Development and age-related characteristics of the organ of vision. Open Library - open library of educational information Features of the structure of the visual organs of preschool children

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

Vision

Basic visual functions

Features of the development of visual functions in children

Features of the development of central vision in children

Features of the development of peripheral vision in children

Features of the development of light perception in children

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

Central vision

Methods for studying central vision

Peripheral vision

Methods for studying peripheral vision

Conclusion

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

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

External inspection is carried out in good lighting. First, the healthy eye is examined, and then the sick eye. You should pay attention to the following factors:

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

The conjunctiva in a normal state is pale pink, smooth, transparent, moist, the vascular pattern is clearly visible.

If there is a pathological process in the eye, an injection is observed:

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

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

Nasolacrimal tests:

1. Nasolacrimal.
2. Rinsing the nasolacrimal duct.
3. Radiography.

Examination 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.

Protrusion of the eyeball outward is called exophthalmos, retraction is called endophthalmos.

Exophthalmos is a hematoma, orbital emphysema, tumor.

To determine the degree of protrusion of the eyeball, exophthalmometry is used.

Side lighting method

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

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

Transmitted light research method:

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

The study is carried out in a dark room. The light source is located at the rear left. The doctor is the opposite. Using a mirror ophthalmoscope, a mirror is used to project a light source into the eye. In normal condition, the indicator should light up red.

Ophthalmoscopy:

1. In reverse. The operation is carried out using an ophthalmoscope, a 13 diopter lens and a light source. Holding the ophthalmoscope in the right hand, look with the right eye, the magnifying glass is in the left hand and is placed on the patient’s brow ridge. The result is a mirror inverted image. The retina and optic nerve are examined.
2. Straightforward. A manual electroophthalmoscope is used. The rule of procedure is that the right eye is examined with the right eye, the left eye with the left.

The reverse ophthalmoscope gives a general idea of ​​the condition of the patient's fundus. Directly – helps to detail 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 there is a depression from which the vessels emerge.

Biomicroscopy:

Biomicroscopy uses a slit lamp. It is a combination of an intense light source and a binocular microscope. The head is positioned with the forehead and chin resting. Provides an adjustable light source to the patient's eye,

Gonioscopy:

This is a method of examining the anterior chamber angle. 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 and the degree of opening of the anterior chamber angle.

Tonometry:

Palpation. The patient is asked to close the eye and, using the index finger, palpating, judges the amount of eye pressure. Judged by the pliability of the eyeball. Kinds:

Tn – pressure is normal.

T+ - moderately dense.

T 2+ - very dense.

T 3+ - dense as a stone.

T -1 – softer than normal

T -2 – soft

T-3 – very soft.

Instrumental. During the procedure, a Maklakov tonometer is used - a metal cylinder 4 cm high, weight - 100 g, with extended white glass platforms at the ends.

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

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

Normal pressure is 18-26 mm Hg.

In the development of the visual analyzer after birth allocate 5 periods:

1) area formation macular spot and the central fovea of ​​the retina during first

half a year life - out of 10 layers of the retina, 4 remain (visual cells, their nuclei and border

membranes);

2) increase functional mobility of visual pathways and their formation during

first half of the year life;

3) improvement of visual cells elements cortex and cortical visual centers V

flow first 2 years life;

4) formation and strengthening of connections visual analyzer with other organs in

flow first years life;

5) morphological and functional development cranial nerves V first 2-4 months life.

Vision newborn characterized by diffuse light perception. As a result of underdevelopment of the cerebral cortex, it is subcortical (hypothalamic), primitive (protopathic). Therefore, the presence of vision in a newborn is being researched calling check in everyone eye pupil reactions(direct and friendly) for illumination with light and general motor reaction(Paper reflex - “from eye to neck”, i.e. tilting the child’s head backward, often to the degree of opisthotonus).

As cortical processes and cranial innervation improve, development visual perception manifests itself in a newborn in tracking reactions initially during seconds(the gaze “drifts” in the direction of the object or against it when it even stops).

Co 2nd week appears short-term fixation (average visual acuity is in the range of 0.002-0.02).

Co. 2nd month appears synchronous(binocular) fixation (visual acuity= 0.01-0.04 - appears formal subject vision and the child reacts vividly to the mother).

TO 6-8 months children distinguish simple geometric shapes (visual acuity = 0.1-0.3).

WITH 1 year– children distinguish between drawings (visual acuity = 0.3-0.6).

WITH 3 years– visual acuity = 0.6-0.9 (in 5-10% of children = 1.0).

IN 5 years– visual acuity = 0.8-1.0.

IN 7 -15 years– visual acuity = 0.9-1.5.

Parallel to the acuity vision develops color vision, But judge about him availability succeeds much later. First more or less distinct reaction to bright red, yellow and green colors appears in a child first half of the year life. For the right development color vision, it is necessary to create conditions for children good lighting And attracting attention to bright toys at a distance of 50 cm or more, changing their colors. Baby garlands for a newborn should have in the center yellow, orange, red and green balls (since the fovea is most sensitive to the yellow-green and orange part of the spectrum), and blue, white and dark balls should be placed around the edges.

Binocular vision is highest form visual perception. Character vision in a newborn at first monocular because he does not fixate objects with his gaze, and his eye movements are not coordinated. Then he becomes monocular alternating. When a 2 months the object fixation reflex develops simultaneous vision. On 4th month - children firmly fix tangible them objects i.e. the so-called planar binocular vision. In addition, pupil constriction occurs, fixation of loved ones items i.e. accommodation, a to 6 months- appear friendly eye movements,convergence. When children start crawl, they, comparing the movement of their body with the spatial arrangement and distance of surrounding objects from their eyes, changes in their size, gradually develop spatial, depth binocular vision. Necessary conditions its developments are sufficient high acuity view in both eyes (with visusе in one eye = 1.0, in the other – no less than 0.3-0.4); normal innervation oculomotor muscles, absence of pathology of the pathways and higher visual centers.Stereoscopic binocular vision the child is already developing at the age of 6, But full-fledgeddeep binocular vision(the highest degree of development of binocular vision) is established by 9-15 years old.

line of sight in the newborn, according to most authors, develops from the center to the periphery, gradually, during first 6 months life. The area of ​​the macula (outside the fovea) is quite well developed morphologically and functionally already in young years. This is confirmed by the fact that protective eyelid closure reflex of a child when an object quickly approaches the eye in the direction of the visual line, i.e. to the center the retina develops first - at the 8th week. Same reflex when an object moves from the side, from periphery is revealed much later - only at 5th month life. At an early age, the visual field has narrow tube-shaped character.

Some idea of ​​the field of view in children of the first years life can be obtained only on the basis of their orientation during movements and walking, by turning the head and eyes towards objects and toys moving at different distances and of different sizes and colors.

In children preschool age the boundaries of the field of view are approximately 10% already, than adults.

Subject: PHYSIOLOGICAL OPTICS, REFRACTION, ACCOMMODATION AND THEIR AGE FEATURES. METHODS FOR CORRECTING REFRACTION ANOMALIES

Learning goal: give an idea of ​​the optical system of the eye, refraction, accommodation and their pathological conditions; as well as about their age characteristics.

School time: 45 min.

Method and location of the lesson: group theoretical lesson in the classroom.

Visual aids:

1. Tables: Section of the eyeball, drawings and diagrams, 3 types

clinical refraction, their correction; eye changes

with progressive complicated myopia. Curve

2) Color slides on the topic - Ophthalmology, part 1-11.

3) Educational videos on the topic.

Lecture outline

The human eyeball develops from several sources. The light-sensitive membrane (retina) comes from the side wall of the brain bladder (the future diencephalon), the lens - from the ectoderm, the choroid and fibrous membrane - from the mesenchyme. At the end of the 1st - beginning of the 2nd month of intrauterine life, a small paired protrusion - the optic vesicles - appears on the lateral walls of the primary brain vesicle. During development, the wall of the optic vesicle indents into it and the vesicle turns into a two-layer optic cup. The outer wall of the glass subsequently becomes thinner and transforms into the outer pigment part (layer). From the inner wall of this bubble, a complex light-receiving (nervous) part of the retina (photosensory layer) is formed. In the 2nd month of intrauterine development, the ectoderm adjacent to the optic cup thickens, then a lens fossa forms in it, turning into a crystal vesicle. Having separated from the ectoderm, the vesicle plunges inside the optic cup, loses its cavity, and the lens is subsequently formed from it.

At the 2nd month of intrauterine life, mesenchymal cells penetrate into the optic cup, from which the blood vascular network and vitreous body are formed inside the optic cup. The mesenchymal cells adjacent to the optic cup form the choroid, and the outer layers form 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 vitreous body disappear; the membrane covering the opening of the pupil (pupillary membrane) dissolves.

The upper and lower eyelids begin to form in the 3rd month of intrauterine life, initially in the form of folds of ectoderm. The epithelium of the conjunctiva, including that covering 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 developing upper eyelid.

The eyeball of a newborn is relatively large, its anteroposterior size is 17.5 mm, its weight is 2.3 g. By 5 years, the weight of the eyeball increases by 70%, and by 20-25 years - 3 times compared to a newborn.

The cornea of ​​a newborn is relatively thick, its curvature remains almost unchanged throughout life. The lens is almost round. The lens grows especially quickly during the 1st year of life; subsequently, its growth rate decreases. The iris is convex anteriorly, there is little pigment in it, the pupil diameter is 2.5 mm. As the child gets older, the thickness of the iris increases, the amount of pigment in it increases, and the diameter of the pupil becomes larger. 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 occurs quite quickly.

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

The lacrimal gland in a newborn is small in size, and the excretory canaliculi of the gland are thin. The function of tear production appears in the 2nd month of a child’s life.

The fatty body of the orbit is poorly developed. In elderly and senile people, the fatty body of the orbit decreases in size, partially atrophies, and the eyeball protrudes less from the orbit.

The palpebral fissure in a newborn is narrow, the medial corner of the eye is rounded. Subsequently, the palpebral fissure rapidly increases. For children under 14-15 years old, it is wide, so the eye appears larger than that of an adult.

Complex development of the eyeball leads to birth defects. More often than others, 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 lengthened) or farsightedness (the visual axis is shortened) appears. A gap in the iris (coloboma) most often occurs in its anteromedial segment. Remnants of the branches of the vitreous artery interfere with the passage of light through the vitreous. Sometimes there is a violation of the transparency of the lens (congenital cataract). Underdevelopment of the venous sinus of the sclera (pglem's canal) or the spaces of the iridocorneal angle (fountain spaces) causes congenital glaucoma.

Control questions

1. List the sense organs, give each of them a functional characteristic.

2.Tell us about 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 functions does each of the auxiliary organs of the eye perform?

5. Tell us about the structure and functions of the accommodative apparatus
eyes.

6.Describe the pathway of the visual analyzer from the receptors that perceive light to the cerebral cortex.

7.Tell about the adaptation of the eye to light and color vision

ORGANS OF HEARING AND EQUILIBRIUM (VESTICOCHELLAR ORGAN)

The organs of hearing and balance, performing different functions, are combined into a complex system (Fig. 108).

The organ of balance is located inside the petrous part (pyramid) of the temporal bone and plays an important role in the orientation of the neck in space.

Rice. 108. Vestibulocochlear organ:

1 - Auricle; 2 - external auditory canal; 3 - eardrum; 4 - tympanic cavity; 5 - hammer; 6 - anvil; 7 - stirrup, 8- semicircular ducts; 9 - vestibule; 10 - snail; 11 - prg-i cochlear nerve; 12 - auditory tube

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 is more lateral than in an adult. The eyeball grows faster in the first year of a child’s life than in subsequent years. By the age of 5, the mass of the eyeball increases by 70%, and by 20-25 years - by 3 times compared to a newborn.

The cornea of ​​a newborn is relatively thick, its curvature remains almost unchanged throughout life; The lens is almost round, the radii of its anterior and posterior curvature are approximately equal. The lens grows especially quickly during the first year of life; subsequently, its growth rate decreases. The iris is convex anteriorly, there is little pigment in it, the diameter of the pupil is 2.5 mm. As the child's age increases, the thickness of the iris increases, the amount of pigment in it increases by two years, and the diameter of the pupil becomes larger. 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 occurs quite quickly. The ability to accommodate is established by the age of 10. The optic nerve in a newborn is thin (0.8 mm) and short. By the age of 20, its diameter almost doubles.

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

The lacrimal gland in a newborn is small in size, and the excretory canaliculi of the gland are thin. In the first month of life, the child cries without tears. The function of tear production appears in the second month of a child’s life. The fatty body of the orbit is poorly developed. In elderly and senile people, the fatty body of the orbit decreases in size, partially atrophies, and the eyeball protrudes less from the orbit.

The palpebral fissure in a newborn is narrow, the medial corner of the eye is rounded. Subsequently, the palpebral fissure rapidly increases. In children under 14-15 years of age, it is wide, so the eye appears larger than that of an adult.

Explain the structure and functions of the auditory analyzer.

Hearing analyzer- This is the second most important analyzer in ensuring adaptive reactions and cognitive activity of a person. Its special role in humans is associated with articulate speech. Auditory perception is the basis of articulate speech. A child who loses his hearing in early childhood also loses his speech ability, although his entire articulatory apparatus remains intact.

Sounds are an adequate stimulus to the auditory analyzer.

The receptor (peripheral) section of the auditory analyzer, which converts the energy of sound waves into the energy of nervous excitation, is represented by the receptor hair cells of the organ of Corti (organ of Corti), located in the cochlea.

Auditory receptors (phonoreceptors) belong to the mechanoreceptors, are secondary and are represented by inner and outer hair cells. Humans have approximately 3,500 inner and 20,000 outer hair cells, which are located on the main membrane inside the middle canal of the inner ear.

The pathways from the receptor to the cerebral cortex constitute the conductive section of the auditory analyzer.

The conductive section of the auditory analyzer is represented by a peripheral bipolar neuron located in the spiral ganglion of the cochlea (the first neuron). The fibers of the auditory or (cochlear) nerve, formed by the axons of the neurons of the spiral ganglion, end on the cells of the nuclei of the cochlear complex of the medulla oblongata (second neuron). Then, after a partial intersection, the fibers go to the medial geniculate body of the metathalamus, where switching occurs again (third neuron), from here the excitation enters the cortex (fourth) neuron. In the medial (internal) geniculate bodies, as well as in the lower tuberosities of the quadrigemina, there are centers of reflex motor reactions that occur when exposed to sound.

The cortical, or central, section of the auditory analyzer is located in the upper part of the temporal lobe of the cerebrum (superior temporal) gyrus, areas 41 and 42 according to Broadmon). The transverse temporal lobes are important for the function of the auditory analyzer, providing regulation of the activity of all levels of Heschl’s gyrus (gyrus). Observations have shown that with bilateral destruction of the indicated
fields, complete deafness occurs. However, in cases where the defeat
limited to one hemisphere, there may be a slight and often
only temporary hearing loss. This is explained by the fact that the conductive paths of the auditory analyzer do not completely intersect. Moreover, both
internal geniculate bodies are interconnected by intermediate
neurons through which impulses can pass from the right side to
left and back. As a result, the cortical cells of each hemisphere receive impulses from both organs of Corti

The auditory sensory system is complemented by feedback mechanisms that provide regulation of the activity of all levels of the auditory analyzer with the participation of descending pathways. Such pathways begin from the cells of the auditory cortex, switching sequentially in the medial geniculate bodies of the metathalamus, the posterior (inferior) colliculus, and in the nuclei of the cochlear complex. As part of the auditory nerve, centrifugal fibers reach the hair cells of the organ of Corti and tune them to perceive specific sound signals.