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| The eye works like a camera. It lets light pass through the front part of the eye known as cornea, which is like a clear watch glass and can be compared to the camera’s aperture. The pupil controls the entry of light. The colour of the iris varies from person to person, from deep brown to blue according to the melanine pigment present within in. |
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Generally dark skinned people have brown iris and the fair skinned people blue. The pupil which constricts and dilates with the help of iris muscles acts like a shutter of the camera. Behind the iris is the crystalline lens that is kept in place by the suspensory from the ciliary body. All round the inside of the back of the eyes is the retina, that acts like the light sensitive film in a camera. |
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| When the eye is looking at distant objects, the light rays are focussed on to the retina. If it is a near vision, the focus of the lens is adjusted by the surrounding ciliary muscle. The retina changes light into electrical energy (just as a light meter does) and processes this into coded impulses to be transmitted to the brain. So, an image passing through the eye lens is transmitted from the retina to the brain via the optic nerves. There is a complex mixing of the impulses so that the right side of the brain sees everything on your left and vice versa. |
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Just like the camera, the image appears upside down on the retina, but the brain instantly converts it so that one sees everything the right way up. The eyes move together and send almost identical images to the brain. The brain then joins these images into a single mental picture. |
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