Eye Anatomy
A guide to the many parts of the human eye
-- how and why they work and
function
Click here for interactive Eye Anatomy animation
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
iris.
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
crystalline 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
retina.
Continuing 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
optic nerve.
The optic nerve 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 they are interpreted
as an image.
Watch the movie
Illustrations and movie by JirehDesign.com
|
