A blocked treat duct describes a partial or complete obstruction in the duct system that carries tears away from the surface of the eye to the nose.

Tears from the surface of the eye are normally drained into the nose by a convoluted tube called the nasolacrimal duct. If this duct is blocked, the tears will accumulate and overflow onto the cheek, even when a person isn't crying.

In children, the duct may not be completely developed at birth. This often resolves on its own. In adults, the duct can be damaged by infection, injury or tumor.

The symptom is increased tearing, which overflows onto the face or cheek.

• Standard ophthalmic exam
• Internal examination of the nose
• Fluorescein eye stain to observe the drainage of tears
• Special X-ray studies may be done to study the duct

For children with incomplete nasolacrimal duct development, massaging the lacrimal sac area several times a day, as instructed by an ophthalmologist, may be enough to open the tear duct. Persistent cases may require opening by a probing procedure. This may occasionally require anesthesia.

Adults require treatment of the cause of the obstruction. This may re-open the duct if there is minimal damage. Often surgical reconstruction (dacryocystorhinostomy) will be needed to re-establish normal tear drainage and stop the overflow onto the cheek.

Congenital tear duct blockage often clears spontaneously by 6 months of age. If it does not clear on its own, the outcome is still likely to be good with treatment.

Tear duct obstruction in adults has a variable outcome depending on the cause.

Tear duct blockage may increase the risk of eye infections.

Anyone with tear overflow onto the cheek requires examination, since one of the possible causes is a tumor. Earlier treatment is more successful, and may be lifesaving.

Many cases cannot be prevented. Adequate treatment of nasal infections and conjunctivitis may reduce risk. Safety measures may reduce the risk of trauma.