Why do eyes need to be moist?

Question

Why do eyes need to be moist? Why do we feel discomfort from dry eyes?

Answer 1

If they're not, every time you blinked, you'd erode at your cornea until there was nothing left.

Answer 2

The "moisture" you refer to serves a variety of functions. It acts to lubricate and protect the eye  - enabling a quick closure of the lids in the presence of grit preserves the epithelial cells of the anterior eye. The tears also contain lysozyme, a natural anti bacterial enzyme which deals with the nasty bugs our eyes encounter daily and washes away debris everytime we blink. Additionally, the tear layer helps the optics of our eyes and allows us to maintain clearer vision by working harmoniously with the lens and corneal optical systems of the eye..