The ocular surface including the cornea and conjunctiva and its overlying tear film are the
first tissues of the eye to interact with the external environment. The tear film is complex
containing multiple layers secreted by different glands and tissues. Each layer contains
specific molecules and proteins that not only maintain the health of the cells on the ocular
surface by providing nourishment and removal of waste products but also protect these cells
from environment. A major protective mechanism that the corneal and conjunctival cells …