Endoscopic dacryocystorhinostomy: anatomical approach

Dacryocystorhinostomy is the surgical treatment for nasolacrimal blockage. In recent years, the endoscopic approach has become more popular due to the development of nasal endoscopes and the ease of surgery in comparison to the external approach. In order to identify the lacrimal duct during surgery, surgeons insert a light pipe into the lacrimal duct and then drill or chisel the hard bone of the frontal process of the maxilla to remove the bony covering of the sac and duct. It is obvious that knowledge of the anatomy of the lacrimal sac/duct within the nose is essential for the surgeon. The lacrimal apparatus in the nose was studied using 10 cadaveric half-heads (5 males and 5 females) to establish the anatomical landmarks and most accessible part of the lacrimal duct from within the nose. Although there was solid bone covering the whole length of the sac and the duct, the posteromedial aspect of the lower sac and upper duct was covered by the ultra thin lacrimal bone (average thickness 0.057 mm) which was consistently found to be lying immediately anterior to the uncinate process in the middle meatus, thus constituting a "surgical window" (average size 2.5 mm x 7.2 mm) whereby surgical entry into the lacrimal duct becomes relatively easy. The lower part of the lacrimal sac and the upper part of the lacrimal duct can therefore be easily accessed from within the nose by following this anatomical approach, thus avoiding the need to drill or chisel the dense frontal process of the maxilla.