Functions of parts-

IRIS- The muscles of the iris dilate and constrict the pupil and thus increases and reduces the amount of light reaching the retina.

EYE-LENS- Lens focuses the light rays passing through it onto the retina and thus creates a clear image of the objects in sight.

CILIARY MUSCLES- The ciliary muscle fibers affect the zonular fibers in eye and thus change the lens shape and thus changes the converging power.

RETINA- Retina receives the light focused by the lens, the photoreceptors In the retina (rods and cones) convert this light into signals and the signals are then passed onto the brain for viewing.

OPTIC NERVE- The optic nerve transmits signals from photoreceptors in the retina to the brain through electric impulses.