ABSTRACT
<p><b>OBJECTIVE</b>To explore the intranasal surface localization of the lacrimal sac in endoscopic dacryocystorhinostomy.</p><p><b>METHODS</b>Fifteen adult cadavers (30 sides) were studied, the data of projection position of the lacrimal sac on the lateral wall of nasal cavity were measured.</p><p><b>RESULTS</b>In 2/3 cadavers, the lacrimal sac is located above the axilla of the middle turbinate, and 1/3 lies below it. A majority of the lacrimal sac (2/3) are located below the entry point of the common lacrimal canaliculus, about 1/3 lies above it. Inner canthal ligament projects on the middle of the lacrimal sac, almost equal to the level of common lacrimal canaliculus. Thirty-two cases (thirty-nine sides) of chronic dacryocystitis were followed-up > 6 months after operation. Thirty-five sides were cured, 2 sides improved and 2 sides ineffective. The cure rate was 89.8%, improve rate 5.1% and ineffective rate 5.1%, respectively, and the total effective rate was 94.9%.</p><p><b>CONCLUSIONS</b>The central position of dacryocystorhinostomy should be 0.2 cm above the front of the axilla of the middle turbinate, to make an curved mucous membrane incision 0.8 cm above and 0. 4 cm below the front of the axilla of the middle turbinate and bone ostium about 1.2 cm x 1.0 cm. It is the best position in endoscopic dacryocystorhinostomy. Locating the inner canthal ligament with a bayonet type forceps to find the projection of lacrimal sac is also a simple and easy method.</p>