FUNCTIONAL-ANATOMY OF THE HUMAN EFFERENT TEAR-DUCTS - A NEW THEORY OFTEAR OUTFLOW MECHANISM

Background: The mechanism of lacrimal drainage under physiological con ditions is controversial. The aim of this study was to analyze the thr ee-dimensional architecture of human efferent tear ducts from function al and clinical points of view. A new theory of tear outflow is discus sed. Methods: Thirty-two prepared lacrimal systems of adults were exam ined by histological, immunohistochemical and scanning electron micros copic techniques. a Results: The wall of the lacrimal sac is made up o f collagen bundles, elastic and reticular fibers arranged in a helical pattern. Wide luminal vascular plexus are embedded in this helical sy stem and connected to the cavernous tissue of the inferior turbinate i n the region of Hasner's valve. Immunohistochemical analysis showed ev idence of type I and type III collagen as well as chondroitin 4- and 6 -sulfate. Conclusion: With blinking, the lacrimal part of the orbicula ris muscle contracts. The fornix of the sac moves in a cranial-lateral direction. Thus the lacrimal sac distends and may be ''wrung out'' du e to its medial attachment and helically arranged fibrillar structures . The vascular plexus may play an important role in the absorption and drainage of lacrimal fluid.