Etiopathogenesis of Primary Acquired Nasolacrimal Duct Obstruction: What We Know and What We Need to Know

Purpose: To provide a systematic review of the literature on the etiopathogenesis of primary acquired nasolacrimal duct obstruction (PANDO). Methods: The authors performed a PubMed search of all articles published in English with specific reference to etiopathogenesis of PANDO or associations of PANDO. Data captured include demographics, study techniques, hypothesis, presumed or confirmed interpretations with regards to pathogenesis, mechanisms, or pathways. Specific emphasis was laid on addressing the lacunae and potential directions for future research. Results: Numerous factors are believed to contribute to the etiopathogenesis of PANDO. The basic pathogenesis involves inflammation, vascular congestion, mucosal edema, fibrosis, obstruction, and stasis. Bony nasolacrimal duct diameter does not appear to play a significant role. There is no convincing data to substantiate nose as the site of disease origin and nasal factors appear to be comorbidities. Hormonal mechanisms are more evidence-based but can only partly explain the pathogenesis. Vascular theories are based on the behavior of perilacrimal cavernous bodies, their autonomic control, and additional structural changes in the helical patterns of connective tissue fiber arrangements. Repeated vascular malfunction leading to structural epithelial and subepithelial changes currently appears to be the most evidence-based and accepted theory. Tear proteomics holds a promise in decoding the etiopathogenesis of PANDO, at least in part. Conclusions: The etiopathogenesis of PANDO appears to be multifactorial. Hormonal microenvironments, vascular factors, and tear proteomics are promising candidates for further work. There is a need for focused work by Clinician-Scientists and the answers can have far reaching clinical implications. Accepted for publication December 12, 2018. M.J.A. received support from the Alexander von Humboldt Foundation for his research and he also receives royalties from Springer for the 2nd edition of the textbook "Principles and Practice of Lacrimal Surgery" and treatise "Atlas of Lacrimal Drainage Disorders." F.P. was supported by Deutsche Forschungsgemeinschaft (DFG) grants PA738/1-1 to 1–5 and PA738/2-1. He received royalties from Elsevier for the 24th edition of the anatomy atlas "Sobotta" and the "Sobotta Textbook of Anatomy." The authors have no conflicts of interest to disclose. Address correspondence and reprint requests to Mohammad Javed Ali, F.R.C.S., Ph.D., L.V. Prasad Eye Institute, Road No. 2, Banjara Hills, Hyderabad 34, India. E-mail: drjaved007@gmail.com © 2019 by The American Society of Ophthalmic Plastic and Reconstructive Surgery, Inc., All rights reserved.

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