The Human Eye Structure.

                                         The Human Eye Structure



*RETINA-- The eye lens system forms an image on a light-sensitive
screen called the retina.
*CORNEA-- Light enters the eye through a thin membrane called the cornea.
It forms the transparent bulge on the front surface of the eyeball
Most of the refraction for the light rays entering the eye occurs at the
outer surface of the cornea.
*EYE LENS-- The crystalline lens merely provides the finer adjustment of focal length
required to focus objects at different distances on the retina.
*IRIS-- Iris is a dark muscular diaphragm that controls the size of the pupil.
*PUPIL--- Pupil regulates and controls the amount of light amount of light entering
the eye.
*CILIARY MUSCLES---
When the muscles are relaxed, the lens becomes thin. Thus its focal length
increases. This enables us to see distant objects clearly.
When we are looking at objects closer to the eye, the ciliary muscles contract.
This increases the curvature of the eye lens. The eye lens then
becomes thicker. Consequently, the focal length of the eye lens decreases
This enables us to see nearby objects clearly
.
*OPTICAL NERVES--- The retina is a delicate membrane having enormous number of
light-sensitive cells. The light-sensitive cells get activated upon
illumination and generate electrical signals. These signals are
sent to the brain via the optic nerves. The brain interprets these
signals, and finally, processes the information so that we
perceive objects as they are.
                                                                                                       Collected By NetKing