Michael J. Ringle, DVM, Dipl. ACVO
The cornea is a unique portion of the outer fibrous tunic of the eye. Being transparent, it is the main refractive structure of the eye due to the air tissue interface. Even though the cornea is constantly exposed to the environment, it is able to maintain its clarity by continually replacing the surface epithelium and by maintaining a preocular tear film with the aid of both the lacrimal system and the eyelids.