MARGINS OF SAFETY IN DACRYOCYSTORHINOSTOMY

We attempted to clarify the anatomic relationships of the lacrimal sac by performing standard orbital dissections to expose the lacrimal can aliculi, lacrimal sac, the ethmoid air cells, nasal septum, frontal si nuses, and the cribriform plate in five human cadaver heads; and then measuring the distance between the internal common punctum (ICP) and f ive key structures. The mean vector distance from the ICP to the anter ior aspect of the cribriform plate was 25.1 +/- 2.95 mm. This measurem ent, along with the others, helps clarify osteotomy placement for dacr yocystorhinostomy, so that, for example, cerebrospinal fluid leak can be prevented. Improved understanding of the anatomy of this region is also valuable in planning surgery for orbital and naso-orbital tumors, trauma, and congenital abnormalities.