Causes of different vision in the eyes. What is lateral vision called - what and how we see from the side

Lateral vision, also called peripheral vision, helps a person navigate in space. If you can well recognize objects that are away from your direct gaze, it means that the functional activity of your peripheral vision is not impaired. The peripheral part of the retina is responsible for lateral vision.

The main thing, of course, is central vision. It is with its help that we can clearly see the shape, color and brightness of objects, and also navigate in the dark. Lateral vision acuity is slightly lower compared to central vision. At the same time, developed peripheral vision is extremely important for drivers, military personnel and athletes.

Impairment in lateral vision can be caused by glaucoma, increased intracranial pressure, as well as damage to the retina or optic nerve. As you can see, a violation may indicate serious pathological processes visual apparatus. This is why it is so important to visit an ophthalmologist in a timely manner.

The peripheral abilities of the retina can be examined using the perimeter. It is important to understand that if lateral vision is lost, even with good central vision acuity, a person simply will not be able to move independently.

Peripheral vision recognizes dynamic objects well, as well as white or contrasting colors. The wider the viewing angle, the more a person will be able to read. With the help of special exercises you can develop and train your visual abilities.

Lateral vision is better developed in women than in men

Peripheral vision in men and women

Scientists say that men have better developed central vision, while women have better lateral vision. This is explained by the fact that a woman has always been the keeper of home comfort and hearth, so she needed to see everything around her. A broad outlook was also necessary in order to promptly detect the danger threatening her and the children.

According to statistics, a large number of car accidents occur because the driver does not notice the danger that is located on the side of the car.

Lateral vision in men is also called tunnel vision by experts. Thanks to high levels of central vision acuity, a man is able to clearly and clearly see objects in front of him. And this even applies to those objects that are located at a distance. In fact, the eyes of the stronger sex are more like a spyglass or binoculars.

Men's vision is adapted for looking into the distance. Because of this, eye fatigue is much higher in men. In order to see an object up close, such as looking in the rearview mirror while driving a car, vision must constantly refocus.

The ability to see in the dark is another difference between women's and men's vision. A woman sees finer details better up close. Along with this, it is difficult for her to understand on which side oncoming vehicles are moving.

Impaired lateral vision

Retinal injuries, as well as brain diseases, can lead to disturbances in peripheral vision. This may affect one or both eyes.

If peripheral vision is lost, a person will see objects as if in a tunnel

Why can the field of vision narrow? Let's consider real reasons such a state:

• increased intraocular pressure. As glaucoma progresses, the optic nerves are damaged and the field of vision narrows. Objects in front of a person's eyes may also blur. On initial stages the narrowing is insignificant. In the absence of timely treatment, it will simply be impossible to restore peripheral function;
• Retinal damage can occur against the background of intense physical activity, changes in blood pressure, stressful situations;
• cerebral circulatory disorders;
• traumatic brain injuries;
• neoplasms;
• strokes;
• dystrophic changes retina;
• age-related changes.

With migraine, patients may complain that everything is swimming before their eyes, and then their head begins to hurt. It is also worth noting hallucinations in the lateral visual field. A person can see fleeting visions most often only from one side. For example, it may seem to him that a mouse ran by or someone passed. Such hallucinations indicate the presence of a mental disorder.

There are several types of lateral vision impairment:

• The space covering the organ of vision decreases. As a result, only a small portion of rectilinear visual space may appear;
• The structure of the eye changes so much that ineffective areas of the retina appear. As a result, patients see dark spots indicating loss of certain areas of the visual field;
• partial loss of visual fields.

Glaucoma can lead to complete loss vision

Impaired visual function manifests itself in the form of decreased visual acuity and limited visual field. Repainting the pupil in a greenish or azure tint is the main external sign pathological process.

Frequent stress, prolonged use of steroid drugs, eye injury, and developmental abnormalities can lead to increased intraocular pressure. Glaucoma is characterized by the appearance of rainbow circles in bright light, blurred vision in the dark, headache, pain in the eyes, redness, and a feeling of heaviness.

Scotoma

Scotoma is loss of visual fields. Cataracts, stress, glaucoma, dystrophic changes in the eye - all this and much more can lead to disorders. Dark spots can be in the form of circles, ovals, arcs, wedges.

Smears in front of the eyes impair both central and peripheral vision. Some patients complain of periodic blurred vision.

Ocular migraine

Visual defects are temporary. More often provoke a violation neurological diseases. According to statistics, ocular migraine with aura appears in pregnant women and young and middle-aged people. Defects can appear as a result of lack of sleep, changes in weather conditions, mental overstrain, emotional outbursts or intense physical activity.

Ocular migraine causes visual defects

The emerging spot goes in the direction of peripheral vision. The formation can be colorless, and sometimes it can be very bright. The aura can manifest itself in the form of visual hallucinations. During an attack, the patient is advised to calm down, lie down and drink hot tea or coffee. A neurologist treats ocular migraines.

Diagnostic examination

You can test your peripheral vision yourself at home. To do this, focus your gaze on an object that is located directly from you. Next, without moving your gaze, try to look at objects on the right and left sides. You can also pick up white pencils and then spread your hands. With normal peripheral vision, a person must simultaneously perceive both objects.

In the ophthalmology office, peripheral vision indicators are examined using a special device. The patient places the chin on a special stand, while one eye is covered with a bandage. The open eye should focus on the white mark that is moving. The perimeter defines the space within which, with the eye position fixed, you can see every point of it.

Using the automatic perimeter, you can determine not only the width of the field of view, but also the existing defects and the sensitivity threshold of the retina. The device is able to report defects in the retina and optic nerve on early stages development.

The perimeter will help identify problems with peripheral vision

How to develop peripheral vision?

Developmental exercises help achieve the following goals:

• improvement of brain activity;
• a person begins to better navigate in space;
• Speed ​​reading develops.

Let's consider effective exercises that will help develop lateral vision indicators:

1. Fix your gaze on the object and try to simultaneously recognize objects located on both sides.
2. Concentrate your gaze on an object located three meters away from you. Take a pencil in your hands and spread your hands. In this case, you should see not only the main object, but also the pencils.
3. Take the pencils again and spread your hands. Right hand lift up and watch the pencil in this hand with your right eye. At the same time, lower the left pencil and watch it with your left eye. Next, the pencils are brought to the center. Then move the objects diagonally and return to the starting position.
4. Draw letters or numbers in bright colors on sheets of paper large sizes. Observe the drawings while constantly increasing your viewing angle. As peripheral vision develops, smaller pictures can be used.
5. Concentrate on the subject, while paying attention to the subject located in the periphery. There should be more and more of these items.

So, peripheral vision is no less important than central vision. The ability to see peripheral objects allows you to navigate well in space. Impaired lateral vision may indicate the presence of serious pathologies, including: glaucoma, scotoma, retinal detachment, disruption of brain function, neoplasms, and others. So as not to miss dangerous diseases, it is important to contact an ophthalmologist in a timely manner and follow his recommendations.

The person processes the information received and makes the necessary adjustments. These processes are unconscious in nature and are implemented in multi-level autonomous correction of distortions. This way, spherical and chromatic aberrations, blind spot effects are eliminated, color correction is carried out, a stereoscopic image is formed, etc. In cases where subconscious information processing is insufficient or excessive, optical illusions arise.

Spectral sensitivity of the eye

Water absorption spectrum

In the process of evolution, light-sensitive receptors have adapted to solar radiation that reaches the surface of the Earth and spreads well in the water of the seas and oceans. The Earth's atmosphere has a significant window of transparency only in the wavelength range 300-1500 nm. In the ultraviolet region, transparency is limited by the absorption of ultraviolet light by the ozone layer and water, in the infrared region - by absorption by water. Therefore, the relatively narrow visible region of the spectrum accounts for more than 40% of the solar radiation energy at the surface.

The human eye is sensitive to electromagnetic radiation in the wavelength range 400-750 nm ( visible radiation) . The retina of the eye is also sensitive to shorter wavelength radiation, but the sensitivity of the eye in this region of the spectrum is limited by the low transparency of the lens, which protects the retina from the destructive effects of ultraviolet radiation.

Physiology of human vision

Color vision

The human eye contains two types of light-sensitive cells (photoreceptors): highly sensitive rods and less sensitive cones. Rods function in relatively low light conditions and are responsible for the night vision mechanism, but they provide only a color-neutral perception of reality, limited to the participation of white, gray and black colors. Cones operate at more high levels illumination than sticks. They are responsible for the mechanism of daytime vision, distinctive feature which is the ability to provide color vision.

Light of different wavelengths stimulates different types of cones differently. For example, yellow-green light stimulates L- and M-type cones equally, but less stimulates S-type cones. Red light stimulates L-type cones much more than M-type cones, and does not stimulate S-type cones at all; green-blue light stimulates M-type receptors more than L-type, and S-type receptors a little more; light with this wavelength also stimulates rods most strongly. Violet light stimulates almost exclusively S-type cones. The brain perceives combined information from different receptors, which provides different perceptions of light with different wavelengths.

Behind color vision In humans and monkeys, genes encoding light-sensitive opsin proteins are responsible. According to proponents of the three-component theory, the presence of three different proteins that respond to different wavelengths is sufficient for color perception. Most mammals have only two of these genes, which is why they have two-color vision. If a person has two proteins encoded by different genes that are too similar or one of the proteins is not synthesized, color blindness develops. N. N. Miklouho-Maclay found that the Papuans of New Guinea, living in the thick of the green jungle, do not have the ability to distinguish the color green.

The red light-sensitive opsin is encoded in humans by the OPN1LW gene.

Other human opsins are encoded by the genes OPN1MW, OPN1MW2 and OPN1SW, the first two of which encode proteins that are sensitive to light at medium wavelengths, and the third is responsible for an opsin that is sensitive to the short-wavelength part of the spectrum.

Necessity three types opsins for color vision was recently proven in experiments on squirrel monkeys (Saimiri), whose males were cured of congenital color blindness by introducing the human opsin gene OPN1LW into their retina. This work (along with similar experiments in mice) showed that the mature brain is able to adapt to the new sensory capabilities of the eye.

The OPN1LW gene, which encodes the pigment responsible for the perception of red color, is highly polymorphic (recent work by Virrelli and Tishkov found 85 alleles in a sample of 256 people), and about 10% of women who have two different alleles of this gene actually have an additional type color receptors and some degree of four-component color vision. Variations in the OPN1MW gene, which encodes the “yellow-green” pigment, are rare and do not affect the spectral sensitivity of the receptors.

The OPN1LW gene and the genes responsible for the perception of medium-wavelength light are located in tandem on the X chromosome, and non-homologous recombination or gene conversion often occurs between them. In this case, gene fusion may occur or the number of their copies in the chromosome may increase. Defects in the OPN1LW gene are the cause of partial color blindness, protanopia.

The three-component theory of color vision was first expressed in 1756 by M. V. Lomonosov, when he wrote “about the three matters of the bottom of the eye.” A hundred years later, it was developed by the German scientist G. Helmholtz, who does not mention Lomonosov’s famous work “On the Origin of Light,” although it was published and summarized in German.

Maximum pupil changes for healthy person- from 1.8 mm to 7.5 mm, which corresponds to a change in pupil area by 17 times. However, the actual range of changes in retinal illumination is limited to a ratio of 10:1, and not 17:1, as would be expected based on changes in pupil area. In fact, retinal illumination is proportional to the product of the area of ​​the pupil, the brightness of the object and the transmittance of the ocular media.

The contribution of the pupil to the regulation of eye sensitivity is extremely insignificant. The entire range of brightness that our visual mechanism is capable of perceiving is enormous: from 10 −6 cd m −2 for an eye completely adapted to darkness to 10 6 cd m −2 for an eye completely adapted to light. The mechanism for such a wide range of sensitivity lies in the decomposition and restoration of photosensitive pigments in the retinal photoreceptors - cones and rods.

The sensitivity of the eye depends on the completeness of adaptation, on the intensity of the light source, the wavelength and angular dimensions of the source, as well as on the duration of the stimulus. The sensitivity of the eye decreases with age due to the deterioration of the optical properties of the sclera and pupil, as well as the receptor component of perception.

Maximum sensitivity in daylight ( day vision) lies at 555-556 nm, and at weak evening/night ( twilight vision/night vision) shifts towards the violet edge of the visible spectrum and is located at 510 nm (during the day it fluctuates between 500-560 nm). This is explained (the dependence of a person’s vision on lighting conditions when he perceives multi-colored objects, the ratio of their apparent brightness - the Purkinje effect) by two types of light-sensitive elements of the eye - in bright light, vision is carried out mainly by cones, and in weak light, preferably only rods are used.

Visual acuity

Ability different people see larger or smaller details of an object from the same distance with the same shape eyeball and the same dioptric refractive power ocular system is determined by the difference in the distance between the sensitive elements of the retina and is called visual acuity.

Visual acuity is the eye's ability to perceive apart two points located at some distance from each other ( detail, fine grain, resolution). The measure of visual acuity is the visual angle, that is, the angle formed by rays emanating from the edges of the object in question (or from two points A And B) to the nodal point ( K) eyes. Visual acuity is inversely proportional to the visual angle, that is, the smaller it is, the higher the visual acuity. Normally, the human eye is capable of apart perceive objects with an angular distance of at least 1′ (1 minute).

Visual acuity is one of the most important functions of vision. A person's visual acuity is limited by his structure. The human eye, unlike the eyes of cephalopods, for example, is an inverted organ, that is, light-sensitive cells are located under a layer of nerves and blood vessels.

Visual acuity depends on the size of the cones located in the area of ​​the macula, the retina, as well as on a number of factors: the refraction of the eye, the width of the pupil, the transparency of the cornea, the lens (and its elasticity), the vitreous body (which makes up the light-refracting apparatus), the state of the retina and optic nerve, age.

The inversely proportional value to visual acuity and/or light sensitivity is called the resolution of the simple (naked) eye ( resolving power).

line of sight

Peripheral vision (field of view); determine the boundaries of the field of view when projecting them onto a spherical surface (using the perimeter). Field of view is the space perceived by the eye with a fixed gaze. The visual field is a function of the peripheral retina; its condition largely determines a person’s ability to freely navigate in space.

Changes in the visual field are caused by organic and/or functional diseases visual analyzer: retina, optic nerve, visual pathway, central nervous system. Violations of the visual field are manifested either by a narrowing of its boundaries (expressed in degrees or linear values), or loss of individual sections of it (Hemianopsia), or the appearance of a scotoma.

Binocularity

Looking at an object with both eyes, we see it only when the axes of vision of the eyes form such an angle of convergence (convergence) at which symmetrical, clear images on the retinas are obtained in certain corresponding places of the sensitive macula ( fovea centralis). Thanks to this binocular vision, we not only judge the relative position and distance of objects, but also perceive relief and volume.

The main characteristics of binocular vision are the presence of elementary binocular, depth and stereoscopic vision, stereo visual acuity and fusional reserves.

The presence of elementary binocular vision is checked by dividing a certain image into fragments, some of which are presented to the left eye, and some to the right eye. The observer has an elementary binocular vision, if he is able to compose a single original image from fragments.

The presence of depth vision is verified by presenting silhouette vision, and stereoscopic vision - random dot stereograms, which should evoke in the observer a specific experience of depth, different from the impression of spatiality based on monocular features.

Stereo visual acuity is the reciprocal of the stereoscopic perception threshold. The stereoscopic threshold is the minimum detectable disparity (angular displacement) between parts of the stereogram. To measure it, the following principle is used. Three pairs of figures are presented separately to the observer's left and right eyes. In one of the pairs the position of the figures coincides, in the other two one of the figures is displaced horizontally by a certain distance. The subject is asked to indicate figures arranged in increasing order of relative distance. If the figures are indicated in the correct sequence, then the test level increases (disparity decreases); if not, the disparity increases.

Fusion reserves are conditions under which motor fusion of the stereogram is possible. Fusion reserves are determined by the maximum disparity between parts of the stereogram, at which it is still perceived as a three-dimensional image. To measure fusion reserves, the principle opposite to that used in the study of stereo visual acuity is used. For example, a subject is asked to combine two vertical stripes into one image, one of which is visible to the left eye and the other to the right eye. At the same time, the experimenter begins to slowly separate the stripes, first with convergent and then with divergent disparity. The image begins to bifurcate at the disparity value, which characterizes the fusion reserve of the observer.

Binocularity may be impaired with strabismus and some other eye diseases. If you are very tired, you may experience temporary strabismus caused by the non-dominant eye switching off.

Contrast sensitivity

Contrast sensitivity is a person’s ability to see objects that differ slightly in brightness from the background. Contrast sensitivity is assessed using sinusoidal gratings. An increase in the contrast sensitivity threshold may be a sign of a number of eye diseases, and therefore its study can be used in diagnostics.

Vision adaptation

The above properties of vision are closely related to the ability of the eye to adapt. Eye adaptation is the adaptation of vision to different lighting conditions. Adaptation occurs to changes in illumination (adaptation to light and darkness is distinguished), color characteristics of lighting (the ability to perceive white objects as white even with a significant change in the spectrum of incident light).

Adaptation to light occurs quickly and ends within 5 minutes, adaptation of the eye to darkness is a slower process. The minimum brightness that causes the sensation of light determines the light sensitivity of the eye. The latter increases rapidly in the first 30 minutes. staying in the dark, its increase practically ends after 50-60 minutes. Adaptation of the eye to darkness is studied using special devices- adaptometers.

Decreased adaptation of the eye to darkness is observed in some eye (retinal pigmentary degeneration, glaucoma) and general (A-vitaminosis) diseases.

Adaptation is also manifested in the ability of vision to partially compensate for defects in the visual apparatus itself (optical defects of the lens, retinal defects, scotomas, etc.)

Processing of visual information

The phenomenon of visual sensations that are not accompanied by the processing of visual information is called the phenomenon of pseudo-blindness.

Visual disturbances

Lens defects

The most common drawback is the discrepancy between the optical power of the eye and its length, leading to deterioration in the visibility of close or distant objects.

Farsightedness

Farsightedness is a refractive error in which rays of light entering the eye are focused not on the retina, but behind it. In mild forms of the eye with a good reserve of accommodation, it compensates for the visual deficiency by increasing the curvature of the lens with the ciliary muscle.

With more severe farsightedness (3 diopters and above), vision is poor not only near, but also at distance, and the eye is not able to compensate for the defect on its own. Farsightedness is usually congenital and does not progress (usually decreases by school age).

For farsightedness, reading glasses are prescribed or constant wearing. For glasses, converging lenses are selected (they move the focus forward to the retina), with the use of which the patient’s vision becomes best.

Slightly different from farsightedness is presbyopia, or age-related farsightedness. Presbyopia develops due to the loss of elasticity of the lens (which is a normal result of its development). This process begins at school age, but a person usually notices weakening of near vision after 40 years. (Although at 10 years old, emmetropic children can read at a distance of 7 cm, at 20 years old - already at least 10 cm, and at 30 - 14 cm, and so on.) Senile farsightedness develops gradually, and by the age of 65-70 a person has completely lost ability to accommodate, development of presbyopia is completed.

Myopia

Myopia is a refractive error of the eye, in which the focus moves forward, and an already out-of-focus image falls on the retina. With myopia, the further point of clear vision lies within 5 meters (normally it lies at infinity). Myopia can be false (when, due to overstrain of the ciliary muscle, its spasm occurs, as a result of which the curvature of the lens remains too large in distance vision) and true (when the eyeball increases in the anterior-posterior axis). In mild cases, distant objects are blurred while near objects remain clear (the furthest point of clear vision lies quite far from the eyes). In cases of high myopia, a significant decrease in vision occurs. Starting at approximately −4 diopters, a person needs glasses for both distance and near distance, otherwise the object in question must be brought very close to the eyes. However, precisely because for good image sharpness myopic person brings an object close to his eyes, he is able to distinguish finer details of this object than a person with normal vision.

IN adolescence myopia often progresses (the eyes constantly strain to work near, which is why the eye compensatoryly grows in length). The progression of myopia sometimes takes malignant form, in which vision drops by 2-3 diopters per year, stretching of the sclera is observed, and degenerative changes in the retina occur. In severe cases, there is a danger of detachment of the overstretched retina when physical activity or sudden impact. Stopping the progression of myopia usually occurs by the age of 25-30, when the body stops growing. With rapid progression, vision by that time drops to −25 diopters and below, severely crippling the eyes and sharply disrupting the quality of vision at distance and near (all that a person sees are cloudy outlines without any detailed vision), and such deviations are very are difficult to fully correct with optics: thick glasses create strong distortions and make objects visually smaller, which is why a person does not see well enough even with glasses. In such cases better effect can be achieved using contact correction.

Despite the fact that hundreds of scientific and medical works have been devoted to the issue of stopping the progression of myopia, there is still no evidence of the effectiveness of any method of treating progressive myopia, including surgery (scleroplasty). There is evidence of small but statistical significant reduction rate of growth of myopia in children when using eye drops of atropine and eye gel pirenzipine [ ] .

For myopia, laser vision correction is often used (exposure to the cornea using a laser beam to reduce its curvature). This correction method is not completely safe, but in most cases it is possible to achieve a significant improvement in vision after surgery.

Defects of myopia and farsightedness can be overcome with the help of glasses, contact lenses or rehabilitative gymnastics courses.

Astigmatism

Astigmatism is a defect in the optics of the eye caused by the irregular shape of the cornea and (or) lens. In all people, the shape of the cornea and lens differs from the ideal body of rotation (that is, all people have astigmatism of varying degrees). In severe cases, the stretching along one of the axes can be very strong, in addition, the cornea may have curvature defects caused by other reasons (wounds, infectious diseases, etc.). With astigmatism, light rays are refracted with different strengths in different meridians, as a result of which the image turns out to be curved and unclear in places. In severe cases, the distortion is so strong that it significantly reduces the quality of vision.

Astigmatism can be easily diagnosed by looking with one eye at a sheet of paper with dark parallel lines - by rotating such a sheet, the astigmatist will notice that the dark lines either blur or become clearer. Most people experience congenital astigmatism up to 0.5 diopters, which does not cause discomfort.

This defect is compensated by glasses with cylindrical lenses having different curvature horizontally and vertically and contact lenses (hard or soft toric), as well as spectacle lenses having different optical powers in different meridians.

Retinal defects

Colorblindness

If the perception of one of the three primary colors in the retina is lost or weakened, then a person does not perceive a certain color. There are “color-blind” ones for red, green and blue-violet. It is rare to find a steam room, or even a full one color blindness. More often there are people who cannot distinguish red from green. This lack of vision was called color blindness - after the English scientist D. Dalton, who himself suffered from such a color vision disorder and first described it.

Color blindness is incurable and is inherited (linked to the X chromosome). Sometimes it occurs after certain eye and nervous diseases.

Colorblind people are not allowed to work related to driving vehicles on public roads. Good color vision is very important for sailors, pilots, chemists, geologists-mineralogists, artists, therefore, for some professions, color vision is checked using special tables.

Scotoma

Other defects

• Day blindness- sharp decrease in vision in conditions of excessive illumination, insufficient adaptation to bright light. Typical causes of day blindness are

Causes of different vision in the eyes

Greetings, Dear friends, readers of my blog! I often hear people complain that one eye sees worse than the other. What causes different vision in the eyes (anisometropia)? What is this connected with? And, most importantly, what should you do to prevent this from happening to you? I will try to answer these and other questions in my article.

Important Organs

Eyes are one of the important human organs. After all, thanks to our eyes, we receive the most information from the world around us. Despite this, we often do not worry when our vision deteriorates. Some people think that weakening vision is due to age or overwork.

Indeed, visual impairment is not always associated with illness. This may be due to fatigue, lack of sleep, constant work at the computer and other reasons. And, it’s true, sometimes in order to normalize vision, you just need to rest and do eye exercises. Exercising can help improve vision and train the eye muscles. But if the exercises still do not help, and your vision continues to deteriorate, then you need to consult a doctor.

What are the causes of different vision in the eyes?

When people's vision declines, they try to correct it with the help of
glasses or lenses. But it happens that vision deteriorates in only one eye. Such symptoms can appear in both children and older people. When a person experiences unilateral visual impairment, his life becomes uncomfortable. It's okay if the difference in vision is not very great. What if it’s big??? Different visual acuity can lead to stress eye muscles, headaches and other problems.

The causes of different vision in the eyes can be either congenital or acquired. Most often, people exhibit congenital (hereditary) anisometropia. So, for example, if a person already has anisometropia in the family, then, most likely, this disease can develop in the next generation. But you need to take into account that in childhood it may not appear at first, but in the future it sometimes leads to bad consequences.

And it doesn’t matter at all which eye of the parents sees worse: this disease in a child can manifest itself in any eye.

One of the reasons for visual impairment in children is huge pressure at school, watching TV for a long time, excessive passion for computer games. As a result, only one eye begins to see worse due to excessive strain. Most often this is preceded by headaches, severe fatigue, and nervous tension. In adults, the cause may be a previous illness or surgery.

How do we feel about it?

Retinal images become different sizes due to asymmetrical projection. In such a situation, usually one eye captures the picture better than the other. Images become blurry and may merge. The perception of what is seen is distorted and may become double. The surrounding world is perceived as blurry and indistinct. This can lead to the fact that a person finds it difficult to navigate in space and has a slow reaction to any external stimuli.

Lazy eye

In order to somehow compensate for this deformation, our brain reflexively “turns off” the eye that sees poorly. After some time, he may stop seeing completely. In medicine, there is even a special term - “lazy eye” (amblyopia).

What to do?

Anisometropia is usually treated in two ways. The first is wearing telescopic glasses or corrective lenses. But I would like to emphasize that in no case should you choose glasses or lenses on your own without the advice of a doctor. This, on the contrary, can only worsen the situation. In addition, this can lead to microtrauma of the cornea, and, as a result, to infection, inflammatory processes and swelling in the eye.

Ophthalmologists confirm that with a disease such as anisometropia, it can be difficult to choose a correction.

The second method is surgical. It is resorted to only as a last resort, when all other methods do not work. Most often this happens at the stage chronic disease. The operation is performed using a laser.

And only as prescribed by the attending physician. This operation has some limitations and contraindications. So, for example, after surgical intervention You can’t put too much strain on your eyes, you need to try to avoid concussions and any injuries, because all this can trigger the disease again.

I would like to note that amblyopia in children can be corrected quite well. But first you need to get rid of the cause of the loss of vision in the eye, and then make this eye work again. Often, for this, doctors advise using occlusion - that is, try to exclude the second, healthy, well-seeing eye from the visual process.

Treatment must be selected strictly individually. It all depends on the age of the person, the type of pathology and the stage of development of the disease.

The best treatment is eye exercises!

One of the means of preventing anisometropia can be exercises for the eyes, reducing (or completely eliminating) watching television, working on the computer, alternating mental and physical activity, walking. fresh air. Remember that any disease is easier to prevent than to treat!

I wish you, dear readers of my blog, good health, a keen eye and rich, bright colors! Let everything you see around you bring you only joy and positive emotions, which will subsequently lead to success! See you on my blog!

From the first day a child is born, vision helps him to learn the world. With the help of the eyes, a person sees a wonderful world of colors and sun, and visually perceives a colossal flow of information. Eyes give a person the opportunity to read and write, get acquainted with works of art and literature. Any professional work requires us to have good, full vision.

A person is constantly exposed to a continuous flow of external stimuli and a variety of information about processes inside the body. A person’s senses allow him to understand this information and correctly respond to a large number of events occurring around him. Among the irritants external environment especially for a person great importance have visual Most of our information about the outside world is related to vision. The visual analyzer (visual sensory system) is the most important of all analyzers, because it provides 90% of the information that goes to the brain from all receptors. With the help of our eyes, we not only perceive light and recognize the color of objects in the surrounding world, but also get an idea of ​​the shape of objects, their distance, size, height, width, depth, in other words, about their spatial location. And all this is thanks to the subtle and complex structure of the eyes and their connections with the cerebral cortex.

The structure of the eye. Accessory eye apparatus

Eye- located in the orbital cavity of the skull - in the orbit, surrounded from behind and on the sides by the muscles that move it. It consists of the eyeball with the optic nerve and auxiliary devices.

Eye- the most mobile of all organs of the human body. He makes constant movements, even in a state of apparent rest. Fine eye movements (micromovements) play a significant role in visual perception. Without them it would be impossible to distinguish objects. In addition, the eyes make noticeable movements (macromovements) - turns, shifting the gaze from one object to another, tracking moving objects. Various movements of the eye, turning sideways, up, down, are provided by the extraocular muscles located in the orbit. There are six of them in total. Four rectus muscles are attached to the front of the sclera - and each of them turns the eye in its own direction. And two oblique muscles, superior and inferior, are attached to the back of the sclera. The coordinated action of the oculomotor muscles ensures the simultaneous rotation of the eyes in one direction or another.

The organ of vision needs protection from damage for normal development and function. Protective devices The eyes are eyebrows, eyelids and tear fluid.

Eyebrow- a paired arched fold of thick skin, covered with hair, into which the underlying muscles are woven. Eyebrows wick sweat away from the forehead and serve as protection from very bright light. Eyelids close reflexively. At the same time, they isolate the retina from the action of light, and the cornea and sclera from any harmful effects. When blinking, tear fluid is evenly distributed over the entire surface of the eye, thereby preventing the eye from drying out. The upper eyelid is larger than the lower eyelid and is raised by a muscle. The eyelids close due to contraction of the orbicularis oculi muscle, which has a circular orientation. muscle fibers. Along the free edge of the eyelids are located eyelashes, which protect the eyes from dust and too bright light.

Lacrimal apparatus. Tear fluid is produced special glands. It contains 97.8% water, 1.4% organic matter and 0.8% salts. Tears moisturize the cornea and help maintain its transparency. In addition, they wash away from the surface of the eye, and sometimes even the eyelids, any substances that have got there. foreign bodies, specks, dust, etc. The tear fluid contains substances that kill microbes through the lacrimal canaliculi, the openings of which are located in the inner corners of the eyes, enters the so-called lacrimal sac, and from here into the nasal cavity.

The eyeball has an irregular spherical shape. The diameter of the eyeball is approximately 2.5 cm. Six muscles are involved in the movement of the eyeball. Of these, four are straight and two are oblique. The muscles lie inside the orbit, start from its bony walls and are attached to the tunica albuginea of ​​the eyeball behind the cornea. The walls of the eyeball are formed by three membranes.

Eye shells

On the outside it is covered with a tunica albuginea ( sclera). It is the thickest, strongest and provides the eyeball with a certain shape. The sclera makes up approximately 5/6 of the outer shell, it is opaque, white and partly visible within the palpebral fissure. The tunica albuginea is a very strong connective tissue membrane that covers the entire eye and protects it from mechanical and chemical damage.

The front part of this shell is transparent. It is called - cornea. The cornea has impeccable cleanliness and transparency due to the fact that it is constantly rubbed by the blinking eyelid and washed with tears. The cornea is the only place in the protein membrane through which light rays penetrate into the eyeball. The sclera and cornea are rather dense formations that ensure the eye maintains its shape and protects its internal part from various external harmful influences. Behind the cornea there is a crystal clear liquid.

The second shell of the eye is adjacent to the sclera from the inside - vascular. It is abundantly supplied with blood vessels (performs a nutritional function) and pigment containing a coloring matter. The anterior part of the choroid is called rainbow. The pigment in it determines the color of the eyes. The color of the iris depends on the amount of melanin pigment. When there is a lot of it, the eyes are dark or light brown, and when there is little, they are gray, greenish or blue. People who lack melanin are called albinos. There is a small hole in the center of the iris - pupil, which, narrowing or expanding, transmits either more or less light. The iris is separated from the choroid proper by the ciliary body. In its thickness is the ciliary muscle, on the thin elastic threads of which is suspended - lens- a transparent body, similar to a magnifying glass, a tiny biconvex lens with a diameter of 10 mm. It refracts light rays and brings them into focus on the retina. When the ciliary muscle contracts or relaxes, the lens changes its shape - the curvature of the surfaces. This property of the lens allows you to clearly see objects both at close and far distances.

Third, inner shell eyes - mesh. The retina has complex structure. It consists of light-sensitive cells - photoreceptors and perceives light entering the eye. It is located only on back wall eyes. There are ten layers of cells in the retina. Especially important have cells called cones and rods. IN retina rods and cones are located unevenly. Rods (about 130 million) are responsible for the perception of light, and cones (about 7 million) are responsible for color perception.

Rods and cones have different purposes in the visual act. The first ones work on a minimum amount of light and constitute the twilight vision apparatus; Cones, on the other hand, operate in large amounts of light and serve for the daytime activities of the visual apparatus. Various function rods and cones provide high sensitivity of the eye to very high and low light levels. The ability of the eye to adapt to different brightness of light is called adaptation.

The human eye is capable of distinguishing an infinite variety of color shades. The perception of a variety of colors is provided by the cones of the retina. Cones are sensitive to colors only in bright light. In low light, color perception deteriorates sharply, and all objects appear gray in the twilight. Cones and rods work together. Nerve fibers depart from them, which then form the optic nerve, which leaves the eyeball and goes to the brain. The optic nerve consists of approximately 1 million fibers. Vessels pass through the central part of the optic nerve. At the exit site of the optic nerve, there are no rods and cones, as a result of which light is not perceived by this part of the retina.

Optic nerve ( pathways)

The retina of the eye is the primary nerve center processing of visual information. The location where the optic nerve exits the retina is called the optic disc ( blind spot ). At the center of the disc, the central retinal artery enters the retina. The optic nerves pass into the cranial cavity through the optic nerve canals.

The optic chiasm forms on the lower surface of the brain - chiasma, but only the fibers coming from the medial parts of the retinas intersect. These crossing visual pathways are called visual tracts. Most of the fibers of the optic tract rush into lateral geniculate body, brain. The lateral geniculate body has a layered structure and is so named because its layers bend like a knee. The neurons of this structure send their axons through the internal capsule, then as part of the visual radiation to the cells of the occipital lobe of the cortex cerebral hemispheres near the calcarine groove. This path carries information only about visual stimuli.

Functions of vision

Systems	Appendages and parts of the eye	Functions
Auxiliary	Brows	Removes sweat from the forehead
	Eyelids	Protects eyes from light rays, dust, drying out
	Lacrimal apparatus	Tears moisten, cleanse, disinfect
Eyeball membranes	Protein	Protection from mechanical and chemical influences. Contains all parts of the eyeball.
	Vascular	Nutrition of the eye
	Retina	Light perception, light receptors
Optical	Cornea	Refracts light rays
	Aqueous moisture	Transmits rays of light
	Iris (iris)	Contains pigment that gives color to the eye, regulates the opening of the pupil
	Pupil	Adjusts the amount of light by expanding and contracting
	Lens	Refracts and focuses light rays, has accommodation
	Vitreous body	Fills the eyeball. transmits rays of light
Light-perceiving (visual receptor)	Photoreceptors (neurons)	Rods perceive shape (low-light vision); cones - color (color vision).
	Optic nerve	Perceives the excitation of receptor cells and transmits it to the visual zone of the cerebral cortex, where the analysis of excitation and the formation of visual images occurs

The eye as an optical device

In a parallel flow, light radiation hits the iris (acts as a diaphragm), with a hole through which light enters the eye; the elastic lens is a kind of biconvex lens that focuses the image; an elastic cavity (vitreous humor) that gives the eye a spherical shape and holds its elements in place. The lens and vitreous body have the properties of transmitting structure visible image with the least distortion. Regulatory organs control involuntary movements of the eye and adapt its functional elements to specific conditions of perception. They change the throughput of the aperture, the focal length of the lens, the pressure inside the elastic cavity and other characteristics. These processes are controlled by centers in the midbrain with the help of many sensitive and executive elements distributed throughout the eyeball. The measurement of light signals occurs in the inner layer of the retina, which consists of many photoreceptors capable of converting light radiation into nerve impulses. Photoreceptors in the retina are distributed unevenly, forming three areas of perception.

First - field of view- located in the central part of the retina. It has the highest density of photoreceptors, so it provides a clear color image of the object. All photoreceptors in this area are basically the same in structure; they differ only in their selective sensitivity to the wavelengths of light radiation. Some of them are most sensitive to radiation (middle parts), others are in the upper part, and others are in the lower part. Humans have three types of photoreceptors that respond to blue, green and red colors. Here, in the retina, the output signals of these photoreceptors are jointly processed, as a result of which the contrast of the image is enhanced, the contours of objects are highlighted and their color is determined.

The volumetric image is reproduced in the cerebral cortex, where video signals from the right and left eyes are sent. A person's field of view covers only 5°, and only within its limits can he carry out visual and comparative measurements (orient himself in space, recognize objects, follow them, determine their relative location and direction of movement). Second area perception performs the function of target acquisition. It is located around the viewing area and does not provide a clear image of the visible picture. Its task is to quickly detect contrasting targets and changes occurring in the external environment. Therefore, in this area of ​​the retina the density of conventional photoreceptors is low (almost 100 times less than in the viewing area), but there are many (150 times more) other, adaptive photoreceptors that respond only to changes in the signal. Joint processing of signals from both photoreceptors ensures high performance of visual perception in this area. In addition, a person is able to quickly detect the slightest movements with peripheral vision. Grasping functions are controlled by parts of the midbrain. Here the object of interest is not examined or recognized, but its relative location, speed and direction of movement are determined and a command is given extraocular muscles- quickly rotate the optical axes of the eyes so that the object falls into the viewing area for detailed examination.

The third area is formed marginal areas of the retina, which do not include the image of the object. The density of photoreceptors in it is the lowest - 4000 times less than in the viewing area. Its task is to measure the average brightness of light, which is used by vision as a reference point to determine the intensity of light streams entering the eye. This is why visual perception changes under different lighting conditions.

It is with the help of vision that a person perceives most of the information from the surrounding world, therefore all facts related to the eyes are interesting to a person. Today there are a huge number of them.

Structure of the eye

Interesting Facts about eyes begin with the fact that man is the only creature on the planet with whites of eyes. The rest of the eyes are filled with cones and rods, as in some animals. These cells are found in the eye in the hundreds of millions and are light sensitive. Cones respond to changes in light and colors more than rods.

In all adults, the size of the eyeball is almost identical and is 24 mm in diameter, while a newborn child has an apple diameter of 18 mm and weighs almost three times less.

Interestingly, sometimes a person can see various floaters before the eyes, which are actually threads of protein.

The cornea of ​​the eye covers its entire visible surface and is the only part of the human body that is not supplied with oxygen from the blood.

The lens of the eye, which provides clear vision, constantly focuses on the surrounding environment at a speed of 50 objects per second. The eye moves with the help of only 6 eye muscles, which are the most active in the entire body.

Interesting facts about the eyes include information about what to sneeze with with open eyes impossible. Scientists explain this with two hypotheses - a reflex contraction of the facial muscles and protection of the eye from germs from the nasal mucosa.

Brain vision

Interesting facts about vision and eyes often have data about what a person actually sees with the brain, and not with the eye. This statement was scientifically established back in 1897, confirming that the human eye perceives surrounding information upside down. Passing through the optic nerve to the center nervous system, the picture turns over to its usual position precisely in the cerebral cortex.

Features of the iris

These include the fact that each person's iris has 256 distinctive characteristics, while fingerprints differ in only forty. The probability of finding a person with the same iris is almost zero.

Color vision impairment

More often this pathology manifests itself as color blindness. Interestingly, at birth all children are colorblind, but with age, most return to normal. Most often, this disorder affects men who are unable to see certain colors.

Normally, a person should distinguish seven primary colors and up to 100 thousand of their shades. Unlike men, 2% of women suffer from a genetic mutation, which, on the contrary, expands the range of their color perception to hundreds of millions of shades.

Alternative medicine

Considering the interesting facts about it, iridology was born. It is an unconventional method for diagnosing diseases of the whole body using the study of the iris

Darkening the eye

Interestingly, pirates did not wear blindfolds to hide their injuries. They closed one eye so that it could quickly adapt to the poor lighting in the holds of the ship. By alternating one eye between dimly lit rooms and brightly lit decks, pirates could fight more effectively.

The first tinted glasses for both eyes appeared not to protect from bright light, but to hide the gaze from strangers. At first they were used only by Chinese judges, so as not to show others personal emotions about the cases under consideration.

Blue or brown?

The color of a person's eyes is determined by the amount of concentration of melanin pigment in the body.

It is located between the cornea and the lens of the eye and consists of two layers:

• front;
• rear

In medical terms they are defined as mesodermal and ectodermal, respectively. It is in the front layer that the coloring pigment is distributed, determining the color of a person’s eyes. Interesting facts about the eyes confirm that only melanin provides color to the iris, regardless of what color the eyes are. The shade changes only due to a change in the concentration of the dye.

At birth, almost all children have this pigment completely absent, which is why the eyes of newborns are blue. With age, they change their color, which is fully established only by the age of 12.

Interesting facts about human eyes also state that color can change depending on certain circumstances. Scientists have now established such a phenomenon as a chameleon. It is a change in eye color when exposed to cold for a long time or in bright light for a long time. Some people claim that the color of their eyes depends not only on the weather, but also on their personal mood.

The most interesting facts about the structure of the human eye contain evidence that in fact all people in the world are blue-eyed. The high concentration of pigment in the iris ensures the absorption of light rays of high and low frequencies, due to which their reflection leads to the appearance of brown or black eyes.

Eye color largely depends on geographic area. So in the northern regions the population with blue eyes predominates. Closer to the south there are a large number of brown-eyed people, and at the equator almost the entire population has a black iris.

More than half a century ago, scientists established an interesting fact - at birth we are all farsighted. Only by the age of six months does vision return to normal. Interesting facts about human eyes and vision also confirm that the eye is fully formed according to physiological parameters by the age of seven.

Vision can also affect general condition body, so when the load on the eyes is exceeded, general fatigue, headaches, fatigue and stress are observed.

Interestingly, the connection between the quality of vision and the carrot vitamin carotene has not been scientifically proven. In fact, this myth dates back to the war, when the British decided to hide the invention of aviation radar. They explained the rapid detection of enemy aircraft sharp vision their pilots who ate carrots.

To test your visual acuity yourself, you should look at the night sky. If there are handles of a large bucket near the middle star ( Ursa Major) if you manage to see a small star, then everything is normal.

Different eyes

Most often, this disorder is genetic and does not affect overall health. Different eye colors are called heterochromia and can be complete or partial. In the first case, each eye is colored with its own color, and in the second, one iris is divided into two parts with different colors.

Negative factors

Cosmetics have the greatest impact on the quality of vision and eye health in general. Wearing tight clothes also has a negative effect, since it impedes blood circulation in all organs, including the eyes.

Interesting facts about the structure and functioning of the eye confirm that a child is not able to cry in the first month of life. More precisely, no tears are released at all.

The composition of tears has three components:

• water;
• slime;

If the proportions of these substances on the surface of the eye are not respected, dryness appears and the person begins to cry. If the flow is excessive, tears can directly enter the nasopharynx.

Statistical studies claim that every man cries on average 7 times per year, and every woman 47.

About blinking

Interestingly, the average person blinks once every 6 seconds, mostly as a reflex. This process Provides the eye with sufficient hydration and timely cleansing of impurities. According to statistics, women blink twice as often as men.

Japanese researchers have found that the blinking process also acts as a reboot for concentration. It is at the moment of closing the eyelids that the activity of the attention neural network decreases, which is why blinking is most often observed after the completion of a certain action.

Reading

Interesting facts about the eyes did not miss such a process as reading. According to scientists, when reading quickly, the eyes become tired much less. At the same time, reading paper books always carried out a quarter faster than electronic media.

Misconceptions

Many people believe that smoking has no effect on eye health, but in fact tobacco smoke leads to blockage of the retinal vessels and leads to the development of many diseases of the optic nerve. Smoking, both active and passive, can lead to clouding of the lens, chronic conjunctivitis, yellow spots retina, blindness. Lycopene also becomes harmful when smoked.

In normal cases, this substance has a beneficial effect on the body, improving vision, slowing down the development of cataracts, age-related changes and protecting the eye from ultraviolet radiation.

Interesting facts about the eyes refute the idea that monitor radiation negatively affects vision. In fact, excessive strain on the eyes is caused by frequent focusing on small details.

Also, many are confident in the need to give birth only by Caesarean if a woman has poor eyesight. In some cases, this is true, but for myopia, you can undergo a course of laser coagulation and prevent the risk of retinal rupture or detachment during childbirth. This procedure is carried out even at the 30th week of gestation and takes only a few minutes, without having any negative impact on the health of both mother and child. But be that as it may, try to regularly visit a specialist and have your vision checked.