Nasolacrimal Duct Probing
Congenital nasolacrimal duct obstruction occurs in approximately 5 % of newborns. The blockage occurs most commonly at the valve of Hasner located at the distal end of the nasolacrimal duct. The rate of spontaneous resolution is estimated to be at 90 % within the first year of life. However, if obstruction does not resolve on its own or with massage, probing may be indicated to ensure patency and even manually open the nasolacrimal passage.
Rush D, Rosenberg ED. Nasolacrimal duct probing. In: Rosenberg ED, Nattis A, Nattis RJ, editors. Operative dictations in ophthalmology. Cham, Switzerland: Springer International Publishing; 2017. pp. 337-9.