Evaluation of Lacrimal Drainage System in Patients with Unilateral Nasolacrimal Duct Obstruction by Computerized Tomography

This study aimed to evaluate morphometric measurements relevant for surgery in patients with unilateral nasolacrimal duct occlusion on CT images, comparing the sides with and without occlusion. Paranasal sinus computed tomography images of 37 patients (28 females, 9 males) who presented with unilateral epiphora and underwent external dacryocystorhinostomy were retrospectively analyzed. Two radiologists with 25 and 10 years of experience performed measurements. The nasolacrimal duct length, transverse diameter of its narrowest part, vertical length of the lacrimal fossa, thickness of the anterior lacrimal crest, its distance to anterior ethmoidal cells, thickness of the intranasal lateral mucosa, frontonasal angle, and distance between the frontozygomatic sutures were measured and compared bilaterally. The narrowest diameter of the nasolacrimal duct on the occluded side was significantly narrower than on the intact side. There were no significant differences between the occluded and patent sides for other measurements or the interclass correlation results between the two radiologists’ evaluations. Stenosis of the nasolacrimal duct on both sides is observed clinically as chronic dacryocystitis in the same patient. Since the bony window for external dacryocystorhinostomy is determined based on the lacrimal fossa’s vertical width, the data from our study are crucial for surgical planning.