Ideal vision: definition, indicators, recommendations

What is vision? Vision is a person's ability to see larger and smaller objects under the same conditions. In medicine, it has been established that a person with vision without any deviations can distinguish objects and parts located at a visual angle of 1 minute between them. This vision is considered 100%. It is very rare to find people with vision of 200%, and even more rarely - with a value of 300%.

World record for human visual acuity

In 1972, the University of Stuttgart set a record within its walls that had never been recorded anywhere before. Student Veronica Seider surprised everyone with vision exceeding perfect vision 20 times the average person. She was able to see and recognize a person by facial features at a distance of about 1600 meters.

Is it possible to affect visual acuity?

Scientists and doctors of ophthalmology have tried to answer this question for many years in a row.

And in the end, they came to a common decision that through special training it is possible to increase visual acuity by 2-3 times. Of course, it is unlikely that it will be possible to break the record, but the visual apparatus will significantly improve its performance. Much exercises are more effective for “improving” vision for children. Because their visual muscles, like many others, are more elastic than those of adults.

What should a person's ideal vision be like?

The average person on the planet has vision of 1.

This number indicates 100% vision. Normally, such a person can see two points in separate places located at an angle of 1 minute between them. To determine visual acuity in medical terminology they use the numbers 0, 1, 1, 2. In one human eye there are over 120 million cells that are sensitive to light. The cerebral cortex deciphers information coming from cells and produces it in various shapes and colors.

The human retina consists of rods and cones. The first are responsible for the ability to see grey colour in low light, and cones for colored objects and details. Ideal vision is easy to confirm; to do this, you need to visit an ophthalmologist's office. The specialist will ask the person to consider special tables and symbols. It is very important that it is the tables hanging in the doctor’s office that can determine visual acuity, but not pictures from the Internet on the computer that “promise” to give an accurate result.

What tables are used to test visual acuity?

Today, there are several types of special tables that make it easier for a doctor to determine how well or poorly a person sees.

• Golovin table. This option consists of identical rings. They have holes in different parts"bodies". The specialist points out to the patient the rings that the person must examine; the patient must sit at a distance of 5 meters from the table.
• Snellen chart. It is used mainly in English-speaking countries. This table consists of 11 rows. The very first line contains one letter big size. In each subsequent line, the size of the letters decreases, and their number in the row increases.
• Orlova's table. It is used to test visual acuity in children. Here, instead of rings or letters, icons in the form of animals and plants are used. Vision is considered normal when a child sees the tenth line, sitting at a distance of 5 meters from the table.

• This is the most common type of perfect vision test. This table consists of letters of the Russian alphabet arranged in 12 lines. In the top line the letters are large, the lower they are, the smaller they are. Perfect vision 0 is when a person manages to recognize letters from the tenth line from a distance of 5 meters.

Deviations in the functioning of the visual apparatus

The most common disorder associated with the functioning of the visual apparatus is myopia. In medicine it is called myopia. This disease is characterized by a person’s ability to see only objects, objects and parts that are nearby. He can't see them from a distance. Also characteristic of myopia is an increase in eyeball. This pathology can be either acquired or acquired during childbirth, that is, congenital. The main symptoms of myopia:

• poor distant vision;
• while the near remains normal;
• When viewed, objects may merge into one object and the image may be distorted.

There are cases when a person develops false myopia, in which case drug treatment can help.

Another pathology in the functioning of the visual apparatus is hypermetropia. This disease is characterized by perfect distance vision and poor near vision. The main symptoms of hypermetropia:

• seeing objects as if in a fog;
• sometimes it is possible to develop strabismus;
• eyes get tired quickly;

Hypermetropia can be functional, normal or pathological.

What is astigmatism?

An equally complex disease of the visual system is astigmatism. It is often combined with myopia and hypermetropia. Astigmatism is characterized by a violation of the sphericity of the lens and cornea. This pathology can be congenital or acquired. Congenital astigmatism is often diagnosed in childhood, and in adult life it does not affect visual acuity in any way. But this is only in cases where the sharpness is not higher than half a diopter. When the pathology has more than one diopter, this indicates that vision is deteriorating. The visual apparatus needs urgent treatment. Acquired astigmatism often results from scarring of the cornea.

What is ideal vision for children?

The eyes are a paired organ that is formed before the age of 18. Vision, in turn, can be stable, but it can also change over time. human life. Children from birth to the first year of life experience development visual system.

After birth only experienced specialist can test the pupil's reaction to light. By the age of one year, children begin to distinguish familiar objects well. Distinguish them from each other by shape and color. After two years of age small man begins to see everything more perfectly and learns to distinguish the distance between objects. When a child goes to kindergarten, the load on the visual system increases. To maintain the child’s ideal vision during this period, it is necessary to take breaks between eye strains, giving them a rest.

Interesting features of the physiology of vision

This real facts, which not every person knows about;

• In ancient times, people tested visual acuity in this way: they looked at the sky at night, found the Big Dipper, then looked at a small star in the handle of a bucket. This was evidence that the visual apparatus was working normally.
• Weight of one human eye approximately 7 g and diameter 24 mm.
• Carrots can improve vision. This is absolutely true, vitamin A, which is found in this vegetable, helps maintain the full functioning of the visual apparatus.
• More than 90% of people in the world are born with gray-blue eyes. Closer to the second year of life, the eye color is formed, which will remain forever.
• Green eyes are the rarest in the world. Only 2% of people have this iris color.

• The lightest-eyed nations are considered to be the Poles, Swedes, and Finns, and the darkest-eyed are the Turks and Portuguese.
• For 1% of people on the planet, the color of the iris of one eye is different from the color of the other. Such people tend to have unusually high intelligence and can be very talented.

• Men blink twice fewer women.
• It is impossible to sneeze without closing your eyes.

Normal vision is vision without deviations in the visual system. First of all, normal vision is associated with normal refraction of the light ray in the eye. This means that the lenses, cornea and lens focus the image exactly on the retina of the eye, and not in front of it or behind it, and in its center, on the macula.

Each person has their own vision norm. It is determined by what line a person sees in the Golovin-Sivtsev table. The unit we are used to (1.0) means that a person sees the 10th line without correction means, this is his normal vision. One (1.0) also corresponds to 100%.

Now let's tell you a little more about the physical essence of normal vision.

What is the focal length of a healthy eye?

The eye is complex optical system, which consists of biological lenses. Each eye lens has its own focal length at which a clear image of visual objects is projected in the eye on the retina. The focal length has a constant value and directly depends on the curvature of the biological lens.

Before hitting the retina, the light beam passes through the cornea, then through the lens, after which it is refracted and focused on the retina.

An eye that perceives visual information without distortion has a focal length equal to the distance between two lenses that are located between the retina and the cornea. On average, this distance in an adult is about 23-24 mm. This focal length allows the eye to perceive visual information normally. When these distances differ, visual information is not focused accurately on the retina and distortion occurs.

Thus, it turns out that normal vision is vision in which visual information is projected exactly onto the retina of the eyeball, without distortion. And each person has his own focal length and his own standard of vision.

Refractive error

The refraction of light rays in the eye is called refraction; the refractive power of light rays is measured in diopters.

If light is refracted correctly, the visual image is focused precisely onto the retina.

Incorrect refraction of light rays (impaired refraction) leads to the development and appearance of diseases such as,. If they are present, a person sees the image blurry, unclear, double, and has difficulty seeing far or near. Used to correct refractive error medical glasses and contact lenses, which force the light beam to focus on the retina of the eye and make the image clear.

You can determine whether you have abnormalities in the functioning of the visual system or whether you have normal vision by going to the EYE Microsurgery Clinic named after Academician S.N. Fedorov.

At the Eye Microsurgery Clinic (Ekaterinburg)

The Microsurgery Clinic “Eye” (Ekaterinburg) performs. The examination is carried out without queues or long waits, using the most modern equipment, by highly qualified ophthalmologists. If you are diagnosed with a particular vision disease, the ophthalmologist will prescribe everything necessary treatment, operations (according to indications), as well as regular monitoring.

Normal odds

The ability of the eyes to see separately and distinguish between two objects located nearby is called visual acuity. Under normal conditions, two points can be seen at a distance of five meters. The distance between these points is 1.45 mm. If there is a decrease in visual acuity, then it will be impossible to successfully pass such testing.

Deviations from the norm (1.0) may occur naturally and caused by the aging of the body. However, vision often deteriorates sharply and decreases in at a young age and even in children. The reasons for this are mass computerization and the emergence of various diseases.

Indicators below 1.0 - what does this mean?

In order to understand the reason for the sudden change, comprehensive examinations. An acuity score below 1.0 usually indicates advanced disease. The most common ailments include:

• Myopia. Focusing occurs in front of the retina. Changes in visual acuity reduce the ability to distinguish objects in the distance, a feeling of rapid fatigue, pain, and headaches appear.
• Farsightedness. The focus of the image is behind the retina. Decreased visual acuity makes a person unable to see well at close range. Accommodation is impaired, blurred vision is observed, and strabismus occurs.
• Astigmatism. The reasons for the sharp decline are irregular shapes lens or cornea. Images are distorted, objects appear in two, and headaches occur.
• Glaucoma. The disease appears due to deviations from the norm inside eye pressure. When eye pressure decreases, the internal structure becomes deformed visual organ, retinal dystrophy. If optic nerve severely damaged, then with this diagnosis the disease leads to complete blindness.
• Cataract. There is clouding of the lens. As the disease worsens, the person begins to react painfully to light and has difficulty distinguishing colors. There are difficulties with reading and orientation at dusk.

The specifics of work can often lead to vision deterioration: improper working conditions, hazardous production, constant pressure attention. However eye diseases are also found in children. In this case, the loss of good vision is often associated with inherited ailments.

Basic Rules for Testing Eye Clarity

Visual acuity impairments are determined using special tables that display letters or numbers. The procedure is performed in an ophthalmologist's office or in specialized stores for the selection of glasses and lenses. Any first sign ocular disorder should be a reason for further diagnosis and treatment.

For an adult, tables with letters are used, for a child who cannot yet read, with symbols. The norm is when the 10th line out of 12 is clearly visible and readable. Based on such a diagnosis and further examination, it will be possible to understand what affects the deterioration of vision and what treatment will be optimal.

Basic verification rules:

1. A man sits at a distance of five meters from the table.
2. The images are located from the window on the opposite side.
3. The 10th line of the diagram is located strictly opposite the eyes.
4. The table must be illuminated with special lamps.
5. Each eye is diagnosed separately - one is open, the other is closed, but not closed (this affects the severity of symptoms and the veracity of the results).
6. You need to recognize a letter or sign within 2-3 seconds - longer time will already indicate a deviation.

How to do a home inspection

Interested in reducing the severity human vision, you can conduct preliminary diagnostics at home. Various online tests will help with this, where the result is given at the end.

You can also use tables for checking, as in an ophthalmology office. Examples of tables can be found on the Internet and printed on a standard A4 sheet. The finished sheet with images is placed on the wall. Installed above the table Fluorescent Lamp or two lamps (40 Watt) on the sides. The presence of the first changes and violations is indicated by the inability to examine the letters or symbols of the 10th line. In this case, you should immediately make an appointment with an ophthalmologist.

Dangerous symptoms

There are the first signs of vision deterioration, which may indicate the emergence and development of diseases:

Loss of visual acuity makes life joyless and causes the development of numerous pathologies. In order to detect deviations in a timely manner and successfully solve the problem, you need to regularly visit an ophthalmologist (at least twice a year). At risk are people with a genetic predisposition to diseases that have been in their family.

Visual acuity often decreases after injuries, for example, when the upper cervical vertebrae are damaged. Many diseases develop due to diabetes mellitus, cervical osteochondrosis, transferred genetic diseases. The organs of older people are subject to changes. Timely consultation with a doctor and diagnosis is the most important step towards a speedy recovery.

Visual acuity is the ability of the eye to see two points separately when they are as close as possible. The size of the image depends on the angle of view that is formed between the nodal point of the eye and the 2 extreme points of the object in question. Visual acuity is provided by cones located in the fovea macular spot retina.

Visual acuity standard

The standard of normal visual acuity is a visual angle of one minute (Naples, 1909, International Congress ophthalmologists), which corresponds to a value equal to 0.004 mm and corresponding to the diameter of one cone. To perceive two points separately, there must be at least one intermediate cone in the fundus between the two cones; it will prevent the images from merging.

What is the difference in visual acuity? The main difference is the distance from which a person sees the same object equally well. For example, people with 1.0 vision can read a car license plate from approximately forty meters. In ophthalmology there is such a thing as diopters. They express optical power contact lenses and glasses. Therefore, you should know that visual acuity and diopters (refraction) are different indicators.

Eye testing equipment

To identify visual acuity, special tables are used, which consist of a separate row of symbols of different sizes. The width of each letter or symbol is visible from a distance at a viewing angle of one minute, and the entire letter is visible from a viewing angle of five minutes. In visual acuity tables, there are numbers opposite each row. You, that on the right, it indicates the visual acuity of the reader of this row. The number on the left indicates the distance from which this line is visible at an angle of 1 minute. The Golovin-Sivtsev tables have 12 rows of letters and cut Landolt rings.

For examination of children preschool age Orlova’s visual acuity table is used, consisting of drawings of objects familiar to children. There are certain requirements for the tables so that the study of visual acuity is as accurate as possible. Marks (optotypes) must be black and printed on clean white paper. The lighting should be constant with a brightness of 700 lux, which is achieved using a 40 W light bulb, which is located at a distance of 25 cm and is covered from the patient with an opaque shield in the Roth lighting apparatus. The visual acuity chart should be placed on the wall opposite the window, at a height of 1.2 m from the floor (for adults).

Vision examination

Visual acuity is determined from a distance of five meters. The patient sits with his back to the window opposite the tables. Each eye is examined separately - first the right eye is examined, then the left. One by one, starting from the first row, the ophthalmologist shows the letters, asking the patient to name them. It is generally accepted that if, during testing, a person sees an object measuring 1.4 mm in illumination of 700 lux, then he has vision of 1.0. That is, this normal indicator for the average person. The tenth row at a viewing angle of 1 minute is visible from a distance of five meters, which is confirmed by the number opposite this row located on the left. The definition of visual acuity is written as follows: VIS OU = 1.0. If the patient sees only the first row with his left eye, the indicator is written as follows: VIS = 0.1. Instead of the letters of the first row, you can show widely spaced fingers against the background of a black shield, asking the patient to count. If the patient sees them closer than 0.5 m, then his visual acuity is recorded as follows: VISUS = finger counting.

In such cases, when the patient does not see their number closer than 0.5 m, the hand is moved in front of the eye in different directions opposite the light source. If the patient correctly names the direction of hand movement, the indicator is written as follows: VISUS = hand movements. When the subject is unable to determine the direction of hand movement, a light perception study is performed. To do this, a table lamp is placed to the left and slightly behind the patient at the level of his head. Using a mirror ophthalmoscope, a bright beam of light is aimed at the eye. By pointing this beam into the eye from different directions (right, left, above, below), the ability of individual parts of the retina to perceive brightness is determined. When the patient correctly indicates the direction of the light beam, it is written as follows: VISUS = 1 / ∞ P. L. C. The absence of the correct projection is written: VISUS = 1 / ∞ P. L. IC. Complete absence light perception is written as follows: VISUS = 0 (zero).

The influence of visual acuity on the formation of concepts

The phase dynamics of concept formation by healthy students and students with visual acuity impairments are the same. But the concepts of children with visual impairments differ quantitatively and qualitatively from the concepts of children in mainstream schools. Visual acuity (norm 1) within the range of 0.05-0.2 dramatically affects the formation of visual ideas. These students are limited in their perception of objects more than 5 meters away from their eyes. This leads to the fact that they form concepts based on verbal description, which are not supported visually. This leads to sketchiness and poverty of concepts. There are serious violations in the representation of the sizes of individual objects and spatial relationships. Children with visual acuity greater than 0.2 are not among those who have a strict relationship between visual acuity and concept formation. With age, the influence of visual acuity on the formation of ideas decreases. In the 4th, 5th, and 6th grades it has a significant influence, but from the 7th grade its role weakens. If visual acuity is greater than 0.2, it does not directly affect the retention of ideas. Mainly the reason causing a decrease vision does not affect the formation of concepts. Students with visual impairments have been found to have a lack of subject matter, fragmented concepts, and deficiencies in displaying the shape and size of objects. Severe conceptual impairments affect mental operations in complex situations.

Visual acuity in children

From the first day of birth, a person’s vision allows him to perceive everything around him. The eye is spherical in shape and protected by a dense membrane called the sclera. Its front part is the iris; the lens is located under the iris. There is a hole in the cornea - the pupil, the diameter of which, depending on the light, can vary from 2 mm to 8 mm. The back of the sclera is covered with a retina. The ability of the lens to change its curvature when the distance to an object changes is called inertia of vision. A newborn from the first week of life is considered sighted if he has a pupil reaction to light and a general mobile reaction. From the second week, the baby is able to briefly observe the movement of an object. From the second month of life, the baby reacts to the mother's breast. On the third, he recognizes his mother and fixates objects with his eyes. A blind baby can only respond to sound. For examination of children 3-5 years old, Orlova tables are used, which consist of drawings of different sizes.

In children in early age visual functions are plastic and amenable to influence, therefore vision correction, namely special exercises, in many cases allows you to restore normal vision. But we need to approach this quite seriously not only kindergarten, but also at home. Perform exercises systematically and consistently, alternate correctly different kinds child activities with rest for the eyes. Use bright toys and objects to make the child interested in doing useful things. This vision correction begins with performing exercises to relax the skeletal muscles. The most convenient position for this is the “coachman’s pose.” The child sits on a high chair, hands hanging freely, feet shoulder-width apart, shoulders slightly hunched, head resting on the chest. This position is the most relaxing a large number of muscles. Very effective and useful exercise To achieve the maximum degree of relaxation of the eyes, “palming” is used (warming the visual tract with the warmth of the hand).

Visual field examination

The patient and the ophthalmologist are positioned opposite each other at a distance of 70-100 cm and close their eyes: the patient is on the left, the ophthalmologist is on the right, or vice versa. The doctor moves his hand in different directions with his fingers spread, asking the patient to tell about the appearance of fingers as soon as he sees them. In this case, the hand should move in a plane located in the middle of the distance between him and the subject.

If the patient and the ophthalmologist simultaneously notice the appearance of fingers, this indicates a normal field of vision. Examination of the visual field using a perimeter is called "perimetry". The main advantage of perimetry is that the visual field is projected onto the concave spherical surface of the retina, which allows one to obtain accurate information about the function of the retina in the periphery.

Features of vision

Peripheral vision is a person's vision through the peripheral portions of the retina. The examination is carried out using projection perimeters, in which a light object is projected onto the inner surface of the arc or hemisphere. The periphery complements central vision and improves the ability to navigate in space. A set of filters and apertures allows you to quickly and measuredly change the size, brightness and colors of an object.

Spheroperimetry - daytime, twilight and night field of vision.

Kinetic perimetry is characterized by ease of execution and is compared with Lister and Goldman perimetry.

Campimetry is a method of examining the visual field on a plane. It allows you to determine central boundaries within 30-40 °. Widely used to determine scotoma - a blind spot in the field of view. This is an area of ​​the retina of the eye with partially altered or completely lost visual acuity, surrounded by relatively intact or normal light-receiving elements of the eye (“cones” and “rods”).

The Amsler grid is one of the methods for testing vision features, the ability to test the smallest changes in central and peripheral vision. Technique:

1. If necessary, wear glasses.

2. Close one eye.

3. Look at the point in the center and focus your gaze on it throughout the entire period of examination.

4. Look only at the center, make sure that only straight lines are visible, and that all squares are the same size.

Perimetry technique

Using perimetry, each eye is examined separately. The patient is closed with one eye (first the left one) and seated with his back to the window in front of the perimeter, which should be illuminated and located opposite the window. The patient places his chin on the perimeter stand, resting against its protrusion with the lower edge of the orbit of the examined eye. The nurse stands opposite the patient and observes him so that the patient fixes the central perimeter mark at all times. The patient is explained what he should say about the moment of the appearance of an object that moves in an arc from the periphery to the center, in the field of view.

You can make movements from the center to the periphery. In such cases, the patient must immediately report the moment the object disappeared. The movement of the object should be smooth, without jerking, approximately 2-3 cm/s. For greater accuracy, the movement of the object can be repeated several times. The counting is carried out on the perimeter arc when the patient indicates the moment of disappearance or appearance of the object. Returning the arc of the perimeter around the axis, the field of view is gradually examined along 8-12 meridians at intervals of 30-45°. Increasing the number of examination meridians increases the accuracy of perimetry, but at the same time the examination time is delayed. On modern projection perimeters, registration of the received data is carried out automatically. If this is not possible, recording of perimetry results is carried out on clean slate paper, where a diagram of 8 meridians is prepared by hand and perimetry data is recorded against each.

Normalized reductions in visual acuity

When using combined glasses with microprism lenses, there is no significant reduction in the illumination and sharpness of the image that the patient observes through the lens. Very effective for the treatment of amblyopia with anisometry and strabismus is a technique using optical elements that affect the decrease in visual acuity of the fixing or dominant eye. For this purpose, appropriate standardized visual acuity attenuators are used, which are a transparent plate with a diameter of 30-40 mm and a thickness of 0.5-2.0 mm, made of optical glass or plastic. An appropriate microrelief is applied to it in such a way that the light intensity decreases by a strictly defined amount. Ophthalmological practice shows that it is advisable to have graduated degrees of reduction: 10, 20, 30, 40, 50, 60 and 80%. The plates can be directly attached to inner surface spherical lens or glass in the form of a spherical lens, which is then installed in an eyeglass frame and used by the patient for constantly wearing points.

Computer syndrome

The so-called “computer syndrome” increasingly leads to loss of visual acuity in modern world. According to statistics, 80% of users suffer from this disease. Not long ago, new vision problems appeared called “computer addiction syndrome,” that is, eye fatigue syndrome for those who work with electronic gadgets. And this is not only computers, but also all modern technology. Already proven harmful influence blue spectrum of radiation that a person receives when working with such devices. For a better understanding, the blue spectrum is the shortest wave that negatively affects the visual system.

In addition, the image on the monitor screen consists of pixels that you cannot immediately see with your eyes. But our brain perceives them, which ultimately tires it: so many small dots it must be collected in the head and submitted to the vision apparatus as an object! It turns out that such actions are a constant stress factor, which results in irritability and insomnia. The risk group includes people aged 15 to 34 years, because they are more connected with electronic devices, moving from one to another: from a computer monitor to a TV, from a TV to a tablet, then to mobile phone... Such continuous change does not allow a person to look away.

What is visual acuity? In Russia and the CIS countries this value is measured in conventional units and its indicators can be different: 0.1; 1; 2, etc. They range from zero (i.e. complete blindness) to infinity.

It is worth explaining that visual acuity is the ability of the eye to separately see two points located at a certain distance from each other.

In the CIS countries and Russia, it is customary to check this value using various posters (Golovin and Sivtseva in adults and Orlova in children).

With visual acuity equal to one 10 lines are clearly visible at a distance of 5 m from the table (this is considered the norm). If 12 lines are visible, then the vision level is 2. C right side indicators of a given value are written from the lines depending on the number of lines that the subject sees at a distance of five meters. That is, if he can distinguish only 1 line, then the indicator is 0.1; if 2 – 0.2, etc.

What does visual acuity one mean? It's important to understand what it is normal level vision (or 100%). According to standards, an eye with this indicator is able to distinguish between two separate points with an angle between them of 1 minute or 1/60 of a degree. In Western terminology, this value is equivalent to 20/20.

If this value is below one, then treatment is necessary.

Tables to check

Special posters are used to carry out diagnostics. They may contain images of various designs, letters, icons or hooks.

• The most popular among Russian ophthalmologists is a poster depicting letters (Sivtsev’s table).
• Sometimes doctors use the Golovin table, which shows rings with ruptures.
• When checking children, ophthalmologists prefer Orlova’s poster with different pictures.

Letters or pictures are located on twelve lines, and their size decreases with each line (starting at the top and going down). On the left side of each line, the symbol “D” indicates the distance from which, with good vision, the subject should see all the symbols. For the top line it is 50 meters, and for the bottom line 2.5. On the right side of the lines, the letter “V” indicates visual acuity indicators, which are correct when the subject reads symbols from 5 meters. This indicator is equal to 2 if the subject distinguishes the bottom line and 0.1 if he sees only the first.

How is the diagnosis carried out?

The subject is seated five meters from the poster. Next, the doctor diagnoses each eye separately. He starts with the right and then moves to the left.

1. First, the ophthalmologist asks you to name a series of letters located on the tenth line of the table. The correct answer means that the visual acuity index is equal to one.
2. If the subject names the letters on line 10 incorrectly or often makes mistakes, the doctor moves to the top, and if the answer is correct, he goes lower and lower until the patient starts making mistakes again.
3. The last line that he can distinguish and will indicate visual acuity (if he sees all 12 lines, then this value will be 2).

In ophthalmology, people are known who have developed visual abilities up to five or six units. This was manifested in the fact that they clearly saw objects located at a distance of 100 meters and further. There have been exceptional cases in the history of medicine when this figure was sixty units and a person could see the rings of Saturn in the starry sky, which with an average value (i.e. one) can only be seen using a telescope.

Entry in the patient's card

After diagnosis, the doctor makes entries in the patient’s chart. Most often they are the following: ViS OD and ViS OS. These symbols are quite easy to decipher. The first entry refers to the right eye, the second, respectively, to the left. At in good condition visual function For both eyes, 1.0 will be written opposite each entry.

Snellen chart

The Snellen chart is most often used foreign countries, especially the USA. Just like on Sivtsev’s poster, large letters occupy the top lines and their size decreases downwards.

Snellen chart

The poster is made in such a way that if a person has 100% vision, then he can read each line from a distance of 60, 36, 24, 18, 12, 9, 6 and 5 meters (which equals 100, 70, 50, 40, 30, 25 and 20 feet respectively) up to the red line.

For diagnosis, the subject is seated at a distance of 6 m (20 feet) from the poster. He is asked to close one eye and read the letters with the other. The lowest row that the patient can distinguish and will indicate his visual acuity.

• Normally, this figure is 6/6 (or 20/20). In this case, the subject can read line 8 from a distance of 6 m (20 feet).
• If he sees only 5 lines, then the visual acuity on the Snellen scale is 6/12 (20/40). In this case, to read line 5, he needs to approach the poster at a distance of 6 m (20 feet), while the subject is good eyesight will see this line from 12 meters (40 feet).

If from a distance of 6 meters a person sees only one, the first line, then in the United States he is recognized as “legally blind.”

To summarize, we can say that if a person has a normally developed visual apparatus, then his visual acuity will most often be equal to one, sometimes two.

Many people confuse visual acuity with refractive ability. The first quantity is represented only by positive values, which range from zero to infinity. Despite the fact that one - average value, and two – good indicator. The refraction of the eyes is measured in diopters, the indicators of which can be either negative or positive. Negative diopters indicate that a person is developing positive values – . Normal value refraction is zero (indicates good health eye).