Meet the Lacrimal Sac: Endoscopic Surgeons' Road Map

Area of Science:

• Anatomy
• Ophthalmology
• Surgical Procedures

Background:

• Successful endoscopic dacryocystorhinostomy (endoscopic DCR) relies on precise anatomical knowledge of the lateral nasal wall relative to the lacrimal apparatus.
• Understanding these landmarks is critical for surgeons to navigate the nasal cavity and access the lacrimal sac effectively.

Purpose of the Study:

• To describe key anatomical landmarks on the lateral nasal wall in relation to the lacrimal apparatus.
• To provide precise measurements for guiding surgical approaches in endoscopic DCR.
• To establish a practical guideline, the 'Rule of 10', for nasal mucosal incisions.

Main Methods:

• A descriptive study involving the sagittal sectioning of ten adult cadaver head specimens (right and left sides).
• Detailed measurements of lateral nasal wall anatomical landmarks and the lacrimal apparatus were taken using digital calipers.
• Identification and spatial relationship analysis of structures like the maxillary line, middle turbinate, and lacrimal sac were performed.

Main Results:

• The maxillary line was identified in 75% of specimens, frequently overlapping the lacrimal sac.
• The genu of the middle turbinate was consistently located at or posterior to the nasolacrimal duct.
• Mean measurements for the lacrimal sac: superior end to axilla (8.88 mm), anterior edge to axilla (10.58 mm), and length (11.72 mm).

Conclusions:

• The derived measurements support the application of a 'Rule of 10' for nasal mucosal incision planning in endoscopic DCR.
• A 'Three Tier Approach' (nasal mucosa, bone, sac mucosa) is proposed to effectively expose the lacrimal sac, ensuring successful endonasal endoscopic dacryocystorhinostomy.