The nasolacrimal duct is the mucosal-lined channel within the nasolacrimal canal that drains tears from the lacrimal sac into the inferior nasal meatus. The duct is approximately 12-15 mm long and 2-3 mm in diameter, opening at the Hasner valve (plica lacrimalis) in the anterior inferior nasal meatus. It drains the lacrimal sac superior to it via the common canaliculus receiving the upper and lower canaliculi from the puncta.
| Location | In the bony nasolacrimal canal of the lateral nasal wall, running down and slightly back from the lacrimal sac to the inferior nasal meatus |
|---|---|
| Parts |
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| Blood Supply | Infraorbital and sphenopalatine branches of the maxillary artery; Angular artery (upper part) |
Carries tears from the lacrimal sac into the nose, which is why crying makes the nose run. Blockage causes a watery eye and can lead to infection of the lacrimal sac.
Nasolacrimal duct obstruction (NLDO) produces epiphora (overflow tearing) and dacryocystitis from stagnant pooling in the lacrimal sac. Congenital NLDO results from a persistent membrane at the Hasner valve, resolving spontaneously in 90% by 12 months; persistent cases are treated by probing and irrigation. Acquired NLDO in adults from dacryoliths, chronic rhinosinusitis, or trauma is managed by dacryocystorhinostomy creating a new drainage window from the lacrimal sac into the nose bypassing the blocked duct.
Stagnant tears in the blocked nasolacrimal duct produce bacterial infection of the lacrimal sac (dacryocystitis) with medial canthal pain, swelling, purulent discharge from the puncta on pressure, and risk of fistula formation; acute dacryocystitis is treated with antibiotics and warm compresses, and DCR definitively treats the underlying obstruction.
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