Methods for assessing binocular vision. Binocular vision - research, treatment of disorders

Use a device designed by the Tochmedpribor plant or a similar test projector of test marks. The operation of the device is based on the principle of dividing the fields of vision of both eyes using color filters.

The removable cover of the device has four holes with light filters arranged in the shape of a lying letter “T”: two holes for green filters, one for red and one for white. The device uses light filters of complementary colors; when placed on top of each other, they do not transmit light.
The study is carried out from a distance of 1 to 5 m. The subject is wearing glasses with a red filter in front of the right eye and with a green filter in front of the left eye.

When examining the colored holes of the device through red-green glasses, a subject with normal binocular vision sees four circles: red on the right, two green ones vertically on the left, and a middle circle, as if consisting of red (right eye) and green (left eye) colors.

If there is a clearly defined dominant eye, the middle circle is painted in the color of the light filter placed in front of this eye.
With monocular vision of the right eye, the subject sees through the red glass only red circles (there are two of them), with monocular vision of the left eye - only green circles (there are three of them).
With simultaneous vision, the subject sees five circles: two red and three green.

Raster haploscopy (Bagolini test)

Raster lenses with the thinnest parallel stripes are placed in the frame in front of the right and left eyes at an angle of 45° and 135°, which ensures mutually perpendicular direction of the raster stripes, or ready-made raster glasses are used. When fixing a point light source placed at a distance of 0.5-1 cm in front of the glasses, its image is transformed into two luminous mutually perpendicular stripes. With monocular vision, the patient sees one of the stripes, with simultaneous vision, two unaligned stripes, with binocular vision, the figure of a cross.

According to the Bagolini test, binocular vision is recorded more often than according to the color test, due to the weaker (non-color) separation of the right and left visual systems.

Chermak's method of sequential visual images

They evoke successive images by illuminating the right and left eyes alternately while fixing the central point: with a bright vertical stripe (right eye), and then with a horizontal stripe (left eye) for 15-20 s (with each eye). Next, successive images are observed on a light background (screen, sheet of white paper on the wall) with light flashes (after 2-3 s) or when blinking the eyes.

By the location of the stripes of foveal visual images in the form of a “cross”, the misalignment of the vertical and horizontal stripes, or the loss of one of them, one judges, respectively, their combination (in persons with binocular vision), misalignment with the same or cross localization, suppression (suppression of one image), presence of monocular vision.

Assessment of binocular functions using a synoptophore

The device performs mechanical haploscopy using two separate movable (for installation at any angle of strabismus) optical systems - right and left. The set consists of three types paired test objects: for combination (for example, “chicken” and “egg”), for fusion (“cat with a tail”, “cat with ears”) and stereotest.

The synoptophore allows you to determine:

ability for bifoveal fusion (when both images are combined at a strabismus angle);
the presence of a zone of regional or total suppression (functional scotoma), its location and size (according to the measuring scale of the device in degrees);
the amount of fusion reserves according to tests for fusion - positive (with convergence), negative (with divergence of paired tests), vertical, torsion;
presence of stereo effect.

Synoptophore data allows you to determine forecast and tactics complex treatment, and also choose the type of orthoptic or diploptic treatment.

Depth Vision Assessment

A Howard-Dolman type device is used. The study is performed in natural conditions without dividing the field of view.

Three vertical poibor rods (right, left and movable middle) are placed in the frontal plane on one horizontal straight line. The subject must perceive the displacement of the middle rod as it approaches or moves away in relation to the two fixed ones. The results are recorded in linear (or angular) values, which for mature people are 3-6 mm for near (from 50.0 cm) and 2-4 cm for distance (from 5.0 m), respectively.

Depth vision is well trained in a real environment: ball games (volleyball, tennis, basketball, etc.).

Stereoscopic vision assessment

Using the flying fly test. The study is carried out using a booklet with polaroid vectograms (fly-test from Titmus). When viewing the picture through the Polaroid glasses supplied with the booklet, you get the impression of a stereoscopic effect.
Based on the recognition of the location and degree of distance of tests with different levels of lateral displacement of paired drawings, the threshold of stereoscopic vision is judged (from the presence of the ability to stereoscopic sensation to 40 arc seconds), using the booklet table.
Using the Lang test. The study is carried out on a Polaroid booklet in Polaroid glasses, similar to the method described above. The method allows one to estimate the threshold of stereoscopic vision in the range from 1200 to 550 arc seconds.
On a lens stereoscope with paired pictures of Pulfrich. Paired pictures are built according to the principle of transverse disparity. The details of the drawings (large, small) make it possible to register the stereoscopic vision threshold of up to 4 arc seconds based on the correct answers of the subject.
Screening methods. Research is carried out using test mark projectors equipped with a measuring ruler for special tests (Carl Zeiss). The test consists of two vertical lines and a round luminous spot under them. A subject with stereoscopic vision, when viewed through Polaroid glasses, distinguishes three figures located at different depths (each of the strokes is visible monocularly, the spot is visible binocularly).

Definition of phoria

Maddox test

The classic technique involves using a red Maddox “stick” from a set of lenses, as well as a Maddox “cross” with a vertical and horizontal measuring scale and a point light source in the center of the cross. The technique can be simplified if you use a point light source, a Meddox “wand” in front of one eye and a prism ophthalmic compensator OKP-1 or OKP-2 in front of the other eye.

The ophthalmic compensator is a biprism of variable strength from 0 to 25 prism diopters. At horizontal position When using the rod, the examinee sees a vertical red stripe, displaced in the presence of heterophoria from the light source outward or inward in relation to the eye in front of which the rod is placed. The strength of the biprism, which compensates for the displacement of the strip, determines the amount of esophoria (when the strip is displaced outward) or exophoria (when displaced inward).

A similar research principle can be implemented using test mark projector tests.

Graefe's test

Draw a horizontal line with a vertical arrow in the middle on a piece of paper. A prism with a strength of 6-8 prism diopters is placed in front of one eye of the subject with the base up or down. A second image of the drawing appears, shifted in height.

In the presence of heterophoria, the arrow moves to the right or left. A displacement of the same name (outward) in relation to the eye in front of which the prism is placed indicates esophoria, and a cross displacement (inward displacement) indicates exophoria. A prism or biprism, which compensates for the degree of displacement of the arrows, determines the magnitude of the phoria. Tangential markings can be applied to the horizontal line with dots corresponding to degrees or prism diopters (instead of biprism). The degree of displacement of the vertical arrows on this scale will indicate the magnitude of the phoria.

The patient is offered test picture-objects created in pairs. The set contains objects for three types of tests:

for combination;
for merger;
for stereo test.

What is determined using a synoptophore:

bifovial fusion (binocular fusion);
functional scotoma (suppression, manifested regionally or totally), its size and location are also determined;
positive or negative fusion reserve (test with the moment of bifurcation of the line);
stereo effect.

The synoptophore allows you to “look” into the picture, which only the patient can see. From the descriptions that the specialist receives from the subject, one can understand what is hindering normal vision patient, give a prognosis for the possibility of recovery and prescribe treatment after testing.

Depth Vision Assessment

The test is carried out without dividing the visual fields, the eyes are in their natural state, the gaze is directed at the device (for example, the Howard-Dolman, Litinsky and others). An example of a study on the so-called three-stick test. There are three vertical rods at one level: two outer rods and one in the center, which is movable. The middle one is moving away or approaching, the task is to catch the moment of displacement relative to the two outer rods. The assessment is made from 50 cm - for near, and from 5 meters for distance. The results are evaluated in angular (or linear) quantities. Visual impairment for mature patients is assessed from 3-6 mm near, and from 2-4 cm at distance.

Stereoscopic vision assessment

A system of tests is carried out using polaroid vectograms with special glasses: The picture effect is stereoscopic. The specialist has a table to check the correctness of the distance: the patient says what he sees, the doctor compares the result.

The threshold of stereoscopic perception is revealed in tests:

Flying fly.
Lang test.
Pulfrich lens stereoscope.
Screening method.

Definition of phoria

Phoria is a deviation or turn of the eyes from the axes, an anomaly. Lack of coordination between the eyes.

To determine phoria, special tests are used:

Maddox test;
Graefe's test.

Special kits, using which an ophthalmologist can determine the nature of a person’s visual impairment. The assessment system is simple: the specialist knows what the results will be with normal binocular function, and what the patient with pathology sees.

Based on the research results, heterophoria, esophoria or exophoria are diagnosed, and the magnitude of phoria is assessed.

Get tested

If you know that the last examination by an ophthalmologist took place quite a long time ago, check your visual acuity again. With age, muscles can lose tone and the ability to focus their gaze as clearly as in youth. Perception disorder may occur due to general condition body or due to working conditions and lifestyle.

That is, if you once saw everything well thanks to binocular vision, perhaps a diagnosis and eye examination will now show that it’s time to begin correction. Violations in initial stage really do not require treatment and can be corrected. To do this, you need to know the appropriate exercises, observe living conditions, and treatment for poor vision.

If you see everything well, then only an examination can confirm whether you really see binocularly. Initial distress may not be assessed subjectively. A person notices that his vision has become worse when the impairment is already quite serious. Even in this case, the specialist will choose the optimal device for diagnosis and treatment and prescribe glasses with the correct lens parameters.

Binocular vision: what is it?

Binocular vision- this is an opportunity to see three-dimensionally. Provides this functionality visual analyzer fusion reflex. It works as follows: the brain receives two images from both retinas and combines them into a complete picture. Stereoscopic vision is possible under certain conditions. A person must have good eyesight, his eyeballs should move synchronously, in coordination. There are other conditions that ensure stereo vision works. In most cases, they relate to the presence or absence of diseases, ocular and non-ophthalmological. When binocular vision is impaired, a person cannot see normally with both eyes. One partially or completely falls out of the visual process, and without stereo vision it is difficult to navigate in space, since a person cannot determine the distance between visible objects.

Determination of binocular vision online

You can determine whether you have binocular vision yourself at home. This is done using a series of simple experiments or computer programs. An online binocular vision test will give you the opportunity to find out whether or not you have problems with visual functions.

How to pass the binocular vision test?

To do this, you need to upload a picture to the server, for example, an apple. It should be large (about 15 cm in diameter) and located in the center of the monitor. Adjust the brightness of the image. The monitor should not be dim or too bright. You should place it at a distance of 40-45 cm from the monitor. The image is at eye level. Next, you need to extend your finger up and keep it on the same visual axis with the object (apple). Look at the apple. You should be able to see the object between your two fingers. At the same time, your hands and fingers will appear transparent. After this, look at your finger. You will notice that the apple has split in half.

The next step is to look at the apple and close your left eye. You should see a finger to the left of the object. When you close your right eye, you will see a finger to the right of the apple.

Evaluation of results

The test is deciphered very simply. If you see all the images described above (a forked apple and a forked finger), then your stereoscopic vision function is working. If there are violations, you will see other images:

one finger is larger than the second;
You only ever see one finger;
fingers disappear and appear, and you cannot focus normally;
the left finger covers the apple, and the right finger is located very far from it.

What to do if the results are negative?

All these signs indicate that one eye is dominant in you. This is not a reason to panic. You may not be able to pass the online vision test the first time. In addition, there are various exercises to train your vision. However, it is better to consult an ophthalmologist for an examination. The test can only give a rough idea of how spatial vision works. In the presence of pathologies, for example, with strabismus, examination with special devices is necessary. One such device is a sign projector.

Wars test. Checking on the sign projector

A sign projector is a device used by ophthalmologists to determine the degree of visual impairment. A projector shows signs on the wall, and a person looks at them through green and red lenses. There are only 5 signs: two green, two red and white. In the presence of binocular vision, the subject sees four figures, if the vision is simultaneous (that is, one and then the second eye works alternately) - 5 figures, and with monocular vision (one eye works) - the patient distinguishes either two red or three green figures.

Advantages of the technique

The sign projector experiment is also called the four-point experiment. It is the most common in ophthalmology, as it allows you to accurately determine the nature of vision. The results of the study can only be deciphered by a doctor. The advantage of this technique is its accuracy. However, it is not suitable for testing vision in very young patients who cannot tell themselves what they see. They are examined using other instruments.

Binocular disturbances can lead to various diseases. In most cases, the prognosis for treatment is favorable. It is important to start treating any disease on time and systematically

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.

Note! 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 systems;
absence of pathology in the structure of the lens, retina and cornea.

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

Note! 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 a sheet of paper is removed, the eyeball occupies 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;
physiotherapy;
eye lenses and glasses;
laser correction.

With heterophoria it is possible fast fatiguability eyes, double vision. IN in this case Prismatic glasses are used for constant wear. 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 pair of markers/pencils: hold one in a horizontal position, the other in a vertical position. 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 fully comprehend the text with your vision and read, it means that motor and sensory functions are not impaired. 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. Wherein, 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 occurs when both eyes participate in the visual act and merge two monocular images into a single visual image. Each eye sees the object of fixation from slightly different positions; the images in the right and left eyes are shifted transversely relative to each other (disparate).

The phenomenon of transverse disparation in binocular vision is the basis of depth vision (in-depth assessment of the visual image). Stereoscopic vision reflects the ability to judge depth in the presence of stereoscopic instruments and devices.

Binocular vision is based on the mechanism of retinal correspondence - the innate property of the foveal and symmetrically distant areas (corresponding zones) of the retinas of both eyes to a single perception of the fixed object. The merging of two monocular images during 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 the image of an object hits different distanced (non-corresponding, disparate) areas of the retinas, a single visual image does not form. The images are perceived as 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 eye becomes functionally dominant - monocular vision develops.

Formation of binocular vision

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

To form binocular vision, the following conditions are necessary:

equal visual acuity in both eyes (not lower than 0.4 in each eye);
the same refraction (degree of farsightedness or myopia) 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.
The location of the two eyes in the same frontal and horizontal plane

It should be noted that with an inequality of image sizes (anizeikonia) 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 practically impossible. Images of different sizes occur with anisometropia - different refraction of the two eyes.

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

Monocular and simultaneous vision allows you to get an idea only of 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 tone oculomotor muscles.

Orthophoria is an ideal balance of the tone of the extraocular muscles.
Heterophoria is a hidden imbalance in the tone of the oculomotor muscles, detected in 70-75% of mature people with binocular vision. There is esophoria (with a tendency to reduce the visual axes) and exophoria (with a tendency to separate them). Heterophoria can cause asthenopia, decreased visual performance, and in some cases, strabismus.

The main qualitative characteristic of binocular vision is deep stereoscopic vision of an object, which allows one to determine its place in space, to see in relief, depth and volume. Images of the external 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, assessing 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 a thread into the eye of a needle, pour water into a glass, etc.

The lack of binocular vision limits a person's professional suitability.

Diagnostics

Indications

Exist the following readings to assess binocular vision:

professional selection (flight professions, precision work, driving Vehicle and etc.);
planned preventive examinations of children and adolescents before school and during training;
pathology of the oculomotor system (strabismus, nystagmus), asthenopia, occupational 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 using haploscopic methods, based on the principle of dividing the visual fields of both eyes using color (four-point, or Wars test), raster (Bagolini test) or polaroid (four-point Polaroid test) haploscopy;
for strabismus - testing using the method of sequential visual images (according to the Chermak principle);
assessment of binocular functions (fusion ability) on a synoptophore (under mechanical haploscopy);
assessment of depth vision (threshold, acuity);
assessment of stereoscopic vision (stereo pair);
phoria research.

Some simple ways determination of binocular vision without the use of instruments.

Binocular coordination of eye movements

Movements eyeball carried out by six external ocular muscles, which are innervated by three cranial nerves: oculomotor (III pair), trochlear (IV pair) and abducens (VI pair). Therefore there are many different nerve connections between cortical visual areas and oculomotor centers in the brainstem.

Quantitative characteristics

Qualitative characteristics include changes in vision parameters, which manifest themselves in the form of various agnostic syndromes:

changes in visual acuity,
changes in visual fields,
changes in electrical excitability of the retina (electroretinography),
changes in cortical time,
changes in retinocortical time,
changes in evoked visual potentials.

visual agnosia,
color agnosia,
literal agnosia,
verbal agnosia,
spatial agnosia,
agnosia for faces (prosopagnosia).

Symptoms of irritation of the visual analyzer may also be observed:

photopsia, false visual sensations in the form of flickering spots, sparks, luminous thin stripes that appear in certain areas of the visual field;
visual hallucinations, when the patient sees various figures or objects that do not really exist. Most often, figures and objects are perceived in a state of movement.

Thus, signals from area 18 of the cortex go to the superior colliculi (superior colliculus), which control neurons that control the direction of gaze. Neurons that control horizontal eye movements are located predominantly in the paramedian reticular formation pons, and the neurons that control vertical eye movements are 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, eye and head movements 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, the secondary visual cortex, the parietal cortex (mainly its area 7). When the paramedian reticular formation of the pons is damaged, horizontal rotation of the eyes in the direction 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 in question, 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 per 1 s) sliding of the gaze from a given direction (by an amount from 3 to 30 arc minutes),
microsaccades (microjumps) - rapid movements of the gaze from 1 to 50 arc minutes.

Drift helps restore the visibility of the image on the retina, and microsaccades help restore the given direction of gaze.

Thus, the visual pathway is represented as a very complex multi-storey hierarchical network of neural structures, becoming significantly more complex towards the cerebral cortex. Functionally, this helps to isolate individual, increasingly complex elements of the visual image. The final functional stage visual pathway is the synthesis of visual images and their recognition by comparison with the existing stock of visual images stored in memory.

Various visual impairments that occur when the visual analyzer is damaged manifest themselves both in changes in the quantitative characteristics of visual functions and in changes in the qualitative characteristics of visual functions.

Lesions at each level (division) of the visual analyzer are manifested by the formation of a fairly characteristic symptom complex. This helps to establish topical and nosological diagnoses.