Primary acquired nasolacrimal duct obstruction (PANDO)

Primary acquired nasolacrimal duct obstruction or PANDO is a chronic inflammatory cause of nasolacrimal drainage apparatus obstruction. 

Epidemiology 

Most commonly seen in middle-aged or elderly women.

Pathology

Aetiology 

The exact cause is still not very well known however it thought to be due to the combination of inflammation, obstruction, and stasis factors. One recent study showed that Gram-negative organisms in particular coagulase-negative Staphylococci, non spore forming anaerobe, gram-positive rods and Pseudomonas aeruginosa were frequently isolated but regardless of what the initial insult is, inflammation causes congestion and oedema worsen the narrowing of the passage.

A congenitally narrow bony canal in some patients (particularly in females) can contribute to this process. Stasis of tears in lacrimal sac predisposes to further inflammation and infection. The more incidence of PANDO in females has been attributed to narrower bony duct size and hormonal changes resulting in shedding of epithelial cells into the canal during menopause.  

Location

PANDO manifests as gradual chronic inflammation and fibrosis along the entire length of the nasolacrimal duct initially more prominent at the sites of physiological narrowing such as the valve of Rosenmuller, the junction between the lacrimal sac and duct. Stenoses develop at symmetrical locations on both sides but usually with lagging of stenosis in one side several years behind the other side so one-sided epiphora is still the most common presentation. The gradual obstruction leads into chronic dacryocystitis with several bouts of acute exacerbations.

Radiographic features

Imaging is not usually required for diagnosis or pre-treatment assessment. But CT scan is recommended after initial balloon dilatation and in recurrent cases. 

Treatment and prognosis

Initially, any infection should be treated with appropriate antibiotics like ciprofloxacin then probing or balloon dacryocystoplasty which usually has a successful outcome. Finally, dacryocystorhinostomy can be performed (an opening is made surgically between the lacrimal sac and nasal cavity proximal to the obstruction).