Contributor: Gordon K. Klintworth
Most cases of dacrocystitis are infectious. The infection spreads to the lacrimal sac from adjacent structures (conjunctiva, nose, and paranasal sinuses). Dacrocystitis is a common complication of conjunctivitis. Aerobic or facultative bacteria, in particular Staphylococcus, are the most common species isolated from pathologic samples with dacrocystitis. Infection is usually preceded by obstruction of the nasolacrimal duct and may occur in any age group. Congenital impatency of the nasolacrimal duct occurs in 3 to 6 percent of term infants. In most of these cases, the nasal end of the duct is blocked by epithelial debris or an imperforated mucosal membrane resulting from incomplete canalization of the embryonic duct. Primary acquired nasolacrimal duct obstruction usually occurs in middle-aged adults with a 3:1 female preponderance and is rare among blacks. Acute dacryocystitis is uncommon in infants and children. It can be congenital due to congenital impatency of the nasolacrimal duct or it can be acquired nasolacimal duct obstruction. Obstruction is thought to be the result of inflammation of the ductal mucosa with progresses to scarring, fibrosis, and eventually obliteration of the lumen due to infectious, inflammatory (both endogenous and exogenous), neoplastic (primary, secondary, and metastatic), traumatic, and mechanical etiologies.

The organisms responsible for dacryocystitis may differ in acute and chronic infections. In severe acute dacryocystitis, involving gram-negative rods (Pseudomonas aeruginosa, Proteus mirabilis, Haemophilus influenzae) or Staphlococcus aureus. In chronic dacryocystitis, mixed bacterial isolates are more commonly found with Streptococcus pneumoniae and staphylococcus spp. predominating. Fungal infections caused by Candida albicans and Aspergillus occur infrequently. Patients with trachoma may have subclinical dacryocystitis leading to submucosal fibrosis and obstruction of the nasolacrimal duct.