Chapter 3 Anatomy of the Eye
The white part of the eyeball is called the sclera (say: sklair-uh). The sclera is made of a tough material and has the important job of covering most of the eyeball. Think of the sclera as your eyeball's outer coat.
Look very closely at the white of the eye, and you'll see lines that look like tiny pink threads. These are blood vessels, the tiny tubes that deliver blood, to the sclera.
The part of the sclera in front of the colored part of the eye is called the cornea (say: kor-nee-uh). Unlike the rest of the sclera, which is white, the cornea is transparent, or completely clear, which lets light travel through it. The cornea helps the eye focus as light makes its way through. It is a very important part of the eye, but you can hardly see it because it's made of clear tissue. Like clear glass, the cornea gives your eye a clear window to view the world through
Behind the cornea are the iris and the pupil. The iris (say: eye-riss) is the colorful part of the eye. When we say a person has blue eyes, we really mean the person has blue irises!
The iris is a muscle. This allows the iris to control how much light goes through the pupil (say: pyoo-pul). The pupil is the black circle in the center of the iris, and it lets light enter the eye. The pupils will get smaller when a light shines near them and they'll open wider when the light is gone.
Between the iris and cornea is the anterior (say: an-teer-ee-ur) chamber. This chamber is filled with a special transparent fluid that gives the eye oxygen, protein, and glucose (a type of sugar in the body) to keep it healthy.
Our tears form a protective layer at the front of the eye and also help to direct the light coming into our eye.
After light enters the pupil, it hits the lens. The lens sits behind the iris and is clear and colorless. The lens' job is to focus light rays on the back of the eyeball - a part called the retina (say: reh-tin-uh).