Most tears come from lacrimal glands, located above each eye. They flow across the eye’s surface and drain through tiny holes (puncta) in the inner corners of the upper and lower eyelids, down small canals in the lids (canaliculi) to the nasolacrimal sac and down the nasolacrimal duct emptying into the nose.
Nearly 20 percent of newborns have a blocked tear duct, which usually resolves on its own within four to six months. In adults, a tear duct obstruction can result from infection, swelling, age, injury or a tumor. To diagnose the problem, fluid is squirted into the punctum where it will either pass freely into the nose or reflux backwards indicating an obstruction.