2.87 Eye response

Seeing things
Light enters your eye through the cornea, it passes through the lens and is focused on the retina.
In the retina there are cells which are sensitive to light called rods and cones.
When light stimulates them they send impulses to the brain along to the optic nerve. Your brain interprets these impulses to make a picture.


Focusing
Most of the bending of the light rays is done by the curved cornea but lens can bend the light rays slightly.
The shape of the lens is controlled by the ciliary muscles.


Looking at distance object:

• the ciliary muscles relax
• the suspensory ligaments tightens 
• The lens is pulled into a thin shape
• The distance object is focused on the retina

Looking at near object:

• the ciliary muscle contract
• this slackens the suspensory ligaments
• the elastic lens goes fatter
• The near objects is focused on the retina.