The cornea is the transparent part of the eye that covers the front portion of the eye. It covers the pupil (the opening at the center of the eye), iris (the colored part of the eye), and anterior chamber (the fluid-filled inside of the eye).
Cornea is the first coat of eye which is transparent circular structure. Functionally it acts as a lens responsible for focusing rays inside the eye. It is an important optical structure through which rays of light enter the eye.
Any damage or injury to this delicate structure can lead to permanent loss of corneal transparency or in other words cause clouding and opacification.