Table of view - what tables are and how do they check the human vision?

Vision is incredibly important for any person, it is with his help that people perceive overwhelming information from the outside world. And vision is a measurable characteristic.You can check its sharpness, resorting to special techniques, mainly - to special tables.What are these tables and how they can help in assessing visual acuity - we'll talk about this later.

Why check

To begin with, we will understand what the concept of visual acuity is in general.Visual acuity is a person's ability to distinguish two isolated points with a minimum distance from them.If the normal acuity is taken conditionally for 100% or for, then the indicators below the norm are usually designated as 5 and so on.

However, indicators may, on the contrary, exceed the norm, for example, a person can easily have vision in, or more - this is not an anomaly.

There are several reasons why a vision test is very important:

• Prophylactic examination of vision.If a person does not follow his eyes correctly, reads or looks at the screen under inappropriate conditions, then his vision will fall - and this is important to keep track of. This is especially true in cases where a person works at a computer. After a short time at a constant load on the eyes, hyperopia begins to develop.
• Diagnosis of eye diseases.If any diseases begin to develop in the visual system, the vision test will be one of the correct methods of their detection. Remember that timely treatment can prevent about 80% of eye diseases.
• Check for compliance with regulations.A certain level of vision is necessary for a certain number of classes, for example, for driving a vehicle.

Whatever your reason, most likely, you will have to deal with special visual inspection tables.Consider what they are.

Existing tables for verification

Although there are fairly simple and sophisticated modern technologies with which you can conduct a survey, ophthalmologists still prefer to apply special tables in their practice.But there is no single table that is used in practice (although some of them are more popular than others). The method for determining visual acuity through the developed tables is called visometry.

Checking visual acuity (visometry)

In addition to visometry, a test for astigmatism, color perception can be performed.

Sivtsev's table

In our country, Sivtsev's table has been used for a long time, since Soviet times.It is based on 12 lines with capital letters. Their size gradually decreases in each line. Each line on the left shows the distance in meters from which a normally seeing person can read letters.

Sivtsev's table

For example, for the top row it is 50 meters, while for the bottom row it is.

On the right side of the table there are other designations - visual acuity when reading letters, carried out from a distance of five meters.For example, if a person sees only the first row, then his vision is, and if he sees even the last row, then his vision is.

Vision is considered normal if a person discovers the tenth line in this table from five meters away.

In the table, only a few letters of the alphabet are used: S, B, M, H, N, K, and also I.It's not just that. The fact is that a person with normal vision should be able to distinguish separately two points, the distance between which is equal to one corner minute. If a person is at a distance of 5 meters, this distance is equal to 5 millimeters, that is, just the distance between the chopsticks of the letter "Ш" on the tenth line of the correctly compiled table.

When checking, the eyes are alternately closed by flaps, after which the person calls the letters that are in one or another row.If he called the whole series correctly, then vision is considered complete if he made mistakes then incomplete.

If the final indicator is less, then the person has myopia (nearsightedness). If more, then far-sightedness. Normal visual acuity is otherwise called emmetropia.

The Snellen table

If the Sittsev table is the most widespread in the post-Soviet space, the Snellen table, created in 1862, is the most widespread in the world.The principle is about the same. It contains lines of Latin letters, which gradually decrease in the direction down. The upper line with the largest letters, a person with normal vision can read from a distance at 60 meters, while the subsequent lines are read with, respectively, 36, 24, 12, 9, 6 and 5 meters.

Snellen table

The vision test is conducted from a distance of six meters. This distance is divided by the distance for which the letters that the patient was able to read are intended. That is, normal vision is 6/6 or 1.

Orlova's Table

Previous tables were based on letters.But what if the vision needs to be checked by a child who at the moment does not know how to read? Especially for such cases, the Orlova table was created.She has the same principle, but instead of letters there are pictures that children understand. In other respects, the principle of determining visual acuity here is analogous to the Sivtsev table.

First, the child is placed at a five-meter distance from the table.He must see the fifth line with each eye, if he has normal vision.If he does not see, then he is gradually brought closer to the table, until he finally starts to clearly and clearly recognize the forms.

Orlova's table for determining visual acuity in children

Golovin's Table

This table is often used not separately, but in conjunction with the table Sivtseva.It consists of ripped rings, that is, rings on one side of which there is a through hole. These rings are lined up in twelve rows and on the way down they gradually decrease.

Golovin's Table

If in the first row the diameter of the rings is 70 millimeters, then in the latter, their diameter is only a millimeter.

The general principle of checking the eyes does not differ from that used in the Sivtsev table. The sharpness is calculated exactly the same way, without changes.

Which tables are checked for drivers' vision

Although visual acuity check is very important for the purpose of identifying potential eye diseases, in most cases people are more interested in its practical application.In particular, for passing exams on rights, which necessarily require verification of visual acuity.

Vision check with drivers

In the overwhelming majority of cases, Sivtsev's table is used to check the visual acuity when surrendering.Sometimes the Golovin table can additionally be applied. If the vision as a result does not meet the necessary standards, the driver is asked to purchase suitable glasses or contact lenses, which will help correct his vision. An operation is also permissible.

Video

conclusions

Vision testing is a very important activity that will be needed not only for, for example, taking exams for management of a vehicle, but also to prevent potential eye diseases and a number of other purposes.So, if verification is required, you should not ignore it, you should conduct it as quickly as possible and with the application of the table that the ophthalmologist chooses.