Valve of Rosenmuller: Endoscopic Real-Time Analysis of Two Subtypes and Potential Functional Implications

Purpose: The aim of this study was to examine the endoscopic anatomy of the valve of Rosenmuller in real-time and its potential functional implications. Methods: High-definition endoscopic documentation of the valve of Rosenmuller (VOR) during 50 powered endoscopic dacryocystorhinostomy over a period of 2 years were reviewed. The presence or absence of the valves were assessed and when present, each of the valves were studied for their anatomical configuration, shape, precise location, and changes with opening and closing of the internal common opening (ICO) and with the presence and absence of the probe. Results: VOR was noted in 68% of the subjects studied and 2 distinct subtypes were noted with type I being more common. The Type 1 VOR was a stand-alone, freely mobile, elliptical valve arising from the superior or postero-superior portion of the medial edge of the ICO. The Type II VOR was a group of a superior and inferior mucosal fold, arising from the superior and inferior portions of the medial edge of the ICO. When the ICO opens slowly, the valve tends to fall outwards towards the lacrimal sac. When the ICO slowly closes back, the valve moves inward towards the common canaliculus. Conclusions: This is the first study to demonstrate the in-vivo presence of VOR. Two different types of VOR were noted with characteristic shapes, locations, and movements of each. Where present, VOR fulfills the criteria of a true valve. The study proposes that the term "valve of Huschke" is a misnomer and when present, is actually part of the overall anatomical and functional unit of VOR. Detailed anatomical features of the valve of Rosenmuller can help our understanding of the focal anatomy and tear rheology.