Binocular (stereoscopic) vision allows us to see the surrounding objects in volume. Thanks to this function, a person is able to correctly estimate the distance between objects. With various pathologies of the eyes and the central nervous system, binocular vision disorders may occur. How do such diseases manifest themselves? And can binocular disorders be cured? We will answer these questions in the article.
General characteristics
What is binocular vision? Normally, a person perceives all surrounding objects and objects with two eyes. But at the same time, he sees not two visual pictures, but one. Information entering the brain from two organs of vision merges into a single three-dimensional (stereoscopic) image. Ophthalmologists call this ability of the human eye binocular vision.
First, each eye separately recognizes the objects of the surrounding world usingretinal photoreceptors (cones and rods). The signals are then transmitted to the visual center of the brain, where they are processed. Information received from the retinas of one and the other eye merges into a single image. Doctors call this process of combining two visual images fusion.
The following conditions are necessary for the normal operation of binocular vision:
- Visual acuity in each eye is not less than 0.3 diopters;
- the ability of the visual analyzer to fuse;
- coordinated work of the muscular and ligamentous apparatus of the eyeballs;
- no deviation of the visual axes from the point of gaze fixation;
- no retinal pathology.
Violation of any of these conditions leads to binocular vision disorders. With such pathologies, the perception of the surrounding world becomes monocular. The coordinated work of the two organs of vision is disrupted. A person perceives all objects alternately: first with one eye, then with the other. Such a patient can correctly perceive the shape and size of objects, but it is very difficult for him to determine their location in space. There are great difficulties in estimating the distances between objects.
Etiology
Consider the most common causes of binocular vision impairment. The following pathologies of the eyes and central nervous system can lead to such a disorder:
- diseases and injuries of the retina;
- cataract;
- corneal burns;
- defects in the structure of the eye muscles;
- intoxication of the body with various poisons;
- chromosomal abnormalities;
- neurological diseases.
Binocular disorders are very rarely a separate pathology. Most often, this is just one of the symptoms of ophthalmic and neurological diseases.
The most common forms of binocular vision impairment are:
- strabismus;
- amblyopia;
- anisometropia.
Next, we will look at the above types of disorders in more detail.
Squint: general description
When strabismus (strabismus) occurs, the visual axis of one or two eyes deviates from the object in question. It occurs due to inconsistent work of the muscles of the organ of vision. In this case, one eye of a person fixes his gaze on a certain object, and the other deviates in any direction and perceives completely different objects. As a result, a single visual image does not add up.
The following types of strabismus are distinguished:
- friendly;
- paralytic.
These types of strabismus have different etiologies and symptoms.
Friendly Strabismus
Concomitant strabismus is the most common type of binocular vision disorder in children. It occurs due to the following reasons:
- neurological disorders;
- adverse effects on the fetus in utero;
- chromosomal abnormalities;
- acquired farsightedness or nearsightedness;
- decrease in visual acuity of oneeyes;
- heterophoria (different strength of the muscles of the left and right eyes);
- complications after infectious pathologies.
With a friendly form of strabismus, the patient has changes in only one of the organs of vision. At the same time, the movements of the eye muscles are not disturbed, and the angles of deviation from the visual axis are the same. This means that if one eye skews by 5 degrees, then the other deviates by the same amount.
Concomitant strabismus often looks like a purely external defect and does not cause any particular inconvenience to the patient. This form of strabismus is not accompanied by double vision. However, over time, strabismus can lead to decreased visual acuity. To see any object, a person has to squint and strain his eyes. This leads to fatigue of the organ of vision and headaches. Therefore, concomitant strabismus must be treated in childhood. Binocular vision disorders in adults are much more difficult to correct.
Paralytic strabismus
The paralytic form of strabismus is quite rare. This pathology occurs more often in adults. Its cause is eye injury, ophthalmic surgery, intoxication. Strabismus develops due to paralysis of the muscles responsible for the movement of the eyeball.
This type of binocular vision disorder is characterized by the complete impossibility of moving the eyeball towards the paralyzed muscle. Patients often experience double vision. In the paralytic form of strabismus, thevisual acuity. Myopia or farsightedness quickly develops. It becomes very difficult for a person to fix his gaze on any object. This form of strabismus is quite difficult to treat.
Amblyopia
With this disorder, the patient's binocular vision is severely impaired. What is amblyopia? Patients often confuse this disease with strabismus. However, these are different pathologies.
Amblyopia develops as a complication of strabismus. Over time, functional changes occur in the squinting eye. He ceases to fully participate in visual perception. This disease is also called "lazy eye syndrome".
At the same time, there are no anatomical changes in the affected organ of vision. All violations are functional. However, the diseased eye is very little involved in the process of visual perception, which leads to a one-sided decrease in visual acuity.
With amblyopia, a person sees differently with a he althy and diseased eye. Therefore, a single visual image in the brain does not add up. The affected organ of vision distinguishes colors and volume of objects well, but recognizes details very poorly.
Anisometropia
The human eye works like a lens that refracts light rays. Doctors call this function of the organ of vision refraction. Normally, the refractive power of the left and right eyes is the same.
If the refractive power of one eye is reduced, then ophthalmologists call this pathology anisometropia. This disease is always accompanied by disordersbinocular vision. If the difference in refractive power between the two eyes is more than 2 diopters, then this is accompanied by severe discomfort.
Anisometropia is most often caused by changes in the shape of the lens or cornea (astigmatism). Pathology can also develop in patients with cataracts and after ophthalmic operations.
With anisometropia, a person sees a clear and bright picture with a he althy eye, and a blurry one with a sick eye. Therefore, a single visual image is not formed in the brain. There is double vision, patients complain of blurred vision. If a person covers his sore eye with his hand, then all symptoms disappear.
Diagnosis
There are several home tests that you can use to check binocular vision yourself:
- Sokolov's method. It is necessary to roll up a tube of paper (like binoculars) and attach it to one of the eyes. Opposite the other eye, you need to place the palm of your hand and hold it at the level of the end of the pipe. If binocular vision is normal, then a person will see a hole in the palm.
- Method with a book. At a distance of 2 - 3 cm from the tip of the nose, you need to place a pencil and try to read the text of the book. With normal binocular vision, a person can do this without difficulty.
- Kalff method. You need to hold two pencils in front of you, one in a vertical position and the other in a horizontal position. Then you need to try to connect their ends together. If a person has problems with binocularity, then it will be difficult for him to perform this test.
These tests will only provide a preliminary assessment of the quality of stereoscopic vision. Only a specialist can accurately identify binocular disorders. If the patient has increased fatigue of the organ of vision, double vision or visible strabismus, then an urgent need to visit an ophthalmologist.
Doctors prescribe the following diagnostic procedures to test binocularity:
- Examination on devices "Monobinoscope" and "Synoptofor". These devices not only help to diagnose strabismus and amblyopia with high accuracy, but are also often used for medical purposes.
- Refractometry. With the help of a special device, the refractive power of both eyes is evaluated and compared.
In addition, ophthalmoscopy and biomicroscopy are performed. This allows you to assess the condition of the tissues of the cornea, lens and fundus.
Therapy Methods
Treatment of binocular vision disorders at an early stage is carried out by conservative methods. The following therapies are used:
- Occlusion. The patient wears special glasses, in which one of the glasses is sealed with a plaster. The sticker is applied to the he althy side. This causes the patient to strain the squinting eye. This treatment method prevents the development of amblyopia due to strabismus.
- Hardware techniques. For treatment, devices "Monobinoscope" or "Synoptofor" are used. With their help, exercises for the eyes are carried out to combine several pictures into one. Also, these devices allow you to stimulate the eye muscles with light signals.
Drug treatment for binocular disorders is ancillary. Assign complexes with beta-carotene, vitamins A and C. This helps to maintain visual acuity. In the paralytic form of strabismus, nootropics, antioxidants and neuroprotectors are indicated.
If there is no effect of conservative therapy for 1.5-2 years, then this is considered an indication for surgery. During surgery, the doctor weakens the eye muscle. This leads to the normalization of eye movements and the elimination of external signs of strabismus. However, binocular disturbances may persist. Therefore, after the operation, a second course of hardware treatment is carried out using the Synoptofor device.
It is important to remember that strabismus and amblyopia are best treated in childhood. In adults, such vision disorders require long and persistent therapy, and sometimes surgical intervention.
