Endoscopic dacryocystorhinostomy: anatomical approach

Area of Science:

• Anatomy
• Otorhinolaryngology
• Ophthalmology

Background:

• Dacryocystorhinostomy (DCR) is surgery for nasolacrimal duct obstruction.
• The endoscopic approach is increasingly favored over external methods.
• Current endoscopic DCR requires drilling or chiseling the maxilla's frontal process to access the lacrimal sac and duct.

Purpose of the Study:

• To identify anatomical landmarks for easier endoscopic dacryocystorhinostomy.
• To determine the most accessible part of the lacrimal duct from within the nasal cavity.
• To establish a less invasive surgical entry point for DCR.

Main Methods:

• Study of 10 human cadaveric half-heads (5 male, 5 female).
• Detailed anatomical dissection and measurement of the lacrimal apparatus within the nasal cavity.
• Identification of bony structures overlying the lacrimal sac and duct.

Main Results:

• The lacrimal sac and duct are covered by bone, primarily the frontal process of the maxilla.
• A thin lacrimal bone (average 0.057 mm thickness) covers the posteromedial aspect of the lower sac and upper duct.
• This thin bone forms a consistent "surgical window" (average 2.5 mm x 7.2 mm) anterior to the uncinate process in the middle meatus.

Conclusions:

• The posteromedial lacrimal bone provides an accessible "surgical window" for endoscopic DCR.
• This approach facilitates easier entry into the lacrimal duct.
• It allows surgeons to bypass the need to drill or chisel the dense frontal process of the maxilla, simplifying the procedure.