What is eye visometry

Visual acuity is one of the main functions of the eyes, which is the ability of the eye to see separately two luminous points at the smallest angle of view. It is determined by an ophthalmologist. Visual acuity depends on abnormalities of refraction, diseases and eye injuries, as well as neurological diseases.

Visorometry is the method used to study visual acuity. To carry it out, the patient needs to recognize objects called optotypes. The definition of visual acuity is most often carried out without current optical correction and with it. In the first case, determine the relative severity (it is unstable, depends on a number of factors), and in the second - absolute.

Method definition

Visometry - a method of diagnosis, which allows you to determine visual acuity. For this procedure, special tables are used. They can be printed on paper or can be displayed on the monitor screen or with the help of a projector. Letters, numbers, rings with ruptures or figures, called optotypes, are presented.

The type of table should be selected individually, taking into account the age and psycho-physiological characteristics of the patient.

Diagnosis is possible without optical correction, if necessary with the use of optical correction.

In Russia, the visometry is most often performed using the Sivtsev-Golovin table, which contains twelve rows of letters.The largest are at the top, and the small ones are at the bottom. Diagnosis is performed alternately with the right and left eye.

Normally, a person should see the tenth line at a distance of five meters (one).

Visometry is one of the initial stages of ophthalmological examination. Sometimes before this procedure, refractometry is performed, which allows you to determine which lenses to insert into the frame for carrying out a vision test with correction.

Application area

At the first signs of visual impairment, it is necessary to consult an ophthalmologist and undergo a procedure to determine visual acuity.Also, visometry helps diagnose astigmatism, hyperopia, myopia.

Visometry is used in the following cases:

• Primary diagnosis of visual impairment.
• Evaluation of the correct selection of corrective glasses and lenses.
• Visual impairments of different origin.
• Controlling the progression of eye diseases.
• Preparation for surgical operations on the eyes.
• Controlling the effectiveness of treatment.
• Prophylactic examinations.

It should be remembered that this procedure can not be carried out to people who have mental disorders, which are accompanied by attacks of aggression and inappropriate behavior.

Tables for determining visual acuity

There are a large number of variants of tables for testing visual acuity. Consider the most famous and often used of them:

1. Sivtsev's table.It is most often used by ophthalmologists. This table consists of twelve lines of letters. The size of the letters in each line decreases from top to bottom. On the left side is the letter "D which means the distance from which a person with normal visual acuity should see the signs. It is two and a half meters for the bottom row and five meters for the upper row. On the right is the letter "V which is a conventional unit, indicating the severity. Vision is normal (unit), if a person can see the tenth line at a distance of five meters.
2. The Snellen table.It consists of eleven lines. On top is the single largest letter. Other letters also decrease from top to bottom. The check is carried out at a distance of six meters.
3. Table Golovin.This table consists of equal in height and width of rings with breaks. In normal vision, a person should distinguish two remote points with an angular resolution equal to one minute at a distance of five meters. The Golovin table can be used both separately and in combination with the Sivtsev table.
4. Orlova's Table.It is used to determine visual acuity in children who are not yet able to read. On the table are various pictures. Their size decreases from top to bottom. The visual acuity is determined in the same way as in the Sivtsev table. Normally, the child should see the tenth line from a distance of five meters.

Procedure

To study the vision and obtain reliable results of visometry, it is necessary to follow the rules of procedure. They include a fixed distance from the patient's face to the table, the illumination, the duration of the procedure.

When carrying out the visometry, the patient should sit on a chair, and the table should be located further by five to six meters. If a visometry is used to determine visual acuity near, the table is about thirty-three centimeters from the eyes.

This procedure can be performed both for diagnosis of monocular vision (separately for the right and left eyes), and for binocular vision (for two eyes simultaneously). If monocular vision is determined, one eye is covered with an opaque shutter.

The ophthalmologist shows the patient certain optotypes, which he must name, beginning with the top line. The lines from the first to the sixth are read if the patient named them without errors.From the seventh row to the tenth one error is allowed.

Visometry should be performed without correction or if necessary selection of glasses or soft contact lenses with optical correction (in this case, frames and a set of glasses with different diopters).

results

The results of the visometry for each eye are recorded separately. There is a special formula for this. The visual acuity of the right eye is designated as Vis OD, and the left one is Vis OS. The result is written in the form of numbers.

, means that the patient has recognized all ten lines of the table, so his vision is equal to one hundred percent.

If, for example, Vis OD then it means that only the symbols of the top five lines are recognized by the right eye, and the person has 50% vision.In the case when the patient named the symbols in the eleventh and twelfth lines, his vision is at the level of one hundred and fifty and two hundred percent respectively. This result is very good.

With visual acuity less than one, a correction of vision is prescribed.To do this, use a special frame with glasses of different diopters. With the help of this select the lens for future glasses.

After the procedure for determining visual acuity with correction in the patient's card, a corresponding entry is made. For example, vis OD = 0.3 sph -0.7 = 1.0.

It is worth noting that now you can carry out visometry without tables.To replace the tables comes the computer method of diagnosis, which allows you to quickly determine the quality of human sight with both eyes.For this, the patient needs to look at the center of the screen. After completing the procedure, the computer will issue a series of recommendations for glasses for glasses, if they are needed.

A big plus of computer diagnostics is the accuracy and speed of the survey.

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conclusions

To diagnose visual acuity, the method of visometry is used. It is considered the standard and the most common method. During the procedure, special metric tables with optotypes are used. The type of the table is selected individually for each patient. Also now, computer diagnostics is used, which allows you to determine visual acuity more quickly and accurately.

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