Age features of the eye in children. Basic visual functions, features of their development in children

In diseases of the organs of vision, patients complain of many factors. Diagnostics includes the following steps, which take into account all age-related features of the organ of vision:

1. Complaints.
2. Anamnesis
3. External inspection.

External inspection is carried out in good light. The healthy eye is examined first, and then the diseased one. You should pay attention to such factors:

1. Skin color around the eyes.
2. The size of the eye gap.
3. The condition of the membranes of the eye is the lapel of the upper or lower eyelid.

conjunctiva in normal condition- pale pink, smooth, transparent, moist, vascular pattern is clearly visible.

If available pathological process an injection is observed in the eye:

1. Superficial (conjunctival) - the conjunctiva is bright red, and the cornea turns pale.
2. Deep (pericornial) - around the cornea, the color is up to purple, pales towards the periphery.
3. Examination of the function of the lacrimal gland (lacrimation is not checked for complaints).

functional test. Take a strip of blotting paper 0.5 cm wide and 3 cm long. One end is bent and inserted into the conjunctival fornix, the second one hangs down the cheek. In the normal state - 1.5 cm of the strip is wetted in 5 minutes. Less than 1.5 cm - hypofunction, more than 1.5 cm - hyperfunction.

Nasal tear tests:

1. Lacrimal-nasal.
2. Washing the nasolacrimal canal.
3. Radiography.

Inspection of a sick apple

When examining the eyeball, the size of the eye is assessed. It depends on refraction. With myopia, the eye increases, with farsightedness, it decreases.

The protrusion of the eyeball to the outside is called exophthalmos, retraction - endophthalmos.

Exophthalmos is a hematoma, orbital emphysema, tumor.

Exophthalmometry is used to determine the degree of protrusion of the eyeball.

Side lighting method

The light source is located to the left and in front of the patient. The doctor sits opposite. During the procedure, a magnifying glass of 20 diopters is used.

Assess: sclera (color, pattern, course of trabeculae) and pupil area.

Transmitted light research method:

This method evaluates the transparent media of the eye - the cornea, the moisture of the anterior chamber, the lens and the vitreous body.

The study is carried out in a dark room. The light source is on the back left. The doctor is the opposite. With the help of a mirror ophthalmoscope, a mirror delivers a light source into the eye. In the normal state, the light should turn red.

Ophthalmoscopy:

1. In reverse. The operation is carried out using an ophthalmoscope, a lens of 13 diopters and a light source. Holding the ophthalmoscope in the right hand, look with the right eye, the magnifying glass in the left hand and is attached to the patient's superciliary arch. The result is a mirror inverted image. The retina and optic nerve are examined.
2. Directly. A manual electro-ophthalmoscope is used. The rule of procedure is that the right eye is examined with the right eye, the left eye with the left.

The ophthalmoscope in reverse gives general idea about the condition of the patient's fundus. In direct - helps to detail the changes.

The technique is carried out in a certain sequence. Algorithm: optic disc - spot - retinal periphery.

Normally, the optic disc is pink with clear contours. In the center is a depression from where the vessels come out.

Biomicroscopy:

Biomicroscopy uses a slit lamp. It is a combination of an intense light source and a binocular microscope. The head is set with emphasis on the forehead and chin. Delivers an adjustable light source into the patient's eye,

Gonioscopy:

This is a method of inspecting the angle of the anterior chamber. It is carried out using a gonioscope and a slit lamp. This is how the Goldmann goneoscope is used.

A goneoscope is a lens that is a system of mirrors. This method examines the root of the iris, the degree of opening of the angle of the anterior chamber.

Tonometry:

Palpation. The patient is asked to close his eyes and index finger, palnating, judge the magnitude of eye pressure. Judged by the compliance of the eyeball. Kinds:

Tn - pressure is normal.

T+ - moderately dense.

T 2+ is very dense.

T 3+ - dense as a stone.

T-1 - softer than normal

T-2 - soft

T-3 - very soft.

Instrumental. During the procedure, Maklakov's tonometer is used - a metal cylinder 4 cm high, weight - 100 g, at the ends - expanded areas of white glass.

Weights are treated with alcohol, then wiped dry with a sterile swab. A special paint is instilled into the eye - collargol.

The weight rests on the holder and is placed on the cornea. Next, the weight is removed and prints are made on paper moistened with alcohol. The result is evaluated using the Polak ruler.

Normal pressure is 18-26 mm Hg.

The organ of vision in phylogeny 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. Average and outer shell 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 g. 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. Growth and differentiation ciliary muscle carried out fairly 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.

In development visual analyzer After birth, 5 periods are distinguished:

1. formation of the area of ​​the macula and the central fovea of ​​the retina during the first six months of life - out of 10 layers of the retina, mainly 4 remain (visual cells, their nuclei and boundary membranes);
2. increased functional mobility visual pathways and their formation during the first half of life
3. improvement of the visual cellular elements of the cortex and cortical visual centers during the first 2 years of life;
4. formation and strengthening of connections of the visual analyzer with other organs during the first years of life;
5. morphological and functional development cranial nerves in the first 2-4 months of life.

The formation of the visual functions of the child occurs in accordance with these stages of development.

Anatomical features

Eyelid skin in newborns, it is very tender, thin, smooth, without folds, the vascular network shines through it. The palpebral fissure is narrow and corresponds to the size of the pupil. The child blinks 7 times less than adults (2-3 blinks per minute). During sleep, there is often no complete closure of the eyelids and a bluish strip of sclera is visible. By 3 months after birth, the mobility of the eyelids increases, the child blinks 3-4 times per minute, by 6 months - 4-5, and by 1 year - 5-6 times per minute. By the age of 2, the palpebral fissure increases, acquires oval shape as a result of the final formation of the muscles of the eyelids and the enlargement of the eyeball. The child blinks 7-8 times per minute. By the age of 7-10, the eyelids and palpebral fissure correspond to those of adults, the child blinks 8-12 times per minute.

Lacrimal gland begins to function only 4-6 weeks or more after birth, children at this time cry without tears. However, the lacrimal accessory glands in the eyelids immediately produce tears, which is well defined by a pronounced lacrimal stream along the edge of the lower eyelid. The absence of a lacrimal stream is regarded as a deviation from the norm and may be the cause of the development of dacryocystitis. By 2-3 months of age, the normal functioning of the lacrimal gland and lacrimation begins. At the birth of a child, the lacrimal ducts in most cases are already formed and passable. However, in about 5% of children, the lower opening of the lacrimal canal opens later or does not open at all, which may cause the development of dacryocystitis in the newborn.

eye socket(orbit) in children under 1 year old is relatively small, so it gives the impression of large eyes. In shape, the orbit of newborns resembles a trihedral pyramid, the bases of the pyramids have a convergent direction. The bone walls, especially the medial one, are very thin and contribute to the development of collateral edema of the eye tissue (cellulitis). The horizontal size of the eye sockets of a newborn is larger than the vertical one, the depth and convergence of the axes of the eye sockets is less, which sometimes creates the impression of convergent strabismus. The size of the eye sockets is about 2/3 of the corresponding size of the eye sockets of an adult. The eye sockets of a newborn are flatter and smaller, therefore they protect the eyeballs from injury less well and give the impression of standing. eyeballs. The palpebral fissures in children are wider due to insufficient development of the temporal wings sphenoid bones. The rudiments of the teeth are located closer to the contents of the orbit, which facilitates the entry of an odontogenic infection into it. The formation of the orbit ends by the age of 7, by 8-10 years the anatomy of the orbit approaches that of adults.

Conjunctiva the newborn is thin, tender, not moist enough, with reduced sensitivity, can be easily injured. By the age of 3 months, it becomes more moist, shiny, sensitive. Pronounced moisture and pattern of the conjunctiva may be a sign of inflammatory diseases (conjunctivitis, dacryocystitis, keratitis, uveitis) or congenital glaucoma.

Cornea newborns is transparent, but in some cases in the first days after birth it is somewhat dull and, as it were, opalescent. Within 1 week, these changes disappear without a trace, the cornea becomes transparent. This opalescence should be distinguished from corneal edema in congenital glaucoma, which is removed by the installation of a hypertonic solution (5%) of glucose. Physiological opalescence does not disappear when these solutions are instilled. It is very important to measure the diameter of the cornea, since its increase is one of the signs of glaucoma in children. The diameter of the cornea of ​​a newborn is 9-9.5 mm, by 1 year it increases by 1 mm, by 2-3 years - by another 1 mm, by 5 years it reaches the diameter of the cornea of ​​an adult - 11.5 mm. In children under 3 months of age, the sensitivity of the cornea is sharply reduced. The weakening of the corneal reflex leads to the fact that the child does not respond to a hit foreign bodies into the eye. Frequent eye examinations in children of this age are important for the prevention of keratitis.

Sclera the newborn is thin, with a bluish tinge, which gradually disappears by the age of 3 years. Should be carefully considered given feature, since blue sclera can be a sign of diseases and stretching of the sclera with increased intraocular pressure in congenital glaucoma.

Front camera in newborns it is small (1.5 mm), the angle of the anterior chamber is very sharp, the root of the iris has a slate color. It is believed that this color is due to the remnants of embryonic tissue, which is completely absorbed by 6-12 months. The angle of the anterior chamber gradually opens up and by the age of 7 becomes the same as in adults.

iris in newborns it is bluish-gray in color due to the small amount of pigment, by the age of 1 it begins to acquire an individual color. The color of the iris is finally established by 10-12 years of age. Direct and friendly pupillary reactions in newborns are not very pronounced, the pupils are poorly dilated by medications. By the age of 1 year, the pupil reaction becomes the same as in adults.

ciliary body in the first 6 months is in a spastic state, which causes myopic clinical refraction without cycloplegia and a sharp change in refraction towards hyperopic after installations of a 1% solution of homatropin.

Ocular fundus newborns are pale pink in color, with more or less pronounced parquet and a lot of light reflections. It is less pigmented than in an adult, the vasculature is clearly visible, retinal pigmentation is often finely punctate or spotted. On the periphery, the retina is grayish in color, the peripheral vascular network is immature. In newborns, the optic nerve head is pale, with a bluish-gray tint, which can be mistaken for its atrophy. Reflexes around the macula are absent and appear during the 1st year of life. During the first 4-6 months of life, the fundus takes on an appearance that is almost identical to fundus an adult, by the age of 3 there is a reddening of the tone of the fundus. In the optic disc, the vascular funnel is not determined, it begins to form by the age of 1 and ends by the age of 7.

Functional Features

Feature of the activity nervous system child after birth is the predominance of subcortical formations. The brain of the newborn is still underdeveloped, the differentiation of the cortex and pyramidal pathways is not completed. As a result, newborns have a tendency to diffuse reactions, to their generalization and irradiation, and such reflexes are caused, which in adults occur only in pathology.

The specified ability of the central nervous system of the newborn has a significant impact on the activity of sensory systems, in particular visual. With a sharp and sudden illumination of the eyes, generalized protective reflexes may occur - a shudder of the body and the Peiper phenomenon, which is expressed in the narrowing of the pupil, the closing of the eyelids and the strong tilting of the child's head back. The main reflexes also appear when other receptors are stimulated, in particular the tactile one. So, with intensive scratching of the skin, the pupils dilate, with a light tapping on the nose, the eyelids close. There is also the phenomenon of "doll eyes", in which the eyeballs move in the opposite direction to the passive movement of the head.

In terms of eye lighting bright light there is a blinking reflex and abduction of the eyeballs upward. Such a protective reaction of the organ of vision to the action of a specific stimulus is obviously due to the fact that the visual system is the only one of all sensory systems that is affected by adequate afferentation only after the birth of a child. It takes some getting used to the light.

As is known, other afferentations - auditory, tactile, interoceptive and proprioceptive - exert their influence on the corresponding analyzers even in the period of intrauterine development. However, it should be emphasized that in postnatal ontogenesis the visual system develops at an accelerated pace, and visual orientation soon outstrips auditory and tactile-proprioceptive ones.

Already at the birth of a child, a number of unconditioned visual reflexes are noted - a direct and friendly reaction of the pupils to light, a short-term orienting reflex of turning both eyes and head to a light source, an attempt to track a moving object. However, the expansion of the pupil in the dark is slower than its narrowing in the light. This is explained by the underdevelopment at an early age of the iris dilator or the nerve innervating this muscle.

On the 2-3rd week, as a result of the appearance of conditioned reflex connections, the complication of the activity of the visual system begins, the formation and improvement of the functions of object, color and spatial vision.

Thus, light sensitivity appears immediately after birth. True, under the action of light, even an elementary visual image does not arise in a newborn, and mainly inadequate general and local defensive reactions are caused. At the same time, from the very first days of a child's life, light has a stimulating effect on the development of the visual system as a whole and serves as the basis for the formation of all its functions.

With the help of objective methods of recording changes in the pupil, as well as other visible reactions (for example, the Peiper reflex) to light different intensity managed to get some idea about the level of light perception in children early age. The sensitivity of the eye to light, measured by the pupillomotor reaction of the pupil with the help of a pupilloscope, increases in the first months of life and reaches the same level as in an adult at school age.

Absolute Light Sensitivity in newborns it is sharply reduced, and under conditions of dark adaptation it is 100 times higher than during adaptation to light. By the end of the first six months of a child's life, light sensitivity increases significantly and corresponds to 2/3 of its level in an adult. In the study of visual dark adaptation in children aged 4-14, it was found that with age, the level of the adaptation curve increases and becomes almost normal by the age of 12-14.

Reduced light sensitivity in newborns is explained by the insufficient development of the visual system, in particular the retina, which is indirectly confirmed by the results of electroretinography. In children younger age the shape of the electroretinogram is close to normal, but its amplitude is reduced. The latter depends on the intensity of the light falling on the eye: the more intense the light, the greater the amplitude of the electroretinogram.

J. Francois and A. de Rouk (1963) found that wave a in the first months of a child's life is below normal and reaches its normal value after 2 years.

• Photopic wave b 1 develops even more slowly and at the age of over 2 years still has a low value.
• Scotopic wave b 2 with weak stimuli in children from 2 to 6 years is significantly lower than in adults.
• The curves of the a and b waves in dual pulses are quite different from those seen in adults.
• The refractory period is shorter at the beginning.

Shaped central vision appears in a child only on the 2nd month of life. In the future, its gradual improvement takes place - from the ability to detect an object to the ability to distinguish and recognize it. The ability to distinguish the simplest configurations is provided by the appropriate level of development of the visual system, while the recognition of complex images is associated with the intellectualization of the visual process and requires training in the psychological sense of the word.

By studying the child's reaction to the presentation of objects of different sizes and shapes, (the ability to differentiate them during the development conditioned reflexes, as well as the reaction of optokinetic nystagmus, it was possible to obtain information about uniform vision in children, even at an early age. So, it has been established that

• at the 2-3rd month notices the mother's breasts,
• at the 4-6th month of life, the child reacts to the appearance of persons serving him,
• at the 7-10th month, the child develops the ability to recognize geometric shapes (cube, pyramid, cone, ball), and
• on the 2-3rd year of life, painted images of objects.

Perfect perception of the shape of objects and normal visual acuity develop in children only during the period of schooling.

In parallel with the development of shaped vision, the formation color vision , which is also primarily a function of the retinal cone apparatus. With the help of a conditioned reflex technique, it was found that the ability to differentiate color first appears in a child at the age of 2-6 months. It is noted that color discrimination begins primarily with the perception of red, while the ability to recognize colors of the short-wavelength part of the spectrum (green, blue) appears later. This is obviously due to the earlier formation of red receivers compared to receivers of other colors.

By the age of 4-5, color vision in children is already well developed, but continues to improve in the future. Anomalies of color perception in them occur with approximately the same frequency and in the same quantitative ratios between males and females as in adults.

Field of vision boundaries in children preschool age about 10% narrower than in adults. At school age, they reach normal values. The dimensions of the blind spot vertically and horizontally, determined by a campimetric study from a distance of 1 m, are on average 2-3 cm larger in children than in adults.

For the emergence binocular vision a functional relationship is necessary between both halves of the visual analyzer, as well as between the optical and motor apparatus of the eyes. Binocular vision develops later than other visual functions.

It is hardly possible to speak about the presence of true binocular vision, i.e., the ability to merge two monocular images into a single visual image, in children infancy. They have only the mechanism of binocular fixation of the object as the basis for the development of binocular vision.

In order to objectively judge the dynamics of the development of binocular vision in children, you can use a test with a prism. The adjusting movement that occurs during this test indicates that there is one of the main components of the combined activity of both eyes - fusion reflex. L.P. Khukhrina (1970), using this technique, found that 30% of children in the first year of life have the ability to move an image shifted in one of the eyes to the central fovea of ​​the retina. The frequency of the phenomenon increases with age and reaches 94.1% in the 4th year of life. In the study using a color device, binocular vision at the 3rd and 4th years of life was detected in 56.6 and 86.6% of children, respectively.

The main feature of binocular vision is, as is known, a more accurate assessment of the third spatial dimension - the depth of space. The average threshold value of binocular deep vision in children aged 4-10 years is gradually decreasing. Consequently, as children grow and develop, the estimation of the spatial dimension becomes more and more accurate.

The following main stages in the development of spatial vision in children can be distinguished. At birth, a child does not have conscious vision. Under the influence of bright light, his pupil constricts, his eyelids close, his head jerkily leans back, but his eyes wander aimlessly independently of each other.

2-5 weeks after birth, strong illumination already encourages the child to keep his eyes relatively still and stare at the light surface. The effect of light is especially noticeable if: it hits the center of the retina, which by this time has developed into a highly valuable area that allows you to get the most detailed and vivid impressions. By the end of the first month of life, optical stimulation of the periphery of the retina causes a reflex movement of the eye, as a result of which the light object is perceived by the center of the retina.

This central fixation is at first fleeting and only on one side, but gradually, due to repetition, it becomes stable and bilateral. The aimless wandering of each eye is replaced by the coordinated movement of both eyes. Arise convergent and tied to them fusional movement, the physiological basis of binocular vision is formed - the optomotor mechanism of bifixation. During this period, the average visual acuity in a child (measured by optokinetic nystagmus) is approximately 0.1, by the age of 2 it rises to 0.2-0.3 and only by 6-7 years reaches 0.8-1.0.

Thus, (the binocular visual system is formed, despite the still obvious inferiority of the monocular visual systems, and is ahead of their development. This occurs, obviously, in order to primarily ensure spatial perception, which to the greatest extent contributes to the perfect adaptation of the organism to conditions external environment. By the time high foveal vision makes more and more stringent demands on the apparatus of binocular vision, it is already quite developed.

During the 2nd month of life, the child begins to master the near space. This involves visual, proprioceptive and tactile stimuli that mutually control and complement each other. At first, close objects are seen in two dimensions (height and width), but thanks to the sense of touch they are perceptible in three dimensions (height, width and depth). This is how the first ideas about the corporeality (volume) of objects are invested.

At the 4th month, children develop a grasping reflex. At the same time, most children determine the direction of objects correctly, but the distance is estimated incorrectly. The child also errs in the definition of the volume of objects, which is also based on an estimate of the distance: he tries to grab the incorporeal sunspots on a blanket and moving shadows.

From the second half of life, the development of distant space begins. The sense of touch is replaced by crawling and walking. They allow you to compare the distance that the body moves with changes in the size of images on the retina and tone. oculomotor muscles: visual representations of the distance are emitted. Therefore, this function develops later than others. It provides a three-dimensional perception of space and is compatible only with complete coordination of the movements of the eyeballs and symmetry in their position.

It should be borne in mind that the mechanism of orientation in space goes beyond the scope of the visual system and is the product of a complex synthetic activity of the brain. In this regard, the further improvement of this mechanism is closely connected with the cognitive activity of the child. Any significant change in the environment, perceived by the visual system, serves as the basis for constructing sensorimotor actions, for acquiring knowledge about the relationship between an action and its result. The ability to remember the consequences of one's actions, in fact, is the process of learning in the psychological sense of the word.

Significant qualitative changes in spatial perception occur at the age of 2-7 years, when the child masters speech and develops abstract thinking. The visual assessment of space is improved at an older age.

In conclusion, it should be noted that both innate mechanisms, developed and fixed in phylogenesis, and mechanisms acquired in the process of accumulation take part in the development of visual sensations. life experience. In this regard, the long-standing dispute between supporters of nativism and empiricism about the leading role of one of these mechanisms in the formation of spatial perception seems pointless.

Features of the optical system and refraction

The eye of a newborn has a significantly shorter anteroposterior axis (approximately 17-18 mm) and a higher refractive power (80.0-90.9 diopters) than the eye of an adult. The differences in the refractive power of the lens are especially significant: 43.0 diopters in children and 20.0 diopters in adults. The refractive power of the cornea of ​​the eye of a newborn is on average 48.0 diopters, an adult - 42.5 diopters.

The eye of a newborn, as a rule, has a hyperopic refraction. Its degree is on average 2.0-4.0 diopters. In the first 3 years of a child's life, intensive growth of the eye occurs, as well as flattening of the cornea and especially the lens. By the 3rd year, the length of the anteroposterior axis of the eye reaches 23 mm, i.e., it is approximately 95% of the size of the adult eye. The growth of the eyeball continues up to 14-15 years. By this age, the length of the axis of the eye reaches an average of 24 mm, the refractive power of the cornea is 43.0 diopters, and the lens is 20.0 diopters.

As the eye grows, the variability of its clinical refraction decreases. The refraction of the eye slowly increases, i.e., it shifts towards emmetropic.

There are good reasons to believe that the growth of the eye and its parts during this period is a self-regulating process, subject to a specific goal - the formation of a weak hyperopic or emmetropic refraction. This is evidenced by the presence of a high inverse correlation (from -0.56 to -0.80) between the length of the anteroposterior axis of the eye and its refractive power.

Static refraction continues to slowly change throughout life. In a general trend towards change medium size refraction (starting from birth and ending at the age of 70), two phases of hypermetropization of the eye can be distinguished weakening (refraction) - in the early childhood and in the period from 30 to 60 years and two stages of myopization of the eye (increased refraction) at the age of 10 to 30 years and after 60 years. It should be borne in mind that the opinion about the weakening of refraction in early childhood and its strengthening after 60 years is not shared by all researchers.

With increasing age, the dynamic refraction of the eye also changes. special attention deserve three age periods.

• The first - from birth to 5 years - is characterized primarily by the instability of the indicators of dynamic refraction of the eye. During this period, the accommodation response to visual requests and the tendency of the ciliary muscle to spasm are not quite adequate. Refraction in the zone of further vision is labile and easily shifts to the side of myopia. Congenital pathological conditions(congenital myopia, nystagmus, etc.), in which the activity of the dynamic refraction of the eye decreases, can delay its normal development. The tone of accommodation usually reaches 5.0-6.0 diopters or more, mainly due to hypermetropic refraction, characteristic of this age period. In violation of binocular vision and binocular interaction of dynamic refraction systems, various types of eye pathology can develop, primarily strabismus. The ciliary muscle is not efficient enough and is not yet ready for active visual work at close range.
• The other two periods are, apparently, critical age periods of increased vulnerability of dynamic refraction: the age of 8-14 years, in which especially active formation systems of dynamic refraction of the eye, and the age of 40-50 years and more, when this system undergoes involution. AT age period At the age of 8-14 years, static refraction approaches emmetropia, as a result of which optimal conditions are created for the activity of dynamic refraction of the eye. At the same time, this is a period when general disturbances of the body and adynamia can have an adverse effect on the ciliary muscle, contributing to its weakening, and the visual load increases significantly. The consequence of this is a tendency to a spastic state of the ciliary muscle and the occurrence of myopia. enhanced growth organism in this prepubertal period contributes to the progression of myopia.

Of the features of the dynamic refraction of the eye in persons 40-50 years of age and older, changes should be distinguished that are natural manifestations of the age-related involution of the eye, and changes associated with the pathology of the organ of vision and general diseases of the elderly and senile age. Typical manifestations of the physiological aging of the eye include presbyopsia, which is mainly due to a decrease in the elasticity of the lens, a decrease in the volume of accommodation, a slow weakening of refraction, a decrease in the degree of myopia, the transition of edimetropic refraction to farsightedness, an increase in the degree of farsightedness, an increase in the relative frequency of astigmatism of the reverse type, more rapid eye fatigue due to decrease in adaptive capacity. Of the conditions associated with age-related pathology of the eye, changes in refraction with the onset of clouding of the lens come to the fore. Of the common diseases that have greatest influence for dynamic reframing, it is necessary to highlight diabetes, in which the optical settings of the eye are characterized by great lability.

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 optic nerves and visual 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 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 conditioned reflexes in a child, color differentiation 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 the age of 6-7 years, binocular vision is formed. 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, in seven-year-olds - in 55%, in nine-year-olds - in 66%, in 12-13-year-olds - 90%, in adolescents 14 - 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 a slight farsightedness (1-3 diopters), due to the spherical shape of the eyeball and a 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 school equipment 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 important organs); mineral metabolism; formation of blood cells.

The chemical composition of the bone: organic matter - ossein protein, included in intercellular substance 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.

Main visual functions, features of their development in children. Central vision: characteristics and research methods. Peripheral vision:
characterization and methods
research.
Completed by: Suzdaleva A.I.

Vision

Sight is sensation (sensory feeling),
ability to perceive light, color and
spatial arrangement of objects in
the form of an image (image).

Basic visual functions

central;
peripheral vision (field of vision);
light perception;
stereoscopic (binocular) vision;
color perception.

Features of the development of visual functions in children

The vision of a newly born child
not fully formed, so it
sees the world a little differently than its adults
parents.
The child is born with a morphological
formed eyeball,
which improves as it grows.
At the same time, visual functions receive
development after childbirth.

Features of the development of central vision in children

Central vision appears in
baby only at 2-3 months
life. Later on, it happens
his gradual
improvement - from
ability to detect
subject to its ability
distinguish and recognize.

Features of the development of peripheral vision in children

Visual field limits in children
preschool age
about 10% narrower than
adults. to school
they reach the age
normal values.
Blind spot dimensions
vertical and horizontal,
determined at
research from a distance 1
m in children on average by 2-3
cm more than adults.

Features of the development of light perception in children

Light sensitivity
appears immediately after
birth. From the very first days
the life of a child has a light
stimulating effect on
development of the visual system
as a whole and serves as the basis
formation of all its functions.
However, under the influence of light
newborn does not occur
visual image, but are caused,
mostly defensive reactions.

Features of the development of stereoscopic (binocular) vision in children

During the 2nd month of life, the child begins
explore the surrounding area.
In the 4th month, children develop
grasping reflex
From the second half of life begins
exploration of distant space.
Significant qualitative changes in
spatial perception occur in
age 2-7 when the child acquires speech
and he develops abstract thinking.

central vision

Central vision is the ability
a person to distinguish not only the shape and color
the subjects under consideration, but also their
small parts, which is provided
central fovea of ​​the macula lutea.
The main characteristic of the central
vision is visual acuity.

Methods for the study of central vision

Study of the central
vision predominantly
carried out through
Sivtsev-Golovin tables.
objective way
determination of visual acuity,
based on
optokinetic nystagmus

peripheral vision

Opportunity for visual work
determined not only by the state of acuteness
distance and near vision
eye. important role in a person's life
playing peripheral vision. It
provided by peripheral departments
retina and is determined by the value and
field of view configuration -
space that is perceived
eye with a fixed gaze.

Methods for the study of peripheral vision

a) control method
b) campimetry
c) perimetry

Conclusion

All listed functions and features
development of the organ of vision is very important for
full human existence, because
visual perception of the environment
space needs more attention.
VISION IS AN IMPORTANT FACTOR OF PERCEPTION OF THE WORLD