Tears are produced by the lacrimal glands to keep the eye moist and
to wash away dust, dirt, germs, and other irritating substances. Tears are
formed to keep the eye moist under normal conditions and also in response to an
irritant (such as an eyelash in the eye) or emotion.
For a person to see well, he or she must produce enough tears to
keep the eye moist, and have a drainage system for tears that functions
properly. When tears cannot drain from the eye, they frequently build up around
the eyeball and flow down the cheek or nose.
