What gives a person binocular vision. Ways to restore binocular vision. Is it possible to test binocular vision at home

Binocular vision appears only when images from both eyes merge into one, which gives volume and depth of perception.

Mechanism and conditions for binocular vision

• Ability to bifoveal fusion (fusion).
• Coordinated work of all oculomotor muscles, which ensures the parallel position of the eyeballs when looking into the distance and the corresponding convergence of the visual axes (convergence) when looking at the near, as well as the correct associated eye movements in the direction of the object under consideration.
• The position of the eyes in the same frontal and horizontal plane. When one of the eyes is displaced due to injury, inflammatory process in the orbit, neoplasms, the symmetry of the alignment of the visual fields is disturbed.
• Visual acuity of both eyes is not less than 0.3-0.4, i.е. sufficient to form a clear image on the retina.
• Equal image sizes on the retina of both eyes - iseikonia. Images of different sizes occur with anisometropia - different refractions of the two eyes. To preserve binocular vision, the permissible degree of anisometropia is up to 2.0-3.0 diopters, this must be taken into account when choosing glasses - if the difference between corrective lenses is very large, then even with high visual acuity in glasses, the patient will not have binocular vision.
• Naturally, the transparency of optical media (cornea, lens, vitreous body), absence pathological changes in the retina optic nerve and higher parts of the visual analyzer (chiasm, optic tract, subcortical centers, cerebral cortex)

How to check?

Binocular vision and strabismus

Binocular vision is the ability of a person to see with both eyes at once. This happens due to the fact that consciousness combines the image from each eye into one picture. This type of vision allows a person to see objects more voluminously, to better understand the location of objects in space.

The second type of vision is called monocular and allows you to see with only one eye. This is precisely its main difference from the binocular type of vision. You can watch with only one eye, even if both function normally and transmit an image.

In rare cases, the monocular type of vision allows you to use two eyes at the same time, but the picture does not merge, and the image is perceived from each eye separately. Cause rapid development This visual defect can be rapidly progressive strabismus.

What is binocular vision for?

Only the image received by two eyes makes it possible to truly assess the environment, to understand at what distance from each other certain objects are located. Apart from more information about objects, a person sees more clearly, that is, in fact, visual acuity improves.

Stereoscopic (synonymous with binocular) vision is also found in many animals, most occupied by mammals. It is thanks to him that primates and squirrels can gracefully move along the very tops of trees, jump from branch to branch and feel confident. For predators, stereoscopic vision makes it possible to successfully track down prey and get food for themselves and their offspring.

Of course, there are living organisms that have a monoscopic type of vision, but their life tasks and everyday life are so limited that they cannot be compared even with a squirrel or other simple mammal.

It was thanks to this vision that our ancestors could successfully hunt, gather, build houses, etc. Modern man not much different from their ancestors, and such an invention of nature as stereoscopic vision is still necessary for us to this day.

How to check

The first sign of a violation of the stereoscopic perception of reality may be poor orientation in space. Notice manifestations given symptom extremely simple. Try pouring water from the kettle into a mug. If you tried, but all the water got past the vessel, then most likely you have problems with binocular vision.

There is another way. To do this, place the index finger of the left hand vertically on the same plane as the eyes, the distance from the face should be 35–55 centimeters. index finger right hand try to hit across the left finger, moving from top to bottom.

A successful result of this simple test will help to understand that binocular vision does not suffer from deviations.

How good are you at moving in space, managing and manipulating objects, how clearly do you understand your own and other people's whereabouts? With a binocular type of vision, a person will not ask such questions. However, if you feel that some of the items on this list are about you, you should go to the hospital as soon as possible and undergo a series of simple tests.

It should be understood that if a person suffers from different types squint, then stereoscopic vision he cannot have. Also, vision can suffer in case of double vision. The cause may be paralytic strabismus, provoked by improper work nerve endings muscles responsible for rotating the eyes. Also, the deviation is due to dystrophy of the fatty layer near the eye area and with independent movement. eyeball finger.

The last experiment is able to show the presence of a monocular type of vision. The participant of the experiment sits upright and concentrates his gaze on one point in space. After completing the first step, you need to slightly press up the lower eyelid of any eye. In the event that vision is complete, the objects should split in two, and one of the images should float slightly upward from the second. Release your finger and observe: if the doubles of objects have disappeared, then everything is in order with vision.

Reasons for the lack of binocular vision

Unfortunately, self-diagnosis the root cause of the disease is almost impossible. In order to find out the source of the problem, you need to go to the hospital, where they will conduct all necessary examinations giving more accurate results than home studies and tests.

Violation can be triggered by both a banal shift of the eyeball, and various tumors and formations, disruption of the muscles and nerve endings of the eye. If the cause is not diagnosed in time and treatment or prevention is not started, the problem can progress and lead to complete or partial inability to see.

Sometimes the problem can be so deep that even experienced doctor not able to immediately report the diagnosis and prescribe treatment. Before taking action, you should thoroughly examine your body.

Why and when violations occur

Violations in normal operation binocular type of vision can affect certain problems with the perception of the world and reality. This has to be endured because of the difficulty with the ratio of things and objects around. Monocular vision imposes many restrictions on the choice future profession and place of work, since most specialties require 100% binocular vision.

It will be almost impossible to get a job as a driver of various Vehicle, medical worker directly involved in operations and procedures that require caution and a high degree of coordination, an athlete, since most sports require one hundred percent vision and excellent orientation in space.

The most widespread problems are dysfunction of the muscles of the eye, pain and processes occurring in the orbit, leading to the movement of the eye to an unnatural position. Various diseases may also manifest as visual impairment.

There is a pathology when the sizes of the figures on the retinas of the eye organs differ from each other, which is called aniseikonia. This often happens because of the strong difference in refraction in the eyes, when the image of the figure from one eye does not appear as one with the other.

Very common cases with weakening different quantity muscles that move the eye. As a result, one eye is in the initially correct position, when the second gradually moves towards the temple, nose, and bridge of the nose. The result of this is strabismus, which suffers great amount of people.

There are many types of violation of the simultaneous interaction of visual axes. The most common is friendly, when the eyes look into opposite sides, but they have an equal deviation in degrees, as well as paralytic, when the deviation of the gaze increases or decreases in any direction. The friendly type can also be divided into some subgroups. In some people, only one eyeball mows, while in others, both at once, but at different intervals in time.

Unfortunately, in addition to banal cosmetic flaws, strabismus can physically disrupt normal functioning organism. The lack of stereoscopic vision does not normally perceive and feel the location of objects in space, people, buildings and almost anything. The path to industrial enterprises and positions requiring work with moving objects remains closed for such a person.

Thanks to multiple medical and sociological surveys, it became known that almost 3% of children of school and preschool age have this defect of perception. Society takes care of such people; special conditions on the street, in shops. Even modern mobile devices support special modes that help people with disabilities visual apparatus normally navigate and control your phone or tablet.

Treatment at home

Surprisingly, one of the most effective methods home treatment visual impairment is natural dark chocolate. However, efficiency this method falls in proportion to the age of the patient. The peak of the effect is observed in children under 4 or 5 years of age, and then begins to decline, as the ability of the eye muscles and organs to regenerate begins to gradually decline. After 12 years, such a method can rightfully be considered completely useless for full treatment. However, regularly eating a bar of dark bitter chocolate can keep your body toned and help medical treatment.

Calamus root in the proportion of 10 grams per cup of boiling water should be consumed infused and filtered 3 times a day half an hour before the next meal. Eating cabbage leaves can also have a very significant effect on your health. Try to eat washed cabbage leaves at least 4 times a day. pine needles, kept in a water bath and well infused, can be taken one tablespoon after each meal. Use this recipe for a long time and your eyesight will improve.

There are many exercises for the eyes, thanks to which eye muscles quickly come to tone:

• Pose standing with your back to the light source. Open an eye that suffers from an illness, and close a healthy one with your hand. Turn your head in the direction of the sore eye until you feel the glare of the sun. Do 11-12 reps per workout.
• Tilt the back of your head back and look at the tip of your nose. For more enthusiasm, imagine a fly sitting right on your nose.
• Stretch your arms away from you, and then touch the bridge of your nose with the index finger of your left and right hands, accompanying each hand with a look. Hands must be moved alternately. At the end of the workout, tears should appear in your eyes, but you should not overwork either.
• Squeeze a long oblong object, such as a stick, with your hand. Make quick and unpredictable swings to them in different directions, and keep your eyes on the end of the wand.
• Extend your hand in front of you and look at your index finger. Step by step, bring it closer to the bridge of your nose, maintaining concentration.
• Rotate your gaze from left to right and from top to bottom, draw an infinity sign in the air.
• Watch the object move away from you. The shuttlecock in tennis would be a great example.
• Look out the window more often. Observe what is happening for several minutes, and then sharply shift your gaze to an object in the room.

Activities for children:

• Apply special pictures. Use puzzles where you need to find 5 differences. Ask the child to search in all parts of the image. Labyrinths will be an excellent simulator. Such a puzzle will not only develop the brain and eyesight, but also entertain the child.
• Get a special entertaining lacing or weave a circle with a dozen holes on your own different forms. Let the child pass the rope through them.
• Divide a sheet of paper into several cells and draw figures. One cell - one figure. Images must be repeated at a certain interval.

Traditional treatment

Treatment of concomitant strabismus begins with identifying the type of disease - accommodative, non-accommodative or partial form. In the first case, glasses or lenses help, in the second it is observed completely reverse effect. Sometimes there are exceptions that are attributed to the third form.

The accommodative type is not treated by surgery. The other two forms are corrected only by surgeons by intervention in the body. The age for the operation is determined individually. In complex forms, one intervention may not be enough for the desired effect. The average interval between operations is up to six months. Longer exposures can negate all the past efforts of doctors. Any treatment has one goal - to return binocular vision to a sick person.

Prevention

Unfortunately, effective prevention this disease you can only with a small child, but following these recommendations can greatly help and protect the baby.

• Do not hang things near the baby's crib that constantly catch the eye. The baby will look only at one point all the time, which can cause muscle dysfunction, and the body will remember the wrong position of the eyes.
• Approach the bed from different angles.
• Try not to place toys and other objects very close to the baby's face. The visual muscles at this age are still very unstable.
• Try not to move abruptly, do not scare the child. From severe stress baby's eyes can literally go in different directions.

In addition to doing exercises and taking decoctions, try to consult with your doctor as often as possible, as various drops and special medications can greatly improve the overall course of the case, give a big impetus to the body and increase the effect of independent exercises and classes several times.

In children in early age often functional strabismus. It looks like a normal one: the eyes look in opposite directions. There is no need to be afraid of this, such behavior is the norm. The child makes the first attempts to fix the gaze after two weeks. The baby has not yet learned to control the body, so the eyes are no exception. In the second and third months, the baby finally consolidates this skill, so that the attacks of strabismus should soon stop.

If the child has birth trauma associated with the head, the posterior longitudinal bundle in the brain may be affected. Also, damage can occur as a result of a lack of oxygen at the time of birth.

Binocular vision disorder is a dangerous, very uncomfortable and serious disease, but even it is quite possible to cure it with the modern level of medicine, timely handling to the hospital and responsible approach to treatment. The main thing to remember and understand is that the treatment process depends only on you. Only your perseverance and desire to remove the disease from your life will help you find strength in yourself and every day stubbornly go towards recovery.

How to check the presence and nature of binocular vision at home?

First, a violation of binocular vision can be suspected when, when you try to pour boiling water from a teapot into a cup, you pour it past the cup.

Secondly, a simple experiment will help to check the function of binocular vision. The index finger of the left hand must be placed vertically at the top at eye level at a distance of 30-50 cm from the face. With the index finger of the right hand, you need to try to quickly hit the end of the left index finger moving from top to bottom.

If this was done the first time, then we can hope that binocular vision is not impaired.

If a person has convergent or divergent strabismus, then, of course, there is no binocular vision.

Double vision is also a sign of impaired binocular vision, more precisely simultaneous, although the absence of such does not indicate the presence of binocular vision. Doubling occurs in two cases.

First, in the case paralytic strabismus caused by disorders in the nervous apparatus that controls the work of the oculomotor muscles. Secondly, if one eye is mechanically displaced from its usual position, this happens with neoplasms, with the development dystrophic process in the fatty pad of the orbit near the eye or with artificial (intentional) displacement of the eyeball with a finger through the eyelid.

The following experiment confirms the presence of binocular vision. the subject looks at a point in the distance. One eye is slightly pressed with a finger up through the lower eyelid. Next, observe what happens to the image. In the presence of full binocular vision, vertical doubling should appear at this moment. A single visual image splits into two, and one image goes up. After the cessation of pressure on the eye, a single visual image is restored again. If during the experiment doubling is not observed and nothing new happens to the image, then the nature of vision is monocular. In this case, the eye that was not displaced works. If doubling is not observed, but during the shift of the eye a single image shifts, then the nature of vision is also monocular, and the eye that was shifted works.

Let's put one more experiment (adjusting movement). The subject looks at a point in the distance. Let's try to cover one eye with the palm of our hand. If after that the fixed point shifts, the nature of vision is monocular and with two eyes open, the one that was covered works. If the fixed point disappears, then the nature of vision with the same eye is also monocular, and the eye that was not covered does not see at all.

Binocular vision occurs with the participation of both eyes in the visual act and the merging of two monocular images into a single visual image. Each eye sees the object of fixation from several different positions, the images in the right and left eyes are transversely displaced relative to each other (disparate).

The phenomenon of transverse disparity in binocular vision is the basis of deep vision (deep assessment of the visual image). Stereoscopic vision reflects the ability to estimate depth in the conditions of stereoscopic instruments and devices.

Binocular vision is based on the mechanism of correspondence of the retinas - an innate property of the foveal and symmetrically remote areas (corresponding zones) of the retinas of both eyes to a single perception of the fixed object. The fusion of two monocular images in binocular vision also occurs under conditions of convergence and separation of the visual axes to a certain limit, which is possible due to fusion reserves (fusion reserves).

When an image of an object hits differently distant (non-corresponding, disparate) areas of the retinas, no single visual image is formed. Images are perceived double and simultaneous vision occurs, which is characteristic of strabismus. To get rid of double vision, the squinting eye is gradually inhibited and the other functional dominance - monocular vision develops.

Formation of binocular vision

Binocular vision begins to develop from an early age. childhood and is formed by 1-2 years. Gradually, it develops, improves, and by the age of 6-8 years, stereoscopic vision is formed, reaching full development by the age of 15.

The following conditions are necessary for the formation of binocular vision:

• the same visual acuity in both eyes (not lower than 0.4 in each eye);
• the same refraction (degree of farsightedness or nearsightedness) in both eyes;
• symmetrical position of the eyeballs; .
• equal image sizes in both eyes - iseikonia.
• Normal functional ability of the retina, pathways and higher visual centers.
• Location of two eyes in the same frontal and horizontal plane

It should be noted that with an inequality of image sizes (aniseikonia) of 1.5-2.5%, unpleasant subjective sensations in the eyes (asthenopic phenomena) occur, and with aniseikonia of 4-5% or more, binocular vision is almost impossible. Images of different sizes occur with anisometropia - different refractions of the two eyes.

With the displacement of one eye during an injury, as well as in the case of the development of an inflammatory or tumor process in the orbit, the symmetry of the alignment of the visual fields is disturbed, stereoscopic vision is lost. If one of these links is disturbed, binocular vision may be upset or not develop at all, or it may become monocular (vision with one eye) or simultaneous, in which impulses are perceived in higher visual centers first from one eye, then from the other eye.

Monocular and simultaneous vision allows you to get an idea only about the height, width and shape of an object without assessing the relative position of objects in space in depth.

Characteristics of binocular vision

An important condition for the existence of binocular vision is the balance of the tone of the oculomotor muscles.

• Orthophoria - the perfect balance of the tone of the oculomotor muscles.
• Heterophoria - hidden disturbances in the balance of the tone of the oculomotor muscles, are detected in 70-75% of individuals middle age with binocular vision. Allocate esophoria (with a tendency to reduce the visual axes) and exophoria (with a tendency to dilute them). Heterophoria can be the cause of asthenopia, reduced visual performance, and in some cases strabismus.

The main qualitative characteristic of binocular vision is the deep stereoscopic vision of an object, which makes it possible to determine its place in space, to see in relief, depth and volume. Images of the outside world are perceived as three-dimensional. With binocular vision, the field of view expands and visual acuity increases (by 0.1-0.2 or more).

With monocular vision, a person adapts and orients himself in space, estimating the size of familiar objects. The further away an object is, the smaller it appears. When you turn your head, objects located at different distances move relative to each other. With such vision, it is most difficult to navigate among nearby objects, for example, it is difficult to get the end of the thread into the eye of a needle, pour water into a glass, etc.

Lack of binocular vision limits a person's professional suitability.

Diagnostics

Indications

There are the following indications for evaluating binocular vision:

• professional selection (flying professions, precision work, driving vehicles, etc.);
• scheduled preventive examinations of children and adolescents before school and during training;
• pathology of the oculomotor apparatus (strabismus, nystagmus), asthenopia, professional ophthalmopathy.

Contraindications

• Acute inflammatory diseases eye.

To assess binocular vision, the following are sequentially carried out:

• study of the presence of binocular, simultaneous or monocular vision haploscopic methods based on the principle of separation of the visual fields of both eyes using color (four-point, or Wors-test), raster (Bagolini test) or polaroid (four-point polaroid test) haploscopy;
• with strabismus - testing by the method of successive visual images (according to the Cermak principle);
• assessment of binocular functions (fusion ability) on the synoptophore (under conditions of mechanical haploscopy);
• evaluation of deep vision (threshold, acuity);
• assessment of stereoscopic vision (stereo pairs);
• phoria research.

Several simple ways determination of binocular vision without the use of devices.

Binocular eye coordination

The movements of the eyeball are carried out by six external eye muscles, which are innervated by three cranial nerves: oculomotor (III pair), block (IV pair) and efferent (VI pair). Therefore, there are many different nerve connections between cortical visual areas and oculomotor centers in the brainstem.

So, signals from the area of ​​​​field 18 of the cortex go to the superior colliculus of the quadrigemina (superior colliculus), which control the neurons that control the direction of gaze. Neurons that control horizontal movements eyes are located mainly in the paramedian reticular formation of the pons, and the neurons that control vertical eye movements are located in the reticular formation of the midbrain. From here, their axons go to the neurons of the nuclei of the abducens, oculomotor and trochlear nerves, as well as to the motor neurons of the upper cervical part. spinal cord. In this regard, the movements of the eyes and head are coordinated with each other.

The level of excitation of the oculomotor centers is regulated by various visual areas of the brain: the superior colliculi of the quadrigemina, the secondary visual cortex, the parietal cortex (mainly its field 7). With the defeat of the paramedian reticular formation of the pons varolii, the horizontal rotation of the eyes to the side where the pathological focus of the brain is located is difficult. Damage to the reticular formation of the midbrain makes it difficult to move the eyes vertically.

For stable vision of the object under consideration, the eye must constantly make small movements, which can be of three types:

• tremor - high-frequency (30-150 Hz) oscillations around the fixation point with a very small amplitude (up to 17 arc seconds),
• drift - slow (up to 6 arc minutes in 1 s) slipping of the gaze from a given direction (by 3 to 30 arc minutes),
• microsaccades (microjumps) - fast eye movements from 1 to 50 minutes of arc.

Drift contributes to the restoration of the visibility of the image on the retina, and microsaccades - to the restoration of a given direction of gaze.

Thus, the visual pathway is presented as a very complex multi-level hierarchical network of neural structures, which become much more complex towards the cerebral cortex. In functional terms, this contributes to the selection of individual increasingly complex elements of the visual image. final functional step visual pathway is the synthesis of visual images and their identification by comparing with the existing stock of visual images stored in memory.

Various visual impairments that occur when the visual analyzer is damaged manifest themselves as a change quantitative characteristics visual functions, as well as in changes quality characteristics visual functions.

Lesions of each level (department) of the visual analyzer are manifested by the formation of a fairly characteristic symptom complex. This contributes to the establishment of topical and nosological diagnoses.

Binocular vision can be tested different methods, among which the study using a 4-point color test (test with a color device) is generally accepted.

The subject observes 4 multi-colored circles (2 green, white and red), glowing through filter glasses (with one red and one green glass). The colors of the circles and lenses are chosen in such a way that one circle is visible only with one eye, two circles - only with the second, and one circle (white) is visible with both eyes.

The patient sits at a distance of 5 m from a direct and strong light source. He puts on filter glasses: the right eye is covered with red glass, and the left eye is green. Before starting diagnostic manipulations, the quality of the filters is checked. To do this, one by one cover the eyes with a special shield, while the patient first sees two red circles with his right eye, and then three green circles with his left eye. The main examination is carried out at the same time open eyes.

There are three options for the results of the examination: binocular (normal), simultaneous and monocular vision.

Sokolov Method (1901)

The method consists in the fact that the patient is asked to look into the tube with one eye (for example, a sheet turned into a tube), a palm is applied to its end from the side of the open eye. In the presence of binocular vision, the impression of a “hole in the palm” is created, through which a picture is perceived, which is visible through the tube. This is because the picture seen through the hole in the tube is superimposed on the picture of the palm in the other eye.

With the simultaneous nature of vision, the “hole” does not coincide with the center of the palm, and with monocular vision, the “hole in the palm” phenomenon does not appear.

The experience with two pencils (they can be replaced with ordinary sticks or felt-tip pens) is indicative. The patient should try to align the tip of his pencil with the tip of the pencil in the doctor's hands so that a clearly straight line is formed. A person with binocular vision easily performs tasks with two eyes open and misses when one eye is closed. Missing is noted in the absence of binocular vision.

Other, more sophisticated methods (prism test, Bogolin striped glass test) use .

Strabismus according to the Hirschberg method

The magnitude of the angle of strabismus is simply and quickly determined by the Hirschberg method: a beam of light is directed into the eyes of the subject and the location of light reflections on the cornea is compared.

A reflex is fixed in the eye and observed near the center of the pupil, or coincides with it, and in the eye that squints, it is determined in a place corresponding to the deviation of the visual line.

One millimeter of its displacement on the cornea corresponds to a strabismus angle of 7 degrees. The larger this angle, the farther from the center of the cornea the light reflex is shifted. So, if the reflex is located on the edge of the pupil with its average width of 3-3.5 mm, then the angle of strabismus is 15 degrees.

A wide pupil makes it difficult to accurately determine the distance between the light reflex and the center of the cornea. More precisely, the angle of strabismus is measured on the perimeter (Golovin's method), on the synoptophore, with a test with prism cover.

Subjective method for determining binocular vision

To determine the level of refraction of light in the eyes by a subjective method, a set of lenses is needed, a test spectacle frame and a table for determining visual acuity.

The subjective method for determining refraction consists of two stages:

• determination of visual acuity;
• rimmed eye application optical lenses(first +0.5 D and then -0.5 D).

In case of emmetropia, a positive glass worsens the Visus, and a negative glass first worsens it, and then does not affect it, since accommodation is turned on. With hypermetropia, “+” glass improves Vizus, and “-” glass first worsens, and then, with a large accommodation voltage, it is not displayed on Vizus.

In young patients with visual acuity equal to one, two types of refraction can be assumed: emmetropia (Em) and hypermetropia (H) low degree with accommodation.

In elderly patients with visual acuity "one", only one type of refraction can be assumed - accommodation is weakened due to age.

With visual acuity less than one, two types of refraction can be assumed: hypermetropia (high degree, accommodation cannot help) and myopia (M). In hypermetropia, a positive glass (+0.5 D) improves Visus, and a negative glass (-0.5 D) worsens Visus. In myopia, positive glass worsens visual acuity, while negative glass improves it.

Astigmatism ( different kinds refraction in different meridians of one eye) is corrected by cylindrical and spherical cylindrical lenses.

When determining the degree of ametropia, the glass changes for the better Visus with it (1.0).

At the same time, in hypermetropia, refraction determines the largest positive glass, with which the patient sees better, and in myopia, the smaller negative glass, with which the patient sees better.

A different kind or degree of refraction in both eyes is called anisometropia. Anisometropia up to 2.0-3.0 D in adults and up to 5.0 D in children is considered tolerable.

Objective methods for determining binocular vision

Skiascopy (shadow test), or retinoscopy - objective method determination of the refraction of the eye. To carry out the method, you need: a light source - a table lamp; mirror ophthalmoscope or skiascope (concave or flat mirror with a hole in the middle); skiascopic rulers (this is a set of cleaning or diffusing lenses from 0.5 D-1.0 D in ascending order).

The study is carried out in a dark room, the light source is placed on the left and somewhat behind the patient. The doctor sits down 1m from him and directs the light reflected from the skiascope into the eye being examined. In the pupils, a light reflex is observed.

Slightly rotating the glass handle, the reflected beam is moved up and down or left and right, and the movement of the skiascopic reflex in the pupils is observed through the opening of the skiascope.

Thus, skiascopy consists of 3 points: obtaining a red reflex; obtaining a shadow, the movement of which depends on the type of mirror, the distance from which it is examined, on the type and degree of refraction; shadow neutralization with a skiascopic ruler.

There are 3 options for the skiascopic reflex (shadows against the background of the red reflex):

• the skiascopic reflex moves in accordance with the movement of the mirror;
• it moves opposite to the movement of the mirror;
• there is no shadow against the background of the red reflection.

In the case of the coincidence of the movement of the reflex and the mirror, we can talk about hypermetropic vision, emetropic or myopic to one diopter.

The second variant of the movement of the skiascopic reflex indicates myopia of more than one diopter.

Only with the third variant of the movement of the reflex do they conclude that myopia is one diopter and the measurements are stopped at this point.

When examining an astigmatic eye, skiascopy is performed in two main meridians. Clinical refraction is calculated for each meridian separately.

In other words, binocular vision can be explored different ways, everything directly depends on the brightness of the symptoms, on the patient's complaints and on the professionalism of the doctor. Remember, strabismus can only be corrected for early stages development and it will take a lot of time.