A tear duct blockage is a condition that some people are born with or acquire with age, according to Mayo Clinic. It is also sometimes the result of a tumor, cancer treatment, injury to the face, eye infection or medication used to treat a condition such as glaucoma.
Some babies are born with a membrane over the tear duct that doesn't allow tears to flow naturally. In most cases tear ducts open by the time the baby is one or two months old, claims Mayo Clinic. This doesn't affect the baby's vision, says WebMD. On the other end of the age spectrum, punctal openings narrow as a person ages, which causes blockages. The puncta are tiny holes in the lower and upper corners of the eyelids that allow tears to drain into the nasolacrimal ducts.
Trauma to the face sometimes damages the bone structure around the eyes and prevents the tear ducts from working properly, states Mayo Clinic. People who are being treated for cancer sometimes find that their tear ducts no longer function properly due to the side effects of chemotherapy or radiation. Blocked tear ducts also occasionally result from nose surgery, says WebMD. They also occur sometimes if the tear duct lining thickens or due to abnormal issue growth in the nose.