action is to achieve the perceived by the eye of equality of colors by mixing colors. The patient looks at the anomaloscope and sees the light streams in a special way. The results of the test are interpreted by the doctor, taking into account how the patient's shades and healthy person should recognize the shades.

Anomaloscope - device for the diagnosis of color perception anomalies

The main way to diagnose color blindness is pseudo-isochromatic tables.

Other tests:

1. Stilling- have the form of 64 pages with different notations and color fields.
2. Holmgren's- involves the use of woolen coils of different colors, all the balls of 133 pieces.
3. Ebeneus and Girinberg- in special instruments are placed plates of two colors, but different shades.

Less often, but also using the method Justova, tests Ishihara and Rabkin.

Visual field loss tests

These tests are used to determine the intervals of the falling fields within the overall visual range.They help in a timely manner to diagnose various pathologies of a general nature and CNS diseases that affect the visual function.

For an accurate assessment of the range of vision, there is usually not one test, but several.

Basic methods of verification:

• Focusing test- held alternately for both eyes. The patient closes one eye and focuses on the nose of the doctor who is standing in front of him. The doctor slowly moves his finger from one edge of the field of view to the other, and the big one signals when he sees a finger in front of him.
• Amsler's grid- allows to diagnose degenerative processes in the macula. The test uses square bars of 4 inches, the straight lines of which form a square. This method is also used for astigmatism.

Amsler test

• On the tangent- you need a black screen with lines and circles that come from its center point. The patient sits in front of the screen, closes one eye (any) and looks intently at the target point. The task is to follow the moving objects and signal about each seen.

There should not be any discomfort during the test.

Diagnosis and prognosis

The diagnosis of complete blindness is put in the complete absence of the pupil's reaction to light, with partial form the visual function suffers to a great extent, but a person can see objects and their characteristics.All types of livestock and hemianopsia are identified using such diagnostic techniques as perimetry and campimetry.

The procedure of computer perimetry

If blindness develops as a result of damage to the optic nerve or stroke, it will not be possible to restore vision.

After a stroke, as a result of damage to the optic nerve develop severe forms of blindness, which can not be fully restored.Compensate for the defect is possible, but insignificantly. A patient with a diagnosis of blindness is recommended to use manuals and books with a special font, appropriate software and so on - the choice of means of adaptation for people with vision problems today large.

Books for the Blind with a special font

Because sudden blindness is a severe shock, many patients develop depression. For this reason, it is necessary to observe not only an ophthalmologist, but also a psychiatrist.

For hemianopsia and scotoma, predictions are more favorable - it is necessary to eliminate the factors that caused their development (for example, a tumor or detachment of the retina).Atrial scotoma, which arose because of spasmodic vascular cells in the brain, is treated with spasmolytic drugs. To get rid of congenital color blindness is impossible, therapy of acquired pathology presupposes elimination of the cause that caused its development.

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conclusions

Blindness is complete, partial, peripheral and color, has an innate or acquired character.To establish an accurate diagnosis, various tests are carried out.Forecasts with complete blindness are not very favorable, congenital color blindness is also not treated, but effective therapy for scotoma and hemianopsia can significantly improve the patient's quality of life. If the diagnosis is "complete blindness a person is given a disability.