To assess the relationship between the internal diameter of the nasolacrimal duct and the success rate of silicone tube intubation in incomplete nasolacrimal duct obstruction patients with epiphora.

Dacryocystography was performed 80 patients with symptoms of epiphora and the anteroposterior (AP) diameters and the lateral diameters of the nasolacrimal ducts were measured. These measurements were compared between the group of patients who demonstrated improvement after the operation, and the group without symptom improvement.

The mean length of the nasolacrimal duct in the group with nasolacrimal stenosis was 11.7±0.1 mm, the mean lateral diameter was 1.0±0.2 mm, and the mean AP diameter was 1.1±0.1 mm. The AP diameter of the symptomatic nasolacrimal duct in the group with successful postoperative results was 1.1±0.1 mm, and 0.9±0.1 mm in the group with unsuccessful results. The group with successful postoperative results had an average of 18.1±7.0% stenosis in the side of the eye with nasolacrimal duct stenosis compared with the asymptomatic side, and the group with unsuccessful postoperative results had an average of 34%±3.6% stenosis.

In cases with nasolacrimal duct stenosis, the success rate of silicone tube intubation was high when the AP diameter of the nasolacrimal duct was more than 1.1±0.1 mm and when the stenosis was less than 18.1±7.0% in the symptomatic side compared with the opposite side. These results are expected to help predict the success rates when preoperatively planning silicone tube intubation.