Good day, dear friends! Do you have myopia and it gives you a lot of inconvenience in your daily life? Are you worried that the disease is inherited and your children will have to wear glasses as well?

Of course, there are two forms of myopia: congenital and acquired, and the child may well inherit the gene for myopia from you. Let's try to figure it out: how is myopia inherited and can the development of the disease be prevented?

As the well-known Koroviev said in Bulgakov's famous novel The Master and Margarita: “Questions of blood are the most difficult in the world! I am not at all wrong if, speaking of this, I mention a fancifully shuffled deck of cards ... ".

After so much time, scientists come to the conclusion that 100% of all pathologies are encoded in our genes.

Each of us has our own genotype, which is passed on from our parents. Each phenotypic manifestation: eye color, hair color, nome shape, lips, facial contours, and even structure eyeball encoded by two genes. One is transmitted by mom, the second by dad. The combination of these genes determines how the trait will appear in the little man: which of the parents he will look like.

Each person has a genotype encoded in chromosomes. There are 23 pairs of them in the body: 22 pairs of so-called somatic chromosomes, and the 23rd pair determines the sex of a person.

Genes are encoded in chromosomes, when decoding which, one can speak with 100% confidence about a person's predisposition to one or another pathology. Adherence to the development of eye diseases, including myopia, is also determined by genes.

It is not necessary that. It can manifest itself in the process of growth and development. It may not appear at all in a child whose parents both wear distance glasses. Why is this happening?

There are several types of genes: dominant and recessive. Dominant - suppressive and main, if it is embedded in the code, then it will always manifest itself - it is designated as large latin letter... A recessive trait will manifest itself only if it finds the same pair for itself, therefore it is designated by a small letter.

The same trait can be linked to the sex chromosome. The sex chromosomes of women are XX, and in men - XY, so if the trait is linked to the Y chromosome, then it will manifest itself in 100% of boys, if with X, it is dominant and is in the dad's genotype, then all boys will be healthy, but the girls will be lucky less since they will all be sick.

Myopia genes

Myopia is weak and medium is betrayed in somatic genes and is a dominant feature, thus the probability of having a sick child from parents whose genoes are Aa in a patient and aa in a healthy one - 50%.

If one has AA, and the other has aa on the chromosome, then 100% of children will develop the disease. If the genotype of the parents is Aa; Aa, then 25% of children have a chance to be born healthy.

A severe degree of myopia, the diopter indices of which are more than -5 diopters, are inherited by a recessive trait. Then the chances of a baby being born healthy are greater, but the disease may manifest itself in the next generation. For example, with the Cc; Cc genotype - 75% of children will be healthy, but more than 66% of them can pass the gene to the next generation.

Thus, the disease will manifest itself in children with genotypes: Aa, AA, ss. With the Cc genotype, the transmission of the disease to subsequent generations is possible, although the child himself will be healthy.

Physiology of myopia

Do not forget that much also depends on our own choice. Sometimes, even with a dominant code, the disease may not appear. This will only happen if a person works hard and hard on himself, loves himself and cares and cherishes his health.

Genes only speak of a predisposition, and whether the disease manifests itself or not depends only on ourselves.

Normally, a child is born with hyperopia of +2.5 - +3 diopters, and then the vision is leveled. Rarely when congenital myopia is recorded and, first of all, the cause of its formation is the effect of the terratogenic factor during intrauterine development of the fetus.

Heredity appears later. Lack of useful substances during the growth and development of a child, non-observance of hygiene rules, uncontrolled use of a computer, lack of physical activity, as well as other reasons can cause and impetus to the development of the disease.

Prolonged intense work of the eye leads to a spasm of muscle fibers, and then irreversible changes are formed.

The spasm of accommodation develops into refractive myopia - a violation of the refraction of the rays, when passing through the refractive structures, since the lens is deformed with constant overstretching.

Axial myopia occurs as a result of pulling the eye forward, when the distance to the retina is physically moved away. By the way, this process can be affected by a person's genetic predisposition to weakness. connective tissue.

Vitreous has an amorphous consistency and has the property of changing the size of the eye, pulling it out. This is another of the mechanisms of adaptation and focusing of the image, while the eye works like a SLR camera - when it stretches it brings the image closer, and when it is flattened, it removes it.

With the weakness of the connective tissue fibers, the elastic properties are significantly reduced and the eye cannot regain its previous shape. Hence and poor eyesight.

Can change be avoided?

Babies with a predisposition to myopia should be monitored by an ophthalmologist from birth. They should receive the daily dosages of all essential substances for the growth and development of the eye: vitamins, minerals. If this cannot be done in a natural way - with the help of a daily food ration, then the deficiency is compensated by preventive doses of vitamin substitution therapy.

From an early age, children need to be taught to relax and train their eyes:

• The fastest blinking for 20-30 seconds will relax the eye muscles and stop the spasm of accommodation, as well as speed up blood circulation and metabolic processes;
• Close eyes tightly, and then maximum opening of the eyes also trains the eye due to alternate tension and relaxation of the muscles;
• Eye massage - performed in a circular motion direction to the inner corner with closed eyelids with two fingers of the same hand. Accelerates blood circulation, reduces intraocular pressure, relaxes the eyes;
• Retracting the eyeballs to the extreme points with fixation of the gaze allows you to maximally strain some muscles and stretch the antagonists.

Such children should strictly regulate the working hours, with a tablet or smartphone; watching cartoons and films on TV. In this case, it is necessary to observe hygiene regimes:
room illumination, distance to the screen or monitor, and even the time of day.

Ophthalmologist examinations should be carried out for children at least twice a year. This is necessary for early diagnosis and prevention. The doctor may prescribe hardware treatment: ophthalmochromotherapy, cetomagnetic stimulation, ophthalmic laxation and so on. And also, perhaps, he will pick up substances that are useful for the eyes.

Dear parents, the health of your child depends primarily on yourself and this is not only about genes. Give him more attention, do not get rid of the child by handing him a tablet, it is better to spend this time outdoors in the park.

Many people - even if they would like to give up glasses - doubt that this is possible.

This skepticism is largely based on delusion. There are five common misconceptions that lead people to think that vision cannot be improved:

1. Poor vision is inherited.
2. Vision inevitably deteriorates with age.
3. Vision deteriorates due to increased eye strain.
4. Deterioration of vision is the result of weakness in the eye muscles.
5. Vision is just a physical, mechanical process.

Let's look at each of these misconceptions in detail.

1. Poor vision is inherited

The first misconception is that vision problems are hereditary: if your parents had poor vision, then you will have the same. Previously, this point of view was generally accepted, but now most experts believe that visual ability is not predetermined at the time of birth.

According to statistics, only 3 out of 100 visually impaired people were born with hereditary visual problems. The remaining 97% have vision problems at some point in their lives. After all, just as we learn to speak or walk, we learn to see.

But since most of us were born with normal eyesight, it would be more correct to say that we learn throughout our lives not see. Of course, we learn this unconsciously, unintentionally, and no one teaches us this, but we use our eyes and mind incorrectly, which leads to visual impairment.

Recent studies have shown that even children as young as one day old are able to focus their gaze clearly. When they are shown a picture of their mother's face, they focus on the picture by varying the sucking speed of the artificial nipple. If they suck at the correct speed, the picture remains clear. If they suck much faster or slower, the picture goes out of focus. By adjusting the sucking speed, babies are able to keep the image in focus.

Prior to this original experiment, scientists mistakenly believed that babies were unable to focus clearly until 3 or 4 months of age. This misconception is the result of insufficient scientific research into infant behavior.

From the very birth we know the world with the help of the five senses. The dominant and most developed vision is vision. Through the eyes, we receive from 80 to 90% of the information. Vision is of paramount importance for communication with the outside world.

A significant number of people wear glasses or lenses. The need to use optics in order to see well is considered the norm. Humanity is no longer able to use one of the most important senses - vision without artificial devices.

The number of people with visual problems has grown 5 times over the past 100 years. This terrifying growth took place in just three to four generations. If poor vision is inherited, then who could have passed it on to us?

2. Vision inevitably deteriorates with age

The second misconception is that vision inevitably deteriorates with age, and everyone will eventually need reading glasses.

The visual system - just like any other system in your body - deteriorates over time. Of course, this happens if you do nothing in order to keep her youthful and elastic, and do not get rid of the tension and rigidity that build up over the years. The process of visual impairment is not inevitable or irreparable. But only you can reverse it.

One example. The Cambridge Institute recently received a letter from an 89-year-old man who used the same vision enhancement system that you are now adopting. He said in his letter: “I have worn reading glasses for 50 years since I was 39. Now, after 2 months of working on a vision improvement program, sometimes I can already read without glasses. I do it well and doesn't require any effort. "

Well, an amazing success, but the most interesting thing happened next: "I realized that I can help myself, and I foresee even more significant changes in the future." What youthful optimism! There is a lot to learn!

Your eyes and visual system respond positively to exercise, relaxation, and stress relief. Success in this matter depends entirely on your attitude and specific steps to preserve your vision.

Our experience shows that so-called senile vision (presbyopia) responds very well to training. Many of those who started using the program are able not only to stop the process of deterioration in vision, but also to restore their original clarity to their eyes.

3. Vision deteriorates due to increased eye strain

The third misconception is that vision deteriorates due to increased eye strain: they say, if you read a lot, or sit at a computer, or watch too much TV, you can spoil your vision.

And statistics on the matter such is.

Only 2% of fourth grade students are nearsighted; in the eighth grade there are about 10-20%; by the time they graduate from college, 50-70% of students are already myopic. This seems to suggest that the more you read or study, the more likely you are to become nearsighted.

But the reason is not the load itself. The reason is as eyes are used when increasing the load. And no one at school teaches how to “use” your eyes correctly and how to preserve the good eyesight with which you were born.

When people are taught to see correctly, vision problems become much less common.

For example, in China, children and adults are taught simple eye exercises that they do every day in school or at work. And the proportion of those suffering from myopia (myopia) has significantly decreased due to this.

Unfortunately, these methods have not yet become common practice in other countries. But in some schools they were still introduced. The results are as promising as in China.

In addition, the increased load on the eyes associated with reading, working at a computer requires proper nutrition eyes and the body as a whole, and if these requirements are not met properly, it also contributes to the deterioration of vision.

But no doubt the wrong ones are critical. habits vision, not by itself on the eyes. The real problem is lack of knowledge. The principles of healthy vision need to be studied, promoted and widely applied.

It is hoped that someday the general attitude towards this problem will change. But you don't have to wait. You can already take action and protect your eyesight by learning how to use your eyes correctly.

4. Deterioration of vision - the result of weakness of the eye muscles

The fourth misconception: blurred vision is the result of weakness in the eye muscles.

In fact, the muscles around the eyes are 150-200 times stronger than they need to function properly. These muscles rarely weaken. On the contrary, from constant stress, they become excessively strengthened, which interferes with their natural flexibility and mobility - they become stiff and inactive.

As an analogy, in a right-handed person, the muscles on the right side of the body become stronger and work with better coordination than the muscles on the left side. Why? Only because some muscles are used more often than others, and not because some are naturally weaker than others.

This is also true for the eye muscles: over time, certain habits and behavior patterns develop, as a result of which some eye muscles become stronger and more consistent than others. But the problem is not the muscles themselves, but the habits. By changing habits, the eyes can be retrained. And symptoms such as myopia, hyperopia, etc., will weaken or disappear.

5. Vision is just a physical, mechanical process

The fifth misconception is based on the statement that vision is a physical, mechanical process and normal vision is due only to the shape of the eye. If the eye has the correct shape, then vision will be normal; if the structure of the eye is deformed, then this can cause myopia, hyperopia or astigmatism.

In fact, the shape of the eye is one, but far from the only, element of the visual system. For example, eye doctors know very well that two people with the same eye refraction (the ability to capture an image at a certain distance from the retina) may have different visual acuity (the ability to see letters on an optometric chart). Mechanical measurements and physical data cannot predict how well a person can see. This is due to factors other than the shape of the eyes.

Many people find that they see better at certain times of the day. Many people report visual impairment due to fatigue or stress. What are these fluctuations associated with?

Does it happen to you that, while driving on a motorway, you are so carried away by your thoughts that you “do not see” the turn you need? Or are you so tired that you don't understand the words as you read page after page?

Vision is a dynamic, changing process that depends on many physical, emotional and mental factors. The shape of the eye can be a factor, but even it can change with training.

This is not the most common information, but a person has several forms of hereditary myopia. It is important to understand that acquired myopia is in no way related to these data: if it occurs, completely different mechanisms play a role. It is also worth explaining what heredity is and what algorithms are used to transfer genetic information.

Features of the transmission of diseases by inheritance

The fact that DNA is responsible for each of our phenotypic manifestations is a well-known fact. However, many people forget that information about what diseases people will suffer is programmed in the same nucleotides - this is both a variety of different hereditary pathologies and an elementary increased susceptibility to certain groups of pathogens and resistance to others.

There are 2 types of transmission of information by inheritance:

• autosomal;
• linked to sex chromosomes.

As follows from the wording, the second is transmitted with the X- and Y-chromosomes, and the autosomal type of inheritance implies a lack of connection with the sex of the child. In this case, there are dominant and recessive types.

Dominant alleles are traditionally designated by capital letters of the Latin alphabet (A, B, C), recessive, respectively, small (a, b, c). They can be transmitted both autosomally and linked.

The inheritance of any trait in an autosomal dominant manner suggests its manifestation, regardless of which allele combination occurred - AA (dominant homozygote) or Aa (heterozygote). Autosomal recessive inheritance, on the contrary, manifests itself only in the case of a combination of alleles in a recessive homozygote - aa.

Myopia and heredity

Myopia in humans is transmitted in two ways: autosomal dominant and autosomal recessive types of inheritance. At the same time, myopia of weak and moderate degree (up to -4) is dominantly (A) transmitted, recessively (b) - a strong degree of myopia (from -4 and above). In addition, it depends a lot on the combination of these genes.

That is, congenital myopia is manifested with the following combinations of alleles: AA, Aa, bb. In other cases - aa, Bb, BB - a person will have normal vision, but if he inherited the Bb heterozygote from his parents, he will be able to pass on myopia to offspring. Roughly speaking, he is a carrier of the gene, unaware of it.

Many diseases are inherited, but it is myopia that is a unique pathology of its kind, precisely because of the mode of inheritance. Myopia can manifest itself both in a person whose parents are sick, and in a child absolutely healthy parents, which is typical only for recessive pathologies.

But at the same time, it may be absent in a child whose both parents wear glasses or lenses. This is possible only in cases of dominant gene inheritance.

This feature surprised scientists and doctors: no allele can be transmitted in two ways at the same time. However, one trait can be encoded by several alleles - this is not uncommon, for example, skin color is transmitted this way. Nevertheless, the inheritance method is still atypical, even if such a tolerance is made.

Therefore, after a series of observations, it was found that hereditary myopia has several forms. That is, a person who is weak or may not pass it on to his child, but at the same time the son or daughter will have severe myopia.

This is possible if the father has genotypes Aa and Bb, and the mother is either heterozygous or recessive homozygous for both (Aa or aa, Bb or bb).

People who have hereditary myopia are often unable to determine exactly which form of inheritance applies to their case. Nevertheless, it is quite easy to do this.

1. If there is a weak - from -0.15 to -2 - form of myopia, then inheritance clearly occurred in a recessive type, the same can be said about the average - up to -4 - degree. This means that the genotype looks like this: Aa or AA, Bb or BB.
2. If myopia is strong enough (from -4 and above), then the genotype looks like this: bb, Aa, AA or aa.

The essence of myopia

It is imperative to touch upon the physiological aspects of myopia. The fact is that the human eyeball must have the shape of an ideal ball. This enables precise focusing of the image on the retina. In this case, vision is perfect, and a person is able to see both what is directly in front of him, and distant objects, in all details.

If the image is focused behind the retina, we can see well in the distance, but we have great difficulty in reading, writing, working with small objects: it becomes very difficult to sculpt, embroider or sew, collect jewelry from beads, etc. This type of vision pathology is called hyperopia.

If the eyeball is oval rather than round, the image is focused in front of the retina. And the distance from the retina to the focal point depends on how elongated it is.

In this case, a person with such a pathology clearly and clearly sees objects located close, often he is able to consider them to the smallest detail, since the eye performs the functions of a magnifying glass.

But he cannot see something far from him. With especially severe forms of myopia, people are not able to see even faces nearby standing people, sometimes the distance of 50 cm becomes too large.

Ophthalmologist, surgeon of the highest category, candidate of medical sciences, chief physician of the VOKA Eye Microsurgery Center Pavel Vasilyevich Belyakovsky talks about vision problems.

- Are vision problems inherited?

In ophthalmology, there are diseases that are hereditary. For example, diseases of the retina, such as degenerative lesions of its central and peripheral parts, or refractive disorders, in particular hyperopia or astigmatism. They can be transmitted genetically. Cataracts and glaucoma are usually not hereditary diseases. As for myopia, the gene responsible for myopia has not been found. Therefore, strictly speaking, there is no scientific confirmation of the hereditary transmission of myopia. In practice, in families where one or both parents have myopia, the child is slightly more likely to develop it over time. In such children, the length of the anteroposterior axis of the eye is longer, which is characteristic of myopia. This can be called a genetic predisposition, but not a guarantee of the development of myopia. Conversely, if both parents have good vision, this does not mean at all that their child will not have myopia.

- From what does myopia appear?

The development of myopia is influenced by different factors... Including general state health and immunity, especially during periods of growth and hormonal changes in the body. Frequent acute respiratory infections and ENT diseases can aggravate the formation and course of myopia. But the most important thing is excessive visual stress at close distance from the eyes. For example, when a person, especially a child, is very addicted to gadgets, he does not keep track of time and does not take breaks. The eyes are constantly under heavy stress, this leads to a spasm of the ciliary muscle (spasm of accommodation): the usual excessive tension is formed, which is gradually fixed - this is how axial myopia occurs. If a person who is predisposed to myopia does not have such visual stress, the disease will most likely not develop.

- That is, in one family, vision problems can be completely different?

Yes. In my practice, there have been cases when the whole family comes to be treated and examined. But this is not about heredity. As a rule, patients bring their spouses, parents or children, because they are satisfied with their own result and want to take care of their loved ones: they bring them for medical examination, for consultations, for surgical treatment of a wide variety of ophthalmological problems. Once my patient had a bad dream, and she, frightened, brought her husband, a professional driver with perfect eyesight, for examination. Prior to that, he regularly underwent routine examinations without comprehensive diagnostics. A fundus examination revealed eight perforated retinal tears, each of which could turn into a retinal detachment! This threatened with serious problems and very expensive treatment, but thanks to female intuition and timely diagnostics, everything ended well.

- How often are ophthalmologic examinations needed and what should be checked?

Each person should undergo a preventive examination by an ophthalmologist about once a year. This recommendation is especially important for people over 40. It is important complex diagnostics with measurement of eye pressure, examination of the fundus, verification of the basic anatomical parameters of the eye. Such diagnostics (and annual monitoring of the dynamics of the results) allows early detection of changes that can later lead to the development of glaucoma or cataracts: they are visible long before the onset of the disease and can appear even in a person with very good eyesight... Diagnostics on the latest high-quality equipment and timely treatment can immediately solve existing eye problems and remove risk factors that could cause very serious consequences in the future.

- Do Belarusians have any national peculiarities of vision?

Yes there is. Belarus is on a par with the most technologically advanced countries in the world in terms of myopia statistics. It has long been noticed: the more technologically developed a country is, that is, the more its inhabitants are engaged in mental work and constantly use computer technology, the more often refractive errors occur, in this case, acquired myopia. Therefore, it is very important for Belarusians to take care of their eyesight.

Top three tips for maintaining good vision

1) Lead healthy image life.

2) Regularly undergo preventive examinations.

3) Observe visual hygiene, dose visual stress.

All the time at the computer?

When working at a computer, ophthalmologists recommend observing the "Rule of 20 minutes" - that is, every 20 minutes of work alternate with 20 minutes of visual rest. Taking regular breaks is an important part of your visual routine. At this time, you can do other work or household chores: make a phone call, chat with someone, drink tea or coffee, move around. It is important to take your mind off the monitor and relax your eyes. It is useful to periodically perform exercises, for example, sitting with your eyes closed, doing gymnastics for the eyes, light massage, palming. You can also install programs on your computer that will remind you to take a break, change the brightness of the monitor depending on the time of day, or help relax your eyes with specially selected images.

ON A NOTE

How the Family Card works

The family card is issued free of charge to patients and close relatives who have used the medical service at the VOKA Eye Microsurgery Center. That is, if you came to the appointment on the same day with your mother, sister, husband, grandfather or other relatives, after the first contact with medical Center you are entitled to a discount on further procedures.

Also, a family card is issued free of charge to a patient who underwent laser vision correction at the VOKA Eye Microsurgery Center.

What is the discount

10% for complex diagnostic tests (standard diagnostics, premium diagnostics, children's diagnostics);

5% on surgical procedures (all types laser correction vision, seamless cataract treatment, surgery squint).

1. In addition to the person with whom this card is registered, close relatives can use a family card.

2. To receive a discount, the patient must present the family card to the administrator or cashier before paying medical services at the VOKA Eye Microsurgery Center.

Voka's ophthalmologists recommend that you take your vision impairment seriously. Keep your digital reading and social media addiction under control. And be sure to be checked by an ophthalmologist after 40 years, paying particular attention to measuring eye pressure.

Nearsightedness (myopia). Causes, types, symptoms, signs and diagnosis

thanks

The site provides background information for informational purposes only. Diagnosis and treatment of diseases must be carried out under the supervision of a specialist. All drugs have contraindications. A specialist consultation is required!

What is myopia?

Myopia ( myopia) Is an eye disease in which a person does not see well far away objects, but sees relatively well near. With time ( especially if the causal factor is not eliminated) myopia may progress, with the result that the patient's vision will gradually deteriorate. For some time this will be compensated by the operation of the accommodation apparatus ( fixtures), however, over time, the compensatory capabilities of the refractive system of the eye will exhaust themselves, as a result of which certain complications will begin to develop, which ultimately can lead to complete loss of vision ( that is, to blindness).

In order to understand the mechanisms of development, the principles of diagnosis and treatment of myopia, certain knowledge about the structure of the eye and the functioning of its refractive system is required.

The human eye is complex system, which provides the perception of images from the surrounding world and their transmission to the brain.

From an anatomical point of view, the human eye consists of:

• Outer shell. The outer shell of the eye is formed by the sclera and cornea. The sclera is an opaque tissue whitewhich covers most eyeball. The cornea is a small area of \u200b\u200bthe outer shell of the eye, which is located on its front surface and has a slightly curved ( outward) form ( in the form of a hemisphere). The cornea is transparent so that light rays pass through it with ease. The cornea is an important organ of the eye's refractive system, that is, the light rays passing through it are refracted and gathered together at a certain point.
• Middle shell. Average ( vascular) the eye shell provides blood supply and nutrition to the eyeball and all intraocular structures. In the area of anterior section eyeball ( right behind the cornea) from choroid an iris forms in the eye ( iris). This is a kind of diaphragm, in the center of which there is a small hole ( pupil). The main function of the iris is to regulate the amount of light entering the eye. In excessively bright light, certain muscles of the iris contract, as a result of which the pupil narrows and the amount of light passing through it decreases. In the dark, the process is reversed. The pupil dilates, as a result of which the eye can pick up more light rays.
• Inner shell. The inner shell of the eye ( retina) is represented by a variety of photosensitive nerve cells. These cells perceive light particles entering the eye ( photons), while generating nerve impulses. These impulses are transmitted through special nerve fibers to the brain, where the image is formed.

Certain elements are also located inside the eye that ensure its normal functioning.

Intraocular structures include:

• Vitreous humor. This is a transparent formation of a gelatinous consistency, which occupies the bulk of the eyeball and performs a fixing function ( that is, it maintains the shape of the eye).
• Lens. It is a small mass just behind the pupil in the shape of a biconvex lens. The very substance of the lens is surrounded by a transparent capsule. Along the edges, special ligaments are attached to the lens capsule, which connect it to ciliary body and ciliary muscle. The lens, like the cornea, is an important component of the eye's refractive system.
• Eye cameras. The chambers of the eye are small slit-like spaces located between the cornea and the iris ( anterior chamber of the eye), iris and lens ( rear camera eyes). The space of these chambers is filled with a special liquid ( aqueous humor), which provides nutrition to the intraocular structures.

In addition to the eyeball and intraocular structures, there are a number of auxiliary organs of the eye that play an important role in its normal functioning ( these are the oculomotor muscles, lacrimal glands, eyelids and so on). With the development of myopia, damage to the oculomotor muscles may be noted, so they will be described in more detail.

TO oculomotor muscles eyes include:

• External rectus muscle - provides abduction ( turn) eyes outward.
• Internal rectus muscle - provides a turn of the eye inward.
• Lower rectus muscle - provides lowering of the eye.
• Superior rectus muscle - provides eye lift.
• Superior oblique muscle - raises and averts his eyes.
• Inferior oblique muscle - lowers and looks away.

As mentioned earlier, the main structures of the refractive system of the eye are the lens and the cornea. The cornea has a constant refractive power of approximately 40 diopters ( diopter - a unit of measure for the refractive power of a lens), while the refractive power of the lens can vary from 19 to 33 diopters.

Under normal conditions, when passing through the cornea and lens, light rays are refracted and collected at one point, which should normally be located ( projected) directly on the retina. In this case, a person gets the clearest possible image of the observed object.

When a person looks into the distance, the refractive power of the lens decreases, as a result of which the image of a distant object becomes clearer. This happens due to relaxation of the ciliary muscle, which leads to tension of the ligaments of the lens and its capsule and flattening of the lens itself.

When examining a closely spaced object, the opposite process takes place. As a result of the contraction of the ciliary muscle, the tension of the ligaments and the capsule of the lens is weakened, it itself acquires a more convex shape, and its refractive power increases, which allows the image to be focused on the retina.

The mechanism for the development of myopia is that, due to various anomalies in the structure of the eyeball or due to a violation of the functioning of its refractive system, images of far-away objects are focused not directly on the retina, but in front of it, as a result of which a person perceives it as fuzzy, vague. At the same time, a person sees closely spaced objects more or less normally.

Causes and forms of myopia

Myopia can develop due to anatomical defects of the eyeball or refractive system of the eye, as well as as a result of poor visual hygiene.

Types of myopia

The immediate cause of myopia can be damage to the eyeball and various components of the refractive system.

Depending on the affected structure, there are:

• Axial ( axial) myopia. It develops as a result of an excessively long anteroposterior size of the eyeball. In this case, the refractive systems of the eye are not affected.
• Lenticular myopia. It develops as a result of an increase in the refractive power of the lens, which can be observed in some diseases ( for example, with diabetes) or when taking certain medications ( hydralazine, chlorthalidone, phenothiazine and others).
• Nearsightedness with damage to the cornea. In this case, the cause of the development of the disease is too large curvature of the cornea, which is combined with its excessively pronounced refractive power.

Depending on the development mechanism, there are:

• true myopia;
• false myopia.

True myopia

True myopia is a number of pathological conditions in which organic damage to the eyeball, cornea or lens occurs. True myopia can be congenital or acquired. Without timely elimination of the cause of the disease, true myopia can progress and lead to the development of complications.

False myopia ( spasm of accommodation)

Accommodation is an eye device that provides a clear vision of objects at different distances from a person. False myopia is pathological condition, developing in children and young people as a result of overvoltage of the accommodation apparatus.

As mentioned earlier, during examination of closely spaced objects, the ciliary muscle contracts and the refractive power of the lens increases. If the ciliary muscle is contracted for several hours, it can disrupt metabolism and nervous regulation in her, as a result of which her spasm will occur ( that is, a pronounced and long-term reduction). If a person tries to look into the distance, the spasmodic ciliary muscle will not relax, and the refractive power of the lens will not decrease, as a result of which an object located in the distance will not be clearly visible. This condition is called accommodation spasm.

The development of accommodation spasm can be facilitated by:

• long continuous reading;
• long-term work at the computer;
• prolonged viewing of TV programs;
• reading ( or work at the computer) in poor lighting;
• non-observance of the work and rest regime;
• inadequate sleep;
• malnutrition.

Since the spasm of accommodation is temporary and almost completely resolves after the cause of its occurrence is eliminated, this condition is usually called false myopia. In this case, no anatomical defects in the eyeball or in the refractive system of the eye are observed, however, with prolonged exposure to the causative factor and often repeated spasms of accommodation, true myopia may develop.

Depending on the cause of development, there are:

• hereditary myopia;
• acquired myopia.

Hereditary myopia

Numerous studies have shown that myopia can be inherited, and different degrees of the disease are inherited through different mechanisms.

The human genetic apparatus consists of 23 pairs of chromosomes located in the nuclei of cells. Each chromosome contains a huge number of different genes that can be active or inactive. It is the activation of certain genes that determines all the properties and functions of cells, tissues, organs and the whole organism.

During conception, the fusion of male and female germ cells occurs, as a result of which the forming embryo inherits 23 chromosomes from the mother and 23 chromosomes from the father. If the obtained chromosomes contain defective genes, it is likely that the child will inherit the existing mutation and develop a certain disease as well.

Mild to moderate myopia is inherited in an autosomal dominant manner. This means that if a child inherits at least 1 defective gene, he will develop the disease. The probability of inheriting this gene depends on which of the parents has myopia. If both parents are sick, the chance of having a sick child is 75 to 100%. If only one of the parents is sick, the child will inherit the defective genes with a 50 to 100% probability.

High myopia is inherited in an autosomal recessive manner. This means that if only one of the parents is sick, and the other is healthy and is not a carrier of the defective gene, their child will be healthy, but they may inherit 1 defective gene and also become an asymptomatic carrier of the disease. If both parents are sick, the chance of having a sick child is 100%. If both parents are asymptomatic carriers of the defective gene, the probability of having a sick child is 25%, and the probability of having an asymptomatic carrier is 50%.

Acquired myopia

They say about acquired myopia when at the moment of birth the child has no signs of this disease, and the probability of a hereditary factor is excluded ( if the child's parents and grandparents did not have myopia, the probability of having genetic predisposition extremely small). In this case, the cause of the development of the disease is environmental factors that affect the organ of vision in the process of human life.

The development of myopia can be facilitated by:

• Failure to observe hygiene of vision. As mentioned earlier, when reading, as well as when working at a computer or watching TV at close range, accommodation tension occurs ( that is, the ciliary muscle is strained, which leads to an increase in the refractive power of the lens). If a person works in this position for a long time, certain changes begin to occur in the ciliary muscle ( it hypertrophies, that is, it becomes thicker and stronger). The process of hypertrophy of the ciliary muscle can take several years, but if this happens, the mechanism of its relaxation is disrupted. When a person looks into the distance, the ciliary muscle will not completely relax, but will remain in a partially contracted state. As a result, the ligaments of the lens capsule will remain relaxed, and the lens itself will not flatten to the required extent, which will be the direct cause of myopia.
• Unfavorable working conditions. Reading or working at a computer in low light requires a more pronounced tension of accommodation, which over time can lead to the development of myopia.
• Avitaminosis. Lack of vitamins ( especially vitamin B2) can also contribute to the development of myopia. This is explained by the fact that vitamin B2 ( riboflavin) normally improves many functions of the eye, in particular, facilitates the processes of dark adaptation ( improve vision in the dark) and eliminates eye fatigue with overwork. With a lack of this vitamin, excessive tension and overwork of the eye structures is also noted.
• Primary weakness of accommodation. This term refers to a pathological condition in which the refractive power of the cornea and / or lens is not sufficiently expressed. The light rays passing through them are focused somewhat behind the retina, and as a compensatory reaction, the eyeball is stretched in the anteroposterior size. If, after a certain time, the disease that caused the weakness of accommodation is eliminated, the overstretched eyeball will cause myopia.
• Injuries. Injuries to the eye, accompanied by damage to the eyeball, cornea or lens, can also cause myopia.

Night myopia

This condition cannot be called pathological, since it also occurs in people with normal vision. The mechanism of development of nocturnal myopia is associated with the fact that in the dark there is an expansion of the pupil, as well as contraction of the ciliary muscle and an increase in the refractive power of the lens, as a result of which images of the observed objects ( located at a distant distance from the eye) focus not directly on the retina, but somewhat in front of it. It is assumed that these adaptive reactions are aimed at improving vision in the dark, since when the pupil expands, a larger number of photons enter the retina, and the development of slight "myopia" forces a person to consider objects at a closer distance.

Nighttime myopia disappears completely during daytime and in good light.

Myopia in children

All of the above factors can lead to the development of myopia in a child. At the same time, there are a number of other pathological and physiological conditions that contribute to the development of myopia in childhood.

Depending on the mechanism of development of myopia in children, there are:

• congenital myopia;
• physiological myopia.

Congenital myopia

Congenital myopia can be observed in premature babies who were born prematurely ( normally, the child should be born no earlier than 37 weeks of intrauterine development). This is explained by the fact that in an embryo at the age of 3 to 4 months, the shape and size of the eye differ from those of an adult. The posterior part of the sclera protrudes slightly posteriorly, as a result of which the anteroposterior size of the eyeball increases. Also at this age, a more pronounced curvature of the cornea and lens is observed, which increases their refractive power. All this leads to the fact that light rays passing through the refractive system of the eye are focused in front of the retina, as a result of which myopia will be noted in a premature baby.

A few months after birth, the shape of the baby's eyeball changes, and the refractive power of the cornea and lens decreases, as a result of which myopia disappears without any correction.

Physiological myopia

Physiological myopia can develop in children aged 5 to 10 years, when there is a particularly intense growth of the eyeball. If its anteroposterior size becomes excessively large, the rays passing through the cornea and lens are focused in front of the retina, that is, myopia develops.

As the child grows, the severity of myopia may increase. This process usually ends by the age of 18, when the growth of the eyeball stops. At the same time, in some cases, the progression of physiological myopia up to 25 years is possible.

Symptoms and signs of myopia

The main complaint of patients with developing myopia is a decrease in visual acuity. Other symptoms may be related to the progression of the disease.

Decreased visual acuity with myopia

The first thing that begins to bother patients with myopia is a blurred vision of distant objects. With a slowly progressive disease, patients do not immediately notice this symptom, often attributing the decrease in visual acuity to overwork and fatigue. Over time, myopia progresses, as a result of which patients begin to see far-away objects worse and worse. Working with objects at close range ( for example reading) does not cause any inconvenience in people with myopia.

Also, people with myopia are constantly squinting, trying to examine far-away objects. The mechanism of development of this symptom is explained by the fact that when the palpebral fissure is partially closed, the pupil is slightly overlapped. As a result, the nature of the light rays passing through it changes, which helps to improve visual acuity. Also, when the eyelids are covered, a slight flattening of the cornea of \u200b\u200bthe eye occurs, which can help improve vision in myopia, combined with corneal astigmatism ( a disease in which there is an irregular, crooked corneal shape).

Other signs of myopia

As the disease progresses, other symptoms associated with damage to the refractive system of the eye and visual impairment may appear.

Myopia can manifest itself:

• Headaches. The development of this symptom is associated with overstrain of the accommodation apparatus, with impaired blood supply to the ciliary muscle and other intraocular structures, as well as with an indistinct image of distant objects, which affects the functioning of the entire central nervous system.
• Burning and pain in the eyes. Occur soon after the start of work with objects at close range ( for example, when working at a computer). The development of these symptoms is also associated with overwork of various intraocular structures and a violation of accommodation. It is worth noting that a burning sensation in the eyes can also indicate a spasm of accommodation.
• Lachrymation. Increased tearing can be noted during prolonged work at the computer and when reading books, however, this symptom can also occur in healthy people (in the latter case, it appears much later and disappears after a few minutes of rest). In addition, in patients with myopia, tearing can be noted on clear sunny days or in bright light. This is explained by the fact that with myopia, a more pronounced ( than normal) expansion of the pupil, which is associated with damage to the ciliary muscle. As a result, too much light enters the eye, and increased tearing is a kind of protective reaction in response to this phenomenon.
• An increase in the size of the palpebral fissure. This symptom may not be noticeable with myopia. weak degree, however, it is usually pronounced in severe progressive myopia. This is explained by an excessive increase in the eyeball, which protrudes somewhat forward, while expanding the eyelids.

Diagnosis of myopia

An ophthalmologist is responsible for the diagnosis and treatment of myopia. It is possible to suspect myopia based on the patient's complaints, however, additional studies are always required to confirm the diagnosis, determine the severity of the disease and prescribe the correct treatment.

To diagnose myopia, use:

• measurement of visual acuity;
• fundus examination;
• examination of visual fields;

• skiascopy;
• refractometry;
• computer keratotopography.

Measurement of visual acuity with myopia

As mentioned earlier, the first thing that suffers with myopia is visual acuity, that is, the ability to clearly see objects at a certain distance from the eye. Objective research methods of this indicator allow us to determine the degree of myopia and plan further diagnostic and therapeutic measures.

The very procedure for examining visual acuity is simple and performed in a matter of minutes. Research is carried out in a well-lit room with a special table. This table contains rows of letters or signs ( characters). The top row contains the largest letters, and each subsequent row contains the smaller ones.

The essence of the study is as follows. The patient sits on a chair, which is located 5 meters from the table. The doctor gives the patient a special opaque shutter and asks to cover one eye with it ( while not closing it, not closing the eyelid), and look at the table with the other eye. The doctor then points to letters of various sizes ( first to large, then to smaller) and asks the patient to name them.

People with normal visual acuity are able to easily ( without squinting) read letters from the tenth ( from above) row of the table. With myopia, patients see worse into the distance, as a result of which small details ( including letters and symbols on the table). If, during the study, a person names any letter incorrectly, the doctor goes back 1 row higher and checks if he sees the letters in it. The degree of myopia is determined depending on the letters from which row the patient can read. After determining the visual acuity in one eye, it should be covered with a shutter and the same study should be carried out with the second eye.

If, during the study, the patient cannot read the letters from the uppermost row, this indicates an extremely pronounced visual impairment. In this case, the doctor stands at a distance of 4 - 5 meters from the patient, shows him a certain number of fingers on his hand and ask him to count them. If the patient cannot do this, the doctor slowly approaches him ( holding hand in the same position), while the patient should name the number of fingers as soon as he can count them. If he cannot do this, even when the doctor's hand is directly in front of his eye, then he is practically blind in this eye ( this condition occurs in advanced cases, with the development of complications of untreated myopia). The last stage of diagnostics in this case will be to check light perception ( the doctor periodically shines a flashlight into the patient's eye and asks to speak when he sees the light). If the patient cannot determine the moment of turning on the light, it means that he is completely blind in the examined eye.

Degrees of myopia

Determination of the degree of myopia is carried out immediately after determining visual acuity. For this, special glasses with removable lenses are put on the patient's eyes. The doctor inserts an opaque plate into the frame in front of one eye, and in front of the other eye begins to alternately install diffusing lenses. These lenses scatter the rays passing through them, resulting in the total refractive power of the refractive system ( i.e. lenses, cornea and lens) decreases and the focus of the image shifts back.

As the lenses are replaced, the doctor asks the patient to read the letters from the different rows of the chart until he can clearly identify the letters ( symbols) from row 10. The degree of myopia in this case will be equal to the strength of the lens required to correct vision.

Depending on the severity of myopia, there are:

• Mild myopia - up to 3 diopters.
• Moderate myopia - from 3 to 6 diopters.
• High degree of myopia - more than 6 diopters.

Examination of the fundus with myopia

With the progression of myopia, an increase in the anteroposterior size of the eyeball almost always occurs. The outer shell of the eye ( sclera) in this case stretches relatively easily, while the retina ( composed of photosensitive nerve cells) is able to withstand stretching only up to certain limits ( which are usually extremely small). That is why with myopia, atrophic changes in the disc area are often observed. optic nerve (the optic disc is the area on the back wall of the eyeball in which nerve fiberstransmitting nerve impulses from photosensitive nerve cells to the brain).

These changes can be identified by examining the fundus ( ophthalmoscopy). The essence of the study is as follows. The doctor puts on his head a special mirror with a hole inside and sits down opposite the patient. After that, he places a magnifying glass in front of the patient's eye and directs the rays of light reflected from the mirror directly into the pupil of the examined eye. As a result, the doctor can study in detail the back ( internal) the wall of the eyeball, assess the state of the optic nerve and identify the so-called myopic cone - the sickle-shaped area of \u200b\u200bthe affected retina, located around the optic nerve head.

Before the study, the patient is usually instilled into the eyes of a few drops of drugs that dilate the pupil ( e.g. atropine). The need for this procedure is due to the fact that during the examination, the doctor directs the rays of light into the patient's eye, which normally leads to a reflex narrowing of the pupil, through which the doctor cannot see anything. Based on this, it follows that ophthalmoscopy is contraindicated if the patient cannot be prescribed these drugs ( for example, with glaucoma - a disease characterized by a persistent increase in intraocular pressure).

Study of visual fields in myopia

With the progression of myopia, not only visual acuity suffers, but also peripheral vision. This is manifested by a narrowing of the visual fields, which can be detected during special studies. The mechanism of development of this symptom lies in the damage to the retina, which is observed with excessive stretching of the eyeball.

You can explore the field of view using an approximate ( subjective) or an objective method. With a subjective research method, the doctor and the patient sit opposite each other so that the patient's right eye looks into the doctor's left eye, while their eyes should be 1 meter apart. The doctor asks the patient to look straight ahead and does the same. Then he places a special white mark on the side of the head, which neither he nor the patient sees at first. After that, the doctor begins to move the mark from the periphery to the center ( to a point located between his eye and the patient's eye). The patient himself must signal the doctor as soon as he notices the movement of the mark. If the doctor notices the mark at the same time as the patient, then the latter's visual fields are normal ( provided that they are normal by the doctor himself).

During the study, the doctor sets a mark to the right, left, above and below the eye, checking the boundaries of the visual fields from all sides.

When objective method studies, the patient sits down opposite a special apparatus, which is a large hemisphere. He places his head on a special stand in the center of the hemisphere, after which he fixes his vision at a point located directly in front of his eyes. Then the doctor begins to move a special mark from the periphery of the sphere to its center, and the patient must give him a sign as soon as he sees it. The main advantage of this method is its independence from the state of vision of the doctor. Moreover, on the reverse ( convex) on the side of the hemisphere there are special rulers with gradation, along which the doctor immediately determines the boundaries of the visual fields in various planes.

The research itself is absolutely safe and does not take more than 5 - 7 minutes. No special training is required to perform the study, and the patient can go home immediately after the end of the procedure.

Skiascopy for myopia

This is a simple research method that allows you to diagnose myopia and determine its degree. With skiascopy, the functions of all refractive structures of the eye ( lens and cornea) simultaneously. The essence of the method is as follows. The doctor sits on a chair in front of the patient and sets a light source 1 meter from the eye being examined ( usually a mirror with a hole in the center that reflects light from a lamp on the side of the patient). Light rays reflected from the mirror pass through the cornea and lens, fall on the retina of the examined eye and are reflected from it, as a result of which the doctor sees a round red spot through the pupil ( red is due blood vesselslocated at the bottom of the eyeball).

If after that the doctor begins to move the mirror up or down, the shape of the reflecting spot will begin to change, and the nature of the changes will depend on the state of the refractive system of the eye. So, for example, if a person has 1 diopter myopia, the rays reflected from the retina will be collected ( focus) at a distance of exactly 1 meter from the eye. In this case, as soon as the doctor moves the mirror to the side, the red spot will immediately disappear.

If the patient has myopia of more than 1 diopter, during the movement of the mirror, the doctor will see a shadow that will move in the direction opposite to the movement of the light source. In this case, the doctor installs a special skiascopic ruler between the mirror and the patient's eye, in which there are many diffusing lenses of various strengths. Then he begins to change lenses until, when the mirror moves, the red spot begins to disappear instantly ( no moving shadow). The degree of myopia in this case is determined depending on the strength of the scattering lens required to achieve this effect.

Other research methods for myopia

After detecting myopia and determining its degree, it is recommended to investigate the components of the refractive system of the eye, which in some cases makes it possible to establish the true cause of the disease.

To identify the cause of myopia, the doctor may prescribe:

• Ophthalmometry. This study allows you to assess the refractive power of the cornea. During the examination, special test marks are projected onto the patient's cornea, the nature of the image of which will depend on its refractive power.
• Refractometry. Principle this study is similar to that in ophthalmometry, however, in this case, test images are projected not onto the cornea, but onto the retina, which makes it possible to simultaneously examine both refractive structures of the eye ( cornea and lens). Refractometry can be done manually ( using special devices) or automatically. In the latter case, all measurements and calculations are performed by a special computer, after which all data of interest to the doctor are displayed on the monitor.
• Computerized keratotopography. The essence of the method is to study the shape and refractive power of the cornea using modern computer technology.

Before use, you must consult with a specialist.