Congenital Nasolacrimal Duct Obstruction
Congenital nasolacrimal duct obstruction (CNLDO) (dacryostenosis) is the most common lacrimal system disorder encountered in pediatric ophthalmology, occurring in approximately 5% of infants, and is more common in patients with Down syndrome (22%) and in those with midfacial abnormalities.
CNLDO can be classified as simple or complex. Simple CNLDO is caused by a thin mucosal membrane at the distal end of the NLD, at the valve of Hasner (Fig 19-4). Complex CNLDO is due to diffuse obstruction or bony obstruction, as is frequently found in patients with midfacial abnormalities.
Clinical Features and Examination
Infants with CNLDO usually present within the first month of life with epiphora, recurrent periocular crusting, or both (Fig 19-5). They do not have photophobia or blepharospasm. Symptoms are usually chronic and worse with nasal congestion; bilateral involvement is common. Applying digital pressure to the lacrimal sac usually results in retrograde discharge of mucoid or mucopurulent material.
Excessive tearing due to CNLDO must be differentiated from epiphora due to infantile glaucoma, which has additional features, including photophobia, blepharospasm, ocular hypertension, corneal clouding with or without enlargement, and breaks in Descemet membrane (see Chapter 22). Besides infantile glaucoma, the differential diagnosis of CNLDO includes conjunctivitis, and epiblepharon with irritation due to trichiasis. A thorough examination is necessary to rule out other ocular abnormalities. A cycloplegic refraction should be performed as results of some studies suggest that there is an increased rate of anisometropia and amblyopia in patients with CNLDO.
A, Typical location of the membrane causing simple nasolacrimal duct obstruction (NLDO) (arrow).B, Diffuse stenosis of the distal NLD.
(Adapted from an illustration by Christine Gralapp.)
Excerpted from BCSC 2020-2021 series: Section 10 - Glaucoma. For more information and to purchase the entire series, please visit https://www.aao.org/bcsc.