Purpose
Radioiodine therapy, a standard treatment for differentiated thyroid carcinomas, is associated with several adverse events including lacrimal drainage system obstruction. Herein, we describe the first case of duct lumen recanalization using dacryoendoscopy for lacrimal passage obstruction and stenosis after radioiodine therapy. Observations: A 48-year-old female treated with radioiodine therapy for differentiated thyroid carcinoma 5 years prior presented with epiphora in both eyes. Dacryocystography showed nasolacrimal duct stenosis in the right eye and nasolacrimal duct obstruction in the left eye. Dacryoendoscopic examination revealed right common canalicular polyps, fibrosis in the right lacrimal sac, right nasolacrimal duct stenosis, and left upper and common canaliculus stenosis. Lacrimal passage recanalization with the insertion of a nasolacrimal stent tube using dacryoendoscopy was performed on the right eye. This successfully resolved the epiphora. Conclusions and importance: Dacryoendoscopic examination for epiphora after radioiodine therapy may help detect early-stage nasolacrimal passage obstruction/stenosis. This condition can be resolved by recanalization and insertion of a lacrimal tube, without the need for a more invasive surgical approach such as dacryocystorhinostomy.