Understanding binocular vision. Methods for assessing binocular vision

Binocular vision is a natural physiological ability that every healthy person possesses. It allows you to look at an object with both eyes and build a single three-dimensional image, which is formed as a result of the merging of pictures from both organs. It is this opportunity that allows a person to experience the depth of perception of the surrounding reality. If there is a violation of this type of vision, it is necessary to begin treatment.

It turns out that it is binocular vision that creates all the conditions so that it is possible to approximately calculate the distance from all kinds of things, objects and objects. Unlike the monocular ability to see (with one eye), binocular vision provides the ability to evaluate the distance and relative position of objects both in the plane and in space.

In addition, it is the review with two eyes that allows you to maximize the field of view and achieve a more accurate adoption of the visual image. This is felt by a person in the quality of his visual data, their quality and sharpness. Binocular vision (it would be more correct to consider the absence of its impairment) seems to be a mandatory item for a whole list of specialties.

What binocular vision is can be understood by considering the features of its functioning:

1. The signal sent to the cerebral cortex causes the main element of this visual ability, which has a clear definition and name of the fusion reflex.
2. Merging two images obtained from both retinas into a whole stereoscopic image is necessary to obtain an inseparable, integral image of a specific object.
3. Extremely an important condition To trigger the fusion reflex, we can call the correspondence of images to each other in size and shape. In addition, they must fall on the same areas of the retina. When merging does not occur due to the fact that the image of the object does not fall on similar areas, what is visible in a person’s eyes splits into two.

As a study by scientists shows, binocular vision is not found in newborns.

The fusion reflex cannot occur, since at this age any healthy baby there is not the slightest coordination of movements between the eyeballs. By 8 weeks, the child is already able to fix any object with his visual organs, and by 3-4 months, the baby does this much more confidently.

The final stage of formation of this ability in a person is completed by the age of 12. Strabismus is the most common disorder binocular vision, is recognized as a disease of preschool children.

Binocular vision status: how to check?

The research carried out by ophthalmologists was not in vain. Today there are several ways to verify the state of your binocular vision.

The most popular and simple techniques are as follows:

• Sokolov's method. A tube (or whatever) must be placed to the subject's eye. A person must peer through it into the very distance. The study begins with placing your hand on the other side of the second eye. With normal binocular vision, images overlap and the effect of the presence of a hole in the middle of the palm is created, through which the image is supposedly visible.

• Kalfa technique. For the miss test (this is also the name of this method, which determines binocular vision and its level), the use of additional sharp objects (knitting needles, pencils, etc.) will be required. The study is as follows: a person, holding a long stick horizontally in a straight hand, tries to touch with it the end of a second, equally thin object located vertically. A miss occurs when binocular vision is absent or malfunctions. It is advisable to perform the experiment with one eye open.
• Pencil reading test. You should place the pencil on your nose and start reading. The object will interfere and some of the letters will disappear from view. This interferes with normal vision, but by using the binocular way of shifting pictures, you can still read. You just need to tilt your head from one side to the other. Then the letters will become accessible first to one eye, and then to the other. But if this does not happen, there is a violation of binocular visual ability.
• The four-point color test is another test that will help check your health. It is based on the principle of a standard division of visual fields related to the right and left eyes. Using multi-colored filters, the binocular perception of the subject is determined.

The most commonly diagnosed pathology of binocular vision can be considered strabismus. When it is present, the visual lines do not “meet” on the object, and one eye deviates in the other direction.

Treatment of strabismus aims to restore binocular visual ability. They can help with this special exercises.

How to learn to see with binocular vision?

To begin treatment and the long process of restoring binocular vision, you should first visit an ophthalmologist. The results of the diagnostics, which must be completed, will predetermine the scheme for further therapy. Often patients are shown surgery. Those patients who have been practicing one of the common recovery methods for a long time have a chance of recovery without surgery.

At home, treatment and exercises for the development of binocular vision are easy to carry out.

1. The first exercises are intended for long-range training of binocular vision. The main object for study is placed on the wall. The distance between him and the patient should be at least 2.5-3 m. Next, clench your fist, and forefinger leave, do not clamp and keep straight upright.
2. Then the hand must be positioned so that it is at a distance of 40 cm from the face. If the end of the extended finger forks, but the hand remains one, the result of the exercise is positive - this is how it should be. Both images must have the same degree of clarity.
3. If this does not happen, and the second eye sees more blurred, you need to start the exercise over again, now loading the weaker eye.

Other lesson plans are based on the use of colored objects. During the exercise, it is important to learn how to focus your gaze on a complex object. It is necessary to begin treatment by studying its largest details, for example, the contour. It is advisable to study each line in detail, and only then move on to other, smaller fragments. Each time, reducing the chosen target, the exercises help develop focus, moving from large objects to more modest ones.

Binocular vision is the norm for everyone healthy person. This is an opportunity to see the world two eyes with the formation of a single visual image. It gives volume and depth of perception, the ability to navigate in space, distinguish objects, and understand how they are located. Binocular visual function is mandatory for the profession of driver, pilot, and 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 joint work allows us to evaluate everything that is around in terms of volume, distance, shape, width and height, and to distinguish colors and shades.

Monocular vision allows you to perceive 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 images 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:

1. the images on the retina must be identical in shape and size;
2. 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 birthday of the movement eyeballs in the infant they 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.
• Finding visual apparatus in one frontal and horizontal plane. 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 should be done:

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 that 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 with one eye closed. 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.

Most precise research binocular vision is performed 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 color 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. A white object 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 muscle weakness.

Types (classification) of strabismus

Strabismus can cause weakening of one or more eyes motor muscles, subdivided 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 towards the temporal region of the head;
• Unilateral - only one eye deviates;
• Alternating – alternating deviation of both eyes occurs.

Classification of strabismus according to the form of eye deviation

If the patient has binocular vision but one or both eyes are deviated from normal position this may indicate that he has a 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

Strabismus of this type can appear 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 that 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.

Binocular vision is a method of visual reproduction in which the image from both eyes becomes a single whole. It is this ability that allows us to perceive the world around us as voluminous and complete. Thanks to monocular vision, a person can estimate the distance to objects, height, width and other characteristics of objects. But exclusively binocular vision makes it possible to assess the spatial position of objects. It promotes an improved understanding of the world around you. Binocular vision research occurs for many important specialties, such as:

• pilot;
• astronaut;
• autopilot;
• surgeon, etc.

The mechanism of binocular vision is the ability to superimpose two pictures into one image. This happens in the cerebral cortex. Two images arriving at both eyes merge there into one stereoscopic one.

In order to end up with a single view, the images formed on the retina must necessarily correspond to each other in shape and size. In this case, they must fall on the corresponding parts of the shell. For any surface point of the retina, there is a corresponding point on the surface of another retina. If the picture hits the disparate points, it causes visual impairment, resulting in double vision.

Only newborns can do without binocular vision. In a healthy person, the development of this vision starts after a month of life, and in the future it allows you to see everything in volume. By the way, it should be noted that newborns have a lack of binocular vision due to weakness eye muscles. The result is uncoordinated eye movements that do not provide clear images. However, the restoration of binocular vision occurs quite quickly, and by the first year of life, the child defines the world around him in the same volume as an adult. Full development of vision occurs by the age of 10.

Conditions

Adequate binocular vision is observed only in certain conditions. A person must have the following features:

• Possibility of fusion.
• Synchronous functioning of the motor muscles of the eyes.
• Finding the eyes in the same frontal as well as horizontal plane. Due to eye injuries or diseases, visual field misalignment may occur.
• Visual acuity is within 0.3-0.4, which is absolutely enough to fully reproduce the image on the retina.
• Iseikonia is the same image size on both retinas of the eyes. In some cases, a phenomenon called anisometropia may occur. This is a disorder in which different refraction of the two eyes occurs. The possible range of degree of anisometropia for the presence of binocular vision is 2.0-3.0. This moment taken into account when choosing glasses. When too big difference Binocular vision becomes impossible between corrective lenses.
• Transparency of optics. This includes parts of the eye such as the cornea, lens, and vitreous body. There should be no pathologies observed in optic nerve, retina. However, it is important that there are no changes in the visual analyzers, namely: the subcortical centers, the optic tract, the chiasm, and the cerebral cortex.

Examination

There are several methods to diagnose binocular vision. Let's look at some of them.

• Kalfa method. The study of binocular function is carried out using two thin and long objects (pencils, etc.). The patient holds the object in outstretched arm, placing it horizontally, and then tries to touch it with the tip of another object placed vertically. At in good condition eye task is completed quite easily. However, if binocular vision is impaired, a miss will occur. This is being checked in a simple way: Closing one eye and repeating the task.
• Sokolov's method. A tube is applied to one eye, this may be a piece of paper folded accordingly. You need to put your palm on the end of the tube, this is done from the side open eye. The result is the appearance of an imaginary hole in the palm, but only if there is adequate binocular vision. That is, there appears to be a hole in the center of the palm.
• Reading with a closing subject. A pencil is located a few centimeters from the eyes, covering part of the text. Binocular vision will allow you to read unhindered, even with a pencil. If there are any violations, this will be difficult to do.
• Color test. This is the most exact method determination of binocular vision, which uses a special four-point color test. IN this method two green, one red and one white images are used. The patient is put on glasses with different lenses, one of which is red, the other green. With binocular vision, both colors will be visible, with white appearing red-green. But when different perceptions eye White color will be the same color as the glasses on the dominant eye.

Diagnoses must be made by a specialist

In conclusion, it remains to add that any visual impairment should only be detected by a specialist. Make a diagnosis yourself, even using simple tests, may be dangerous. Therefore, it is best to consult an ophthalmologist for advice and examination. He will do all the necessary manipulations, conduct tests, on the basis of which he will make an accurate conclusion.

Binocular or stereoscopic vision allows a person to perceive the world three-dimensionally - the ability to see objects with two eyes, forming one visual image. When binocular vision is impaired, the field of vision narrows and visual acuity decreases. These disorders can be provoked by ophthalmological and other pathologies.

What is binocular vision?

Binocular vision is one of the essential functions visual apparatus. It begins to form in children almost immediately after birth and develops until the age of 12-14 years. A person with stereoscopic vision perceives the world in 3D format, that is, he can not only see the shapes and outlines of objects, their size in width and height, but also approximately determine the distance between them.

Lack of binocular vision leads to many problems. It is difficult for a person to distinguish the distance between objects and navigate in space. In everyday life, this manifests itself in difficulties when trying to pour water into a glass or thread a thread into eye of a needle. In professional life, problems arise with employment and choice of profession. Thus, impaired binocular vision is a serious limitation for becoming a pilot or driver.

Binocularity disorders can appear at any age and according to various reasons. Before we look at these reasons, we need to know how binocular vision works.

Mechanism and conditions for binocularity

If a person can combine two images from both retinas into one picture, he has developed binocular vision. This unification occurs in the cerebral cortex and is ensured by the fusion reflex. To do this, it is necessary that the brain receives two absolutely identical pictures from both eyes, that is, they must match each other in size and shape. Light rays For spatial vision to function, they must fall on identical points on the retina. These points are called corresponding points. Each point on one retina has a corresponding point on the other retina. If light falls on them, the pictures come together, as if superimposed on each other. If focusing is on different points, then the pictures are different. This leads to diplopia - double image.

Vision will be binocular if:

• there is the ability for fusion (merging images in the brain);
• the eyeballs move in concert and are located symmetrically and parallelly in the same frontal and horizontal plane;
• visual acuity is sufficient for normal visual perception surrounding (not lower than 0.3-0.4 diopters);
• there is no aniseikonia, when the eyes see images of different sizes;
• there are no opacities of the cornea, lens or vitreous body, which are accompanied by a decrease in visual acuity in one eye;
• there are no pathologies of the central nervous system.

There are many conditions for the formation of stereoscopic vision. Moreover, the above factors apply not only to the organs of vision, but also to other systems of the body. Lack of binocularity can be a symptom of both eye diseases and non-ophthalmological pathologies.

Binocular vision disorders and eye diseases

Almost all pathologies of the visual organs can be accompanied by impaired binocularity. Binocular vision is absent when:

• anisometropia (different refraction);
• damage to the oculomotor and other eye muscles, which lead to inconsistency in the movements of the eyeballs;
• infectious eye diseases;
• malignant and benign neoplasms eye;
• mechanical injuries visual organs, including burns that lead to displacement of the eyeballs;
• pathologies of bones and orbital cavity;
• cataracts;
• retinal diseases (hemorrhages, rupture).

Other causes of binocular impairment:

• infectious diseases brain;
• poisonings in which the brain stem is damaged;
• tumors in the brain;
• problems with the activity of the nervous system.

This is a list of a few diseases in which binocular vision is absent. On visual functions Other pathologies of the body may also have a negative effect.

Treatment of binocular vision disorders

Lack of spatial vision is not an independent pathology. This is a sign of another disease that needs to be treated. After all the symptoms of the disease are eliminated, binocular vision is restored. So, anisometropia is treated with surgical intervention. You can also correct this visual pathology glasses or contact lenses.

To restore stereoscopic function, you must first accurately identify the cause of its absence. This can only be done through a thorough examination. In this case, you may have to see not only an ophthalmologist, but also other specialists.

The most common pathology in which normal binocular vision is absent is strabismus (strabismus). With this disease, the movements of the eyeballs are not coordinated. In other words, the eyes look in different directions. One of them may completely disappear from the visual process. Strabismus can be congenital or acquired. It can be treated as surgically, and by hardware procedures and using eye exercises. The main direction of treatment for strabismus is the restoration of binocularity.

Treatment of binocular vision disorders due to strabismus

There are two main hardware methods for restoring stereoscopic function in strabismus: orthoptics and diploptics. Orthoptic treatment involves training by showing a person two slightly different images that need to be combined. The patient is shown split images through a synoptophore, which he tries to combine into one visual image.

Diploptics is the next stage of treatment. This method involves the doctor using an optical prism, which causes double images. The patient eliminates diplopia through his own efforts. The ophthalmologist changes the prisms, changing the angle of inclination until the eyes become accustomed to looking parallel without the use of lenses.

The final stage The treatment will be eye exercises. There are a lot of them. An ophthalmologist selects a specific technique for each patient.

Binocular vision training

Hardware treatment methods are available only in the clinic, but eye exercises can be done at home. There are two simple exercises, which help restore binocular vision. For the first exercise, you will need a sheet of paper on which you need to draw a vertical line approximately 1 cm wide with a marker. The sheet must be fixed on the wall at eye level and moved 1-2 meters away from it. Look at the line and tilt your head down until the line begins to double. Next time, turn your head left and right. The duration of the exercise is 5 minutes. It is advisable to do it three times a day every day. Within two weeks you should notice that your vision has improved.

For the second exercise, you will again need a piece of paper with some kind of drawing on it. Hang it on the wall and move 2-3 meters away from it. Next, you should raise your hand from clenched fist and a finger extended upward at eye level, but on the same visual axis with the object on the wall. You should look at the tip of your finger and at the drawing alternately. When you look at the drawing, your finger doubles, and when you look at the tip of your finger, the image on the wall blurs. You need to train both eyes for 3-5 minutes daily. After just a few weeks of training, you will notice that your visual acuity has improved.

Prevention of binocular vision disorders

As for adults, in order to avoid vision problems, you need to follow a work and rest schedule, correct image life and eat right, visit an ophthalmologist regularly, do eye exercises, especially if the work involves heavy load on visual organs. In addition, you need to consult a doctor promptly if you suspect you have eye disease.

Measures to prevent binocular disorders must be taken starting from the first days after the birth of the child. There are a few simple rules that parents must follow:

• hang toys above the baby’s crib at least 50 cm from his face (otherwise his eyes will squint towards his nose);
• toys should be on both sides of the face;
• Change the location of toys several times a week so that the newborn's gaze does not focus on one point.

At first alarming symptoms Be sure to show your child to the doctor.

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 for bifoveal fusion (fusion).
• Coordinated work of everyone oculomotor muscles, ensuring a parallel position of the eyeballs when looking at a distance and a corresponding reduction of the visual axes (convergence) when looking close, as well as correct associated eye movements in the direction of the object in question.
• The position of the eyes is in the same frontal and horizontal plane. If one of the eyes is displaced due to injury, inflammatory process in the orbit, the neoplasm disrupts the symmetry of the combination of visual fields.
• Visual acuity of both eyes is at least 0.3-0.4, i.e. sufficient to form a clear image on the retina.
• Equal sizes of images on the retina of both eyes - iseikonia. Images of different sizes occur with anisometropia - different refraction 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 selecting glasses - if the difference between the corrective lenses is very large, then even with high visual acuity in glasses, the patient will not have binocular vision.
• Naturally, the transparency of the optical media (cornea, lens, vitreous body) is necessary, the absence pathological changes in the retina, optic nerve and more high departments visual analyzer(chiasma, optic tract, subcortical centers, cerebral cortex)

How to check?

Binocular vision and strabismus