An anatomic analysis of the efferent lacrimal system in cadaveric specimens

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Investigative Ophthalmology & Visual Science

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Purpose: : There is a lack of literature describing the anatomy and physiology of the efferent lacrimal system. Furthermore, there is a disconnect between some of the current clinical treatment modalities and some recent anatomic descriptions. These include descriptions of a cavernous body surrounding the nasolacrimal duct, helical arrangements of collagen fibers surrounding the nasolacrimal duct, and the presence of an absorptive epithelial surface lining the lumen of the duct. These anatomic features all suggest that the physiology of the nasolacrimal duct is much more active than the current clinical paradigm, and additionally, there is some evidence to suggest that the nasolacrimal duct may play a role in tear production. This is in contrast to current management, which operates under the paradigm that the efferent lacrimal system and is merely a passive conduit and thus seeks either to dilate the nasolacrimal system manually or to circumvent the native passage altogether. This study will describe the efferent lacrimal system - the canaliculi, lacrimal sac, and nasolacrimal duct with accompanying cavernous body in both gross and microscopic detail with special attention toward the physiologic functions subserved by these anatomic features. This information will be used as a framework for better understanding the physiology of this system and its role in the maintenance of tear film homeostasis.

Methods: : The right and left efferent nasolacrimal systems were dissected from a cadaveric specimen and preserved in formalin prior to histologic preparation and analysis with hematoxylin and eosin staining.

Results: : Based on histopathologic review with hematoxylin and eosin staining, there was suggestion of a vascular cavernous body surrounding the nasolacrimal ducts. However, further detail was precluded due to the frozen state of the specimen prior to dissection.

Conclusions: : The efferent lacrimal system is likely more physiologically active than currently considered in the literature and in clinical practice. Initial studies suggest the presence of a vascular cavernous body surrounding the nasolacrimal system. Further histologic analysis on subsequent fresh or formalin preserved specimens will be performed to elucidate the gross and microscopic features of the efferent nasolacrimal system.