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External protection.

Your body is designed in such a way that vulnerable eyes are well protected. If you hit your head, the bones of your skull provide great protection for your eye. The eyebrows collect sweat from the forehead and do not get into the eyes. The eyelids and eyelashes protect them from dust and other harmful particles. Tears help them stay moist and clean at all times. Over the course of your life, you produce approximately 65 liters of tears. They flow not only when you cry, but constantly perform an important protective function.

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Iris color.

The iris can be blue, green, gray, brown... depending on the amount of melanin (the substance that gives color). If there is a lot of melanin, then the eyes are brown, if there is less - blue, green, gray. Everyone around us has eyes of different colors.

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From eyes to brain!

When you look at any object, it becomes an image in your brain, that is, a picture of exactly the same shape and color. Your eyes also give your brain information about how far away an object is. Millions of visual stimuli received by the retina are converted into nerve impulses. They travel at high speed along the optic nerves to the brain, where the light information is converted into an image.

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Glasses!

Glasses are needed not only to see better. In fact, glasses are an excellent means of protecting your eyes. When going, for example, to the beach to swim and sunbathe, you need to wear protective sunglasses. If you have trouble reading your eye doctor's checklist, you may have vision problems and need glasses. In some cases, glasses can be replaced with contact lenses.

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The eye (lat. oculus) is a sensory organ of animals that has the ability to perceive electromagnetic radiation in the light wavelength range and provides the function of vision. 90% of information from the surrounding world comes through the eye. The eye of vertebrates is the peripheral part of the visual analyzer, in which the retinal neurons perform the receptor function.

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Even the simplest invertebrate animals have the ability to phototropism due to their, albeit extremely imperfect, vision. Invertebrates have very diverse eyes and ocelli in terms of structure and visual capabilities - unicellular and multicellular, straight and inverted, parenchymal and epithelial, simple and complex. In arthropods often several simple eyes or a pair of compound compound eyes are present. Among arthropods, some species have both simple and compound eyes: for example, wasps have two compound eyes and three simple eyes (ocelli). In evolution, compound eyes arose from the fusion of simple ocelli. The human eye consists of the eyeball and the optic nerve with its membranes. Humans and vertebrates each have two eyes located in the eye sockets of the skull.

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Only the anterior, smaller, most convex part of the eyeball - the cornea, and the part surrounding it - is accessible for inspection. There are two poles in the eyeball: anterior and posterior. The anterior pole corresponds to the most convex central part of the anterior surface of the cornea. The posterior pole is located in the center of the posterior segment of the eyeball. The line connecting both poles of the eyeball is called the external axis of the eyeball. Another axis in the eyeball is the internal axis - it connects a point on the inner surface of the cornea, corresponding to its anterior pole, with a point on the retina. With a longer internal axis, light rays are collected at a focus in front of the retina. At the same time, good vision of objects is possible only at a close distance - myopia, myopia. If the internal axis of the eyeball is relatively short, then the rays of light are concentrated in a focus behind the retina. In this case, distance vision is better than near vision - farsightedness, hypermetropia.

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Pupil The autonomic nervous system is responsible for regulating the size of the pupils. The pupils are dilated by a dilator controlled by sympathetic fibers and constricted by a sphincter controlled by parasympathetic fibers. In humans and other higher vertebrates, changes in the size of the pupils are carried out reflexively, depending on the amount of light falling on the retina. The diameter of the human pupil can vary from 1.1 to 8 mm. The size of the pupil changes due to a number of factors: it dilates in the dark, with emotional arousal, pain, the introduction of sympathomimetic, hallucinogenic and anticholinergic drugs into the body, contracts (miosis) in bright light, from the effects of sedatives such as alcohol and opioids, as well as acetylcholinesterase inhibitors .

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IrisIris, iris, iris (lat. iris), thin movable diaphragm of the eye in vertebrates - with a hole (pupil) in the center; located behind the cornea, between the anterior and posterior chambers of the eye, in front of the lens. Almost lightproof. Contains pigment cells (melanocytes in mammals), circular muscles that constrict the pupil, and radial muscles that dilate it. Lack of pigment in the iris (in this case, the eyes have a reddish tint) is combined with insufficient pigmentation of the skin and hair (albinism).

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Eyelids are movable folds of skin around the eyes in vertebrates and humans. They protect the eyes from external damage, promote their wetting with tear fluid, and cleanse the cornea and sclera. In mammals, on the free edge of the eyelid there are eyelashes and the mouths of the glands. The lower eyelid is limited below by the infraorbital groove. The shape of the lower eyelid varies little. The upper eyelid reveals significant differences in its structure, which largely determine the characteristics of the eye area as a whole. There are several types of folds of the upper eyelid: ---upper - supra-sulcated (orbital), located in the very upper part of the eyelid; --middle - sulcular, starting below the furrow; - lower - tarsal, starting even lower.

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Internal structure of the eye The eyeball consists of membranes that surround the inner core of the eye. The nucleus of the eyeball is surrounded by three membranes: outer, middle and inner. The outer, or fibrous, membrane of the eyeball (tunica fibrosa bulbi), to which the external muscles of the eyeball are attached, performs a protective function. It consists of an anterior transparent part - the cornea, and a posterior opaque whitish part - the sclera. The middle, or choroid, layer of the eyeball (tunica vasculosa bulbi) plays an important role in metabolic processes, providing nutrition to the eye and removing metabolic products. It is formed by the iris, the ciliary body and the choroid itself. The inner, or retinal, shell of the eyeball (tunica interna bulbi), - the retina is the receptor part of the visual analyzer, here the direct perception of light occurs. The light-refracting apparatus of the eye is a complex system of lenses that forms a reduced and inverted image of the outside world on the retina, includes itself the cornea, fluids of the anterior and posterior chambers of the eye, the lens, as well as the vitreous body, behind which lies the retina, which perceives light.

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Internal structure of the human eye1 posterior chamber 2 serrated margin 3 ciliary muscle 4 ciliary belt 5 Schlemm's canal 6 pupil 7 anterior chamber 8 cornea 9 iris 10 lens cortex 11 lens nucleus 12 ciliary process 13 conjunctiva 14 inferior oblique muscle 15 inferior rectus muscle 16 medial straight muscle 17 arteries and veins of the retina 18 blind spot (papilla of the optic nerve) 19 dura mater 20 central retinal artery 21 central retinal vein 22 optic nerve 23 vorticose vein 24 vagina of the eyeball 25 macula 26 central fovea 27 sclera 28 choroid 29 superior rectus muscle

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Accommodative apparatus The accommodative apparatus of the eye ensures the focusing of the image on the retina, as well as the adaptation of the eye to the intensity of light. It includes the iris with a hole in the center - the pupil - and the ciliary body with the ciliary band of the lens. Focusing of the image is ensured by changing the curvature of the lens, which is regulated by the ciliary muscle. As the curvature increases, the lens becomes more convex and refracts light more strongly, tuning itself to seeing nearby objects. When the muscle relaxes, the lens becomes flatter, and the eye adapts to see distant objects. The pupil is a variable-sized hole in the iris. It acts as the eye's diaphragm, regulating the amount of light falling on the retina. In bright light, the circular muscles of the iris contract and the radial muscles relax, while the pupil narrows and the amount of light entering the retina decreases, this protects it from damage. In low light, on the contrary, the radial muscles contract and the pupil dilates, letting more light into the eye.

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Receptor apparatus The receptor apparatus of the eye is represented by the visual part of the retina, containing photoreceptor cells, as well as the bodies and axons of neurons that form the optic nerve. The retina also has a layered structure. Light enters the eye through the cornea, passes sequentially through the fluid of the anterior chamber, the lens and the vitreous body and, having passed through the entire thickness of the retina, hits the processes of light-sensitive cells - rods and cones. Photochemical processes take place in them, providing color vision (for more details, see Color). In its posterior pole there is a small depression - the central fovea - the most sensitive part of the retina, which contains only cones. The place on the retina where there are no rods or cones is called a blind spot; This is where the optic nerve leaves the eye.

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Eye diseasesThe science of ophthalmology deals with the study of eye diseases. There are many diseases that damage the organ of vision. In some of them, the pathology occurs primarily in the eye itself; in other diseases, the involvement of the organ of vision in the process occurs as a complication of already existing diseases. The first include congenital anomalies of the visual organ, tumors, damage to the visual organ, as well as infectious and non-infectious eye diseases in children and adults. Eye damage also occurs with such common diseases as diabetes mellitus, Graves' disease, hypertension and others. Some of the primary eye diseases are: Cataract Glaucoma Myopia (Nearsightedness) Retinal detachment Retinopathy Retinoblastoma Color blindness Demodicosis Eye burn

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Cataract Cataract (from Latin cataracta - “waterfall”) is an ophthalmological disease associated with clouding of the lens of the eye and causing varying degrees of visual impairment. The disease can develop under the influence of external factors, for example under the influence of radiation, or as a result of certain diseases, in particular diabetes mellitus . Physically, clouding of the lens is caused by denaturation of the protein that makes up this organ.

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Cataract The only way to eliminate cataracts is a microsurgical operation, which involves removing the clouded lens and replacing it with an artificial one. Modern technologies provide very high efficiency of surgical treatment of cataracts: vision is almost completely restored. In addition, the latest ideas about cataracts refute the previously existing opinion about the advisability of performing surgery after the “maturation” of the cataract. It has now been established that the earlier treatment is started, the better results can be achieved. Currently, in the practice of eye clinics, a progressive painless method of sutureless cataract surgery is used, in which cataract extraction is carried out using ultrasonic phacoemulsification, and an artificial lens is implanted through an ultra-small incision.

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MyopiaNearsightedness, or Myopia, is a vision defect (refractive error) in which the image falls not on the retina, but in front of it due to the fact that the refractive system of the eye has increased optical power and focuses too much. In this case, a person sees well near, but sees poorly at a distance and must use glasses or contact lenses with negative optical powers. Over the past decades, the number of people suffering from myopia has increased significantly. And although the hereditary factor is quite important in the development of myopia, it is not always decisive. Myopia most often develops during school years, as well as during studies in secondary and higher educational institutions and is associated mainly with prolonged visual work at close range (reading, writing, drawing), especially in poor lighting and poor hygienic conditions. If measures are not taken in time, myopia progresses, which can lead to serious irreversible changes in the eye and significant loss of vision. And as a result - to partial or complete loss of ability to work. The development of myopia also contributes to weakening of the eye muscles. This deficiency can be corrected with the help of specially designed sets of physical exercises designed to strengthen muscles. As a result, the progression of myopia is often stopped or slowed down.

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Astigmatism Astigmatism (medicine) is a vision defect associated with a violation of the shape of the lens or cornea, as a result of which a person loses the ability to see clearly. With spherical optical lenses, the defect is not completely compensated. It is one of the types of ametropia. With astigmatism, a violation of the uniform curvature of the cornea and/or lens leads to distortion of vision. Light rays do not converge at one point on the retina, as happens in a normal eye; as a result, an image of a point is formed on the retina in the form of a blurred ellipse, line segment or “figure eight”. In some cases, vertical lines may appear blurry; in others, horizontal or diagonal lines may appear out of focus. Astigmatism often develops at an early age (usually together with farsightedness and nearsightedness) and usually forms after the first years of life. Symptoms of astigmatism are decreased vision, sometimes seeing objects as curved, their doubling, rapid eye fatigue when working, and headache. In one of the methods, final confirmation is obtained after dilating the pupils with atropine solution and performing skiascopy (shadow test).

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The Mandelbaum effect The Mandelbaum effect is an optical effect in which, in poor visibility conditions, a person's gaze is focused close. It was first recorded by Mandelbaum in 1960. Because dirty windows can enhance this effect, the pilot or driver may not notice an obstacle or danger. When visibility is low, such as at night during a thunderstorm or fog, the eye tends to relax and focus at the best distance, which is called the "blank" field, or focal length of the eye in the dark. This distance is usually less than one meter, but it varies greatly from person to person. It has been shown that the Mandelbaum effect is not an error resulting from inadequate refraction. The effect is due to the normal variability of the brain's perception, and not to the design features of the eye. As with the aviation situation of spatial disorientation, it has been found that in some people the Mandelbaum effect manifests itself to a significant extent, and in others it does not manifest itself at all. In aviation and automobile safety research, the Mandelbaum effect is used to identify subjective bias in situation assessment under stressful conditions. Pilots and drivers in low visibility conditions appear to have persistent differences in visual perception. Ways to compensate for the Mandelbaum effect are still being explored.

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Conditions for the appearance of the red-eye effect in people Conditions for the appearance of the red-eye effect in people can occur when using the flash built into the camera or attached to it. If a lot of light is reflected, the pupils are red. If little light is reflected, then the pupils have a natural color, and the false red color has low brightness and saturation. Less light is reflected from the fundus of the eye when the pupils of a person's eyes are constricted. Pupils dilate in the dark and flash is used in poor lighting. When the pupils of the eyes are dilated, a lot of light is reflected from the fundus of the eye and the likelihood of false coloration of the pupils of the human eyes in the photograph increases and the defect in the color transmission of the pupils of the human eyes increases. The pupils can be dilated in any light under the influence of alcohol, drugs, medications, etc. A weak and slow reaction to light (constriction of the pupils of the human eyes when exposed to bright light) is observed in small children, animals and adults under the influence of alcohol, drugs, medications, etc.

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Interesting facts Pekingese dogs sometimes have problems keeping their eyes in place. The deep-sea fish Macropinna microstoma has a transparent head through which it can see with its tubular eyes. At the same time, the head helps protect the eyes. One spectroscopist scientist who lost the lens of his eye during an accident was prescribed glasses that were transparent in the near-UV region, and the professor was able to see in the ultraviolet. For example, he could adjust UV spectrometers by eye, which made him widely known among his colleagues.

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Presentation on the topic: Human vision

Prepared and executed

Student of the TP8-14 group

Maspanova Daria

Introduction According to world statistics, every third inhabitant of the Blue Planet has poor vision. Our eyes are a very delicate and sensitive mechanism. It is not surprising that constant eye strain, especially during prolonged communication with a computer and TV - the two main interlocutors of modern man, provokes various eye diseases. Weakening of the accommodative apparatus of the eye (the cause of acquired myopia) occurs not only with prolonged work of the eyes at close range with constant tension of the eye muscles, but also with long-term stay in closed spaces, deterioration of the blood supply to the eye caused by chronic tonsillitis, rheumatism and other diseases. Elimination of these causes will be the prevention of myopia. The most effective means of prevention and treatment are special exercises aimed at strengthening and relaxing the eye muscles in combination with general strengthening physical exercises and a healthy lifestyle. Only in this case the methods given below give the desired effect. This is where physical therapy (physical therapy) will come to your aid.

By far the most common eye disease is nearsightedness or myopia. Globally, more than 30% of people suffer from it. And among residents of developed countries this percentage is much higher. The most unpleasant thing is that every year the army of myopics is replenished with an increasing number of young people, students and even schoolchildren - the most active computer users. Another eye disease in the emergence and progression of which long-term work on a computer can play a direct role is farsightedness. It is believed that farsightedness mainly affects older people. This is not entirely true. Visual impairments that lead to farsightedness often develop in youth, in childhood, and are also congenital. It’s just that young people, as a rule, have good accommodative ability, which gradually decreases with age. Perhaps the most “computer” of eye diseases is dry eye syndrome. Moistening of the cornea occurs when blinking. We usually blink about twenty times per minute. When we look motionlessly at the screen (or at a book), we blink 3 times less often. The result is that the eye becomes “dry”.

Speaking of other common eye diseases such as astigmatism, cataracts, glaucoma, conjunctivitis, strabismus, amblyopia, retinal detachment, we note that it is hardly possible to talk about the direct influence of the computer on their occurrence and development, but, of course, prolonged eye strain, which is inevitable when working at a monitor, does not have a very favorable effect on the course of these diseases, and may also be one of the factors contributing to their occurrence . If you have vision problems (nearsightedness or farsightedness, strabismus or astigmatism) and you don’t want to put up with it, know that everything is in your hands. But keep in mind: vision was damaged slowly, and it will be restored slowly. We are not talking about surgical, laser or contact correction, but about restoring your own normal vision naturally. You have worked for years to ruin your eyesight. It is you, not the doctor, who must work hard to fix it. This vision defect is associated with a violation of the shape of the lens or cornea, as a result of which a person loses the ability to see equally well horizontally and vertically, and begins to see objects distorted, in which some lines are clear, others are blurred. It is easy to diagnose by examining with one eye a sheet of paper with dark parallel lines - by rotating such a sheet, an astigmatist will notice that the dark lines either blur or become clearer. Most people have congenital astigmatism up to 0.5 diopters, which does not cause discomfort.

A set of exercises to improve vision 1. Horizontal eye movements: right-left. 2. Movement of the eyeballs vertically up and down. 3. Circular movements of the eyes: clockwise and in the opposite direction. 4. Intense squeezing and unclenching of the eyes at a fast pace. 5. Movement of the eyes diagonally: squint your eyes to the lower left corner, then move your gaze upward in a straight line. Likewise in the opposite direction. 6. Bringing the eyes to the nose. To do this, place your finger on the bridge of your nose and look at it - your eyes will easily “connect”. 7. Frequent blinking of the eyes. 8. Eye work "at a distance." Go to the window, look carefully at a close, clearly visible detail: a branch of a tree growing outside the window, or a scratch on the glass. You can stick a tiny circle of paper on the glass. Then look into the distance, trying to see the most distant objects. Each exercise should be repeated at least 6 times in each direction.

To prevent myopia The following exercises are useful (starting position sitting, each repeated 5-6 times): 1. Leaning back, take a deep breath, then, bending forward, exhale. 2. Leaning back in the chair, close your eyelids, close your eyes tightly, open your eyelids. 3. Hands on your belt, turn your head to the right, look at the elbow of your right hand; turn your head to the left, look at the elbow of your left hand, return to the starting position. 4. Raise your eyes upward, make circular movements with them clockwise, then counterclockwise. 5. Hands forward, look at your fingertips, raise your hands up (inhale), follow the movement of your hands with your eyes without raising your head, lower your hands (exhale). It is advisable to repeat these exercises every 40-50 minutes of working at the computer. The duration of a single workout is 3-5 minutes.

Relieve eye fatigue The following exercises will help: 1. Look straight ahead for 2-3 seconds. Place your finger at a distance of 25-30 cm from your eyes, look at it for 3-5 seconds. Lower your hand and look into the distance again. Repeat 10-12 times. 2. Move the pencil from arm's length to the tip of your nose and back, watching its movement. Repeat 10-12 times. 3. Attach a round mark with a diameter of 3-5 mm to the window glass at eye level. Shift your gaze from distant objects outside the window to the mark and back. Repeat 10-12 times. 4. With open eyes, slowly, in time with your breathing, smoothly draw a figure eight in space with your eyes: horizontally, vertically, diagonally. Repeat 5-7 times in each direction. 5. Place your thumb at a distance of 20-30 cm from your eyes, look with both eyes at the end of the finger for 3-5 seconds, close one eye for 3-5 seconds, then look again with both eyes, close the other eye. Repeat 10-12 times. 6. Look for 5-6 seconds at the thumb of your right hand extended at eye level. Slowly move your hand to the right, follow your finger with your gaze without turning your head. Do the same with your left hand. Repeat 5-7 times in each direction. 7. Without turning your head, move your gaze to the lower left corner, then to the upper right. Then to the lower right, and then to the upper left. Repeat 5-7 times, then in reverse order. Eye gymnastics increases the tone of the eye muscles and eliminates fatigue.

Gymnastics for tired eyes 1. Take a deep breath, closing your eyes as tightly as possible. Tighten the muscles of your neck, face, and head. Hold your breath for 2-3 seconds, then quickly exhale, opening your eyes wide as you exhale. Repeat 5 times. 2. Close your eyes, massage the brow ridges and the lower parts of the eye sockets in a circular motion - from the nose to the temples. 3. Close your eyes, relax your eyebrows. Rotate your eyeballs from left to right and right to left. Repeat 10 times. 4. Place your thumb at a distance of 25-30 cm from your eyes, look with both eyes at the end of the finger for 3-5 seconds, close one eye for 3-5 seconds, then look again with both eyes, close the other eye. Repeat 10 times. 5. Place your fingertips on your temples, squeezing them lightly. Blink quickly and lightly 10 times. Close your eyes and relax, taking 2-3 deep breaths. Repeat 3 times.

Literature · Esakova G. – Your eyes: How to preserve and improve vision. Moscow. 2000 · Eye diseases - Kopaeva V.G. · Methods for improving vision: how to get rid of glasses - Fedorov A.I.· Wikipedia-visual system · Medical encyclopedia http://bibliofond.ru/view.aspx?id=459446 http://www.ronl.ru/referaty/fizra_i_sport/212976