Morphometric analysis of bony nasolacrimal canal and sinonasal anatomical variations in primary acquired nasolacrimal duct obstruction.

Objective: This study aims to assess morphometric variations in bony nasolacrimal ducts (BNLDs) and sinonasal anatomy in Asian patients with unilateral primary acquired nasolacrimal duct obstruction (PANDO) through computed tomography (CT).

Methods: We enrolled 34 patients with unilateral PANDO who underwent endoscopic dacryocystorhinostomy, alongside 34 age- and sex-matched control patients without documented epiphora complaints. We compared BNLD and sinonasal parameters on CT images between the affected and unaffected sides of PANDO patients and the control group.

Results: The entrance area of the BNLD was larger on the affected side of unilateral PANDO patients compared to both the unaffected side (p = 0.012) and the control group (p = 0.046). The open angle in the coronal plane was greater on both the affected (p = 0.044) and unaffected side (p = 0.028) than in the control group. Minimal area and distal area in the axial plane showed no differences among the 3 groups. Paranasal parameters did not differ between the study and control groups. More patients in the study group had superiorly located nasal septum deviation than the control group (p = 0.048). A trend suggested that more patients in the study group had anteriorly located nasal septum deviation than the control group (p = 0.056), although not reaching statistical significance.

Conclusion: The increased angular tilt in PANDO patients could impede fluid drainage from a fluidics standpoint. The larger BNLD area on the affected side reflects inflammation-induced osteolysis. Additionally, sinonasal variations, particularly nasal septum deviation at the anterior and superior half, have been identified as contributing to a higher risk of PANDO.