Intra-Sac Portion of the Lacrimal Canaliculus.

Purpose: The aim of this study was to examine the length and diameter of the intra-sac portion of the lacrimal canaliculus and to propose a modified functional valve model at the common internal ostium. Methods: We examined 14 eyelid and orbital specimens from 10 cadavers (seven right, seven left; aged 45-85 years at death), fixed in 10% buffered formalin. Sliced specimens were dehydrated and embedded in paraffin, cut into 7 μm thickness sections, and stained with Masson's trichrome. We then measured the length and diameter of the intra-sac portion of the lacrimal canaliculus. Results: The average length of the intra-sac portion of the lacrimal canaliculus was 1344.9 μm (range, 920.2-1821.5 μm), and its average diameter was 287.5 μm (range, 199.1-523.3 μm). Conclusion: The intra-sac portion of the lacrimal canaliculus had an average length and diameter of 1344.9 μm and 287.5 μm, respectively. The lacrimal sac mucosa changes its thickness with autonomic stimulation, and the length and diameter of the intra-sac portion of the lacrimal canaliculus is likely changed concurrently. The long length and small diameter of the intra-sac lacrimal canaliculus presumably contribute to it acting as an autonomic functional valve at the common internal ostium. [ABSTRACT FROM AUTHOR]