Why are tears important to the cornea?

Every time we blink, tears are distributed across the cornea to keep the eye moist, help wounds heal, and protect against infection. Tears form in three layers:

• An outer, oily (lipid) layer that keeps tears from evaporating too quickly and helps tears remain on the eye;
• A middle (aqueous) layer that nourishes the cornea and the conjunctiva – the mucous membrane that covers the front of the eye and the inside of the eyelids;
• A bottom (mucin) layer that helps spread the aqueous layer across the eye to ensure that the eye remains wet.