Excessive tearing can result from several causes, including: a blocked tear duct, abnormal eyelid position, and (ironically) chronic dry eyes. Regardless of the cause, chronic tearing is annoying, at best, and frequently unhealthy for the eyes.
To understand the problem, it helps to understand how our tearing system works. Small glands under the eyelids produce tears. Those tears are eliminated by evaporation and drainage. With each blink, the tear is guided over the lower eyelids and then drained through a tiny tear duct opening located in the inner corner of the eyelid. The tear is then removed through the main tear drainage duct located within the bony portion of the nose.
An abnormality in any part of this system can cause the tearing problem. A common cause is blockage of the tear drainage duct. When this happens, the patient suffers from chronic tearing as well as associated infection in the eyes. An infection within the tear duct can be quite painful. In such cases, initial treatment with an antibiotic is needed, followed by surgical correction to open the blocked tear duct.
Another common cause of tearing is lower eyelid changes where the eyelid either turns in or out. When the eyelid turns in (entropion), the eyelashes irritate the eye, resulting in tearing, pain, and sometimes infection. When the eyelid turns out (ectropion), the poor protection over the eye surface results in similar symptoms. These eyelid abnormalities can be corrected with outpatient surgery.