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Explain the structure of eye

Answer» Eye is the most important organ of our body. It consists of a tough fibrous membrane called sclera that protects the internal parts of the eye. Cornea is the membrane covering the front of the eye that is bulged out and is responsible for the maximum refraction of the light that enters the eye. Behind it lies aqueous humour that enables the eye to cope up with the atmospheric changes. Iris forms the coloured part of the eye. It adjusts the size of the pupil, thereby controls the amount of light entering the eye. Behind it lies the crystalline lens, a biconvex structure that helps in fine adjustment to the refracted light so that it is focused on the screen of the eye, which is referred to as retina. Ciliary muscle helps in adjusting the focal length of the lens by contraction or relaxing. Behind the lens lies vitreous humour which is a dense, clear, jelly like fluid which helps to maintain the shape of the eye and focus the image clearly on the retina.Retina is actually a canopy of the nerve endings of the optical nerve through which images are converted into electrical impulses and transferred to the brain for realization of the image. The eye can focus near objects as well distant objects and this is accommodation of the eye. The minimum distance of the object at which an eye can focus clearly is the near point the maximum is called the far point. If an eye is unable to focus the nearby objects and is able to view clearly the far off objects, the defect is called hypermetropia or long sightedness and can be corrected by a suitable convex lens. On the other hand if a person is able to view the nearby objects clearly and unable to view the distant objects the defect is myopia or short sightedness and can be corrected by a suitable concave lens. The power of the corrective lens is calculated by using lens formula and is measured in dioptre.


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