Objective: By simulating transnasal endoscopic resection of nasolacrimal duct and lacrimal sac on cadaveric
specimens with vascular perfusion, the basic process of this procedure and the anatomical relationship between
nasolacrimal duct and lacrimal sac were explored, providing anatomical basis for clinical application. Methods: Five
adult cadaver head specimens (10 sides in total) were used for anatomical study. The nasolacrimal duct and lacrimal
sac were exposed under transnasal endoscopy, and the anatomical landmarks and their relationship with adjacent
areas during the resection of nasolacrimal duct and lacrimal sac were observed. Results: Ten sides of nasolacrimal duct and lacrimal sac showed that all lacrimal sacs were located anterior and slightly lateral to the nasal mound. The
roof of lacrimal sac was almost the same height as the roof of nasal mound. The body of lacrimal sac was almost
located above the horizontal line of the middle turbinate axilla. The posterior inner wall of the lacrimal fossa
was composed of lacrimal bone. The posterior inner side of the lacrimal bone was adjacent to the agger nasi cell.
The bottom of the lacrimal sac moved downward as the membranous part of the nasolacrimal duct located in the
bony part of the nasolacrimal duct. The projection of the nasolacrimal duct on the lateral nasal wall was located
about 3–7 mm in front of the anterior edge of the vertical part of the uncinate process. The distance between the
inferior meatus opening of the nasolacrimal duct and the anterior end of the inferior turbinate was (16±3) mm.
The length of the lacrimal sac was (13.8±1.8) mm, and the length of the nasolacrimal duct was (23.2±3.6) mm. Conclusion: The transnasal endoscopic approach can fully expose and resect the nasolacrimal duct and
lacrimal sac. The basic operation process and anatomical landmarks demonstrated in this anatomical study
provide an anatomical reference for the clinical development of transnasal endoscopic resection of nasolacrimal
duct and lacrimal sac.