A well-distributed, high-quality tear film is necessary for the correct functioning of the eye. In the tear apparatus a good function of all of its parts is necessary; more specifically the lacrimal glands, eyelids and tear ducts. The eye and nose are connected by a gentle duct serving for the drainage of excess tears into the nose. In some cases, due to frequent inflammations, injury or congenital narrowness this duct gets obstructed. This condition is manifested in excessive tearing (epiphora) and associated infections due to blockages in the lacrimal bag which is located at the beginning of the duct.

In cases where the inflammation can not be resolved by antibiotic therapy and the flow of the ducts can't be restored an operation called dacryocystorhinostomy (DCR) can be performed. This is a surgical procedure that re-establishes continuity in the nasolacrimal duct allowing the drainage of excess tears from the eye in the tear bag through tear ducts into the nasal cavity. During the procedure a silicone tube is incorporated in the duct and left in the eye during six months. The procedure is done under general anesthesia, and the first control is usually scheduled next morning. In seven days the patient can usually return to work.

. In the cases of congenital nasolacrimal duct obstruction if the tear duct does not open spontaneously with a massage and proper hygiene, in the second year of life probing under general anesthesia has to be performed. If the duct fails to open after the surgery if performedt, probing is repeated with the installation of a silicone tube.