eye

The white part of the eye is called the sclera. Healthy corneas have no blood vessels or discolorations. Many diseases, however, cause grey patches (opacities) to appear in cornea. Sometimes vessels grow into the cornea. Vision becomes blurred when the cornea is cloudy.Contact lenses sometimes irritate the cornea. Contact lenses may make vessels to grow into cornea.

The cornea is the clear membrane in the front of the eye over the black circle (pupil) and colored ring (iris). The cornea has numerous nerve endings. Therefore even slight irritations such as a hair touching the cornea may hurt. Also if a piece of dirt gets under the eye lid and scratches the cornea it is very painful. If the cornea becomes dry the surface (called epithelium) shrinks a little and the nerve endings are stretched. This causes a pain that often is as if a pin was stuck into the eye. The pain disappears if one closes the eye for a few seconds.