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• Introduction 2
• 1. Organ of vision 3
• 8
• 12
• 13
• Conclusion 15
• Literature 16

Introduction

The relevance of the topic of our work is obvious. The organ of vision, organum visus, plays an important role in a person's life, in his communication with external environment. In the process of evolution, this organ has gone from light-sensitive cells on the surface of the animal body to a complex organ capable of moving in the direction of the light beam and sending this beam to special light-sensitive cells in the thickness rear wall eyeball, perceiving both black and white and color images. Having reached perfection, the organ of vision in a person captures pictures of the external world, transforms light irritation into a nerve impulse.

The organ of vision is located in the orbit and includes the eye and auxiliary organs of vision. Happens with age certain changes in the organs of vision, which leads to general deterioration human well-being, to social and psychological problems.

The purpose of our work is to find out what age-related changes in the organs of vision are.

The task is to study and analyze the literature on this topic.

1. Organ of vision

The eye, oculus (Greek ophthalmos), consists of the eyeball and the optic nerve with its membranes. Eyeball, bulbus oculi, rounded. The poles are distinguished in it - anterior and posterior, polus anterior et polus posterior. The first corresponds to the most protruding point of the cornea, the second is located lateral to the exit point of the optic nerve from the eyeball. The line connecting these points is called the outer axis of the eye, axis bulbi externus. It is approximately 24 mm and is located in the plane of the meridian of the eyeball. The internal axis of the eyeball, axis bulbi internus (from the posterior surface of the cornea to the retina), is 21.75 mm. In the presence of a longer internal axis, the rays of light, after being refracted in the eyeball, are concentrated in front of the retina. At the same time, good vision of objects is possible only at close distances - myopia, myopia (from the Greek myops - squinting eye). The focal length of myopic people is shorter than the inner axis of the eyeball.

If the inner axis of the eyeball is relatively short, then the rays of light after refraction are collected in focus behind the retina. Distance vision is better than near - farsightedness, hypermetropia (from the Greek metron - measure, ops - gender, opos - vision). The focal length of the far-sighted is longer than the inner axis of the eyeball.

The vertical size of the eyeball is 23.5 mm, and the transverse size is 23.8 mm. These two dimensions are in the plane of the equator.

Allocate the visual axis of the eyeball, axis opticus, which extends from its anterior pole to the central fossa of the retina - the point of best vision. (Fig. 202).

The eyeball consists of the membranes that surround the nucleus of the eye (aqueous humor in the anterior and posterior chambers, the lens, the vitreous body). There are three membranes: external fibrous, middle vascular and internal sensitive.

The fibrous membrane of the eyeball, tunica fibrosa bulbi, performs protective function. The front part of it is transparent and is called the cornea, and the large back part, because of the whitish color, is called the albuginea, or sclera. The boundary between the cornea and the sclera is a shallow circular sulcus of the sclera, sulcus sclerae.

The cornea, cornea, is one of the transparent media of the eye and is devoid of blood vessels. It has the appearance of an hour glass, convex in front and concave in the back. Corneal diameter - 12 mm, thickness - about 1 mm. The peripheral edge (limb) of the cornea, limbus corneae, is, as it were, inserted into the anterior part of the sclera, into which the cornea passes.

Sclera, sclera, consists of dense fibrous connective tissue. In its back part there are numerous openings through which bundles of optic nerve fibers exit and vessels pass. The thickness of the sclera at the exit of the optic nerve is about 1 mm, and in the region of the equator of the eyeball and in the anterior section - 0.4-0.6 mm. On the border with the cornea in the thickness of the sclera lies a narrow circular canal filled with venous blood - the venous sinus of the sclera, sinus venosus sclerae (Schlemm's canal).

The choroid of the eyeball, tunica vasculosa bulbi, is rich in blood vessels and pigment. It is directly adjacent to the sclera from the inside, with which it is firmly fused at the exit from the eyeball of the optic nerve and at the border of the sclera with the cornea. The choroid is divided into three parts: the choroid proper, the ciliary body, and the iris.

Actually choroid, choroidea, lines the large posterior part of the sclera, with which, in addition to the indicated places, it is loosely fused, limiting the so-called perivascular space between the membranes, spatium perichoroideale.

The ciliary body, corpus ciliare, is the middle thickened section of the choroid, located in the form of a circular roller in the region of the transition of the cornea to the sclera, behind the iris. The ciliary body is fused with the outer ciliary edge of the iris. The back of the ciliary body - the ciliary circle, orbiculus ciliaris, has the form of a thickened circular strip 4 mm wide, passes into the choroid proper. The anterior part of the ciliary body forms about 70 radially oriented folds, thickened at the ends, up to 3 mm long each - ciliary processes, processus ciliares. These processes consist mainly of blood vessels and make up the ciliary crown, corona ciliaris.

In the thickness of the ciliary body lies the ciliary muscle, m. ciliaris, consisting of intricately intertwined bundles of smooth muscle cells. When the muscle contracts, accommodation of the eye occurs - an adaptation to a clear vision of objects located at different distances. In the ciliary muscle, meridional, circular and radial bundles of unstriated (smooth) muscle cells are isolated. Meridional (longitudinal) fibers, fibrae meridionales (longitudinales), of this muscle originate from the edge of the cornea and from the sclera and are woven into the anterior part of the choroid itself. With their contraction, the shell shifts anteriorly, as a result of which the tension of the ciliary band, zonula ciliaris, on which the lens is attached, decreases. In this case, the lens capsule relaxes, the lens changes its curvature, becomes more convex, and its refractive power increases. Circular fibers, fibrae circulares, starting together with the meridional fibers, are located medially from the latter in a circular direction. With its contraction, the ciliary body is narrowed, bringing it closer to the lens, which also contributes to the relaxation of the lens capsule. Radial fibers, fibrae radiales, start from the cornea and sclera in the region of the iridocorneal angle, are located between the meridional and circular bundles ciliary muscle, bringing these bundles together during their contraction. The elastic fibers present in the thickness of the ciliary body straighten the ciliary body when its muscles are relaxed.

The iris, iris, is the most anterior part of the choroid, visible through the transparent cornea. It has the form of a disk about 0.4 mm thick, placed in the frontal plane. In the center of the iris there is a round hole - the pupil, pirilla. The pupil diameter is variable: the pupil constricts in strong light and expands in the dark, acting as the diaphragm of the eyeball. The pupil is limited by the pupillary edge of the iris, margo pupillaris. The outer ciliary edge, margo ciliaris, is connected to the ciliary body and to the sclera with the help of the comb ligament, lig. pectinatum iridis (BNA). This ligament fills the iridocorneal angle formed by the iris and cornea, angulus iridocornealis. The anterior surface of the iris faces the anterior chamber of the eyeball, and the posterior surface faces the posterior chamber and lens. The connective tissue stroma of the iris contains blood vessels. The cells of the posterior epithelium are rich in pigment, the amount of which determines the color of the iris (eye). In the presence of a large amount of pigment, the color of the eye is dark (brown, hazel) or almost black. If there is little pigment, then the iris will have a light gray or light blue color. In the absence of pigment (albinos), the iris is reddish in color, as blood vessels shine through it. Two muscles lie in the thickness of the iris. Around the pupil, bundles of smooth muscle cells are circularly located - the sphincter of the pupil, m. sphincter pupillae, and radially from the ciliary edge of the iris to its pupillary edge extend thin bundles of the muscle that dilates the pupil, m. dilatator pupillae (pupil dilator).

The inner (sensitive) shell of the eyeball (retina), tunica interna (sensoria) bulbi (retina), is tightly attached from the inside to the choroid along its entire length, from the exit of the optic nerve to the edge of the pupil. In the retina, which develops from the wall of the anterior cerebral bladder, two layers (leaves) are distinguished: the outer pigment part, pars pigmentosa, and the complex internal photosensitive part, called the nervous part, pars nervosa. Accordingly, the functions distinguish a large posterior visual part of the retina, pars optica retinae, containing sensitive elements - rod-shaped and cone-shaped visual cells (rods and cones), and a smaller, "blind" part of the retina, devoid of rods and cones. The "blind" part of the retina combines the ciliary part of the retina, pars ciliaris retinae, and the iris part of the retina, pars iridica retinae. The boundary between the visual and "blind" parts is the jagged edge, ora serrata, which is clearly visible on the preparation of the opened eyeball. It corresponds to the place of transition of the choroid proper to the ciliary circle, orbiculus ciliaris, choroid.

In the posterior part of the retina at the bottom of the eyeball in a living person, using an ophthalmoscope, you can see a whitish spot with a diameter of about 1.7 mm - the optic disc, discus nervi optici, with raised edges in the form of a roller and a small depression, excavatio disci, in the center (Fig. 203).

The disc is the exit point of the optic nerve fibers from the eyeball. The latter, being surrounded by shells (a continuation of the meninges of the brain), forming the outer and inner sheaths of the optic nerve, vagina externa et vagina interna n. optici, is directed towards the optic canal, which opens into the cranial cavity. Due to the absence of light-sensitive visual cells (rods and cones), the disc area is called the blind spot. In the center of the disk, its central artery entering the retina is visible, a. centralis retinae. Lateral to the optic disc by about 4 mm, which corresponds to the posterior pole of the eye, there is a yellowish spot, macula, with a small depression - the central fossa, fovea centralis. The fovea is the place of the best vision: only cones are concentrated here. There are no sticks in this place.

The inner part of the eyeball is filled with aqueous humor located in the anterior and posterior chambers of the eyeball, the lens and the vitreous body. Together with the cornea, all these formations are the light-refracting media of the eyeball. The anterior chamber of the eyeball, camera anterior bulbi, containing aqueous humor, humor aquosus, is located between the cornea in front and the anterior surface of the iris behind. Through the opening of the pupil, the anterior chamber communicates with the posterior chamber of the eyeball, camera posterior bulbi, which is located behind the iris and bounded behind by the lens. The posterior chamber communicates with the spaces between the fibers of the lens, the fibrae zonulares, which connect the lens sac to the ciliary body. Girdle spaces, spatia zonularia, look like a circular fissure (petite canal) lying along the periphery of the lens. They, like the posterior chamber, are filled with aqueous humor, which is formed with the participation of numerous blood vessels and capillaries that lie in the thickness of the ciliary body.

Located behind the chambers of the eyeball, the lens, lens, has the shape of a biconvex lens and has a large light refractive power. The anterior surface of the lens, facies anterior lentis, and its most protruding point, the anterior pole, polus anterior, are turned to the side. rear camera eyeball. The more convex posterior surface, facies posterior, and the posterior pole of the lens, polus posterior lentis, are adjacent to the anterior surface of the vitreous body. The vitreous body, corpus vitreum, covered along the periphery with a membrane, is located in the vitreous chamber of the eyeball, camera vitrea bulbi, behind the lens, where it is tightly adjacent to the inner surface of the retina. The lens, as it were, is pressed into the anterior part of the vitreous body, which in this place has a depression called the vitreous fossa, fossa hyaloidea. The vitreous body is a jelly-like mass, transparent, devoid of blood vessels and nerves. The refractive power of the vitreous body is close to the refractive index of the aqueous humor filling the chambers of the eye.

2. Development and age-related features of the organ of vision

The organ of vision in phylogenesis has gone from separate ectodermal origin of light-sensitive cells (in intestinal cavities) to complex paired eyes in mammals. In vertebrates, the eyes develop in a complex way: a light-sensitive membrane, the retina, is formed from the lateral outgrowths of the brain. The middle and outer shells of the eyeball, the vitreous body are formed from the mesoderm (middle germinal layer), the lens - from the ectoderm.

The inner shell (retina) is shaped like a double-walled glass. The pigment part (layer) of the retina develops from the thin outer wall of the glass. Visual (photoreceptor, light-sensitive) cells are located in the thicker inner layer of the glass. In fish, the differentiation of visual cells into rod-shaped (rods) and cone-shaped (cones) is weakly expressed, in reptiles there are only cones, in mammals the retina contains mainly rods; in aquatic and nocturnal animals, cones are absent in the retina. As part of the middle (vascular) membrane, already in fish, the ciliary body begins to form, which becomes more complicated in its development in birds and mammals. Muscles in the iris and in the ciliary body first appear in amphibians. The outer shell of the eyeball in lower vertebrates consists mainly of cartilaginous tissue (in fish, partly in amphibians, in most lizard-like and monotremes). In mammals, it is built only from fibrous (fibrous) tissue. The anterior part of the fibrous membrane (cornea) is transparent. The lens of fish and amphibians is rounded. Accommodation is achieved due to the movement of the lens and the contraction of a special muscle that moves the lens. In reptiles and birds, the lens is able not only to move, but also to change its curvature. In mammals, the lens occupies a permanent place, accommodation is carried out due to a change in the curvature of the lens. The vitreous body, which initially has a fibrous structure, gradually becomes transparent.

Simultaneously with the complication of the structure of the eyeball, auxiliary organs of the eye develop. The first to appear are six oculomotor muscles, which are transformed from the myotomes of three pairs of head somites. Eyelids begin to form in fish in the form of a single annular skin fold. Terrestrial vertebrates develop upper and lower eyelids, and most of them also have a nictitating membrane (third eyelid) at the medial corner of the eye. In monkeys and humans, the remnants of this membrane are preserved in the form of a semilunar fold of the conjunctiva. In terrestrial vertebrates, the lacrimal gland develops, and the lacrimal apparatus is formed.

The human eyeball also develops from several sources. The light-sensitive membrane (retina) comes from the side wall of the brain bladder (the future diencephalon); the main lens of the eye - the lens - directly from the ectoderm; vascular and fibrous membranes - from the mesenchyme. At an early stage of development of the embryo (the end of the 1st, the beginning of the 2nd month of intrauterine life), a small paired protrusion appears on the side walls of the primary cerebral bladder (prosencephalon) - eye bubbles. Their terminal sections expand, grow towards the ectoderm, and the legs connecting with the brain narrow and later turn into optic nerves. In the process of development, the wall of the optic vesicle protrudes into it and the vesicle turns into a two-layer ophthalmic cup. The outer wall of the glass further becomes thinner and transforms into the outer pigment part (layer), and from inner wall a complexly arranged light-perceiving (nervous) part of the retina (photosensory layer) is formed. At the stage of formation of the eyecup and differentiation of its walls, at the 2nd month of intrauterine development, the ectoderm adjacent to the eyecup in front thickens at first, and then a lens fossa is formed, which turns into a lens vesicle. Separated from the ectoderm, the vesicle plunges into the eye cup, loses the cavity, and the lens is subsequently formed from it.

At the 2nd month of intrauterine life, mesenchymal cells penetrate into the eye cup through the gap formed on its lower side. These cells form a blood vascular network inside the glass in the vitreous body that is forming here and around the growing lens. From the mesenchymal cells adjacent to the eye cup, the choroid is formed, and from the outer layers, the fibrous membrane. The anterior part of the fibrous membrane becomes transparent and turns into the cornea. The fetus is 6-8 months old. the blood vessels in the lens capsule and in the vitreous disappear; the membrane covering the opening of the pupil (pupillary membrane) is resorbed.

The upper and lower eyelids begin to form in the 3rd month of intrauterine life, initially in the form of ectoderm folds. The epithelium of the conjunctiva, including the one that covers the front of the cornea, comes from the ectoderm. The lacrimal gland develops from outgrowths of the conjunctival epithelium that appear on the 3rd month of intrauterine life in the lateral part of the emerging upper eyelid.

The eyeball of a newborn is relatively large, its anteroposterior size is 17.5 mm, weight is 2.3 g. The visual axis of the eyeball runs more lateral than in an adult. The eyeball grows in the first year of a child's life faster than in subsequent years. By the age of 5, the mass of the eyeball increases by 70%, and by the age of 20-25 - 3 times compared with a newborn.

The cornea of ​​a newborn is relatively thick, its curvature almost does not change during life; the lens is almost round, the radii of its anterior and posterior curvature are approximately equal. The lens grows especially rapidly during the first year of life, and then its growth rate decreases. The iris is convex anteriorly, there is little pigment in it, the pupil diameter is 2.5 mm. As the age of the child increases, the thickness of the iris increases, the amount of pigment in it increases, and the diameter of the pupil becomes large. At the age of 40-50 years, the pupil narrows slightly.

The ciliary body in a newborn is poorly developed. The growth and differentiation of the ciliary muscle is carried out quite quickly. The optic nerve in a newborn is thin (0.8 mm), short. By the age of 20, its diameter almost doubles.

The muscles of the eyeball in a newborn are well developed, except for their tendon part. Therefore, eye movement is possible immediately after birth, but the coordination of these movements begins from the 2nd month of a child's life.

The lacrimal gland in a newborn is small, the excretory ducts of the gland are thin. The function of tearing appears on the 2nd month of a child's life. The vagina of the eyeball in a newborn and infants is thin, the fatty body of the orbit is poorly developed. In elderly people and old age the fatty body of the orbit decreases in size, partially atrophies, the eyeball protrudes less from the orbit.

The palpebral fissure in a newborn is narrow, the medial angle of the eye is rounded. In the future, the palpebral fissure rapidly increases. In children under 14-15 years old, it is wide, so the eye seems larger than in an adult.

3. Anomalies in the development of the eyeball

The complex development of the eyeball leads to birth defects. More often than others, an irregular curvature of the cornea or lens occurs, as a result of which the image on the retina is distorted (astigmatism). When the proportions of the eyeball are disturbed, congenital myopia (the visual axis is elongated) or hyperopia (the visual axis is shortened) appear. A gap in the iris (coloboma) often occurs in its anteromedial segment.

The remnants of the branches of the artery of the vitreous body interfere with the passage of light in the vitreous body. Sometimes there is a violation of the transparency of the lens (congenital cataract). Underdevelopment of the venous sinus of the sclera (canal schlemms) or spaces of the iridocorneal angle (fountain spaces) causes congenital glaucoma.

4. Determination of visual acuity and its age characteristics

Visual acuity reflects the ability of the optical system of the eye to build a clear image on the retina, that is, it characterizes the spatial resolution of the eye. It is measured by determining the smallest distance between two points, sufficient so that they do not merge, so that the rays from them fall on different receptors in the retina.

The measure of visual acuity is the angle that is formed between the rays coming from two points of the object to the eye - the angle of view. The smaller this angle, the higher the visual acuity. Normally, this angle is 1 minute (1"), or 1 unit. In some people, visual acuity may be less than one. With visual impairments (for example, with myopia), visual acuity deteriorates and becomes greater than one.

Visual acuity improves with age.

Table 12. Age-related changes in visual acuity with normal refractive properties of the eye.
	Visual acuity (in conventional units)
6 months
adults

In the table parallel rows of letters are arranged horizontally, the size of which decreases from the top row to the bottom. For each row, the distance is determined from which the two points limiting each letter are perceived at an angle of view of 1 ". The letters of the uppermost row are perceived by the normal eye from a distance of 50 meters, and the lower - 5 meters. To determine visual acuity in relative units, the distance, from which the subject can read the line is divided by the distance from which it should be read under the condition of normal vision.

The experiment is carried out as follows.

Place the subject at a distance of 5 meters from the table, which must be well sanctified. Cover one eye of the subject with a screen. Ask the subject to name the letters in the table from top to bottom. Mark the last of the lines that the subject was able to read correctly. By dividing the distance at which the subject is from the table (5 meters) by the distance from which he read the last of the lines he distinguished (for example, 10 meters), find visual acuity. For this example: 5 / 10 = 0.5.

Study protocol.
		Visual acuity for the right eye (in conventional units)	Visual acuity for the left eye (in conventional units)

Conclusion

So, in the course of writing our work, we came to the following conclusions:

- The organ of vision develops and changes with the age of a person.

The complex development of the eyeball leads to birth defects. More often than others, an irregular curvature of the cornea or lens occurs, as a result of which the image on the retina is distorted (astigmatism). When the proportions of the eyeball are disturbed, congenital myopia (the visual axis is elongated) or hyperopia (the visual axis is shortened) appear.

The measure of visual acuity is the angle that is formed between the rays coming from two points of the object to the eye - the angle of view. The smaller this angle, the higher the visual acuity. Normally, this angle is 1 minute (1"), or 1 unit. In some people, visual acuity may be less than one. With visual impairments (for example, with myopia), visual acuity deteriorates and becomes greater than one.

Age-related changes in the organ of vision must be studied and controlled, since vision is one of the most important human senses.

Literature

1. M.R. Guseva, I.M. Mosin, T.M. Tskhovrebov, I.I. Bushev. Features of the course of optic neuritis in children. Tez. 3 All-Union Conference on topical issues pediatric ophthalmology. M.1989; pp.136-138

2. E.I. Sidorenko, M.R. Guseva, L.A. Dubovskaya. Cerebrolysian in treatment partial atrophy optic nerve in children. J. Neuropathology and psychiatry. 1995; 95:51-54.

3. M.R. Guseva, M.E. Guseva, O.I. Maslova. Research results immune status in children with optic neuritis and a number of demyelinating conditions. Book. Age features organ of vision in normal and pathological conditions. M., 1992, p.58-61

4. E.I. Sidorenko, A.V. Khvatova, M.R. Guseva. Diagnosis and treatment of optic neuritis in children. Guidelines. M., 1992, 22 p.

5. M.R. Guseva, L.I. Filchikova, I.M. Mosin et al. Electrophysiological methods in assessing the risk of multiple sclerosis in children and adolescents with monosymptomatic optic neuritis J.Neuropatology and psychiatry. 1993; 93:64-68.

6. I.A. Zavalishin, M.N. Zakharova, A.N. Dziuba et al. Pathogenesis of retrobulbar neuritis. J. Neuropathology and Psychiatry. 1992; 92:3-5.

7. I.M. Mosin. Differential and topical diagnosis of optic neuritis in children. Candidate of Medical Sciences (14.00.13) Moscow Research Institute of Eye Diseases. Helmholtz M., 1994, 256 s,

8. M.E. Guseva Clinical and paraclinical criteria for demyelinating diseases in children. Abstract of diss.c.m.s., 1994

9. M.R. Guseva Diagnosis and pathogenetic therapy of uveitis in children. Diss. doctor of medical sciences in the form of a scientific report. M.1996, 63s.

10. IZ Karlova Clinical and immunological features of optic neuritis in multiple sclerosis. Abstract of diss.c.m.s., 1997

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Development peripheral department. Differentiation of the cellular elements of the retina occurs at the 6-10th week of intrauterine development. By the 3rd month of embryonic life, the retina includes all types of nerve elements. In a newborn, only rods function in the retina, providing black and white vision. The cones responsible for color vision are not yet mature and their number is small. And although newborns have the functions of color perception, the full inclusion of cones in work occurs only by the end of the 3rd year of life. As the cones mature, children begin to distinguish first yellow, then green, and then red (already from the age of 3 months, it was possible to develop conditioned reflexes to these colors); color recognition at an earlier age depends on the brightness, and not on the spectral characteristics of the color. Children begin to fully distinguish colors from the end of the 3rd year of life. IN school age the distinctive color sensitivity of the eye is increased. The sensation of color reaches its maximum development by the age of 30 and then gradually decreases. Training is essential for developing this ability. The final morphological maturation of the retina ends by 10-12 years.

Development of additional elements of the organ of vision (prereceptor structures). In a newborn, the diameter of the eyeball is 16 mm and its weight is 3.0 g. The growth of the eyeball continues after birth. It grows most intensively during the first 5 years of life, less intensively - up to 9-12 years. In adults, the diameter of the eyeball is about 24 mm, and the weight is 8.0 g. In newborns, the shape of the eyeball is more spherical than in adults, the anteroposterior axis of the eye is shortened. As a result, in 80-94% of cases, they have far-sighted refraction. Increased extensibility and elasticity of the sclera in children contributes to slight deformation of the eyeball, which is important in the formation of refraction of the eye. So, if a child plays, draws or reads, tilting his head low, due to the pressure of the liquid on the front wall, the eyeball lengthens and myopia develops. The cornea is more convex than in adults. In the first years of life, the iris contains few pigments and has a bluish-grayish tint, and the final formation of its color is completed only by the age of 10-12. In newborns, due to the underdeveloped muscles of the iris, the pupils are narrow. Pupil diameter increases with age. At the age of 6-8 years, the pupils are wide due to the predominance of the tone of the sympathetic nerves that innervate the muscles of the iris, which increases the risk of retinal sunburn. At 8-10 years old, the pupil becomes narrow again, and by the age of 12-13, the speed and intensity of the pupillary reaction to light is the same as in an adult. In newborns and preschool children, the lens is more convex and more elastic than in an adult, and its refractive power is higher. This makes it possible to clearly see the object when it is closer to the eye than in an adult. In turn, the habit of viewing objects at a short distance can lead to the development of strabismus. The lacrimal glands and regulatory centers develop during the period from 2 to 4 months of life, and therefore tears during crying appear at the beginning of the second, and sometimes 3-4 months after birth.

Maturation conductor department visual analyzer manifests itself:

• 1) myelination of pathways, starting at the 8-9th month of intrauterine life and ending by 3-4 years;
• 2) differentiation of subcortical centers.

The cortical part of the visual analyzer has the main signs of adults already in a 6-7-month-old fetus, however, the nerve cells of this part of the analyzer, like other parts of the visual analyzer, are immature. The final maturation of the visual cortex occurs by the age of 7. In functional terms, this leads to the possibility of forming associative and temporal connections in the final analysis of visual sensations. The functional maturation of the visual zones of the cerebral cortex, according to some data, occurs already by the birth of a child, according to others - somewhat later. So, in the first months after birth, the child confuses the top and bottom of the object. If you show him a burning candle, then he, trying to grab the flame, will stretch out his hand not to the upper, but to the lower end.

Development of the functionality of the visual sensory system.

The light-perceiving function in children can be judged by the pupillary reflex, closure of the eyelids with the abduction of the eyeballs upward and other quantitative indicators of light perception, which are determined using adaptometer devices only from 4-5 years of age. The photosensitive function develops very early. Visual reflex to light (pupil constriction) - from the 6th month of intrauterine development. A protective blinking reflex to sudden light irritation is present from the first days of life. Closing of the eyelids when an object approaches the eyes appears on the 2nd-4th month of life. With age, the degree of constriction of the pupils in the light and their expansion in the dark increases (Table 14.1). Constriction of the pupils when fixing the gaze of an object occurs from the 4th week of life. Visual concentration in the form of fixing the gaze on an object with simultaneous inhibition of movements manifests itself in the 2nd week of life and lasts 1-2 minutes. The duration of this reaction increases with age. Following the development of fixation, the ability to follow a moving object with the eye and the convergence of visual axes develop. Until the 10th week of life, eye movements are uncoordinated. Eye movement coordination develops with the development of fixation, tracking, and convergence. Convergence occurs on the 2-3rd week and becomes resistant to 2-2.5 months of life. Thus, the child has a sense of light essentially from the moment of birth, but a clear visual perception in the form of visual samples is not available to him, since although the retina is developed at the time of birth, the fovea has not completed its development, the final differentiation of cones ends by the end of the year, and subcortical and cortical centers in newborns are morphologically and functionally immature. These features determine the lack of object vision and perception of space up to 3 months of life. Only from this time on, the child's behavior begins to be determined by visual afferentation: before feeding, he visually finds his mother's breast, examines his hands, and grasps toys located at a distance. The development of object vision is also associated with the perfection of visual acuity, eye motility, with the formation of complex interanalyzer connections when visual sensations are combined with tactile and proprioceptive ones. The difference in the shapes of objects appears on the 5th month.

Changes in the quantitative indicators of light perception in the form of a threshold of light sensitivity of the dark-adapted eye in children compared with adults are presented in Table. 14.2. Measurements have shown that the sensitivity to light of a dark-adapted eye sharply increases up to 20 years, and then gradually decreases. Due to the great elasticity of the lens, the eyes of children are more capable of accommodation than those of adults. With age, the lens gradually loses its elasticity and its refractive properties deteriorate, the volume of accommodation decreases (i.e., it reduces the increase in the refractive power of the lens when it is convex), the point of proximal vision is removed (Table 14.3).

Table 14.1

Age-related changes in the diameter and reactions of pupillary constriction to light

Table 14.2

Light sensitivity of the dark-adapted eye of people of different ages

Table 14.3

Change in the volume of accommodation with age

Color perception in children is manifested from the moment of birth, but on various colors, it does not seem to be the same. According to the results of the electroretinogram (ERG), in children, the functioning of cones to orange light was established from 6 hours of life after birth. There is evidence that in the last weeks of embryonic development, the cone apparatus is able to respond to red and green colors. It is believed that from the moment of birth to 6- one month old the order of perception of color discrimination is as follows: yellow, white, pink, red, brown, black, blue, green, violet. At 6 months, children distinguish all colors, but correctly name them only from 3 years.

Visual acuity increases with age and in 80-94% of children and adolescents it is greater than in adults. For comparison, we present data on visual acuity (in arbitrary units) in children of different ages (Table 14.4).

Table 14.4

Visual acuity in children of different ages

Due to the spherical shape of the eyeball, short anteroposterior axis, large convexity of the cornea and lens in newborns, the refraction value is 1-3 diopters. In preschoolers and schoolchildren, farsightedness (if any) is explained flat shape lens. Children in preschool and school may develop myopia when reading for a long time in a sitting position with a large tilt of the head and with accommodation tension that occurs in poor lighting while reading or looking at small objects. These conditions lead to an increase in blood supply to the eye, an increase in intraocular pressure and a change in the shape of the eyeball, which is the cause of the development of myopia.

With age, stereoscopic vision also improves. It begins to form from the 5th month of life. This is facilitated by improving the coordination of eye movement, fixing the gaze on the object, improving visual acuity, and the interaction of the visual analyzer with others (especially with the tactile one). By the 6-9th month, an idea arises of the depth and remoteness of the location of objects. Stereoscopic vision by the age of 17-22 reaches its optimal level, and from the age of 6 girls have sharpness stereoscopic vision higher than boys.

The field of view is formed by the 5th month. Until this time, children fail to evoke a defensive blinking reflex when an object is introduced from the periphery. With age, the field of view increases, especially intensively from 6 to 7.5 years. By the age of 7, its size is approximately 80% of the size of the field of view of an adult. In the development of the visual field, sexual characteristics are observed. The expansion of the field of vision continues up to 20-30 years. The field of view determines the amount of educational information perceived by the child, i.e. throughput of the visual analyzer, and, consequently, learning opportunities. In the process of ontogenesis, the bandwidth of the visual analyzer (bps) also changes and reaches different levels. age periods the following values ​​(Table 14. 5).

Table 14.5

Bandwidth of the visual analyzer, bit/s

Sensory and motor functions of vision develop simultaneously. In the first days after birth, eye movements are asynchronous, with the immobility of one eye, you can observe the movement of the other. The ability to fix an object with a glance, or, figuratively speaking, a "fine tuning mechanism", is formed at the age of 5 days to 3-5 months. A reaction to the shape of an object is noted already in a 5-month-old child. In preschoolers, the first reaction is the shape of the object, then its size, and lastly, the color.

At 7-8 years old, the eye in children is much better than in preschoolers, but worse than in adults; has no gender differences. In the future, in boys, the linear eye becomes better than in girls.

The functional mobility (lability) of the receptor and cortical parts of the visual analyzer is the lower, the younger the child.

Violations and correction of vision. The high plasticity of the nervous system, which makes it possible to compensate for the missing functions at the expense of the remaining ones, is of great importance in the process of teaching and educating children with sensory organ defects. It is known that deaf-blind children have increased sensitivity of tactile, gustatory and olfactory analyzers. With the help of the sense of smell, they can navigate the area well and recognize relatives and friends. The more pronounced the degree of damage to the child's sense organs, the more difficult the educational work with him becomes. The vast majority of all information from the outside world (about 90%) enters our brain through the visual and auditory channels, therefore, for a normal physical and mental development children and adolescents, the organs of vision and hearing are of particular importance.

The most common visual impairment is various forms refractive errors of the optical system of the eye or violations of the normal length of the eyeball. As a result, the rays coming from the object are not refracted on the retina. With a weak refraction of the eye due to a violation of the functions of the lens - its flattening, or with a shortening of the eyeball, the image of the object is behind the retina. People with such visual impairments have trouble seeing close objects; such a defect is called farsightedness (Fig. 14.4.).

When the physical refraction of the eye is increased, for example, due to an increase in the curvature of the lens, or an elongation of the eyeball, the image of the object is focused in front of the retina, which disrupts the perception of distant objects. This visual defect is called myopia (see Fig. 14.4.).

Rice. 14.4. Refraction scheme: in the far-sighted (a), normal (b) and myopic (c) eye

With the development of myopia, the student does not see well what is written on the blackboard, and asks to be transferred to the first desks. When reading, he brings the book closer to his eyes, bows his head strongly while writing, in the cinema or in the theater he tends to take a seat closer to the screen or stage. When examining an object, the child squints his eyes. To make the image on the retina clearer, it brings the object being viewed too close to the eyes, which causes a significant load on muscular apparatus eyes. Often the muscles do not cope with such work, and one eye deviates towards the temple - strabismus occurs. Myopia can develop with diseases such as rickets, tuberculosis, rheumatism.

A partial violation of color vision is called color blindness (after the English chemist Dalton, who first discovered this defect). Color blind people usually do not distinguish between red and green colors (they seem to them to be gray in different shades). About 4-5% of all men are color blind. In women, it is less common (up to 0.5%). To detect color blindness, special color tables are used.

Prevention of visual impairment is based on the creation of optimal conditions for the functioning of the organ of vision. Visual fatigue leads to a sharp decrease in the performance of children, which affects their general condition. Timely change of activities, changes in the environment in which training sessions are held, contribute to the increase in working capacity.

Of great importance is the correct mode of work and rest, school furniture that meets physiological features students, sufficient lighting of the workplace, etc. While reading, every 40-60 minutes you need to take a break for 10-15 minutes to give your eyes a rest; to relieve the tension of the accommodation apparatus, children are advised to look into the distance.

Besides, important role in the protection of vision and its function belongs to the protective apparatus of the eye (eyelids, eyelashes), which require careful care, compliance with hygiene requirements and timely treatment. Improper use of cosmetics can lead to conjunctivitis, blepharitis and other diseases of the organs of vision.

Particular attention should be paid to the organization of work with computers, as well as watching television. If visual impairment is suspected, an ophthalmologist should be consulted.

Up to 5 years, hypermetropia (farsightedness) predominates in children. With this defect, glasses with collective biconvex glasses help (giving the rays passing through them a converging direction), which improve visual acuity and reduce excessive accommodation stress.

In the future, due to the load during training, the frequency of hypermetropia decreases, and the frequency of emmetropia (normal refraction) and myopia (nearsightedness) increases. By the end of school compared to elementary grades the prevalence of myopia increases 5 times.

The formation and progression of myopia contributes to the lack of light. Visual acuity and stability of clear vision in students are significantly reduced by the end of the lessons, and this decrease is the sharper, the lower the level of illumination. With an increase in the level of illumination in children and adolescents, the speed of distinguishing visual stimuli increases, the speed of reading increases, and the quality of work improves. With workplace illumination of 400 lux, 74% of the work was performed without errors, with illumination of 100 lux and 50 lux, respectively, 47 and 37%.

With good lighting in normally hearing children, adolescents have an aggravated hearing acuity, which also favors working capacity and has a positive effect on the quality of work. So, if the dictations were conducted at an illumination level of 150 lux, the number of omitted or misspelled words was 47% less than in similar dictations conducted at an illumination level of 35 lux.

The development of myopia is influenced by the study load, which is directly related to the need to consider objects at close range, its duration during the day.

You should also know that in students who are little or not at all in the air around noon, when the intensity of ultraviolet radiation is maximum, phosphorus-calcium metabolism is disturbed. This leads to a decrease in the tone of the eye muscles, which, with high visual load and insufficient illumination, contributes to the development of myopia and its progression.

Myopic children are considered to be those whose myopic refraction is 3.25 diopters and above, and corrected visual acuity is 0.5-0.9. Such students are recommended physical education classes only on special program. They are also contraindicated in heavy physical work, long stay in a bent position with the head tilted.

With myopia, glasses with scattering biconcave glasses are prescribed, which turn parallel rays into divergent ones. Myopia in most cases is congenital, but it can increase at school age from elementary to senior grades. In severe cases, myopia is accompanied by changes in the retina, which leads to a decrease in vision and even retinal detachment. Therefore, children suffering from myopia must strictly follow the instructions of the ophthalmologist. Timely wearing of glasses by schoolchildren is mandatory.

Development and age-related features of the organ of vision

The organ of vision in phylogenesis has gone from separate ectodermal origin of light-sensitive cells (in intestinal cavities) to complex paired eyes in mammals. In vertebrates, the eyes develop in a complex way: a light-sensitive membrane, the retina, is formed from the lateral outgrowths of the brain. The middle and outer shells of the eyeball, the vitreous body are formed from the mesoderm (middle germinal layer), the lens - from the ectoderm.

The pigment part (layer) of the retina develops from the thin outer wall of the glass. Visual (photoreceptor, light-sensitive) cells are located in the thicker inner layer of the glass. In fish, the differentiation of visual cells into rod-shaped (rods) and cone-shaped (cones) is weakly expressed, in reptiles there are only cones, in mammals the retina contains mainly rods; in aquatic and nocturnal animals, cones are absent in the retina. As part of the middle (vascular) membrane, already in fish, the ciliary body begins to form, which becomes more complicated in its development in birds and mammals.

The muscle in the iris and in the ciliary body first appears in amphibians. The outer shell of the eyeball in lower vertebrates consists mainly of cartilaginous tissue (in fish, amphibians, most lizards). In mammals, it is built only from fibrous (fibrous) tissue.

The lens of fish and amphibians is rounded. Accommodation is achieved due to the movement of the lens and the contraction of a special muscle that moves the lens. In reptiles and birds, the lens is able not only to mix, but also to change its curvature. In mammals, the lens occupies a permanent place, accommodation is carried out due to a change in the curvature of the lens. The vitreous body, which initially has a fibrous structure, gradually becomes transparent.

Simultaneously with the complication of the structure of the eyeball, auxiliary organs of the eye develop. The first to appear are six oculomotor muscles, which are transformed from the myotomes of three pairs of head somites. Eyelids begin to form in fish in the form of a single annular skin fold. Terrestrial vertebrates develop upper and lower eyelids, and most of them also have a nictitating membrane (third eyelid) at the medial corner of the eye. In monkeys and humans, the remnants of this membrane are preserved in the form of a semilunar fold of the conjunctiva. In terrestrial vertebrates, the lacrimal gland develops, and the lacrimal apparatus is formed.

The human eyeball also develops from several sources. The light-sensitive membrane (retina) comes from the side wall of the brain bladder (the future diencephalon); the main lens of the eye - the lens - directly from the ectoderm; vascular and fibrous membranes - from the mesenchyme. At an early stage of embryonic development (end of the 1st, beginning of the 2nd month of intrauterine life) on the side walls of the primary brain bladder ( prosencephalon) there is a small paired protrusion - eye bubbles. Their terminal sections expand, grow towards the ectoderm, and the legs connecting with the brain narrow and later turn into optic nerves. In the process of development, the wall of the optic vesicle protrudes into it and the vesicle turns into a two-layer ophthalmic cup. The outer wall of the glass further becomes thinner and transforms into the outer pigment part (layer), and the complex light-perceiving (nervous) part of the retina (photosensory layer) is formed from the inner wall. At the stage of formation of the eyecup and differentiation of its walls, at the 2nd month of intrauterine development, the ectoderm adjacent to the eyecup in front thickens at first, and then a lens fossa is formed, which turns into a lens vesicle. Separated from the ectoderm, the vesicle plunges into the eye cup, loses the cavity, and the lens is subsequently formed from it.

At the 2nd month of intrauterine life, mesenchymal cells penetrate into the eye cup through the gap formed on its lower side. These cells form a blood vascular network inside the glass in the vitreous body that is forming here and around the growing lens. From the mesenchymal cells adjacent to the eye cup, the choroid is formed, and from the outer layers, the fibrous membrane. The anterior part of the fibrous membrane becomes transparent and turns into the cornea. In a fetus of 6-8 months, the blood vessels located in the lens capsule and in the vitreous body disappear; the membrane covering the opening of the pupil (pupillary membrane) is resorbed.

The upper and lower eyelids begin to form in the 3rd month of intrauterine life, initially in the form of ectoderm folds. The epithelium of the conjunctiva, including the one that covers the front of the cornea, comes from the ectoderm. The lacrimal gland develops from outgrowths of the conjunctival epithelium that appear on the 3rd month of intrauterine life in the lateral part of the emerging upper eyelid.

The eyeball of a newborn is relatively large, its anteroposterior size is 17.5 mm, its weight is 2.3 ᴦ. The visual axis of the eyeball runs laterally than in an adult. The eyeball grows in the first year of a child's life faster than in subsequent years. By the age of 5, the mass of the eyeball increases by 70%, and by the age of 20-25 - 3 times compared with a newborn.

The cornea of ​​a newborn is relatively thick, its curvature almost does not change during life; the lens is almost round, the radii of its anterior and posterior curvature are approximately equal. The lens grows especially rapidly during the first year of life, and then its growth rate decreases. The iris is convex anteriorly, there is little pigment in it, the pupil diameter is 2.5 mm. As the age of the child increases, the thickness of the iris increases, the amount of pigment in it increases, and the diameter of the pupil becomes large. At the age of 40-50 years, the pupil narrows slightly.

The ciliary body in a newborn is poorly developed. The growth and differentiation of the ciliary muscle are realized quite quickly. The optic nerve in a newborn is thin (0.8 mm), short. By the age of 20, its diameter almost doubles.

The muscles of the eyeball in a newborn are well developed, except for their tendon part. For this reason, eye movement is possible immediately after birth, but coordination of these movements occurs from the 2nd month of a child's life.

The lacrimal gland in a newborn is small, the excretory ducts of the gland are thin. The function of tearing appears on the 2nd month of a child's life. The vagina of the eyeball in a newborn and infants is thin, the fatty body of the orbit is poorly developed. In elderly and senile people, the fat body of the orbit decreases in size, partially atrophies, the eyeball protrudes less from the orbit.

The palpebral fissure in a newborn is narrow, the medial angle of the eye is rounded. In the future, the palpebral fissure rapidly increases. In children under 14-15 years old, it is wide, in connection with this, the eye seems larger than in an adult.

In newborns, the size of the eyeball is smaller than in adults (the diameter of the eyeball is 17.3 mm, and in an adult it is 24.3 mm). In this regard, the rays of light coming from distant objects converge behind the retina, that is, the newborn is characterized by natural farsightedness. An early visual reaction of a child can be attributed to an orienting reflex to light irritation, or to a flashing object. The child reacts to light irritation or an approaching object by turning the head and torso. At 3-6 weeks, the baby is able to fix his gaze. Up to 2 years, the eyeball increases by 40%, by 5 years - by 70% of its original volume, and by the age of 12-14 it reaches the size of an adult's eyeball.

The visual analyzer is immature at the time of the birth of the child. The development of the retina ends by 12 months of age. Myelination of the optic nerves and optic nerve pathways begins at the end of the intrauterine period of development and ends at 3-4 months of a child's life. The maturation of the cortical part of the analyzer ends only by the age of 7 years.

Lacrimal fluid has an important protective value, because it moisturizes the anterior surface of the cornea and conjunctiva. At birth, it is secreted in a small amount, and by 1.5-2 months during crying, there is an increase in the formation of lacrimal fluid. In a newborn, the pupils are narrow due to the underdevelopment of the iris muscle.

In the first days of a child's life, there is no coordination of eye movements (the eyes move independently of each other). It appears after 2-3 weeks. Visual concentration - fixation of the gaze on the object appears 3-4 weeks after birth. The duration of this eye reaction is only 1-2 minutes. As the child grows and develops, the coordination of eye movements improves, fixing the gaze becomes longer.

Age features of color perception . A newborn child does not differentiate colors due to the immaturity of the cones in the retina. In addition, there are fewer of them than sticks. Judging by the development of the child conditioned reflexes, differentiation of colors begins from 5-6 months. It is by the 6th month of a child's life that the central part of the retina develops, where the cones are concentrated. However, the conscious perception of colors is formed later. Children can correctly name colors at the age of 2.5-3 years. At 3 years old, the child distinguishes the ratio of the brightness of colors (darker, paler colored object). For the development of color differentiation, it is advisable for parents to demonstrate colored toys. By the age of 4, the child perceives all colors . The ability to distinguish colors increases significantly by 10-12 years.

Age features of the optical system of the eye. The lens in children is very elastic, so it has a greater ability to change its curvature than in adults. However, starting from the age of 10, the elasticity of the lens decreases and decreases. accommodation volume- the adoption by the lens of the most convex shape after the maximum flattening, or vice versa, the adoption of the lens of the maximum flattening after the most convex shape. In this regard, the position of the nearest point of clear vision changes. Closest point of clear vision(the smallest distance from the eye at which the object is clearly visible) moves away with age: at 10 years old it is at a distance of 7 cm, at 15 years old - 8 cm, 20 - 9 cm, at 22 years old -10 cm, at 25 years old - 12 cm, at 30 years old - 14 cm, etc. Thus, with age, in order to see better, the object must be removed from the eyes.

At 6 - 7 years formed binocular vision. During this period, the boundaries of the field of view expand significantly.

Visual acuity in children of different ages

In newborns, visual acuity is very low. By 6 months it increases and is 0.1, at 12 months - 0.2, and at the age of 5-6 years it is 0.8-1.0. In adolescents, visual acuity rises to 0.9-1.0. In the first months of a child's life, visual acuity is very low; at the age of three, only 5% of children have it normal; 16 years old - visual acuity, as in an adult.

The field of view in children is narrower than in adults, but by the age of 6-8 it expands rapidly and this process continues up to 20 years. The perception of space (spatial vision) in a child is formed from the age of 3 months due to the maturation of the retina and the cortical part of the visual analyzer. The perception of the shape of an object (volumetric vision) begins to form from the age of 5 months. The child determines the shape of the object by eye at the age of 5-6 years.

At an early age, between 6-9 months, the child begins to develop a stereoscopic perception of space (he perceives the depth, remoteness of the location of objects).

Most six-year-old children develop acute visual perception and all departments of the visual analyzer are completely differentiated. By the age of 6, visual acuity approaches normal.

In blind children, the peripheral, conductive, or central structures of the visual system are morphologically and functionally not differentiated.

The eyes of young children are characterized by slight farsightedness (1-3 diopters), due to the spherical shape of the eyeball and the shortened anterior-posterior axis of the eye (table 7). By the age of 7-12, farsightedness (hypermetropia) disappears and the eyes become emmetropic, as a result of an increase in the anterior-posterior axis of the eye. However, in 30-40% of children, due to a significant increase in the anterior-posterior size of the eyeballs and, accordingly, the removal of the retina from the refractive media of the eye (lens), myopia develops.

Age patterns of skeletal development. Prevention of disorders of the musculoskeletal system

Prevention of disorders of the musculoskeletal system in children. Hygienic requirements for the equipment of schools or preschool institutions (4 hours)

1. Functions of the musculoskeletal system. Composition and growth of children's bones.

2. Features of the formation of the bones of the hand, spinal column, chest, pelvis, bones of the brain and facial skull.

3. Curves of the spine, their formation and timing of fixation.

4. Heterochronism of muscle development. Development of motor skills in children. The formation of mass, muscle strength. Resilience in children and adolescents. motor mode.

5. Features of the reaction to physical activity at different ages.

6. Correct posture in a sitting position standing, walking. Postural disorders (scoliosis, increased natural curves of the spine - lordosis and kyphosis), causes, prevention. Flat feet.

7. School furniture. Hygienic requirements for school furniture (distance and differentiation). Selection, arrangement of furniture and seating of students in the classroom.

Functions, classification, structure, connection and growth of bones

Skeleton - a set of hard tissues in the human body - bone and cartilage.

Skeleton Functions: supporting (muscles are attached to the bones); motor (separate parts of the skeleton form levers, which are set in motion by muscles attached to the bones); protective (bones form cavities in which vital organs are located); mineral metabolism; formation of blood cells.

The chemical composition of the bone: organic matter - ossein protein, which is part of the intercellular substance of bone tissue, is only 1/3 of the bone mass; 2/3 of its mass is represented by inorganic substances, mainly calcium, magnesium, and phosphorus salts.

The skeleton consists of about 210 bones.

The structure of the bones:

periosteum, consisting of connective tissue containing blood vessels that feed the bone; actual bone, consisting of compact And spongy substances. Features of its structure: body - diaphysis and two thickenings at the ends - upper and lower epiphyses. On the border between the epiphysis and the diaphysis is a cartilaginous plate - epiphyseal cartilage, due to cell division of which the bone grows in length. A dense connective tissue membrane - the periosteum, in addition to blood vessels and nerves, contains dividing cells, osteoblasts. Thanks to osteoblasts, bone thickening occurs, as well as the healing of bone fractures.

Distinguish axial skeleton and additional.

Axial skeleton includes head skeleton (skull) and torso skeleton.

Scoliosis- lateral curvature of the spine, in which the so-called. "scoliotic posture". Signs of scoliosis: sitting at the table, the child stoops, leans on his side. With severe lateral curvature of the spinal column, the shoulders, shoulder blades and pelvis are asymmetrical. scoliosis there are congenital And acquired. Congenital scoliosis occurs in 23% of cases. They are based on various deformations of the vertebrae: underdevelopment, their wedge-shaped form, additional vertebrae, etc.

Acquired scoliosis includes:

1) rachitic, manifested by various deformations of the musculoskeletal system due to a deficiency in the body of calcium. They are caused by soft bones and weak muscles;

2) paralytic, arising after infantile paralysis, with unilateral muscle damage;

3) habitual (school), the cause of which may be an incorrectly selected table or desk, seating students without taking into account their height and desk numbers, carrying briefcases, bags, and not knapsacks, sitting at a table or desk for a long time, etc.

Acquired scoliosis accounts for about 80%. With scoliosis, asymmetry of the shoulder girdle and shoulder blades is noted. With jointly expressed lordosis and kyphosis - a protruding head, a round or flat back, a protruding abdomen. Distinguish the following types scoliosis: thoracic right-sided and left-sided, thoracolumbar.

The vision of each person is able to change, often it depends on age. Vision correction and age are directly related, the most significant changes in human vision parameters occur in infancy, adolescence and old age. Consider the features of each period.

Vision of children from birth to six years

In the period up to three months, the baby sees objects only at a distance of 40 to 50 centimeters. Often it seems to parents that his eyes squint a little. In fact, the final formation of the eyeball occurs in the child, his vision during this period has farsightedness. Only at 6 months can a specialist diagnose a particular visual impairment, if any. After 3.5-4 months, the baby's vision improves significantly, he can focus on a certain object and take it in his hands. It is possible to develop a child's vision from birth, observing simple rules:

• Place the crib in a well-lit room that combines daylight and electric light to promote eye movement.
• Decorate the room in soft soothing colors so as not to irritate the baby's eyes.
• The distance between toys and the bed should be at least 30 centimeters. Hang objects of different colors and shapes.
• It is not necessary to teach a child from infancy to view moving pictures on a TV or tablet, this increases the load on his eyes.

From one to two years, the baby develops visual acuity, which is determined by the ability to see two points at once, located at some distance from each other. The norm of this indicator in an adult is equal to one, in a child under two years old it varies from 0.3 to 0.5.

A child older than 2 years is already able to perceive the speech of adults and respond to their facial expressions and gestures. If the baby's vision develops correctly, then his speech will improve. Otherwise, if the development of the organs of vision is impaired, he will react poorly to the articulation of the parent's speech, and therefore the child will have problems with speech reproduction skills. At three years old, it is necessary to check the visual acuity of the baby with a specialist. As a rule, for this, doctors use the Orlova table, which consists of ten rows of different images. This indicator is determined by the row number in the table. By four years, the norm of the parameter is 0.7-0.8. Often at this age, children begin to squint, this may be a sign of myopia (nearsightedness), in this case, the ophthalmologist may prescribe the wearing of glasses and gymnastics procedures for the eyes.

The vision of preschool children continues to develop, so it is important for the parents of the child to monitor his development and attend scheduled checkups. At the age of 5-6, the organs of vision of children are under great stress, as preschoolers begin to attend various circles and sections. During this period, it is important to give the child's eyes a rest: after a 30-minute lesson, you must take a break of at least 15 minutes. It is worth using a TV or computer for no more than one and a half hours a day.

Vision in adolescence

The greatest load on the eyes occurs during the period when a person reaches puberty. In addition to reading textbooks, watching TV and using a computer, hormonal changes in the body and its active growth affect vision. These factors often lead a teenager to such a visual deviation as myopia. During this period, it is important for parents to monitor changes in their child's vision parameters by visiting an ophthalmologist's office at least once every six months. In this age range, doctors recommend using. They will help not only correct vision, but also save the child from complexes. Indeed, unlike glasses, they are completely invisible to the eyes. Another advantage of lenses for the eyes is the high image quality and more effective improvement of vision than with glasses. However, before allowing a teenager to wear such optical products, familiarize him with the rules for their operation, because the lenses require careful care and hygiene.

Features of vision in old age

After the human body is fully formed, in the absence of congenital and acquired visual impairments, ophthalmologists recommend being examined once a year.

It has been found that vision deteriorates with age. When a person passes the age of forty, a disease such as presbyopia may occur. This is a completely natural deterioration, which is characterized by a weakening of the focus of vision, a person can hardly see objects close up, it is difficult for him to read books and use a mobile phone without vision correctors. Elderly age often causes more serious illnesses: cataracts, glaucoma, macular degeneration and diabetic retinopathy. As a rule, such deviations occur already in a more mature period, after 60-65 years.

The appearance of age-related cataracts is associated with a violation of oxidative processes in the lens, this is due to a lack of ascorbic acid or vitamin B2 in the body. In this case, experts prescribe these components for oral administration or eye drops containing riboflavin. Severe cataracts may require surgery.

Increased intraocular pressure, or glaucoma, affects the optic nerve. This disease is usually difficult to detect on its own, as it is not characterized by pronounced symptoms. Its untimely detection can lead to blindness. For the treatment of glaucoma, normalization of pressure is necessary with the help of eye drops or trabeculoplasty - laser therapy.

Macular degeneration occurs when the most sensitive area of ​​the retina, the macula, atrophies; it is responsible for the perception of small details and objects by the eye. A person with this disease has a sharp decrease in visual acuity, he loses the ability to drive a car, read or perform other familiar daily activities. Sometimes the patient does not distinguish colors. To prevent further development of the disease, it is necessary to wear contact lenses or glasses and take the right drugs, but the most efficient way is laser therapy. A huge risk of acquiring macular degeneration is smoking.

Diabetic retinopathy is a consequence of a severe stage diabetes, which can cause abnormal changes in the blood vessels of the retina of the eye. Due to their thinning, hemorrhages occur in different areas. visual organs, after which the vessels exfoliate and die. That is why with this disease a person sees a muddy picture. Retinopathy is characteristic pain in the eyes, and sometimes loss of vision. There is no complete cure for this deviation, but laser surgery will help the patient remain sighted, the operation must be done before damage to the retina.

One of the features of all of the above diseases is a hereditary predisposition to them. Therefore, from childhood it is necessary to pay special attention to vision.

At any age, it is important to monitor the condition of the eyes by attending routine examinations with a doctor and following his recommendations. The online store of contact lenses presents to your attention all the necessary products to maintain healthy vision. On the site you can order lenses and care products for them. You can buy goods at any convenient time at a bargain price.