Morphometric Measurements of Bony Nasolacrimal Canal in Children

Etiopathogenesis of primary acquired nasolacrimal duct obstruction (PANDO)

Primary acquired nasolacrimal duct obstruction, or PANDO, is a common adult lacrimal drainage disorder. The current treatment modality of dacryocystorhinostomy to bypass the obstructed nasolacrimal duct has excellent outcomes. However, the understanding of the disease etiopathogenesis needs to be revisited. There are not many studies that specifically assessed any hypothesis or ones that convincingly put forth the presumed or confirmed interpretations regarding the PANDO pathogenesis or the mechanisms or pathways involved therein. Histopathological evidence points to recurrent inflammation of the nasolacrimal duct, subsequent fibrosis, and the resultant obstruction. The disease etiopathogenesis is considered multifactorial. Several implicated suspects include anatomical narrowing of the bony nasolacrimal duct, vascular factors, local hormonal imbalance, microbial influence, nasal abnormalities, autonomic dysregulation, surfactants, lysosomal dysfunction, gastroesophageal reflux, tear proteins, and deranged local host defenses. The present work reviewed the literature on the etiopathogenesis of primary acquired nasolacrimal duct obstruction (PANDO) to gain insights into the present state of the understanding and the high-value translational implications of precisely decoding the disease etiology.

Complex Stenoses and CT Features of the Nasolacrimal Canal in Congenital Nasolacrimal Duct Obstruction

PURPOSE

To study the CT appearance of the nasolacrimal canal (NLC) in cases of congenital nasolacrimal duct obstruction (CNLDO) where there is a tactile sensation of a hard contact (HC) stop in the duct preventing stent intubation.

METHODS

The authors retrospectively reviewed all consecutive cases of chronic CNLDO observed between 2003 and 2018 in which an apparent HC obstruction prevented nasolacrimal intubation. CT scans were reviewed to determine the cause of probing failure: distal stenosis, loss of parallelism of the NLC walls, abnormal angulations or an adjacent obstacle blocking tear outflow.

RESULTS

Nine patients (12 sides) met the following criteria: CNLDO + HC + probing failure. The mean age at the time of the first HC was 3.9 years (range: 0.8-8.1 years) and at the time of a second confirmation of HC with subsequent dacryocystorhinostomy was 7.8 years (range: 4.1-9.2 years). Nasolacrimal duct opacification was noted in 33% of cases (4/12). Abnormalities of the NLC occurred in 8 of the 12 cases of CNLDO (8/12 = 66.6%) and on the asymptomatic side in 1 case (1/6 = 16.6%). A canine tooth bud situated in the same plane as the NLC was observed in 9 cases of CNLDO (9/12 = 75%) and on the asymptomatic side in 2 cases (2/6 = 33.3%).

CONCLUSIONS

HC noted during probing is a sensitive but relatively nonspecific sign which, nevertheless, does indicate either a complex obstruction or at least potential intubation difficulties. As confirmed by CT imaging, a significant anatomical variant is not necessarily predictive of epiphora, but nevertheless may complicate the intubation procedure.The authors describe hard contact palpation during probing for CLNDO and its relationship to anatomic location and etiologies of obstruction in the nasolacrimal canal by CT imaging.