Evaluation and Management of Congenital Nasolacrimal Duct Obstruction

Congenital nasolacrimal duct obstruction (NLDO) is a blockage of the lacrimal drainage system and the most common cause of persistent tearing and ocular discharge in infants and young children. The anatomic site of obstruction is an imperforate membrane at the valve of Hasner located at the distal end of the nasolacrimal duct. The obstruction can be unilateral or bilateral, and signs usually consist of epiphora, discharge, and an increased tear lake. Although most cases resolve spontaneously by age 6 months, several effective treatment options exist for persistent cases. Because of the high rate of resolution, conservative measures are preferred before considering surgical treatment. Recent studies assist the clinician in selection and timing of treatment. Endoscopy has become an important diagnostic and therapeutic tool in patients with anomalous anatomy and surgical failures.

Epidemiology and Risk Factors

Epidemiology

NLDO is diagnosed in up to 6% of newborns, although evidence of impaired lacrimal drainage reportedly exists in up to 20% of infants during the first year of life. Signs of NLDO occur early, with one study reporting 95% of children with NLDO were symptomatic in the first month of life. There is an age-dependent decrease in the rate of spontaneous resolution, with 90% of cases resolving spontaneously by 6 months of age. For cases persisting to 6 to 10 months, about 66% demonstrate resolution. NLDO beyond 1 year is less likely to resolve spontaneously.

Most patients have unilateral NLDO, although about 31% have bilateral disease. Unilateral obstructions appear to resolve slightly earlier than bilateral obstructions. One study found that in infants with NLDO, 38% affected the right eye and 32% affected the left eye. Males and females are equally affected. However, males have symptom resolution slightly earlier than females, which has been hypothesized to be secondary to an anatomically larger nasolacrimal fossa.

Risk Factors

Prematurity may be a risk factor for the development of NLDO, and some degree of blockage has been observed in 16% of premature infants. Bilateral obstruction has been observed in extremely premature children, with the percentage affected inversely correlated with gestational age. Patients with midface anomalies also have higher rates of NLDO. One study found NLDO to be present in almost 22% of patients with Down syndrome. Patients with Down syndrome were found to have distal sites of obstruction, in addition to higher rates of canalicular atresia and stenosis. Children with mandibulofacial dysostosis are also at increased risk of NLDO, and high rates of punctal atresia have been found in this patient population.

Pathophysiology

The nasolacrimal system begins development at gestational day 32. Initially the ectoderm thickens within the nasooptic fissure. This thickened ectoderm resides between the nasal and maxillary processes and eventually becomes more well differentiated. As it extends, an upper branch forms the canaliculi and a lower forms the nasolacrimal duct. Canalization is already occurring in the 60-day embryo. The interface between the distal end of the nasolacrimal duct and the mucus membrane of the inferior meatus, known as the valve of Hasner, is the last point in the ductal system to become patent ( Fig. 11.1 ).

Perhaps not coincidentally, the valve of Hasner is the most common site of obstruction. An assessment of stillborn infants found that 73.3% did not have a patent nasolacrimal passage to the nose. More complicated sites of obstruction include diffuse stenosis of the nasolacrimal duct, intranasal mucoceles/dacryocystoceles, and proximal outflow dysgenesis occurring concurrently with distal obstruction.

Diagnosis

Symptoms of NLDO are often observed within the first weeks of life. The three hallmark signs are epiphora, mucoid discharge, and increased tear lake. Each may present in varying degrees. One study showed that 95% of patients had an increased tear lake, 80% had epiphora, and 68% had mucoid discharge, whereas another study found tearing was the main presenting symptom in 93.4%. Lack of irritation or photophobia is an important consideration when differentiating from other causes of tearing and discharge.

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