CIMDL must be readily recognized by clinicians to provide appropriate treatment. Immunosuppressive therapy has no role in the treatment of CIMDL. Only abstinence can interrupt the progression of the disease.

Purpose External dacryocystorhinostomy (EXT-DCR) is a surgical approach commonly used to treat post-canalicular acquired lacrimal obstruction whose success rate has been described, equally with endoscopic DCR, to be superior to other available treatments. Methods At San Raffaele Hospital, Milan (Italy), from January 2008 to December 2020, 245 EXT-DCRs were performed. All patients underwent routine pre-operative work-up including Jones tests and probing and irrigation of the lacrimal pathway; when necessary, a multidisciplinary approach with nasal endoscopy was performed. The surgical approach was followed by positioning of a bicanalicular stent which was left in place for 6 months. Success was defined as resolution of clinical signs/symptoms and free lacrimal flow on functional test. Results Of the cases enrolled, 26.9% were treated for recurrent epiphora (group 1), and 73.1% for epiphora associated with chronic dacryocystitis (group 2). After a median follow-up of 71 months, group 1 had success at T0 (1 month) and T1 (long-term) of 81.8% and 60.6%, respectively, compared to 93.8% and 77.7% in group 2. Statistical analysis showed a significant association with surgery both at T0 ( p = 0.018) and T1 ( p = 0.012) with group 2 showing better outcomes. Additionally, the cosmetic outcome of the external scar was defined as invisible in 91.8% of cases and slightly visible in 8.2%. Conclusions External dacryocystorhinostomy provides long-term reliable results particularly in case of chronic dacryocystitis. Moreover, the optimal esthetic outcome of the external scar should be no longer considered the only guiding principle of treatment modality, particularly in the elderly.

Our case adds NLDO to the long list of complications arising from dental impactions, highlighting the importance of correct early management of the latter condition. This case also shows that dental impaction can be included among the secondary mechanical causes of NLDO.