Anatomy of lacrimal sac fossa affecting success rate in endoscopic and external dacryocystorhinostomy surgery in Mongolians.

To study the affect of anatomical variance of lacrimal sac fossa on dacryocystorhinostomies (DCR) performed by the traditional external (EX-DCR) approach or an endoscopic (EN-DCR) endonasal approach. A total of 292 consecutive cases with primary nasolacrimal obstruction underwent DCR surgery. Orbital computed tomography scan was used to measure lacrimal sac fossa and other related structures and Lac-Q questionnaire was used to compare surgery result.