Distant objects : When the rays of light are coming from the distant objects they are diverging at the beginning but become parallel when they reach our eye.And the function of cone-shaped cells is to make us see colours and distinguish between them. The function of rod-shaped cells is to respond to the brightness of the light. The light-sensitive cells in the retina of our eye are of two shapes rod shape and cone shape. The adjustment of the size of the pupil takes some time and this is the reason when we go outside in the sunlight from a dark room we feel glare in our eyes or if we enter a dark room after coming from outside we see things clearly after some time. If the amount of light entering the eye is less then the pupil expands so that more light can enter the eye and in case the amount of light entering the eye is large then the pupil contracts. The function of iris is to adjust the size of the pupil. World Sight Day 2020: Current Theme, History, Significance, and Key Facts The function of iris and pupil So, the eye lens is the convex lens and the retina is the screen of the eye. Also, even though the image formed on the retina is inverted our mind interprets it as erect. After the image is formed on the retina it sends electrical signals to the brain and we have a sensation of image. Retina has a large number of light-sensitive cells that can generate electrical signals. The eye lens then converges the light rays and produce an image of the object on the retina which is real and inverted. The light rays coming from the object enter the eyes through the pupil and fall on the eye lens. The eye lens is flexible and thus can change its focal length and shape with the help of ciliary muscles.īehind the eye lens is the retina on which the image is formed in the eye. It is due to the support of ciliary muscles that the eye lens is held in position. Then behind it is the eye lens which is a convex lens. A hole in the middle of the iris is called the pupil.
Just behind the cornea is the iris which is also called coloured diaphragm.
It is through the cornea that the light coming from objects enters the eyes. The front part of the eye called the cornea is made of a transparent substance and its outer surface is convex in shape. The human eye consists of the cornea, iris, pupil, ciliary muscles, eye lens, retina, and optical nerve. And the ability to see is called vision, eyesight, or drishti. The Human eye works on the refraction of light through a natural convex lens made up of transparent living material and enables us to see things around us. The day aims to focus attention worldwide on blindness and vision impairment. World Sight Day 2020: It is observed on the second Thursday of October and this year it falls on 8 October.
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