Three-dimensional volumetric assessment of the nasolacrimal duct in patients with obstruction.
Academic Article
Overview
abstract
PURPOSE: The purpose of this study was to determine if a significant difference exists in the nasolacrimal duct volume of subjects with primary nasolacrimal duct obstruction compared with that of controls. METHODS: This was a retrospective, case-control study of 70 subjects with prior maxillofacial CT scans, including 35 subjects with obstruction and 35 controls. Volume measurements of the nasolacrimal duct were made on a GE Advantage Workstation using volume viewer software, and measurements were compared using an unpaired Student t test. Interrater and intrarater reliabilities were calculated. RESULTS: There was no significant difference in the nasolacrimal duct volume of patients (0.411 ± 0.18 cm) compared with that of controls (0.380 ± 0.13 cm(3)) (p = 0.23). Women had smaller volume ducts (0.356 ± 0.11 cm(3)) than that of men (0.482 ± 0.19 cm(3)) (p < 0.001). Male patients had smaller volume ducts (0.470 ± 0.23 cm(3)) than that of male controls (0.493 ± 0.14 cm(3)) (p = 0.70), while female patients (0.384 ± 0.13 cm(3)) had significantly larger volume ducts than that of female controls (0.328 ± 0.08 cm(3)) (p = 0.01). There was excellent interrater and intrarater reliabilities. CONCLUSIONS: CT 3-dimensional volumetric software can be used to accurately measure the nasolacrimal duct volume in patients with obstruction. Both the absence of a significant difference in patient's and control's nasolacrimal duct volumes and the overlap in range between the 2 groups imply that the volume of the tear duct is likely not related to the etiology of obstruction. The increase in volume seen in females with obstruction may be due to expansion of the bony canal during the postmenopausal years. The exact etiology of primary nasolacrimal duct obstruction requires further investigation.
