What is the nasolacrimal duct?

The nasolacrimal duct (NLD) is the terminal part of the nasolacrimal apparatus. Gross anatomy The nasolacrimal duct is the inferior continuation of the lacrimal sac and is ~17 mm in length in total. The duct runs in the bony nasolacrimal canal….

What happens if the nasolacrimal duct is blocked?

Obstruction of the nasolacrimal duct may occur. This leads to the excess overflow of tears called epiphora (chronic low-grade nasolacrimal duct occlusion). A congenital obstruction can cause cystic expansion of the duct and is called a dacryocystocele or Timo cyst.

What is the prevalence of congenital nasolacrimal duct obstruction?

Congenital nasolacrimal duct obstruction occurs in approximately 5% of normal newborn infants. The blockage occurs most commonly at the valve of Hasner at the distal end of the duct.

How is nasolacrimal duct obstruction diagnosed in dacryocystitis?

If the dacryocystitis is severe, rupture of the abscessed sac through skin can occur. A fluorescein dye disappearance test can be helpful in confirming the diagnosis of nasolacrimal duct obstruction. A drop of fluorescein is instilled into the eyes or introduced on a moistened pledget.

What is the nasolacrimal duct in ear infection?

During an ear infection, excess mucus may drain through the nasolacrimal duct in the opposite way tears drain. The canal containing the nasolacrimal duct is called the nasolacrimal canal . In humans, the tear ducts in males tend to be larger than the ones in females.

How is nasal nasolacrimal duct patency confirmed?

Nasolacrimal duct patency can be confirmed several ways: The distal end of the probe in the nose can be palpated with another probe, achieving metal-on-metal contact. A small bolus of saline can be irrigated through the duct. If the infant is awake, the bolus will illicit a swallowing reflex.