Pathology of the lower nasolacrimal duct mucosa at multiple time points after lacrimal retrograde catheterization in rabbit.

Lacrimal duct obstruction is a common eye disease, and obstruction of the nasolacrimal duct accounts for over 50% of these cases. Nasolacrimal duct obstruction is usually treated surgically. Lacrimal retrograde catheterization is a novel surgical approach with a high success rate and a relatively high recurrence rate. In this study, we examined the postoperative pathological changes in the lower nasolacrimal duct mucosa at multiple time points (2, 4, 6, 8, 10, 12, and 14 weeks) after retrograde lacrimal dilated drainage tube implantation in rabbits. One side of the nasolacrimal duct was obstructed in 14 rabbits. Compared to the control side, the 2-, 4-, 6-, and 8-week groups presented no obvious changes in hematoxylin and eosin (H&E)-stained tissue. The 10-week group presented isolated granulomas. The 12- and 14-week groups presented scattered granulomas. The granulomas were smaller and the density of fibroblasts was lower in the 12-week group compared with the 14-week group. Transforming growth factor-β1 immunohistochemistry resulted in strong immunoreactivity in the 14-week group and weak immunoreactivity in the 12-week group, and the difference was statistically significant (P < 0.05). Fibroblast apoptosis was observed in the 4- and 6-week groups, and disorganized fibers were observed in the 10-week group. Most fibroblasts in the 12- and 14-week groups were the active type with mechanocytes. Granulomas were induced after a long time by the implantation of silicone tubes in rabbits. Thus, recurrent obstructions of the nasolacrimal duct may be caused by granulomas, progressive fibrosis, and/or adhesion of the surrounding tissues.