In good light, the yellow spot is most sensitive to detail and the image is automatically formed there. Electrical signals then travel along the optic nerve to the brain to be interpreted. In the eye, the image is formed on the retina by successive refractions at the cornea, the aqueous humor, the lens and the vitreous humor. The use of two eyes (binocular vision) is necessary to obtain the correct perception of depth. One eye is usually dominant, controlling perspective. The optic nerve of each eye sends the information to the opposite hemisphere of the brain. The optic nerve transmits impulses to the brain. The blind spot, located where the optic nerve meets the eye, contains no photo-receptors. The ability of the eye to form an image on the curved surface of the retina is extremely important in human vision.
When image is formed on the retina the image is inverted, real, and diminished. They allow us to see in dim light conditions. Cones are sensitive to bright light and colour (blue, red and green). It plays the role of the film in a camera. Rods are sensitive to dim light and do not respond to colour. It consists of an array of light-sensitive receptors called rods and cones which convert the light energy into electrical signals. You should also know that the Retina is the coating of the interior surface at the back of the eye. NCERT solutions for class 8 Science prepared by pw will help you to solve your NCERT text book exercise. Vitreous humor : The space between eye lens and retina is filled with another liquid called vitreous humor. An image formed at this point is not sent to the brain.Īqueous humor : It is a clear liquid region between the cornea and the lens. Retina : It is the back surface of the eye.īlind spot : It is the point at which the optic nerve leaves the eye. Pupil : It is the small hole in the iris.Įye lens : It is a transparent lens made of jelly like material.Ĭiliary muscles : These muscles hold the lens in position. Iris : It is the coloured diaphragm between the cornea and lens. A simplified anatomy of the eye is shown in the diagram below.Ĭornea : It is the transparent spherical membrane covering the front of the eye. The eye is essentially a closed sphere into which light passes through a lens and strikes a light sensitive surface. The structure and working of the eye is as follows : It is like a camera having a lens system and forming an inverted, real image on a light sensitive screen inside the eye. The human eye is one of the most sensitive sense organs of sight which enables us to see the wonderful world of light and colour around us.
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