The convergence of the eyes is the reduction of the visual axes when fixing on a closely located object. During this, the pupil narrows. Eye convergence occurs reflexively with binocular vision. Its insufficiency provokes the development of divergent strabismus.
The role of eye convergence
The convergence of the eyes plays an important role in binocular vision during the combination of monocular visual images, creating the necessary conditions for their fusion. In children, it is often disturbed.
Violations of convergence often lead to the appearance and intensification of myopia, the development of axial myopia. The phenomenon is serious and undesirable, especially for children and their parents. For this, eye convergence must be diagnosed. How to check?
- An adult needs to put the child facing him, close one eye to himself.
- Around the middle of the distance, put the pencil vertically so that the adult with an open eye sees it laid on half of the child’s face, and the upper end is at the level of his eyes.
- Invite the child to look into the open eye of an adult and find out how many pencils he sees at the same time.
- If the child sees a “single” pencil, the process ends. His binocular vision is impaired.
- If there are “two” pencils, it is necessary that he looks only at the top of the object, which should be slowly brought closer to the child’s face.
- If there is no convergence, as the pencil draws closer to the face of the child, one eye tends more to the nose, the second to the temple.
- In the presence of convergence, the child’s eyes rotate symmetrically to the nose until the distance decreases to 5 cm.
- Then the child is invited to look at the pencil for 1-1.5 minutes. If the convergence of the eyes is stable, they should be equally turned towards the nose.
- Offer the baby without a pencil to focus both eyes to the nose. If this turns out, then he has a "strong-willed convergence."
Treatment for convergence disorders
If there is no convergence of the eyes, a therapeutic exercise should be performed daily:
- Set a pencil at a distance of 30 cm and look past it. In this case, two images of the subject should be seen.
- First you need to look at the image of the “right” pencil so that the “left” one is visible, then look at the “left” one without losing sight of the other.
- Continue to do such a fixation, first at a slow, then at an accelerating pace.
To enhance convergence, apply exercises that are done daily. They can alternate throughout the day.
Exercise 1. Set the pencil vertically 20 cm from the eyes, look away for 20 seconds, fixing attention on double images of the object, then look at the pencil and look at it for 5 seconds, then look into the distance again and repeat the steps.
Exercise 2. Set the pencil vertically at arm's length, slowly bring it closer to the eyes until it doubles, and then slowly move it away from you.
Exercise 3 to apply for volitional convergence. Stand facing the window so that the horizon is visible. By force of will, to reduce the eyes to the bridge of the nose, holding in this position for 7 seconds, then look into the distance and again reduce the eyes.
The structure of the human eye
More than 80% of the information people get due to what and how we see it. The structure of the visual organ is very complex. It depends on the function of the eyes.
The human eyeball is a sphere of irregular shape. It is located inside the orbits of the skull. From birth to death, the eye sockets double.
An important place is occupied by the optic nerve. It passes information to the occipital cortex, then is analyzed.
Thanks to the lacrimal gland, the surface of the eye remains wet. Tears lubricate the conjunctiva well.
In the structure of the human eye , the muscles of the eyeball act in concert with each other. The eyelids cover the eye, protecting from negative factors. A similar function is performed by the eyelashes.
The relationship of the structure and function of the eyes
To understand the structure of the visual organ, you should compare it with a camera. It creates an image by focusing on the subject and allowing a certain amount of light to pass through the diaphragm.
When the beam enters the eyes, it passes through the cornea, where 75% of the focusing of light is achieved. Then it falls on the pupil, where its number is regulated.
The lens is the second lens of the eye. Its shape is altered by tension or muscle relaxation. Focused light reaches the retina, in which it is transformed into a nerve impulse. When the image reaches the brain centers, it becomes possible to enjoy the world, watch colors and objects. In other words, everything is as we see in real life.
The structure proves how complex the eyes are. Experts still cannot find a way to transplant the muscles of the eyeball, since the optic nerve is very sensitive.
Central vision
It got its name because it is provided by the central part of the retina and the central fossa. Such vision allows a person to distinguish between the shapes and small details of objects.
If it even decreases slightly, it will immediately become noticeable to a person.
The main characteristic of central vision is sharpness. Her research is important in assessing the visual apparatus of a person as a whole, to track various pathological processes.
Visual acuity is the ability of the eye to see two points that are located close to each other, at a certain distance.
There is also the concept of an angle of view, which is the angle that is formed between the extreme points of the observed object and the nodal point of the visual organ.
Peripheral vision
Thanks to him, a person can navigate in space and see in the darkness.
You should turn your head to the right and catch an object with your eyes, let it be a picture on the wall, and fix your eyes on its separate element. If it is visible well, it speaks of central vision. However, besides this object, other big things come into view . For example, a door to a room, a closet, a dog sitting nearby on the floor. These objects are not clearly visible, but are in the field of view, and it is possible to detect movement. This is peripheral vision.
The eyes of people, without moving, can cover 180 degrees of the horizon and a little less (about 130 about ) along the vertical meridian.
The severity of central vision is greater than peripheral. This is due to the fact that the number of cones from the center to the peripheral part of the retina is much reduced.
What vision is considered normal?
Normal vision in a person is associated with the refraction of a light ray in the eye, not deviated from the norm. This means that lenses, cornea, and lens transmit the image to the retina of the eye, to the yellow spot.
Each person has his own norm of vision. It is determined by what line the patient sees on the Golovin-Sivtsev table. A well-known unit means that he reads the 10th line. This is normal vision.
Refraction disorder
Refraction is the refraction of light in the eye.
If the beam is refracted correctly, the image is focused exactly on the retina. The opposite situation (violation of refraction) provokes the development and appearance of hyperopia and myopia. If available, the image is seen blurry, double. For correction, medical glasses and lenses are used, which make the light beam focus on the retina.