Binocular vision. Binocular vision - research, treatment of disorders

The eye is the most difficult optical system, For normal functioning which needs coordinated work all its parts.

A person with healthy eyes sees not only the outlines of surrounding objects.

But he also distinguishes what color they are, evaluates their size, shape, determines their relative position in space and perceives their volume.

One of the mechanisms that provides three-dimensional vision of the surrounding world is binocular vision.

What is it?

Binocular vision is the ability of a person to see with both eyes simultaneously in such a way that the images received by each eye separately ultimately merge into one.

It is thanks to the mechanism of binocular vision that we can easily determine at what distance objects are located, do not lose orientation in space, and also see three-dimensional objects in three dimensions at once.

In addition, if this mechanism is not broken, we see not only in front of us, but also on the sides, above and below.

This stereoscopic vision begins to appear with infancy: Already at the age of two years, a child is able to see a three-dimensional image.

The formation of binocularity ends only by the age of 14-16 years.

What is necessary to develop binocular vision?

Not all people can develop binocular vision. For its full development, the following conditions must be simultaneously met:

equal vision in the right and left eyes (no less than 0.5 dioptre);
the same shape of the cornea in both eyes (the degree of refraction must be the same);
symmetry of the eyeballs (due to injuries, infectious diseases or the growth of the tumor, the position of the eyeballs may change);
proper functioning of the eye muscles;
proper functioning of the central and peripheral nervous system;
the same projection of the image on the retina of both eyes;
normal operation of each optical medium;
absence pathological changes retina, lens and cornea, optic nerves.

If one of the conditions is violated, vision cannot be fully binocular.

How does this work?

It is believed that binocular vision occurs due to the work of the cortex big brain. It is this part of the brain that seems to connect the two images received from both eyes into a single whole.

Every point retina eye has an identical (corresponding) point on the retina of the second eye. Images of the same size and shape are projected onto corresponding points on the retina.

If images are projected onto a disparate point, the connection of the two images cannot occur. Then the person sees the surrounding objects as double.

How to check binocular vision?

There are many methods for determining binocular vision. You can test your vision without special devices.

Sokolov's experience

The patient brings the rolled-up form to the eye. spyglass a piece of paper (or any other hollow object that resembles a tube) and looks through the hole at any object in the distance.

Next, the subject brings his palm to the second eye at the same distance as the end of the folded sheet. If binocular vision is not impaired, a person will see a hole in his palm through which the objects in question will be visible.

Kalf's Experience

The patient is given two pencils, one of which he holds horizontally and the other vertically. The patient’s task is to hit the horizontal pencil with a vertical pencil.

If vision is not impaired, the subject copes with the task with ease, since binocular vision helps to correctly assess the position of objects in space and determine the distance between them.

Reading experience

The patient is given a piece of paper with printed text and a pencil. He should hold the pencil at a distance of 2-3 centimeters from the tip of his nose and try to read the text without moving his head, hand or moving the piece of paper with the text.

If binocular vision is formed correctly, the pencil will not prevent the subject from reading the entire written text. This occurs by merging two images obtained from both eyes.

Four point test

This verification method is the most accurate. The doctor places objects of different colors in front of the patient: red, white and two green. Next, the patient is asked to put on special glasses.

One lens of the glasses is red and the other is green. If the mechanism of binocular vision is not impaired, a person will see all four objects.

Red and green will not change color, but white will look like red-green, since the finished image is formed by both eyes at once.

If vision is monocular, then the subject will see only the object whose color matches the color of the lens placed on the dominant eye. The white object will also be colored the same color as the lens of the dominant eye.

Binocular vision can also be tested using special ophthalmic devices:

slit lamp;
ophthalmoscope;
perimeter;
autofluorofractometer;
monobinoscope.

Causes of binocular vision impairment

There are many known reasons causing disruption binocular vision. It is very important to install the real reason pathology, because only in this case is adequate and effective treatment.

Here are the main reasons:

anisometropia (different eye refraction);
various lesions of the eye muscles;
disruption of muscle innervation;
pathology of the bones of the orbit;
pathology of the orbital cavity;
brain stem diseases;
infectious diseases of the eyes, surrounding tissues, and brain;
poisoning with toxic substances;
tumor diseases of the organs of vision and brain.

Binocular vision disorders

The most clinically significant and common disease accompanied by impaired binocular vision is strabismus.

Strabismus is a condition in which one eye (sometimes both) deviates in any direction, and the axes of vision of the eyes no longer coincide.

Patients suffering from strabismus may complain of the following symptoms:

double vision;
the need to tilt the head to the side in which the eye muscle is affected;
dizziness;
nausea;
severe headaches;
impaired mobility of the affected person eyeball.

Strabismus can be either hereditary or acquired. Here are the main reasons why it develops:

ametropia;
previous injuries;
severe infectious diseases;
psychiatric diseases;
pathologies of the central nervous system;
malformations of the eye muscles.

Treatment of strabismus

Strabismus, accompanied by impaired binocular vision, causes significant discomfort to the patient and reduces the quality of life.

Medicine offers several effective ways to treat this condition. The method of therapy should be selected only by a doctor, taking into account the characteristics of the patient’s disease and its severity:

1	Correction using specially selected glasses and contact lenses
2	Improving vision with microcurrents and physiotherapy
3	Execution restorative gymnastics on a regular basis
4

Binocular vision allows a person to look with both eyes at the same time and get a three-dimensional image. With its help, we see not only nearby objects, but also what is located at a distance. In medicine similar phenomenon is called stereoscopic vision. If it is impaired, a person develops strabismus, visual acuity decreases, and other ophthalmological abnormalities appear.

This is one of the most important functions in the visual apparatus. It begins to form in childhood Almost immediately after the baby is born, the development process is completed by the age of twelve or fourteen.

Stereoscopic vision helps a person perceive the world around us in 3D format, in other words, he is able to not only easily examine the shape, parameters and contour of an object, but also approximately determine at what distance it is located.

The lack of binocular vision leads to serious problems; it is difficult for a person to navigate in space. It cannot determine how far away an object is. Difficulties also arise in everyday life, for example, when trying to pour water into a mug or thread a needle.

Mechanism and conditions for binocularity

If you can combine two pictures into a single whole, then everything is in order with your eye health. The “puzzle” is put together in the brain and is responsible for the fusion reflex. To ensure that the process does not fail, it is necessary that main body The central nervous system received a pair of identical images, corresponding in size and shape.

For spatial vision to work, light fluxes must penetrate the same points on the retina. They are also called correspondents. Each mark on the shell has a “neighbor” on the retina of the second eye. If light falls on them, the images merge into a single whole, as if superimposed on top of each other. If focusing is disrupted, rays are reflected from different points and the patterns are different, this leads to the development of diplopia.

Vision is considered binocular if a number of conditions are met:

There is the ability to merge two pictures into one in the brain;
The eyeballs are located symmetrically and move in concert;
Visual acuity not lower than 0.3 diopters (this is quite enough for normal optical perception);
There is no pathology called aniseikonia (the eyes see pictures of different sizes);
There is no opacification of the cornea or lens, which is accompanied by a decrease in visual acuity;
Central nervous system works without failures.

There are many conditions for the normal functioning of stereoscopic vision. Moreover, the factors listed above apply not only to the eyes, but to the entire body. A problem with binocularity may indicate the development of not only ophthalmological diseases, but also a malfunction of other systems.

Causes of binocular vision impairment

Exists large number factors that can lead to the appearance of pathology. It is important to discover the cause in order to find effective treatment. So, deviations in binocularity can be caused by:

Anisometropia;
Damage to the muscles of the organ of vision;
Problems with muscle innervation;
Pathological processes in the bone mass of the orbit;
Brain stem diseases;
Infectious diseases affecting the visual apparatus and surrounding tissues;
Intoxication of the body;
Cataract;
Mechanical eye injury;
Diseases of the retina (rupture, detachment);
New growths in the brain or eyes.

This is only a minimal list of ailments that can negatively affect stereoscopic vision.

How to check binocularity?

There are several methods for determining binocular vision. In some cases, no additional equipment is required for analysis.

Sokolov's experience

Bring a sheet of paper rolled into a tube to your eyes. Or you can use any hollow object. Look through the formed hole into the distance.

Then bring your palm to the second eye at the same distance as the end of the “spyglass”. If stereoscopic vision is normal, the patient will see a hole in the hand through which the objects in question are leaking.

Kalf's Experience

Take two pencils, place one vertically, the other horizontally. The subject's task is to hit a horizontal object with a vertical object. If binocularity is in order, then performing the exercise will not be difficult for the patient. Since he will be able to easily determine the position of objects in space and approximately calculate the distance between them.

Reading experience

Take the sheet of paper on which the text is typed and a pen. Hold the writing utensil at a distance of two centimeters from the tip of your nose and try to read what is written on the paper. In this case, the head remains in a static position, and the sheet cannot be moved either.

If stereoscopic vision is normal, the pen will not interfere with the patient's ability to read the text. Because two pictures merge into a single whole without any problems.

Four point test

One of the most exact ways checks. Objects of different colors are placed in front of the patient: scarlet, two emeralds and snow-white. Next, the subject puts on special optical products.

One lens in the glasses is red, the other is green. If binocularity works without failures, a person will look at all objects. Scarlet and emerald will remain the same shade, but snow-white will look like red-green, since the final picture is formed by the left and right eyes simultaneously.

Monocular vision is characterized by the fact that the patient will see only an object whose shade matches the color of the lens of the dominant eye. The white object will also take on the tone of the eyepiece of the dominant eye.

In addition, several hardware techniques are used to check binocularity:

Ophthalmoscopy;
Perimetry;
Autorefractometry.

Treatment of binocular vision disorders

Lack of stereoscopic vision is not considered an independent disease. This is a symptom of another abnormality developing in the body, which needs to be treated. After eliminating the signs of the disease, binocularity will be restored. For example, anisometropia is treated with surgery. Corrective glasses or lenses are also used to correct this pathology.

To restore spatial visibility, you must first figure out why it disappeared. Detailed diagnostics will help identify this. In some cases, in addition to consulting an ophthalmologist, an examination by specialized specialists is required.

The most common anomaly in which binocularity disappears is strabismus. The disease is accompanied by inconsistency in the movements of the eyeballs. Simply put, the left and right eyes look in opposite directions. In some situations, one eye may completely fall out of the visual process.

Binocular vision and strabismus

With the development of the disease, spatial visibility is always absent, since one eye deviates to the side and the optical axes do not converge on the object in question. Main goal strabismus therapy – restoration of binocularity.

It is by the presence or absence of stereoscopic vision that imaginary strabismus is determined from real one. The first is characterized by the fact that the discrepancy between the visual and optical axis reaches a maximum (in some cases the deviation is ten degrees).

Also, with imaginary strabismus, the center of the cornea shifts to the left or right side, forming a false strabismus. However, as this pathology develops, binocularity is preserved, which helps doctors make the correct diagnosis. Imaginary strabismus does not require additional therapy.

Hidden strabismus makes itself felt when the visual apparatus is relaxed and not focused on the object. If the patient tries to concentrate on an object by covering one eye, then in the presence of heterophoria the second one deviates to the side.

What is strabismus?

Strabismus is Not correct position organ of vision, in which deviation of one or both eyes is detected in turn when looking straight. With a symmetrical arrangement, the image falls on central part retina of each eye. Then two separate patterns in the cortical part of the organ of vision are combined into one.

With the development of strabismus, fusion does not occur and as a result, the central nervous system, trying to protect itself from diplopia, “crosses out” the picture received from the squinting eye. If a person remains in this state for a long time, amblyopia begins to develop (exclusion of the damaged eye from the visual process).

Depending on the type of strabismus, the disease is divided into converging, divergent, superior or inferior. Strabismus is not only cosmetic defect, it prevents us from fully perceiving environment. If the pathology develops in children or people old age, it is often accompanied by diplopia.

Causes of strabismus

Severe form of hypermetropia, myopia, astigmatism. If the correction of the disease was not carried out on time or was chosen incorrectly, then strabismus develops;
Traumatic brain injury and diseases of the main organ of the central nervous system;
Excessive physical or mental stress;
Inflammation in the visual apparatus or the formation of tumors in the muscles of the eye;
Congenital pathologies;
Hereditary predisposition, paralysis;
Heavy stress on the child's visual organ.

The disease is congenital or acquired. The first form is caused by genetics, which leads to the appearance of anomalies in the oculomotor muscles. The reason for the development of such deviations lies in health problems in the mother during pregnancy.

Acquired strabismus develops for many reasons: infectious diseases, trauma to the organ of vision, diseases of the central nervous system, etc.

Types of strabismus

There are two forms of strabismus: friendly and paralytic.

In the first case, he squints the left and right eye in turn. The size of the deviations from the straight position is approximately identical. Main reason the appearance of conjugate strabismus is ametropia. The more developed it is, the more it influences the development of strabismus. The causes of the disease also include:

Pathologies of the organ of vision leading to sharp fall eye acuity;
Uncorrected hypermetropia or myopia;
Disease of the retina or optic nerve;
Anomalies of the central nervous system;
Congenital abnormalities in anatomical structure eye;
State visual apparatus when the sharpness of one eye is much lower than the other.

Friendly strabismus is accompanied by the following symptoms:

Possible drop in visual acuity in the squinting eye;
Alternating deviation from the central axis of the left and right eye;
When fixating the gaze on a static object, one eye deviates to the side;
No diplopia
The mobility of the damaged eye is maintained in all directions;
Lack of stereoscopic vision.

The reason for the appearance of the anomaly lies in the defeat of the corresponding nerve endings or impaired functionality of the muscles of the organ of vision. Similar pathologies are congenital or develop as a result of injury, past infection or the formation of neoplasms.

The clinical picture of paralytic strabismus is as follows:

Limited mobility of the eye towards the damaged muscle or its complete static state;
Split image;
Lack of spatial vision;
Forced tilt of the head in the direction where the muscles are changed;
Regular dizziness.

Strabismus is also divided into three forms:

Convergent (eyes directed towards the bridge of the nose). The disease is often accompanied by hypermetropia;
Divergent (the organ of vision is deviated towards the temple). In parallel, the development of myopia is possible;
Vertical. The eye squints up or down.

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

Firstly, a violation of binocular vision can be suspected when, when trying to pour boiling water from a kettle into a cup, you pour it past the cup.

Secondly, a simple experiment will help test 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. Index finger 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, or rather simultaneous vision, although the absence of it does not indicate the presence of binocular vision. Double vision occurs in two cases.

Firstly, in the case of paralytic strabismus caused by disturbances in the nervous apparatus that controls the work oculomotor muscles. Secondly, if one eye is mechanically displaced from its usual position, this happens with neoplasms, with the development dystrophic process in the orbital fat pad 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 upward with a finger through the lower eyelid. Next, observe what happens to the image. If you have full binocular vision, vertical double vision should appear at this moment. A single visual image bifurcates, and one image goes upward. After the pressure on the eye stops, a single visual image is restored again. If during the experiment no double vision is observed and nothing new happens to the image, then the nature of vision is monocular. In this case, the eye that has not been displaced works. If double vision is not observed, but during the displacement of the eye a single image is shifted, then the nature of vision is also monocular, and the eye that was displaced is working.

Let's do one more experiment (installation movement). The subject looks at some point in the distance. Let's try to cover one eye with our palm. If after this the fixed point moves, the nature of vision is monocular and with both 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 provides three-dimensional perception of the surrounding world in three-dimensional space. With the help of this visual function, a person can cover with attention not only the objects in front of him, but also those located on the sides. Binocular vision is also called stereoscopic vision. What are the consequences of a violation of stereoscopic perception of the world, and how to improve visual function? Let's look at the questions in the article.

Feature of stereoscopic perception of the world

What is binocular vision? Its function is to provide a monolithic visual picture by combining the images of both eyes into a single image. A feature of binocular perception is the formation of a three-dimensional picture of the world with the determination of the location of objects in perspective and the distance between them.

Monocular vision is capable of determining the height and volume of an object, but does not provide an idea of the relative position of objects on a plane. Binocularity is a spatial perception of the world, giving a complete 3D picture of the surrounding reality.

Pay attention! Binocularity improves visual acuity, providing clear perception of visual images.

Three-dimensionality of perception begins to form at the age of two years: the child is able to perceive the world in a three-dimensional image. Immediately after birth, this ability is absent due to inconsistency in the movement of the eyeballs - the eyes “float”. By the age of two months, a baby can already fixate an object with its eyes. At three months, the baby tracks objects in motion located in close proximity to the eyes - hanging bright toys. That is, binocular fixation and fusion reflex are formed.

At six months of age, babies are already able to see objects at different distances. By the age of 12-16 years, the fundus of the eye is completely stabilized, which indicates the completion of the process of formation of binocularity.

Why is binocular vision impaired? For the perfect development of stereoscopic images, certain conditions are necessary:

absence of strabismus;
coordinated work of the eye muscles;
coordinated movements of the eyeballs;
visual acuity from 0.4;
equal visual acuity in both eyes;
proper functioning of the peripheral and central nervous system;
absence of pathology in the structure of the lens, retina and cornea.

Ditto for normal operation visual centers require symmetry in the location of the eyeballs, the absence of pathology of the optic nerves, the coincidence of the degree of refraction of the corneas of both eyes and the same vision in both eyes. In the absence of these parameters, binocular vision is impaired. Also, stereoscopic vision is impossible in the absence of one eye.

Pay attention! Stereoscopic vision depends on proper operation visual centers of the brain, which coordinates the fusion reflex of merging two images into one.

Stereoscopic vision impairment

To obtain a clear three-dimensional image, coordinated work of both eyes is required. If the functioning of the eyes is not coordinated, we're talking about about pathology of visual function.

Binocular vision impairment may occur for the following reasons:

pathology of muscle coordination—motility disorder;
pathology of the mechanism for synchronizing images into one whole - sensory disorder;
combination of sensory and motor disorder.

Binocular vision is determined using orthoptic devices. The first test is carried out at three years: children are tested for the functioning of the sensory and motor components of visual function. In case of strabismus, an additional test of the sensory component of binocular vision is performed. An ophthalmologist specializes in problems of stereoscopic vision.

Important! Timely examination of the child by an ophthalmologist prevents the development of strabismus and serious problems with vision for the future.

What causes a violation of stereoscopic vision? These include:

inconsistent eye refraction;
eye muscle defects;
deformation of the cranial bones;
pathological processes of orbital tissue;
brain pathologies;
toxic poisoning;
neoplasms in the brain;
tumors of the visual organs.

The consequence of impaired binocularity is strabismus, the most common pathology of the visual system.

Strabismus

Strabismus is always a lack of binocular vision, since the visual axes of both eyeballs do not converge. There are several forms of pathology:

valid;
false;
hidden.

With a false form of strabismus, stereoscopic perception of the world is present - this makes it possible to distinguish it from real strabismus. False strabismus does not require treatment.

Heterophoria ( hidden strabismus) is detected following method. If a patient covers one eye with a sheet of paper, it will deviate to the side. If the sheet of paper is removed, the eyeball takes the correct position. This feature is not a defect and does not require treatment.

Impaired visual function with strabismus is expressed in the following symptoms:

bifurcation of the resulting picture of the world;
frequent dizziness with nausea;
tilting the head towards the affected eye muscle;
blocking the mobility of the eye muscle.

The reasons for the development of strabismus are as follows:

hereditary factor;
head injury;
severe infections;
mental disorder;
pathologies of the central nervous system.

Strabismus can be corrected, especially in early age. Various methods are used to treat the disease:

the use of physiotherapy;
therapeutic exercises;
eye lenses and glasses;
laser correction.

With heterophoria, rapid eye fatigue and double vision are possible. In this case, prismatic glasses are used for constant wearing. In case of severe heterophoria, it is carried out surgical correction, as with obvious strabismus.

With paralytic strabismus, the cause that caused the visual defect is first removed. Congenital paralytic strabismus in children must be treated as early as possible. Acquired paralytic strabismus is typical for adult patients who have suffered severe infections or illnesses internal organs. Treatment to eliminate the cause of strabismus is usually long-term.

Post-traumatic strabismus is not corrected immediately: 6 months must pass from the moment of injury. In this case, surgical intervention is indicated.

How to diagnose binocular vision

Binocular vision is determined using the following instruments:

autofluorofractometer;
ophthalmoscope;
slit lamp;
monobinoscope.

How to determine binocular vision yourself? Simple techniques have been developed for this. Let's look at them.

Sokolov's technique

Hold a hollow, binocular-like object, such as rolled-up paper, toward one eye. Focus your gaze through the pipe on one distant object. Now bring it to open eye your palm: it is located near the end of the pipe. If binocularity is not balanced, you will find a hole in your palm through which you can view a distant object.

Kalfa technique

Take a couple of markers/pencils: hold one in horizontal position, the other - in vertical. Now try to aim and connect the vertical pencil with the horizontal one. If binocularity is not impaired, you can do this without difficulty, because spatial orientation is well developed.

Reading method

Hold a pen or pencil in front of the tip of your nose (2-3 cm) and try to read the printed text. If you can completely cover the text with your vision and read, it means that your motor and touch functions not violated. Foreign object(pen in front of the nose) should not interfere with the perception of the text.

Prevention of binocular defects

Binocular vision in adults can be impaired for several reasons. The correction consists of exercises to strengthen the eye muscles. At the same time, healthy eye closed, and the patient is loaded.

Exercise

This exercise for developing stereoscopic vision can be performed at home. The algorithm of actions is as follows:

Attach the visual object to the wall.
Move two meters away from the wall.
Extend your arm forward with your index finger raised up.
Shift your focus to the visual object and look at it through the tip of your finger - the tip of your finger should bifurcate.
Shift your focus from your finger to the visual object - now it should split in two.

The purpose of this exercise is to alternately switch the focus of attention from the finger to the object. An important indicator The correct development of stereoscopic vision is the clarity of the perceived image. If the image is blurry, this indicates monocular vision.

Important! Any eye exercises should be discussed in advance with an ophthalmologist.

Prevention of visual impairment in children and adults:

You can’t read books while lying down;
the workplace should be well lit;
Take vitamin C regularly to prevent age-related vision loss;
regularly replenish your body with a complex of essential minerals;
should be unloaded regularly eye muscles from tension - look into the distance, close and open your eyes, rotate your eyeballs.

You should also be regularly examined by an ophthalmologist and adhere to healthy image life, relieve the eyes and not allow them to get tired, perform eye exercises, treat eye diseases in a timely manner.

Bottom line

Binocular vision is the ability to perceive the picture of the world with both eyes, determine the shape and parameters of objects, navigate in space and determine the location of objects relative to each other. Lack of binocularity is always a decrease in the quality of life due to limited perception of the worldview, as well as a health problem. Strabismus is one of the consequences of impaired binocular vision, which can be congenital or acquired. Modern medicine easily copes with the restoration of visual functions. The sooner you start vision correction, the more successful the result will be.

Binocular vision is the norm for everyone healthy person. This is the ability to see the world around us with two eyes, forming a single visual image. It gives volume and depth of perception, the ability to navigate in space, distinguish between objects, and understand how they are located. Binocular visual function obligatory for the profession of driver, pilot, surgeon.

To understand the difference between stereoscopic and binocular vision, you need to know that stereoscopy is one of the qualities of binocular vision, which is responsible for the three-dimensional perception of objects.

A newborn does not have binocular vision because he has floating eyeballs. Patients suffering from diseases of the retina or lens of the eye do not have such vision. In any case, to answer the question of whether a person has the ability to see with both eyes, special testing is carried out.

So, binocular is called vision with both eyes, and monocular - with one. Only the ability to see with two eyes gives a person the opportunity to adequately perceive objects around him using the stereoscopic function. The eyes are a paired organ and their collaboration allows you to evaluate everything that is around in terms of volume, distance, shape, width and height, to distinguish colors and shades.

Monocular vision allows you to perceive the environment only indirectly, without volume, based on the size and shape of objects. A person who sees with one eye will not be able to pour water into a glass or thread a thread into an eye.

Only both types of vision create full picture visible space and help navigate it.

Mechanism of action

Stereoscopic vision is created using the fusion reflex. It helps to combine two pictures from both retinas into one image by merging them. The retinas of the left and right eyes have identical (corresponding) and asymmetrical (disparate) points. For volumetric vision, it is important that the image falls on identical retinal currents. If the image falls on disparate points of the retina, double vision will occur.

To obtain a single image, several conditions must be met:

the images on the retina must be identical in shape and size;
should fall on the corresponding areas of the retina.

When these conditions are met, a clear image is formed in a person.

Formation of visual ability

From the first day of birth, the movements of the baby's eyeballs are not coordinated, so there is no binocular vision. After six to eight weeks from birth, the child can already focus on an object with both eyes. At three to four months the baby develops a fusion reflex.

A child begins to see fully with both eyes by the age of twelve. It is because of this that strabismus () is typical for children who go to a nursery or kindergarten.

Infographics about the formation of binocular vision in children (from birth to 10 years)

Signs of normal binocular vision

In healthy people it is characterized by a number of signs:

A fully formed fusion reflex, which makes it possible to produce bifoveal fusion (fusion).
The coordinated functioning of the oculomotor muscle tissues, which ensures the parallel position of the eyes when looking at distant objects and the convergence of the visual axes when viewing nearby objects. In addition, it ensures simultaneous eye movement when observing a moving object.
By placing the visual apparatus in the same frontal and horizontal planes. If one eye becomes dislodged as a result of injury or inflammation, the symmetry of the fusion of visual fields becomes distorted.
Visual acuity is at least 0.3 – 0.4. Since such indicators are quite enough to form an image with clear outlines on the retina.
Both retinas should have the same image size (iseikonia). With different eye refractions (anisometropia), unequal images appear. To maintain the ability to see with both eyes, the degree of anisometropia should be no more than three diopters. It is important to take this parameter into account when selecting glasses or contact lenses. With a difference between the two lenses of more than 3.0 diopters, even with high visual acuity, a person will not have binocular vision.
Cornea, lens and vitreous must be completely transparent.

There is no stereoscopic vision with cataracts

Testing binocular and monocular vision

Several methods have been developed to test whether a person has binocular ability:

Sokolov's experience

The Sokolov experiment or “hole in the palm”

This technique has another name – “hole in the palm”.

What to do:

The essence of the technique is that a folded sheet of paper is placed to the patient’s right eye, through which he must examine distant objects. At this time left hand I extend it so that my palm is at a distance of 15 cm from my left eye. That is, a person sees a “palm” and a “tunnel”. If there is binocular vision, then the images overlap each other and it seems as if there is a hole in the palm through which we see the picture.

Another name for the technique is a miss test.

In order to determine the presence of binocular vision using this method, you will need two long objects (for example, 2 pens or 2 pencils). But in principle, you can use your own fingers, although the accuracy will decrease slightly.

Miss test (Kalf method)

What to do:

Take the pencil in one hand and hold it horizontally.
In your other hand, take the second pencil and hold it vertically.
Place them at different distances, move your hands in different sides to confuse yourself, and then try to bring the ends of the pencils together.

If you have stereoscopic vision, then this task is quite simple. Without this ability, you will miss. To verify this, you can repeat the same experiment with closed eye. Since when only one eye is working, 3D perception is disrupted.

"Reading with a Pencil"

You will need: a book and a pencil.

Instructions:

You need to take a book in one hand and a pencil in the other, placing it against the background of the book’s pages.
The pencil should cover some letters.
If binocular ability is present, the patient can read the text even despite the obstacle. This happens by merging the images in the review.

The most accurate study of binocular vision is carried out using a four-point color test. It is based on the fact that visual views can be separated using color filters. To do this you need two objects that are colored green and one each in red and white. The subject needs to wear glasses, with one red and the other green glass.

If the subject has binocular vision, he will only see red and green colors of objects. The object white will appear red-green because perception occurs with both eyes.
If one eye is dominant, then the white object will take on the color of the lens opposite that eye.
If the patient has simultaneous vision (that is, the visual centers receive impulses from one or the other eye), he will see 5 objects.
If the subject has monocular vision, then he will perceive only those objects that are colored the same color as the lens in the seeing eye, without reading a colorless object that will be the same color.

Strabismus

Strabismus (strabismus, heterotropia) is a disease characterized by unformed binocular vision in both eyes. This happens because one eye deviates to one side or another due to weakness of the muscular system.

Types (classification) of strabismus

Strabismus can cause weakening of one or more extraocular muscles, divided into:

Convergent (esotropia) – with it there will be a deviation of the eyeball towards the bridge of the nose;
Divergent (exotropia) – deviation of the organ of the visual apparatus occurs to the side temporal region heads;
Unilateral - only one eye deviates;
Alternating – alternating deviation of both eyes occurs.

Classification of strabismus according to the form of eye deviation

If a patient has binocular vision, but one or both eyes are deviated from the normal position, this may indicate the presence of false (imaginary or hidden) strabismus (pseudostrabismus).

Imaginary strabismus

It is characterized by a large discrepancy between the visual and optical axes. Also, the centers of the cornea can shift to one side. But treatment in this case is not required.

Hidden strabismus

This type of strabismus can occur periodically when the gaze is not fixed on any object.

Checked this type pathology as follows:

The patient fixes his gaze on one moving object and covers his eye with his hand. If the eye, which is covered, follows the trajectory of the object, then this indicates hidden strabismus in the patient. This disease does not require treatment.

Binocular vision is the norm for a healthy person and the basis of his life, both in everyday life and in professional terms.