Age features of vision. Age features of the visual sensory system. Anomaly in the position and shape of the eyelids

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. You can develop a child’s vision from birth, following 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 its development and attend scheduled examinations. 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. Old age is often the cause of more serious diseases: 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 necessary drugs, but laser therapy is the most effective way. A huge risk of acquiring macular degeneration is smoking.

Diabetic retinopathy is a consequence of severe diabetes mellitus, which can cause abnormal changes in the blood vessels in the retina of the eye. Due to their thinning, hemorrhages occur in different areas of the visual organs, after which the vessels exfoliate and die. That is why with this disease a person sees a muddy picture. Retinopathy is characterized by 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.

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 the 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, an increase in the formation of lacrimal fluid is observed. 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 conditioned reflexes in a child, color differentiation begins at 5–6 months of age. 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 the age of 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 of 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 increases 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, like an adult.

The field of vision 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 have developed visual acuity and all parts 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.

Development and age-related features of the organ of vision

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. 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 circulatory 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 tubules of the gland are thin. The function of lacrimation 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.

23-02-2012, 17:06

Description

Lesson order. Visual functions are examined in each other and in children of different ages with a decrease in functions due to refractive errors, hydrophthalmos, cataracts, retinal detachment, etc. They master the technique of working with devices, methods and features of the study of individual functions in children of different ages. Consistently checked direct and friendly reaction of the pupils to light, the reaction of tracking and fixing the gaze. Next, approximately determine the sharpness and field of view, color perception and binocular vision. Following an indicative study of visual functions, they are determined on the apparatus.

Already in a child of 3 years old, if you establish contact with him, you can quite accurately determine visual acuity.

Visual acuity is the ability to distinguish separately two points or details of an object. To determine visual acuity serve as children's tables (Fig. 12),

Rice. 12. Orlova tables for the study of visual acuity in children.

tables with Landolt's optotypes placed in Roth's apparatus. Previously, the child is shown a table with pictures at close range. Then visual acuity is checked with both eyes open from a distance of 5 m, and then, alternately closing one or the other eye with a shutter (Fig. 13),

Rice. 13. A translucent shield-shutter to turn off the non-examined eye.

examine the vision of each eye. The display of pictures or signs starts from the top lines. School-age children show letters in the Sivtsev and Golovin table (Fig. 14)

Rice. fourteen. Determination of visual acuity according to the Golovin-Sivtsev table.

should start from the bottom rows. If the child sees almost all the letters of the 10th line, with the exception of one or two, then his visual acuity is 1.0. This line should be at the eye level of the seated child.

When assessing visual acuity it is necessary to remember the age-related dynamics of central vision, therefore, if a child of 3-4 years old sees only signs of the 5th-7th line, this does not indicate the presence of organic changes in the organ of vision. To exclude them, it is necessary to carefully examine the anterior segment of the eye and determine at least the type of reflex from the fundus with a narrow pupil.

If there are no opacities in the refractive media of the eye and there are not even indirect signs indicating the pathology of the fundus, then most often the decrease in vision may be due to refractive errors. To confirm or exclude this cause, it is necessary to try to improve vision. by substituting appropriate glasses in front of the eye (Fig. 15).

Rice. fifteen. Determination of visual acuity with correction by optical glasses.

When checking visual acuity may be below 0.1; in such cases, the child should be brought to the table (or the table should be brought to him) until he begins to distinguish letters or pictures of the first line. visual acuity
should be calculated according to the Snellen formula: V = d/D where V is visual acuity; d is the distance from which the subject sees the letters of the given line. D is the distance from which the strokes of the letters differ at an angle of 1 (i.e., with a visual acuity of 1.0).

If visual acuity is expressed in hundredths of a unit, then calculations using the formula become impractical. In such cases, it is necessary to resort to showing the sick fingers (on a dark background), the width of which approximately corresponds to the strokes of the letters of the first line, and note from what distance he counts them (Fig. 16).

Rice. 16. Determination of visual acuity below 0.1 on the fingers.

With some lesions of the organ of vision, the child may lose object vision, then he does not even see the fingers raised to his face. In these cases, it is very important to determine whether he still has at least a sense of light or whether there is absolute blindness. You can check this by observing the direct reaction of the pupil to light. An older child himself can note the presence or absence of light perception in him, if his eye is illuminated with an ophthalmoscope.

However, install the presence of light perception the subject is still not enough. You should find out if all parts of the retina are functioning adequately. This is found out by examining the correctness of the light projection. It is most convenient to check it in a child by placing a lamp behind him and throwing a light beam onto the cornea of ​​​​the eye from different points in space using an ophthalmoscope. This study is also possible in young children who are asked to point their finger at a moving light source. Correct light projection indicates the normal function of the peripheral part of the retina.

Light projection data are of particular importance when clouding of the optical media of the eyes and when ophthalmoscopy is not possible, for example, in a child with congenital cataract when deciding whether an optical operation is appropriate. Correct light projection indicates the safety of the visual-nerve apparatus of the eye.

The presence of an incorrect (uncertain) light projection most often indicates gross changes in the retina, pathways, or the central part of the visual analyzer.

Significant difficulties are encountered in the study of vision in children of the first years of life. It is natural that quantitative characteristics they almost cannot be specified. In the first week of life, the presence of vision in a child can be judged by the pupillary reaction to light. Given the narrowness of the pupil at this age and the lack of mobility of the iris, studies should be carried out in a darkened room and it is better to use a bright light source (mirror ophthalmoscope) to illuminate the pupil. Illumination of the eyes with bright light often causes the child to close the eyelids (Paper's reflex), throw back the head.

At the 2-3rd week of a child's life, one can judge the state of his vision by detecting a short-term fixation with a glance of a light source or a bright object. Illuminating the child's eyes with the light of a moving ophthalmoscope or showing bright toys, one can see that the child briefly follows them. In children aged 4-5 weeks with good vision, stable central fixation of the gaze is determined: the child is able to keep his eyes on a light source or bright objects for a long time.

Due to the fact that it is not possible to quantify visual acuity in children even at the 3-4th month of life using methods available to the doctor, one should resort to descriptive characteristic. For example, a child of 3-4 months follows bright toys shown at different distances, at 4-6 months he begins to recognize his mother from afar, as evidenced by his behavior, facial expressions; measuring these distances and correlating them with the size of the letters of the first row of the table, one can approximately characterize visual acuity.

In the first years of life, the visual acuity of the child should also be judged by the fact How far does he know surrounding people, toys, orientation in an unfamiliar room. Visual acuity in children increases gradually, and the rate of this growth is different. So, by the age of 3, visual acuity in at least 10% of children is 1.0, in 30% - 0.5-0.8, in the rest - below 0.5. By the age of 7, most children have visual acuity of 0.8-1.0. In cases where visual acuity is 1.0, it should be remembered that this is not the limit, and continue the study, since it can be (in about 15% of children) and much higher (1.5 and 2.0 and even more ).

Peripheral vision is characterized by the field of view (the totality of all points in space that are simultaneously perceived by the fixed eye).

Visual field examination necessary in the diagnosis of a number of ocular and general diseases, especially neurological, associated with damage to the visual pathways. The study of peripheral vision has two goals: determining the boundaries of the field of view and identifying limited areas of loss (cattle) in it.

The field of vision in children under the age of 2-3 years should first of all be judged by their orientation in the environment.

In young children, and in some cases in older children, approximately peripheral vision should be preliminarily determined in the simplest way (control). The subject is seated opposite the doctor so that their eyes are at the same level. Determine the field of view of each eye separately. To do this, the subject closes, for example, the left eye, and the researcher closes the right eye, then vice versa. The object is an object (a piece of cotton wool, a pencil) moved from the periphery along the midline between the doctor and the patient (Fig. 17).

Rice. 17. Control method of studying the field of view.

The subject marks the moment when a moving object appears in the field of view. The researcher judges the field of view, focusing on the state of his own field of view (obviously known).

The definition of the boundaries of the fields of view in degrees is carried out on perimeters. The most common of them is the desktop perimeter (Fig. 18)

Rice. eighteen. Desktop perimeter.

and projection-registration.

The study of the field of view is carried out using special object labels(black stick with a white object at the end) on the desktop perimeter - in a lighted room, on the projection - in a darkened one. Most often they use a white object with a diameter of 5 mm. The boundaries of the visual field are usually examined in 8 meridians. The perimeter arc is easy to rotate. The subject's head is placed on the perimeter stand. One eye fixes the mark in the central part of the arc. The object is slowly (2 cm / sec) moved from the periphery to the center. The subject notes the appearance of a moving object in the field of view and the moments of its disappearance from the field of view.

Projection-registration perimeters have a number of advantages. Thanks to the existing device, you can change the magnitude and intensity of illumination of objects, as well as their color, while simultaneously marking the received data on the diagram. It is also important that repeated studies can be carried out under the same lighting conditions. The most perfect is projection spheroperimeter(Fig. 19).

Rice. 19. Study of the field of view on the spheroperimeter.

To obtain more accurate data on the state of peripheral vision, studies are carried out using objects of smaller size (3-1 mm) and different illumination (on the projection perimeters). With the help of these studies, even minor changes in the visual analyzer can be detected.

If in the study of peripheral vision find a concentric constriction, this may indicate that the child has an inflammatory disease of the optic nerve, its atrophy, glaucoma. A concentric narrowing of the visual field is also observed in the retinal pigment degeneration. A significant narrowing of the field of view in any sector is often noted with retinal detachment, extensive areas of its concussion as a result of trauma.

Loss of the central portion of the visual field, combined, as a rule, with a decrease in central vision, possibly with retrobulbar neuritis, degenerative changes in the macular region, inflammatory foci in it, etc. Bilateral changes in the visual fields are most often observed with damage to the visual pathways in the cranial cavity. So, bitemporal and binasal hemianopsia occur with lesions of the chiasm, right- and left-sided homonymous hemianopia - with damage to the visual pathways above the chiasm.

In some cases, with insufficient clarity of the identified changes, a more subtle study should be resorted to. with colored objects(red, green blue). All data obtained are recorded in the existing diagrams of the visual fields (Fig. 20).

Rice. twenty. Blank diagram of the visual field and the boundaries of the visual field on white in children of different ages and in adults. Solid line - adult; dotted line with dots - children 9-11 years old; dotted line - children 5-7 years old; points - children under 3 years.

Field of view width in children is directly related to age. So in children 3 years old, the borders are white narrower than in adults, along all radii by an average of 15 ° (nasal - 45 °, temporal - 75 °, upper - 40 °, lower - 55 °. Then there is a gradual expansion of the boundaries, and in 12-14-year-old children, they almost do not differ from the boundaries in adults (nasal - 60 °, temporal - 90 °, upper - 55 °, lower - 70 °).

When examining the perimeter, they can quite clearly be identified large scotomas. However, the shape and size of scotomas located within 30-40 ° from the central fossa are best determined on campimeter. This method is also used to determine the size and shape of the blind spot. In this case, the optic nerve head is projected on a black matte board located at a distance of 1 m from the subject, whose head is placed on a stand. There is a white fixation point on the board opposite the examined eye, which it must fix. A white object with a diameter of 3-5 mm is moved along the board in a place corresponding to the projection of the optic nerve head. The boundaries of the blind spot are identified by the moment the object appears or disappears from the field of view. The size of the blind spot for the appearance of an object is normally 12 X 14 cm in children of older age groups. In case of inflammatory, congestive phenomena in the optic nerve, glaucoma, the blind spot may increase in size. Especially valuable are dynamic studies with cattle, which make it possible to judge changes in the course of the process.

In some cases, in order to judge the state of the visual analyzer, it is necessary to determine the function of light perception (the ability to perceive minimal light irritation).

Most often check light perception with glaucoma, retinitis pigmentosa, choroiditis and other diseases. The study consists in determining the threshold of light irritation in a sick child separately for each eye, i.e., the minimum light irritation captured by the eye, and monitoring the change in this threshold during the patient's stay in the dark. The threshold changes depending on the degree of illumination. During a stay in the dark, the threshold of light irritation decreases. This process is called dark adaptation.

Adaptometry is usually done on the Belostotsky-Hoffmann adaptometer (Fig. 21).

Rice. 21. Study of light sensitivity on an adaptometer.

The study is carried out in the dark after a 10-minute illumination of the eyes with a bright light source. The threshold of light irritation, as a rule, is determined every 5 minutes for 45 minutes. If there are changes in the rod apparatus of the retina, the level of the dark adaptation curve may be lower than in a healthy child of the same age, the irritation threshold may remain high for a long time. To control the effectiveness of treatment, repeated adaptometric studies are carried out.

The sensitivity of the dark-adapted eye in children increases with age. The highest level
The curve of dark adaptation is observed in children 12-14 years old, it significantly exceeds the level of the curve of an adult.

On the stability of the functioning of the retina can be judged by photo (light) stress. The research methodology is as follows. After a preliminary determination of visual acuity, the examined eye is exposed to a bright light source (flash lamp or eye illumination with a manual electro-ophthalmoscope for 30 seconds). Then determine the time during which vision reaches the original value. Restoration of vision within 30-40 seconds indicates the normal functioning of the fovea of ​​the retina.

An important visual function is color vision. According to the state of color vision, diseases of the retina and visual pathways can be judged.

Exist mute and vowel methods for studying color perception. For research using the vowel method, Rabkin's polychromatic tables are used, on the color field of which numbers are depicted, made up of multi-colored circles (Fig. 22).

Rice. 22. Polychromatic table for the study of color perception.

Due to the fact that color anomalies judge color tones by their brightness, the background of the tables and the numbers on them have the same brightness, but different color shades. Therefore, patients with impaired color perception cannot correctly name the signs drawn on the table. Based on the analysis of the results of the study, it is possible to differentiate one type of color perception disorder from another, to judge which color perception suffers more in the patient - red (protanopia) or green (deuteranopia). With the help of special tables, it is possible to distinguish between acquired color vision disorders and congenital ones.?

Exploring the color sense using Rabkin's polychromatic tables, they are carried out as follows: (Fig. 23)

Rice. 23. Study of color perception.

the subject sits in front of the window, and the doctor - with his back to the window at a distance of 1 m from the patient and holds the tables. The display of each of them continues for 5-6 seconds. The silent method of studying color vision consists in showing the subject skeins of threads that are very close in tone, and suggesting that they be divided into separate groups of the corresponding color.

For the correct formation of color vision it is necessary that the child from the first days of life was in a well-lit room. From the age of three months, from the moment a strong binocular fixation appears, bright toys should be used, given that the most effective stimuli that have a stimulating effect on the functions of the organ of vision are medium-wave radiation - yellow, yellow-green, red, orange and green colors.

It should be remembered that a color anomaly occurs in about 5% of men, and in women it is 100 times less common.

The state of binocular vision (the ability of spatial perception of an image with the participation of both eyes in the act of vision) is extremely important for some types of professional activity.

binocular vision and its highest form - stereoscopic vision - give depth perception, allow you to estimate the distance of objects from the researcher and from each other. It is possible with a sufficiently high (0.3 and higher) visual acuity of each eye, normal operation of the sensory and motor apparatus.

monocular vision more common in patients with strabismus, with significant (over 3.0 D) anisometropia (different refraction of the eyes) and aniseikonia (different image sizes on the retina and in the visual centers), uncorrected high degree of farsightedness and astigmatism. The non-functioning eye in such cases is included in the work only when the functioning eye is closed. With monocular vision, the child is deprived of the opportunity to correctly assess the depth of the location of objects. However, life experience and acquired skills help even a person with one eye to some extent compensate for the existing deficiency and correctly orientate themselves in the environment.

A more perfect form compared to the monocular is simultaneous vision. In this case, both eyes function, but with separate fields of vision. Therefore, the participation of both eyes in vision is possible until attention is fixed on any object. When attention is fixed on one of the points in space, the image belonging to one of the eyes is excluded from perception.

The development of binocular vision begins with binocular fixation in a child at the 3rd month of life, and its formation ends by 6-12 years.

The equipment for the study of binocular vision is diverse. At the heart of the design of all devices is principle of separation of visual fields of the right and left eyes. The most simple and easy to use device in which this separation is carried out with the help of complementary colors; these colors, when superimposed on each other, do not transmit light - a four-point color apparatus (Fig. 24).

Rice. 24. Four-point color apparatus.
a - location of color tests in the device; b - when viewed with colored glasses (red glass in front of the right eye, green - in front of the left) in the presence of binocular vision, when the leading eye is right; in - the same when the leading eye is left; d - with monocular vision of the left eye; e - with monocular vision of the right eye, f - with simultaneous vision.

Red and green colors are used. On the front surface of the device there are several holes with red and green light filters, and one hole is covered with frosted glass; inside the device is illuminated by a lamp. The subject puts on glasses with red-green filters. In this case, the eye in front of which there is a red glass sees only red objects, the other - green. A colorless object can be seen with both the right and left eyes. Therefore, with monocular vision (suppose, the eye is involved in the vision, in front of which there is a red glass), the subject will see red objects and a colorless object colored red. With normal binocular vision, all red and green objects are visible, and colorless objects appear to be colored red-green, as they are perceived by both the right and left eyes. If there is a pronounced leading eye, then the colorless circle will be colored in the color of the glass placed in front of the leading eye. With simultaneous vision, the subject sees 5 objects.

elementary the presence of binocular vision can be judged by the appearance of double vision when one of the eyes is displaced, when a finger is pressed on it through the eyelid. Binocular vision is also determined by the installation movement of the eyes. If, during fixation by the subject of any object, one of his eyes is covered with the palm of his hand, then in the presence of hidden strabismus, the eye under the palm will deviate to the side. When the hand is taken away, if the patient has binocular vision, the eye will make an adjusting movement to obtain binocular perception.

Practical skills:
1. Check visual acuity approximately and according to the tables.
2. Examine the field of view in a control way and on the perimeter.
3. Explore color perception using Rabkin's polychromatic tables and in a dumb way.
4. Determine the nature of vision on a four-point color apparatus and an approximate method.

Article from the book: .

The human eyeball develops from several sources. The light-sensitive membrane (retina) comes from the side wall of the cerebral bladder (future diencephalon), the lens - from the ectoderm, the vascular and fibrous membranes - from the mesenchyme. At the end of the 1st, beginning of the 2nd month of intrauterine life, a small paired protrusion appears on the side walls of the primary cerebral bladder - eye bubbles. 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). A complex light-perceiving (nervous) part of the retina (photosensory layer) is formed from the inner wall of this bubble. At the 2nd month of intrauterine development, the ectoderm adjacent to the eye cup thickens,
then a lens fossa is formed in it, turning into a crystal bubble. 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, from which the blood vascular network and the vitreous body are formed inside the glass. 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 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 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 - 2.3 g. By the age of 5, the mass of the eyeball increases by 70%, and by 20-25 years - 3 times compared to the newborn.
The cornea of ​​a newborn is relatively thick, its curvature almost does not change during life. The lens is almost round. 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 quite fast.
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 fatty body of the orbit is poorly developed. In elderly and senile people, fatty
the 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.
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 (Schlemm's canal) or spaces of the iridocorneal angle (fountain spaces) causes congenital glaucoma.
Questions for repetition and self-control:

1. List the sense organs, give each of them a functional description.
2. Describe the structure of the membranes of the eyeball.
3. Name the structures related to the transparent media of the eye.
4. List the organs that belong to the auxiliary apparatus of the eye. What are the functions of each of the auxiliary organs of the eye?
5. Describe the structure and functions of the accommodative apparatus of the eye.
6. Describe the pathway of the visual analyzer from the receptors that perceive light to the cerebral cortex.
7. Describe the adaptation of the eye to light and color vision.