EYE Eye is the important sense organ that makes vision possible. It consists of three layers, the outer most layer sclera that provides firmness to the eyeball. The anterior portion of the sclera forms a transparent layer called cornea that allows the light to pass through it. Sclera is covered by conjunctiva except the anterior portion cornea. It keeps the moisture of eye. Middle layer is choroid with number of blood vessels that provide nutrients to eye. The anterior part of choroid forms iris, that regulate amount of light by adjusting the size of pupil. Pupil is an aperture formed in between iris. There is a convex lens located behind the iris that focusses light onto retina. Lens is attached to ciliary muscles from choroid by small ligaments. Retina is inner most layer consisting of number of photoreceptor cells. Photoreceptor cells mainly concentrated at yellow spot, and spot where there is no photoreceptor cells called blind spot. Optic nerve starts at blind s...
