Visometry - method features and table types

Every man has checked his visual acuity at least once in his life. Someone does this for preventive purposes, someone in the framework of planned surveys, someone, for example, to obtain a driver's license. And, as a rule, it is quite easy to determine visual acuity, because there are proven methods, thanks to which it becomes a very simple task. They include visometry.

Method definition

Visometry is a special diagnostic method by which visual acuity is checked.To implement this procedure, special metric tables are used, on which there are so-called optotypes.

The choice of tables is carried out individually for each patient on the basis of psychophysiological and age characteristics.

If necessary, optical correction is also performed during the diagnostics.

Application area

This diagnostic procedure is applied in a wide range of situations, when visual acuity testing is necessary.

This can be both preventive situations, and checks for the issuance of permits of various types.For example, drivers need to pass an ophthalmologist in a timely manner. visual impairments can affect the quality of the work, which in case of lack of attention to one's own eyes will lead to an accident.In addition to the classic test, drivers are required to pass a color perception test.

An example of a color perception test

Tables for determining visual acuity

For this type of research, not one fixed type of tables is used, but several are used at once. These include the following:

• The Sivtsev-Golovin table.Perhaps the most commonly used type of table, as the main optotypes in it, the usual letters of the Cyrillic alphabet are used.
• The Snellen table.A similar table, except that the letters this time apply Latin, but the main essence is the same.
• Orlova's Table.It is used in the first place when working with young children who do not yet know how to read. Instead of letters in the table are placed various simple figures that are easy enough for children to recognize. It, for example, a mushroom, an apple, an asterisk and similar figures.
• Table Landolta.In this case, the optotypes are semirings whose tears are in different sides, then to the left, then to the right, then from above, then from below.

  Sivtsev-Golovin table for visual acuity testing

Procedure

At a fixed distance from the patient there are specialized tables that are divided into a row. Each line contains a certain number of optotypes, that is, signs or symbols that need to be identified to the patient from the distance allocated to him.

Although the procedure seems simple, but in fact it is important to take into account a lot of different factors, which include the distance to the patient's face, lighting, the duration of each optotype, and much other.

The patient is seated on a chair, then at a distance of about 5-6 meters from him have a table, if you want to test the vision in the distance.

If you need to check your vision near, then the table is located about 33 centimeters.

Further, visometry is performed separately for the left and right eyes, while the unused eye is covered with an opaque shutter. After this, the diagnosis for the two eyes is carried out immediately. Further the doctor names optotypes which should be named as the researched person. He starts from the top lines, then gradually moves to the lower lines, where these same optotypes gradually decrease.

If errors are inadmissible in the first six lines, then from the seventh to the tenth it is permissible to call one of the displayed signs incorrectly.

results

Depending on what the results of the diagnosis were, the doctor decides on the need for vision correction. The rule is that a person calls 10 lines from a distance of 5-6 meters, this is one hundred percent vision. If he recognizes the lines above, then, respectively, he is determined by a smaller visual acuity, for example, the eighth line is 80%.

In case of abnormalities, such diseases can be diagnosed:

• Myopia or myopia;
• hyperopia or hypermetropia;
• astigmatism.

  Diseases diagnosed by visometry

Maybe even a vision of 120-130%, if the patient reads the appropriate lines.

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conclusions

The implementation of visometry is very simple. Moreover, recently there are interesting alternatives, for example, a computer analogue of the procedure, when all you need to do is look at one point on a special screen. Therefore, if you have a need to check your eyesight, do not be afraid to do it.

Also, read about the peculiarities of the development of children with vision problems, and about how vision is determined by disability.