nasolacrimal duct surgery
Many children are born with an underdeveloped tear-duct system, a problem that can lead to tear-duct blockage, excess tearing, and infection. Blocked tear ducts are common in infants; as many as one third may be born with this condition.
Eyelids move tears across the eyes. Tears keep the eyes lubricated and clean. They drain out of the eyes through two openings (puncta, or lacrimal ducts), one on each of the upper and lower lids.
From these puncta, tears enter small tubes called canaliculi or ducts, located at the inner corner of the eyelids, then pass into the lacrimal sac, which is next to the inner corner of the eyes.
From the lacrimal sacs, tears move down through the nasolacrimal duct and drain into the back of the nose. When you blink, the motion forces the lacrimal sacs to compress, squeezing tears out of them, away from the eyes, and into the nasolacrimal duct.
The nasolacrimal duct and the lacrimal ducts are also known as tear ducts. However, it's the nasolacrimal duct that's involved in tear-duct blockage.