Evaluation of the canalicular entrance into the lacrimal sac: an anatomical study.

PURPOSE: The purpose of this study was to investigate the prevalence of a common canalicular entrance in the lacrimal sac and to investigate the anatomy of the canalicular/lacrimal sac junction with direct visualization using a novel cadaveric dissection technique. METHODS: Preserved cadavers were dissected to allow direct visualization of the canalicular entrance(s) to the lumen of the lacrimal sac. The prevalence of a common canaliculus and the anatomical variations of the canalicular/lacrimal sac mucosal fold of tissue were recorded. RESULTS: One hundred twenty-four lacrimal systems (95 cadavers; 43 female, 52 male) were included in the study analysis. Overall, 123 lacrimal systems demonstrated a common canaliculus entering the lacrimal sac. Only one demonstrated 2 separate orifices (right orbit; male) in the sac (0.08%; 95% confidence interval, 0.1%-4.4%). Seventy-four lacrimal systems had some variation of a canalicular/lacrimal sac mucosal fold (59.7%). The remaining 50 (40.3%) had no visible canalicular/lacrimal sac mucosal fold. CONCLUSIONS: This study provides direct anatomical evidence that the prevalence of separate canalicular orifices in the lacrimal sac is lower than previously reported (<1%). Additionally, the presence of a valve-like structure at the canalicular/lacrimal sac junction is common. These observations can potentially play a role in evaluating and treating lacrimal system pathology.