Tears are produced by the lacrimal and eyelid glands and are responsible for protecting and keeping the eye moist. When the ducts responsible for draining the tears become clogged or closed, excessive tearing occurs. Blockages occur in one of three areas:

Blockage of the tear drain in the nose (nasolacrimal duct obstruction)
Blockage of the tear drain in the eyelid (canalicular obstruction)
Blockage of the tear drain opening on the eyelid margin (punctal stenosis)
Tearing is common. It also can be associated with other conditions, such as allergy, inflammation or medication, that only temporally cause tear duct blockage. Therefore, allergy or inflammation should be treated first in patients who have these conditions before considering surgical interventions.

In infants, tear duct obstruction is usually caused by a thin membrane blocking the opening of the tear duct in the nose. This typically resolves itself before the child is one year old. During this time, the infant is treated conservatively with massages of the lacrimal system. If the problem persists or causes infection, it may be necessary to open the blocked tear duct surgically.

In adults, a blocked tear duct rarely resolves itself when not caused by allergy, inflammation, infection or medication. It usually necessary to have surgery to open the blocked tear duct. Tear duct surgery options include:
Tear duct intubation (stenting) – For narrowed punctum, canaliculus or tear duct (usually related to medication), tubes (or stents) can be placed in the tear ducts for a few months to prevent further or permanent scarring. This procedure is done in the operating room under either intravenous sedation or general anesthesia, depending on the patient's comfort level. Tube removal is performed in the office and is painless.
Dacryocystorhinostomy (DCR) – If damage to the tear duct is irreparable, an alternative communication needs to be created between the tear sac and the nose to allow tears to bypass the blockage and drain. This procedure is performed in the operating room under general anesthesia. It also involves placing tubes (or stents) in the lacrimal ducts for a few months. Tube removal is performed in the office and is painless. The success rate is 90-95%.
Jones Tube placement (cDCR) – When there are no open lacrimal canaliculi in the eyelids, a rigid plastic tube (the Jones tube) is placed in the inner corner of the eye into the nose. This Jones tube will stay in place permanently, although occasionally it needs to be replaced or adjusted. This procedure is usually the last resort, as the success rate is 50%.