To investigate the clinical characteristics and dacryoendoscopic findings and clinical efficacy of silicone tube intubation in the patients who referred to our hospital due to failed with conventional silicone tube intubation. Methods:We retrospectively reviewed the medical records of 61 cases from 50 patients who underwent silicone tube intubation or endo-dacryocytorhinostomy using dacryoendoscopy from January 2016 to May 2021. Clinical characteristics, tear meniscus height, lacrimal irrigation test, dacryocystographic findings, dacryoendoscopic findings and surgical outcomes were evaluated. Results:The study included 12 males and 38 females (mean age 64.1 ± 13.2). In the preoperative lacrimal irrigation test, passage was found in 33 eyes (54.1%) and no passage in 28 eyes (45.9%). The causes of lacrimal duct obstruction were stenosis (31.1%), mucus (27.9%), membrane (24.6%), granulation (13.1%), stone (3.3%) in order and the location were nasolacrimal duct (39.3%), lacrimal sac (36.1%), canaliculus (21.3%), inferior meatus (3.3%) in order. As for the characteristics of obstruction, the secretory type was 21 eyes (34.4%) and structural change type was 40 eyes (65.6%). The silicone tube intubation group consisted of 57 eyes (93.4%) and endo-dacryocytorhinostomy consisted of 4 eyes (6.6%). The overall success rate was 83.9%. Clinical results were correlated with dacryoendoscopic finding (P=0.015), but not with lacrimal irrigation test or dacryocystography. The structural change type had a higher surgical success rate than the secretory type (84.4% vs. 66.7%, P=0.015). In particular, the structural change type showed higher success rate than the secretory type below the lacrimal sac (95.5% vs. 61.9%, P=0.034). Conclusion:Silicone tube intubation using dacryoendoscopy has a higher surgical success rate than conventional silicone tube intubation since dacryoendoscopy provides direct visualization of nasolacrimal duct obstruction. It could be useful in increasing the surgical success rate in patients with structural changes below lacrimal sac.