What Are Visual Defects And How Common Are They ?

What Are Visual Defects and How Common Are They ?


by


Nate Schackow 2nd Period December 17,  1996


     The human eye does alot more than allowing you to see.  It is very

complex and has many parts and features which can have defects.  However, to

understand defects you must first know how the eye works.

     First light passes through the cornea, which is the transparent part of

the sclera, or white of the eye, which is composed of tough fiberous tissue.

Behind the sclera is a watery fluid called the aqueous humor.  This fluid fills

a cresent-shaped space which with the cornea helps bend the light toward the

center of the eye.

     Under the aqueous humor is the iris which gives the eye color.  The

color of the iris has no effect on how you see and is inherited through genes.

The iris contols how much light is allowed to enter your  by opening up further

when it is dark and closing up more to block out some light when it is bright.

Everything that passes through the pupil, which looks like a black dot, is what

you see.

     
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