Ideal vision: definition, indicators, recommendations. Vision test What should your vision be like?

We are faced with the need for a vision test every time we go to school or get a new job, undergo a medical examination at the military registration and enlistment office or to obtain a driver's license. But are we always aware of what exactly is determined in the ophthalmologist’s office and what is meant by a “vision test”? In many cases, an eye test simply involves checking visual acuity, although this is not the only important characteristic of our eyes.

Currently, a large number of sites offer online vision testing. The process looks simple - you need to select a vision test table that matches the diagonal of your monitor and move away 1-2 meters. However, vision testing in such conditions gives an extremely approximate result and there are several reasons for this: the size of optotypes (letters, geometric figures), the required image contrast, as well as the distance to the table, which must be at least 4 meters (standard in Russia - 5 meters, in foreign countries - 6 meters) to avoid the influence of accommodation on the result obtained.

Another drawback of such tests is that they omit checking such a rather important vision parameter as refraction. Then how can you use this indicator to determine whether you have , and/or .

We offer you the option of checking basic vision parameters at home, which gives the closest approximation to vision testing in medical institutions. You may find it a little more complicated than on other sites, and it will take a little more time, but the result will be much more accurate.

Before proceeding directly to the vision test, it is necessary to make some clarifications regarding visual acuity (VA) and refraction. Most people confuse these concepts. We will try to explain their meaning as clearly as possible, resorting to a certain simplification and deviating from the formulations accepted in ophthalmology.

Visual acuity

In accordance with professional terminology, visual acuity is the ability of the eye to distinguish between two points with a minimum distance between them. According to the conventionally accepted norm, an eye with 100% vision (V=1.0) is able to distinguish between two distant points with an angular resolution of 1 minute (or 1/60 of a degree).

In a strong simplification, this means that visual acuity is a qualitative indicator of eye vigilance, making it possible to measure how well (clearly) a person sees. Visual acuity of 1.0 (100%) is accepted as the norm - the so-called unit. It is determined using special tables with optotypes. In our country, the most common is the Golovin-Sivtsev table (or simply the Sivtsev table).

A person may have visual acuity greater than normal, for example - 1.2 or 1.5, or even 3.0 or more. In the case of problems such as refractive errors (myopia, farsightedness), astigmatism, cataracts, glaucoma, etc., visual acuity drops below normal, for example - 0.8 or 0.4, or 0.05, etc.

There are often attempts to express visual acuity as a percentage. However, it should be borne in mind that simply converting this indicator into a percentage is incorrect. In such a recalculation, everything is much more complicated, since it is necessary to take into account other parameters that determine the quality of vision. Therefore, although 1.0 is 100% vision, but, for example, 0.2 is not 20, but 49% of the norm. Similarly, any indicators of visual acuity that differ from one cannot be converted into percentages by ordinary arithmetic.

What is the difference in visual acuity? The main difference is the distance from which people see the same object equally clearly. For example, a person with visual acuity of 1.0 can read a license plate from approximately 40 meters, provided there is sufficient lighting. The lower the HP, the shorter the distance from which the number will be read. With a visual acuity of 0.4, this distance will be approximately 16 meters. At a greater distance, numbers and letters will already merge or become simply indistinguishable.

Another example is that a person with visual acuity of 1.0 reads the top line of the test table from a distance of 50 meters, and with a visual acuity of 0.1 - from no further than 5 meters.

Refraction of the eye

The eye is a complex optical system consisting of several refractive media: the cornea, lens, vitreous humor and aqueous humor. Like any optical system, the eye has a focal length (focus). The position of the focal point of the eye relative to the retina is called clinical refraction, or simply refraction of the eye.

Normally, the focus is on the surface of the retina and this condition is called emmetropia (the refraction is zero). With myopia, the back focus of the eye is located in front of the retina, and with farsightedness, it is behind the retina.

Even in the absence of serious vision problems, it is useful to know the refraction of your eyes. This will help predict future deviations from the norm in adulthood and old age (for example, in the case of latent farsightedness). If visual acuity is less than normal, then perhaps the cause is refractive errors that require correction. And when the refraction is normal, it is necessary to look for other reasons related to a decrease in the transparency of the optical media of the eye (for example, this could be amblyopia, clouding of the cornea or lens due to cataracts) or problems of a neurological nature.

Refraction is often confused with visual acuity. But visual acuity is a quantity that does not have a unit of measurement, while refraction is measured in diopters and is indicated using a unit of measurement, for example, 1.0 D (diopter or diopter). Sometimes in medical reports, prescriptions, etc., units of measurement are omitted (although this is incorrect); in such cases, the fact that we are talking about refraction is indicated by the entries: sph or cyl.

Refraction affects visual acuity - the greater the deviation of refraction from the norm, the more visual acuity decreases, although there is no direct relationship. That is, it is impossible to calculate how much visual acuity will decrease if the refraction deviates by a certain number of diopters. There is no feedback either - visual acuity does not affect refraction.

Determination of visual acuity using the Sivtsev table

First of all, you need to make a test table. Download and print it on a laser printer. It is important to consider the following requirements:
. the paper should be white, matte, without shades of yellow;
. When printing PDF files, Page Scaling must be turned off;
. Printing paper size = A4 (not Letter), orientation - Landscape.
We glue three sheets together and attach the resulting table to the wall using tape or pins. Depending on whether you will be checking your vision standing or sitting, the height of the table is selected - the 10th line should be at eye level.

The table must be illuminated with one incandescent lamp or two fluorescent lamps, so that the illumination is 700 lux (40 W incandescent lamp). The light from the lamp(s) should be directed only towards the table.

The proposed Sivtsev table contains optotypes for determining visual acuity in the range of 0.1 - 5.0 from a distance of 5 m, with the first 10 rows (with V = 0.1-1.0) differing in steps of 0.1, the next two rows (V=1.5-2.0) - at 0.5, and three additional rows (V=3.0-5.0) - at 1.0. The Sivtsev table, usually used in ophthalmology offices, contains only the first 12 rows.

The check must be carried out for each eye separately, i.e., cover the other eye with the palm of your hand or a piece of dense material, for example, cardboard, plastic (do not close your eyes!). Visual acuity is considered complete if in the rows with V=0.3-0.6 you made no more than one error when reading, and in the rows with V>0.7 - no more than two. It takes 2-3 seconds to recognize the sign. The numerical value of your visual acuity is equal to the numerical value of the letter V in the last of the lines in which you did not make errors beyond the norm. If a subject sees more than 10 lines from 5 meters, contrary to popular misconception, this is not farsightedness. In this case, we are dealing with visual acuity above the average (what is sometimes called eagle vision).

If you get a visual acuity value of less than 1.0, then it is advisable to check your refraction (see the next section - measuring refraction). If the results of the test below reveal a deviation from the norm, it means that a possible reason for the decrease in VA is a refractive error.

We hope that it is now clearer why and how far from the standard the vision tests that are offered on the vast majority of sites are. And even the test we propose does not guarantee 100% compliance with the result obtained during a professional examination by an ophthalmologist. But for a home vision test, the result is quite accurate.

Determination of refraction

In order to determine the refraction of the eye, you need to measure the distance to its farthest point of clear vision (DTYAZ - i.e., the point beyond which all images become blurry, because they are no longer focused clearly on the retina), having first made it artificially myopic by installing appropriate positive (or negative - for high myopia) lenses. Since the most optimal distance when doing manual work is 20-50 cm, the total refraction of the eye together with the lens should be from −2 to −5 diopters. Thus, with myopia of about 1 diopter, any lens (glasses) from +1 D, but not more than +4 D, should be placed on the eye (otherwise the error in determining the DTP increases). Myopes wearing glasses with a power of −2 to −5 D can determine refraction directly without installing any lens. Hypermetropes will have to add two or three diopters to their current full correction. If you are not aware of the presence of refractive errors and your visual acuity is 1.0, then the refraction determination must be carried out using a lens with a power of +3 D.

Materials
. a 50 cm ruler, or more conveniently, a construction tape with a lock and a bubble level indicator.
. small text (preferably a linear barcode of any product), a spherical lens with optical power calculated as described above.

Methodology
Holding the end of the ruler (or tape measure) and the lens with one hand, slowly move small text or barcode closer to your eye until all the letters (lines) become very clear - and measure in centimeters the distance from the lens (or eye, if the lens was not used) up to this point, i.e., before TTYAZ. Convert the resulting distance into optical power (100/DTYAZ) and discarding the optical power value of the attached lens (if it was used), obtain the refractive value of your own eye.

Example 1. A weak myopic person wearing +2.5 D glasses determined the DTY of one of his eyes at 33 cm, and the other at 25 cm. This means that his myopic refraction is 100/33 - 2.5 = 0.5 diopters for the first eye and 100/25 - 2.5 = 1.5 diopters for the second.
Example 2. A weak hypermetropic person wearing +4.0 D glasses determined the DTY of his eyes at 40 cm. Hypermetropia is -= 1.5 diopters.

With a high degree of myopia, there is a risk of obtaining inflated results, because an attached negative lens can provoke the activation of accommodation - then it is better to repeat the measurement under conditions of cycloplegia (this can only be done in a medical facility).

Astigmatism
1. Determine the position of one (usually weaker) meridian, to do this, first use the usual test for astigmatism, for example, the so-called figure radiate.

Those lines that are visible very clearly when looking at the test or the first to become clear when the test approaches the eyes, as a rule, correspond to the weak meridian (for simple and complex myopic, as well as mixed astigmatists; in the case of hyperopic astigmatism, the situation is the opposite, so artificially myopize your eye with the corresponding positive sphere).

2. Armed with a barcode (small text is not suitable) and turning it at an angle at which the image of the lines is most clear (based on the predetermined position of the axis of the main meridian in step 1), determine the TTYZ using the same method.

3. Turn the barcode 90 degrees in any direction and determine the DTY for this meridian, bringing the barcode closer to the eyes until the lines completely merge.

Rule. The clarity of vertical (or close to vertical) lines is given by refraction in the horizontal (or oblique, close to horizontal) meridian; the clarity of horizontal lines is in the vertical meridian.

Example 3. TTY along the vertical lines of the barcode in glasses with sph +1.0 is 31 cm, and along the horizontal lines - 25 cm. This means that the myopia of the horizontal meridian is 100/31 - 1.0 = 2.25 D, and the vertical - 100/25 -1.0 = 3.0 D. Diagnosis: complex myopic astigmatism.

The methods described above for determining visual acuity and refraction may seem difficult to perform, but in reality it does not require much time and effort. This investment will be repaid with results that are much more accurate than those that can be obtained using other testing options. And this is the advantage of the unique method described on our website (author) for determining eye refraction.

If you have any problems or questions about determining refraction using this method, you can ask a question in.

Eye test chart

Below you can download Sivtsev’s table in different formats.
CorelDraw— (2 large pages 297×630 mm)
PDF— (3 pages A4 landscape) and (3 pages A4 landscape)
SVG- and (1 large page 297×630 mm).

Page updated date: 19.02.2019

Simply put, visual acuity is a measure of a person's vigilance, providing the ability to measure the clarity of vision. Visual acuity of 1.0, the so-called unity, was taken as the norm. Today, visual acuity is determined using special tables with optotypes. In Russia, as a rule, Sivtsev tables are used to test vision.

The procedure for checking visual acuity using a special table is one of the items in the standard vision diagnostic kit. In such a table, only 7 letters are used: “SH”, “B”, “M”, “N”, “K”, “Y”, “I”, they can be located in rows in different combinations, but there are no other letters applies! Such signs are called “optotypes”; they are equal in width and height in each row, but decrease in size with each row, from top to bottom.

What do the columns mean?

To the side of the letters you can easily notice two columns, which are primarily of interest to the specialist conducting the study (ophthalmologist, optometrist):

First column D (50-2.5). Moreover, the letter D is derived from the term “Distance”, i.e. the distance in meters from which a person with 100% vision sees this line. Thus, “ШБ”, the topmost line is seen from 50m, and the tenth line - from 5m. 5m is the standard distance for vision testing.

The second column is V (0.1-2.0), and the indicator in this case means “Visus” - visual acuity. Thus, if from a five-meter standard distance a person is able to see only the second line of “MNC”, then his visual acuity is V = 0.2, which corresponds to 20 percent of the norm, etc.

Visual acuity test

– a standard study, which is carried out under standard conditions. The subject is placed 5 m from Sivtsev’s table (strictly in a straight line). One of the indispensable test conditions is the illumination level, which is 700 lux. First, visual acuity of the right eye is determined, then the left. The eye not involved in the test is covered with a special shutter to prevent the person from squinting. Visual acuity will be considered complete if no errors were made from lines 1 to 3, only one error was made from lines 4 to 6, and only 2 errors were made from lines 7 to 10.

True, there are also 11 and 12 lines, which are used for people with 150 or 200 percent vision (“eagle vision”) or when the cabinet is insufficiently long.

As a rule, normal vision indicates a healthy state of the human body, and also indicates the normal functioning of the liver and other organs. Most of the negative processes that occur in the human body, one way or another, contribute to the deterioration of vision.

What vision is considered normal?

Many people believe that normal vision is a sense. In fact, they are practically right, since vision is officially considered to be a kind of sensory perception or sensation.

Doctors believe that vision is the ability to perceive colors, light, see the location of objects or objects from a long or close distance, which represent entire images or images.

Humans and almost all animals have optical vision, but there are other types of perception of the surrounding world, among which we can distinguish, for example, ultrasonic sensations, which are characteristic of bats.

Refraction is considered a fairly common disorder of the eye processes. Today, about thirty percent of the world's population suffers from diseases caused by refractive errors.

The fact is that ideal vision must correspond to a group of parameters:

• refraction, which is 0;
• acuity, at which the normal vision is 1 or 100%;
• intraocular pressure - 22-24 mm Hg. in a healthy adult.

Good refraction of the eye, in simple words, is when the image falls exactly on the retina. In this case, the analyzer sends the correct impulse to the brain, and we see a clear, clear, legible picture. Diopters are a unit of measurement of refraction. When asking your doctor about your health, remember that normal vision is not a question of how many diopters you have, because ideally there should be 0.

Visual acuity is the ability of the eye to see as well as possible both far and close. The norm of visual acuity is 1. This means that a person is able to distinguish objects of a certain size at a distance corresponding to the standards. Determined by the angle between the minimally distant two points. Ideally it is equal to 1 minute or 0.004 mm, which is the size of the cone of the eyeball. That is, if there is at least one separating point between two cones, then the image of the two points will not merge.

The IOP indicator is not key, but it significantly affects the clarity of the transmission of what is seen, as well as the health of the visual apparatus as a whole.

What is ideal vision for children?

At each age, it is customary to place different demands on the body. A baby is born with 20% of the ability to see that an adult has. And so far his helplessness does not bother anyone, but only touches him. But over time, the baby develops and the eyes along with it. Children have their own vision standards.

Nborn sees all objects as spots of light, his visual capabilities are limited at a distance of a meter. IN first month the child perceives the world in black and white colors. IN 2-3 months attempts to focus attention on objects appear, the baby remembers the faces of his mother and father, notices when he gets into another room. IN 4-6 months The baby acquires his favorite toys, as he has already learned to distinguish between colors and shapes.

IN 1 year Normal vision is 50% of adult acuity. IN 2-4 years A child's development can be effectively checked with the help of ophthalmic charts, since he has already learned the signs on them and acquired communication skills. The sharpness on average reaches 70%.

Rapid development of the body and high loads on the eyes often lead to a sharp decrease in visual acuity by 7-8 years. You should be attentive to your child at this time and do not miss scheduled visits to the ophthalmologist.

IN 10 years the next surge of diseases occurs, this happens due to hormonal disruptions against the background of puberty. It is important to be prepared to support a psychologically emotional teenager if doctors recommend wearing glasses. It is also worth noting that at the moment at this age it is already permitted to wear soft lenses.

The video will tell you more about vision diagnostics in children:

What are the deviations?

Deviations from the norm arise for various reasons. Sometimes this is a congenital predisposition or an intrauterine developmental disorder. But to a greater extent, deviations appear as a result of life activity:

• excessive load on the visual apparatus;
• working in a poorly lit room;
• lack of nutrients in the diet;
• violation of operating rules when working with welding and lighting devices.

Failure to seek medical help in a timely manner or neglect of medical recommendations also has an impact. For example, children often act up while wearing glasses, take them off, and even damage them. By giving up optics, parents make their life easier, but in reality, throughout this period the child sees poorly, does not develop, and the disease continues to progress.

Doctors call the following diseases common types of disorders, both in adults and children:

1. Myopia or myopia. The problem is that the focal point is in front of the retina. The patient begins to have trouble seeing distant objects and notices that his eyes get tired very quickly. Sharp pain in the temporal part of the head is also characteristic. The disease does not affect objects that are nearby. A person can clearly distinguish the features of the interlocutor at arm's length, but when your friend without glasses walks across the road, do not be offended if he does not say hello.
2. Farsightedness or hypermetropia. In this case, the focus is located behind the retina, which makes it difficult to distinguish close objects. A clear symptom is also blurring of the picture. Sometimes strabismus occurs. It is difficult for such people to read, and it is practically impossible to work at a computer without glasses.
3. Astigmatism. The focal point of the retina is completely ignored. It can be located above or below it. The disease occurs due to deformation of the lens or cornea. Symptoms include:

Eye testing equipment

Medical clinics are filled with sophisticated equipment for diagnosing and treating eyes. Improvements in technology make it possible to detect diseases in the early stages and restore lost vision almost without a trace.
But ensuring prompt inspection at places of work or study, in institutions of regional centers and villages requires maximum efficiency with minimal investment. Therefore, ophthalmologists around the world do not use electronic devices, but the invention of Soviet doctors.

Vision examination

In modern medicine, the first step in diagnosing the capabilities of the visual organs is tables. To determine visual acuity, it is customary to use graphic systems with various kinds of signs. At a distance of 5 meters, a healthy person clearly sees the top line, from 2.5 meters - the very last, twelfth. There are three popular tables in ophthalmology:

• Sivtseva - letters are depicted;
• Head - open rings;
• Orlova - children's pictures.

The standard procedure assumes that the patient will be at a distance of 5 meters, while he must look at the signs on the tenth line. Such indicators indicate 100% visual acuity. It is important that the office is well lit, and the table has uniform lighting, both at the top and on the sides. The examination is carried out first for one eye, with the second covered with a white shield, then for the other.

Entry in the patient's card

If the person being examined finds it difficult to answer, the doctor goes up one line, and so on until the correct symbol is named. Thus, the entry in the map displays a line that a person can clearly see from 5 meters. The table necessarily contains transcripts: visual acuity (V) on the right and healthy “distance” (D) on the left.

Explanations of the symbols you see on the cards will help you decipher the doctor’s notes:

• Vis OD—visual acuity for the right eye;
• Vis OS is a similar indicator for the left;
• 1.0 - if this designation appears opposite both points, congratulations, you have excellent vision;
• 0.4 - When the doctor leaves a note like this, the acuity of that eye is only 40%.

The human eye is an entire optical system, quite complex in its design. It contains biological lenses that have their own separate and unique focus. This is how, when light is refracted, a picture is projected. And if the system is working properly, the image will be clear. The focal length has its own value; it is constant and depends on how curved the biological lenses are. In healthy eyes, the average distance should not exceed 24 mm - this is the norm, which is equal to the distance between the cornea and the retina.

When light is refracted, a process called refraction occurs, which has its own measurement values ​​- diopters. If refraction occurs without any deviation, the image falls directly on the retina and is focused there. The definition of normal vision is usually considered to be one or 100%, but this value is relative depending on the individual case.

What is the norm

It has been established that visual acuity is considered to be the norm - 100% or V = 1.0, eye refraction is 0, - 22-24 mm Hg.

The norm is considered to be a combination of indicators of refraction and acuity; pressure in this case refers to third-party assessment factors, but in some cases plays a significant role, because primarily affects the clarity of vision.

Why acuity and refraction are key:

• Refraction is the position of the focal point relative to the retina. The optical system of the eye consists of the lens, vitreous body, cornea and aqueous body. The incoming beam passes through each refractive medium in turn and reaches the macula - a small spot on the back wall of the eye, consisting of nerve endings, cones responsible for color perception, and blood vessels. The reflected beam projects an image and transmits it to the visual analyzer in the brain. And as a result, we see the image, and how well it enters the analyzer is the work of refraction. During the normal functioning of the totality of all systems, the focal point is on the surface of the retina, and this is called emmetropia (indicators are equal to 0). Refraction is measured in Diopters.
• Visual acuity- this is the ability to perceive two points at a minimum distance between them. Simply put, this indicator determines the quality of the reproduced picture in the brain. The difference between refraction is that acuity does not have an exact mathematical model of calculation, unlike refraction. All designations for visual acuity are conditional and vary depending on the individuality of the organism.

• Farsightedness. In this case, the focus of the image is behind the retina. A person sees poorly at a distance close to the eyes. Fogging occurs, it is obvious on the face, and may occur.

Treatment of farsightedness is possible with the information available.

• . Here there is an inability to focus on the retina. The basis of the disorder is the irregular shape of the cornea or lens. The main symptoms: distortion of the image, doubling of objects, fatigue after a short period of time (asthenopia), persistent tension and, as a result, headaches.

• Glaucoma. A complex of diseases based on deviations from normal intraocular pressure. Increased IOP is diagnosed more often than decreased IOP, and has different consequences. When reduced, it develops, when. With severe damage to the optic nerve, severe deterioration of vision occurs, up to complete blindness. This disease can only be treated surgically and there are several different forms, some of which are irreversible.

Read about the causes of congenital glaucoma.

• Cataract. A disease with progressive effects. The disease can occur at a young age, but mainly develops in the elderly. A person begins to react painfully to light, to distinguish color shades poorly, difficulties arise when reading, and vision decreases significantly in twilight () and darkness.

Some diseases occur throughout life. This is due to factors such as the specifics of the work, daily eye strain, hazardous production or improper working conditions. Often such diseases can be inherited and eye diseases can be diagnosed in children at a very early age.

Preventive methods

These methods include:

• Rejection of bad habits. Smoking causes vascular spasms, and alcohol destroys the liver, which most directly affects the eyes.
• A healthy and balanced diet will keep the vascular system healthy, which means blood circulation will be at the proper level.
• Vitamin therapy of local and general nature. And what eye vitamins to improve vision are described in this article. There are also .
• Regular exercise helps improve blood circulation.
• Avoid heavy loads, heavy loads, and prolonged work at the monitor.
• Do eye exercises and palming - this allows you to keep your muscles toned and relax your eyes after severe fatigue.

Exercises

Among the most common and simple exercises, there are several. They will help strengthen the muscle groups of the eyes, and therefore stimulate the strengthening of the position of the cornea and lens, blood circulation and the enrichment of all parts of the eye with oxygen.

1. Sit up straight and make the following eye movements several times: left and right, up and down, circular in one direction and the other. Blink.
2. Look into the distance and choose an object to look at. Hold your gaze for a few seconds. Then move your gaze to the point marked on the glass and focus your gaze on it. Look into the distance again. Blink.
3. Close your eyes tightly and open them. Repeat several times.
4. To relax your eyes, use palming.

According to Bates

A famous ophthalmologist of the 19th century, who stated that visual deviations depend on overstrain of groups of extraocular muscles, W. Bates invented a unique method of relaxing the eyes - palming. Nothing is required to use it. Except your own palms. Rub them to create heat and apply them to the eyeballs, pressing lightly with the back of them. Repeat several times. Mentally imagine a beautiful landscape or picture, remember pleasant things, and continue until you feel relaxation in the eye muscles. An indicator will be the fact that the flashes will begin to disappear with your eyes closed.