What are tears made of?

Tears are primarily made of salt water, mucus and oil. Certain minerals and vitamins necessary to normal cell function are also present. Tears also contain natural bacteria-fighting agents called lysozymes.

The cornea is a clear, dome-shaped lens that covers the iris and the pupil of the eye. It provides a shield, protecting the inner eye from dust, germs and other foreign matter. Since the cornea has no blood vessels, tears provide a way of bringing nutrients to its cells. Tears also keep the surface of the cornea moist and clean. The oil in tears prevents evaporation, allowing the eyes to stay moist longer, while the mucus binds the tear layer to the surface of the eye.