Eye Anatomy
The eye is like a camera...
The eye functions much like a camera. Suppose you are
going to take a picture of your spouse. Light rays
bounce off your spouse. The image which is composed of
light rays travels through the camera and is focused
(brought to a point) by the lens on the camera.
If the image is in focus, the light rays strike the film
 producing
a sharp image. If for some reason the lens is dirty,
scratched, or is out of focus, the image is blurred or
distorted. You then drop the film off at the store to be
developed. If you have a working camera, good film and
correct focus, an hour later you have a clear picture of
your loved one.
How does vision work?
Suppose that you are looking at your spouse. Light
bounces off your spouse and passes through the cornea
(the clear front surface of the eye), through the pupil
(the black circle) in the center of the iris (the
colored part of the eye) and then through the lens
inside your eye. The iris opens and closes to adjust the
total amount of light entering the eye. The human lens,
acting just like the camera lens, focuses the light onto
the retina.
 In young people, (under the age of 40), the human lens can
adjust to add focusing power to bring near objects into
better focus. The cornea contributes some of the
focusing power of the eye, but it is not able to adjust
like the human lens. The retina translates the light
into electrical impulses which then travel to the brain
via the optic nerve. The brain converts these impulses
into the picture of your spouse.
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