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Plan The main function of - The eye is to perceive light and transform it into a visible image, a complex and complex process. The human eye can be regarded as a kind of biological camera, equipped with an optical apparatus with a variable focal length and aperture.
Diagram of the structure of the eyeball 1 - cornea 2 - iris 3 - tunica albuginea (sclera) 4 - choroid 5 - pigment layer 6 - yellow spot 7 - optic nerve 8 - retina 9 - muscle 10 - lens ligaments 11 - lens 12 - pupil Cornea - The cornea is your eye’s clear, protective outer layer. Along with the sclera (the white of your eye), it serves as a barrier against dirt, germs, and other things that can cause damage. Fun fact: Your cornea can also filter out some of the sun's ultraviolet light. But not much, so your best bet to keep ithealth is to wear a pair of wraparound sunglasses when you're outdoors.
- It also plays a key role in vision. As light enters your eye, it gets refracted, or bent, by the cornea’s curved edge. This helps determine how well your eye can focus on objects close-up and far away.
Iris - the iris (plural: irides or irises) is a thin, annular structure in the eye, responsible for controlling the diameter and size of the pupil, thus the amount of light reaching the retina. Eye color is defined by that of the iris. In optical terms, the pupil is the eye's aperture, while the iris is the diaphragm.
Choroid Coat - The part of the eye which contains the most blood, the choroid coat has numerous vessels and arteries. It also harbours a vast supply of dark pigment deposits. The job of the choroid coat is to provide nourishment to the eye, to darken the intra-ocular sections against outside light and to continuously provide the retina with the fresh oxygen and nutrients without which vision would be impossible.
How the eye works - The human eye is a complex optical system that basically works like a camera: the iris serves as the aperture that controls the amount of light rays reaching cornea and lens (photographic objective), and the retina works as the film.
Through the fibers of the optic nerve, impulses arrive at the optic chiasm, where information is sent to the optic tract. Then the impulses are conducted to the subcortical centers of vision, located in the middle and diencephalon. From the lateral geniculate bodies of the diencephalon, by visual radiance, impulses are directed to the cortical center of vision. It provides a conscious assessment of the information received. Normal vision is emmetropia. Nearsightedness-myopia. Farsightedness - hyperopia. Myopia - Myopia is mostly a hereditary disease, when during the period of intense visual stress, due to weakness of the ciliary muscle, circulatory disorders in the eye, the dense shell of the eyeball (sclera) is stretched in the anteroposterior direction. Instead of a spherical eye, the eye acquires the shape of an ellipsoid. Due to this lengthening of the longitudinal axis of the eye, the images of objects are focused not on the retina itself, but in front of it, and the person seeks to bring everything closer to the eyes, uses glasses with scattering ("minus") lenses to reduce the refractive power of the lens. Myopia is unpleasant because with the progression of the disease, dystrophic foci appear in the membranes of the eye, leading to irreversible loss of vision, loss of vision that cannot be corrected by glasses. To prevent this, it is necessary to combine the experience and knowledge of an ophthalmologist with the patient's persistence and will in matters of rational distribution of visual load, periodic self-monitoring of the state of their visual functions.
Farsightedness - Farsightedness is a congenital condition, a feature of the structure of the eyeball: it is either a short eye or an eye with weak optics. In this case, the rays are collected behind the retina. In order for such an eye to see well, collecting ("plus") lenses must be placed in front of it. This condition can "hide" for a long time and manifest itself at the age of 20-30 and later; it all depends on the reserves of the eye and the degree of hyperopia. Age-related hyperopia (presbyopia). With age, the force of accommodation gradually decreases due to a decrease in the elasticity of the lens and ciliary muscle.
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References G. E. Kreidlin. Gestures of the eyes and visual communicative behavior // Proceedings on cultural anthropology M .: 2002. P. 236-251 Thank you for your attention!
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