Involvement of Laryngopharyngeal Reflux in Ocular Diseases: A State-of-the-Art Review.

BACKGROUND: Laryngopharyngeal reflux-associated symptoms embrace a wide variety of head and neck manifestations. Its participation in eye disorders has recently been postulated, and there is currently no consensus in this regard. The aim of this manuscript is to review the role of reflux in the development of ocular signs and symptoms, and its physio-pathological mechanisms. METHODS: A systematic approach based on the preferred reporting Items for a systematic review and meta-analysis checklist with a modified population, intervention, comparison, and outcome framework was used to structure the review process of studies that evaluated the possible association, with clear diagnostic methods, of laryngopharyngeal reflux and ocular signs and symptoms. Search was conducted in different indexed databases (PubMed/MEDLINE, the Cochrane Library, Scielo and Web of Science) and through the meta-searcher Trip Database with the keywords: reflux, laryngitis, laryngopharyngeal, gastroesophageal, ocular, eye, symptoms, signs, conjunctivitis, keratitis, dacryocystitis, dry eye. RESULTS: Seven studies met the inclusion criteria, in which the primary acquired nasolacrimal duct obstruction and the ocular surface disease were evaluated. The local increase of eye pepsin concentration (>2.5 ng/mL) may affect ocular surface though its direct proteolytic activity and the local expression of proinflammatory cytokines. The H. Pylori, with a similar mechanism to reach the lacrimonasal duct, would be associated with the release of proinflammatory and vasoactive substances that would lead to a mucosa injury and chronic inflammation. Ocular Surface Disease Index seems to correlate directly with the reflux severity, with cut-off of 41.67 score as predictor for disease. DISCUSSION: The role of laryngopharyngeal reflux in the development of ocular disorders has not yet been demonstrated and data are limited and heterogeneous. It seems theoretically conceivable that pepsin may reach lachrymal duct area through hypopharyngeal-nasal gaseous reflux events. Future studies using objective testing for diagnosis and pepsin detection into the tear and nasal mucosa are needed in order to explore this potential relationship.

MUC16 in the lacrimal apparatus.

The aim of the present study was to determine the possible expression of the mucin MUC16 in the lacrimal apparatus. Expression and distribution of MUC16 in lacrimal gland, accessory lacrimal glands, and nasolacrimal ducts was monitored by RT-PCR and immunohistochemistry. MUC16 was expressed and detected in all tissues investigated. Comparable to conjunctiva and cornea it was membrane-anchored in accessory lacrimal glands whereas in lacrimal gland acinar cells and columnar cells of the nasolacrimal ducts it was stored in intracytoplasmic vesicles without membrane-association. Subepithelial serous glands of the nasolacrimal ducts revealed staining of the secretion product. Intracelluar production of MUC16 is present in lacrimal gland and epithelial cells of the nasolacrimal ducts but it is not clear whether this MUC16 is secreted. MUC16 seems to be shedded or secreted from the epithelial surface of subepithelial serous glands of the nasolacrimal ducts. Our results show that MUC16 is present in the whole lacrimal apparatus. Its distribution pattern suggests different physiological functions with regard to tear film physiology and tear outflow. Moreover, the results demonstrate the existence of so far not recognized qualitative differences in the secretion product of main lacrimal gland and accessory lacrimal glands (glands of Krause).

Functional anatomy of the human efferent tear ducts: a new theory of tear outflow mechanism.

BACKGROUND: The mechanism of lacrimal drainage under physiological conditions is controversial. The aim of this study was to analyze the three-dimensional architecture of human efferent tear ducts from functional and clinical points of view. A new theory of tear outflow is discussed. METHODS: Thirty-two prepared lacrimal systems of adults were examined by histological, immunohistochemical and scanning electron microscopic techniques. RESULTS: The wall of the lacrimal sac is made up of collagen bundles, elastic and reticular fibers arranged in a helical pattern. Wide luminal vascular plexus are embedded in this helical system and connected to the cavernous tissue of the inferior turbinate in the region of Hasner's valve. Immunohistochemical analysis showed evidence of type I and type III collagen as well as chondroitin 4- and 6-sulfate. CONCLUSION: With blinking, the lacrimal part of the orbicularis muscle contracts. The fornix of the sac moves in a cranial-lateral direction. Thus the lacrimal sac distends and may be "wrung out" due 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.