The human eyeball, the organ responsible
for the sense of sight, is a very complex
structure. We use our vision in almost every
activity, so the eye is one of the most
important organs in the body.
How it works
Sight begins when light rays from an object
enter the eye through the
cornea, the clear
front “window” of the eyeball. The cornea is
actually responsible for about sixty percent
of the eyeball’s light-ray-bending
capability. The cornea’s refractive power
bends the light rays in such a way that they
pass freely through the pupil, the
size-changing hole in the
The iris, the structure that gives the eye
color, works like a shutter in a camera. It
has the ability to enlarge and shrink,
depending on how much light the environment
is sending into the eye.
After passing through the iris, the light
rays strike the eye’s
lens. This clear, flexible structure
works much like the lens in a camera –
shortening and lengthening its width in
order to focus light rays properly.
In a normal eye, after exiting the back of
the lens, the light rays pass through the
vitreous -- a
clear, jelly-like substance that fills the
globe of the eyeball. The vitreous humor
helps the eye hold its spherical shape.
Finally, the light rays land and come to a
sharp focusing point on the
with our “camera” analogy, the retina’s
function is 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
is sort of like an extension of the brain.
It is a bundled cord of more than a million
nerve fibers. The light impulses travel
through this nerve fiber to the brain, where
Illustrations by JirehDesign.com
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