The normal production of tears in the lacrimal gland develops several days to 2 weeks after birth. Tears cross the cornea, exit via the superior and inferior puncta on the lids, and travel through the nasolacrimal system. Tears reach the nose thru Hasner’s valve, the terminal part of the nasolacrimal duct.
There are 2 physiologic types of tearing. The first is basal tear production, which keeps the eye moist and during normal conditions. The second is reflex tearing, which occurs as a response to eye irritation or emotion. The medical term epiphora is used to describe a condition caused by either an increase in tear production or an obstruction in the nasolacrimal outflow system.
The most common cause of tearing in the neonatal period is nasolacrimal duct obstruction. Most of the time, the obstruction is due to an impatent Hasner’s valve. Infants with congenital NLDO present with a watery eye and an increased tear meniscus, matting of eyelashes, and mucus in the medial canthal area. If left untreated, most obstructed nasolacrimal ducts open spontaneously by 6 months of age. The incidence of spontaneously resolution decreases after 12 months of age.
During the observational period, medical management involves a combination of nasolacrimal sac massage and intermittent topical antibiotics. Antibiotic drops or ointment should not be used if there is no sign of infection, such as mucopurulent discharge.
Probing of the nasolacrimal duct between 6-12 months of age is recommended. This allows time for spontaneous resolution. However, probing should be performed on an urgent basis when there is swelling of the lacrimal sac, a condition called dacryocystocoele.
Nasolacrimal duct probing is a simple but delicate procedure. A very small steel wire is passed thru the nasolacrimal system, through Hasner’s valve, and into the nose. For the child’s comfort, doing the procedure under general anesthesia is suggested. The success rate of probing is approximately 90% particularly when done before 18 months of age. Intubation with silicone tubes is indicated in ducts that fail to open with two probing procedures.