Light rays enter the eye through the cornea, the
clear front “window” of the eye. The cornea’s refractive power bends the light
rays in such a way that they pass freely through the pupil the opening in the
center of the iris through which light enters the eye. The iris works like a
shutter in a camera. It has the ability to enlarge and shrink, depending on how
much light is entering the eye. After passing through the iris,
the light rays
pass thru the eye’s natural crystalline lens. This clear, flexible structure
works like the lens in a camera, shortening and lengthening its width in order
to focus light rays properly. Light rays pass through a dense, transparent
gel-like substance, called the vitreous that fills the globe of the eyeball and
helps the eye hold its spherical shape.
In a normal eye, the light rays come to
a sharp focusing point on the retina. The retina functions much like the film
in a camera. It is responsible for capturing all of the light rays, processing
them into light impulses through millions of tiny nerve endings, then sending
these light impulses through over a million nerve fibers to the optic nerve in the
brain where it is interpreted.
CHICK HERE to see animated video of how the eyes works
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