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C. I. Zoumalan, J. Joseph, G. J. Lelli, Jr., K. L. Segal, M. Kazim, R. D. Lisman; Evaluation of the Canalicular System and Lacrimal Sac: An Anatomic Study. Invest. Ophthalmol. Vis. Sci. 2010;51(13):6309.
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It is stated in the literature that 90% of individuals have a common canaliculus while the remaning 2-10% have an upper and lower canaliculus that enter the lacrimal sac separately. To our knowledge no prior study has evaluated this through direct anatomical dissection of the human lacrimal drainage system. The purpose of our study is to investigate the frequency of a common canaliculus with direct visualization using a novel technique of cadaveric dissection.
69 preserved cadavers were dissected to allow direct visualization of the canalicular entrance(s) to the lumen of the lacrimal sac. Cadavers were excluded from the study if there was osteotomy evidence of prior dacryocystorhinostomy (DCR) or canalicular obstruction noted on probing. The dissection was achieved first with exposure of the lacrimal sac with a classic external DCR incision followed by blunt dissection to expose the sac in the lacrimal fossa. The upper and lower puncta were dilated with a punctal dilator. A lacrimal cannula was then used to inject surgical lubricant to reinflate the lacrimal sac, which is found to be shrunken secondary to post mortem changes and the preservation process. The medial canthal tendon was then incised allowing for better exposure. The lacrimal sac was then incised at its medial most location with a curved blade and opened to expose the lumen. Lacrimal probes were then inserted into the superior and inferior canaliculi and their entrance to the lacrimal sac was directly visualized.
69 cadavers (95 lacrimal systems) were explored using the technique described above. All 95 lacrimal systems demonstrated a common canaliculus entering the lacrimal sac. The anatomic variations of the Rosenmüller valve were recorded for 95 of the valves encountered. We described the valves according to their location in circumferential degrees.
This novel approach to dissection allows direct visualization which provides a more accurate description of the lacrimal sac anatomy. Dissection of 95 lacrimal systems in 69 cadavers revealed a common canalicular entrance in all orbits.This data varies from previously reported incidence of a common canaliculus (90-98%). Though larger sample size will need to confirm our current results, such data will enable better understanding of the lacrimal system in certain congential and acquired disease states and when performing canalicular and lacrimal sac reconstructive surgery.
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