First page
THE HUMAN EYE AND THE COLOURFUL WORLD
STRUCTURE OF HUMAN EYE
==QUIZ==Eye lens --- double convex lens The retina --- contains numerous light sensitive cells which generate electrical signals which are sent to brain via optic nerve Cornea---The transparent spherical membrane covering the front of the eye. Iris--The coloured diaphragm between the cornea and lens. Pupil ---The small hole in the iris. Eye lens--- It is a transparent lens made of jelly like material. Ciliary muscles--These muscles hold the lens in position. Retina--The back surface of the eye. Blind spot--The point at which the optic nerve leaves the eye. An image formed at this point is not sent to the brain. Aqueous humour---A clear liquid region between the cornea and the lens. Vitreous humour--The space between eye lens and retina is is filled with another liquid called Vitreous humour. Persistence of vision--The image of an object seen persists on the retina for 1/16 second even after the removal of the object. This continuance of sensation of eye for some timed is called persistence of vision. Colour blindness-- It is said to occur when a person cannot distinguish between colours Accomodation--The ability of the eye to focus both near and distant objects, by adjusting the focal length, is called the accommodation of the eye. Far Point of the Eye-- It is the farthest point at which the object can be seen clearly. For a normal eye, the far point lies at infinity. Near point of the Eye-- It is the closest point at which an object can be seen clearly. For normal eye, the near point lies at 25 cm from the eye(least distance of distinct vision).
