Eye is an organ that can sense light.The simplest structure of the eye can detect ambient light and shade,more complex structures can provide visual eye.Usually in the arthropod compound eye (such as insects) and found that often there are many simple little eye surface composition,and produce a video (not usually think more images).In many vertebrates and some mollusks,the eye of light projected through the light-sensitive retinal imaging,where the light is received and converted into signals passing through the optic nerve to the brain.Usually the eyes are spherical,which is full of a transparent gelatinous substance,there is a focus with the lens,usually there is a can control how much light enters the eye iris.
