Test for vision: how is it done?

Verification of visual acuity is the main ophthalmological study, from which any diagnosis begins. Tables for testing can be found in each office of the ophthalmologist. And absolutely not in vain, since it is from the visual acuity that the person's ability to perceive the world as fully as possible can depend on it. For this, complex research or equipment is not needed.

Why check

Timely verification of visual acuity allows time to reveal many pathologies.Most of them do not pose a threat to life, but seriously reduce its quality. It is on the basis of the results of visionimetry that glasses or contact lenses are selected. At the heart of the verification is the ability of a person to distinguish the image not only near, but also at a distance.

Determination of visual acuity (visometry)

To test visual acuity, the person is shown a graphic table. They are based on special graphic signs, or optotypes. They are created on the basis of letters of the alphabet, ripped rings or other images.

The accuracy of visual acuity testing directly depends on such conditions:

1. Type of optotypes.Cyrillic or other alphabet letters are recognizable much better than rings. But for children under the age of 7 the most recognizable can be optotypes based on images of animals, plants and simple objects.
2. The distance between the optotypes, as well as between the periods.This also affects the accuracy of the results of the study.
3. Age of the person. In children under 10 years old, as well as in the elderly, visual acuity can be reduced even by day.
4. Illumination in the ophthalmology room. The brightness of the table or screen backlight should be the same as the overall lighting.
5. The distance at which the study is conducted. It should be 5 or 6 meters.
6. Times of Day.In the morning and in the afternoon the visual acuity is higher than in the evening.

Tables with images of optotypes that are most often used to control visual acuity

The psychological state of a person during research is also important. Fatigue or stress significantly affect the reliability of the study.

By checking, you can identify the presence of such diseases as hyperopia, myopia.When a deviation is detected, a number of additional studies are conducted to confirm the diagnosis or to reveal the true cause of the reduction in severity. It is important to understand that reducing visual acuity is a common sign in the presence of defects in the retina, poor performance of the components of the anterior chamber of the eye (cornea, lens), optic nerve.

In addition to visual acuity, the reaction to color perception, astigmatism is checked, the eye bottom is examined by means of a slit lamp, and the fields of vision are checked.If necessary, they can prescribe keratotopography, tonometry.

Tonometry for determination of intraocular pressure

If a person wears glasses or contact lenses, the test is carried out 2 times. The first time the study is done with lenses, and the second time without them.

Existing tables for verification

The traditional version of the table for checking the eyesight is a familiar poster with graphic symbols.Recently, it is increasingly replaced by a special screen of frosted glass, which is projected image of optotypes.

A collimating research method is also used, which makes it possible to conduct a study even in a small office. Actually, the image is close to the human eye, the required distance is achieved with the help of an optical effect.

A special screen of frosted glass, on which the image of optotypes is projected

Research is recommended to begin with the eyes that see worse. Then they begin to test a healthy eye.

Sivtsev's table

Table Sivtseva most familiar with everything since childhood.It represents 12 lines of Cyrillic letters of various sizes. At sight in, optotypes of the tenth line are read from a distance of 5 meters. 10 and 11 lines are used to test the sight quite rarely. In this case, it is especially important to check the visual acuity on both eyes.

Sivtsev's table

Simultaneously with the table Sivtsev often use the table Golovin. This allows you to get the most accurate result.

The Snellen table

To check the eyes of people using the Latin alphabet use the Snellen table.Its main difference from Sivtsev's table is that it contains 11 lines. The first line should be visible from 60 meters. At a sharp sight it is necessary to distinguish the sixth row from a distance of 6 meters.

Snellen table

The best indicator of visual acuity is 6/6. It is the Snellen table that is the prototype of the Cyrillic tables.

Orlova's Table

To check the eyesight of preschool children, the Orlova table is used.The principle of its operation is identical to the Sivtsev table. But optotypes are not letters, but pictures. When examining the vision of a small child, you must first bring it to the table and ask them to name the objects in the pictures. This will help the child to quickly understand what is required of him.

Orlova's Table

At such research children quickly get tired. It is recommended to start showing the dates from the topmost one, one image per line. The rest of the images are asked to be called only if the child can not see the first one.

Golovin's Table

The Golovin table is constructed on the same principle as the Sivtsev table.But instead of the letters of the Cyrillic alphabet, it uses optotypes in the form of broken rings.These are the so-called Landolt rings. The gaps in each of the rings are directed in different directions: to the right, to the left, upwards or downwards.

Golovin's Table

When conducting the Visionometry, it is used together with the Sivtsev table.

Which tables are checked for drivers' vision

When checking the eyes of drivers, as well as when passing medical examination for obtaining a driver's license, the tables of Sivtsev and Golovin are used in parallel.The specificity of such a study is that the check is performed separately for the eye, seeing better and worse.

Simultaneous check on the table of Sivtsev and Golovin

If there is a decrease in visual acuity, it can be eliminated with the help of glasses or contact lenses. In rare cases, surgical intervention or laser correction may be required.

Video

conclusions

Verification of visual acuity is carried out using special graphic tables. They are in every ophthalmologic cabinet, as research with their help in goes to a standard examination procedure. The most frequently used table Sivtseva, if necessary in conjunction with the table Golovin. To study visual acuity in preschool children, the Orlova table is used. Its basis is not letters, but pictures.