Intranasal localization of the lacrimal sac.

OBJECTIVE To optimize the approach to the lacrimal sac during intranasal dacryocystorhinostomy. DESIGN Microscopic measurement of anatomical landmarks in cadaver sagittal head sections. SETTING The anatomy department of a large university hospital. PARTICIPANTS Twenty adult cadaver sagittal head sections (12 right and 8 left) fixed with 10% formaldehyde solution were evaluated. INTERVENTION During endoscopic dissections, the maxillary line, lacrimomaxillary suture, nasolacrimal duct, and lacrimal sac were exposed. MAIN OUTCOME MEASURES Greater knowledge of the relationship among anatomical structures. RESULTS The entire lacrimal sac was in 2 of 20 sides anterior and in 3 of 20 sides posterior to the axilla of the middle nasal concha. The fornix of the lacrimal sac was situated above the axilla in all sides. We evaluated the localization of the lacrimal sac to the maxillary line, which is of clinical importance in intranasal osteotomy during dacryocystorhinostomy. In 17 of 20 sides it is possible to reveal the axilla of the middle nasal concha during osteotomy. CONCLUSIONS Underexposure or lack of true localization of the sac are the most frequently encountered reasons for dacryocystorhinostomy failure. The maxillary line and adhesion point of the middle nasal concha are the 2 most important landmarks in localization of the sac. A mucosal incision anterior to the maxillary line and dissection up to the point where the middle concha adheres, followed by osteotomy on the lacrimomaxillary suture, nearly always ensure the exposure of the sac.