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Swarup Sai Swaminathan, Pedro Monsalve, Mabel Enriquez-Algeciras, Xiao Yi Zhou, Sanjoy K Bhattacharya, Sander R Dubovy, Anna K Junk; Histologic Analysis of Trabecular Meshwork Obtained from Kahook Dual Blade Goniotomy. Invest. Ophthalmol. Vis. Sci. 2018;59(9):483.
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© ARVO (1962-2015); The Authors (2016-present)
The Kahook Dual Blade (KDB) is a novel ab interno goniotomy device used to strip trabecular meshwork (TM) from Schlemm’s canal to augment aqueous outflow and lower intraocular pressure. While a previous study examined tissue from ex vivo cadaveric eyes, no studies have been completed using tissue from live patients. The purpose of this study was to complete histologic analysis of excised in vivo TM samples.
University of Miami Institutional Review Board approval was obtained. Patients undergoing KDB goniotomy at the Bascom Palmer Eye Institute and Miami Veterans Affairs Hospital were identified. After the tissue was excised using KDB, Utrata forceps were utilized to externalize the TM from the anterior chamber. The tissue was submitted in 10% formalin to the Florida Lions Ocular Pathology Laboratory.
A series of 9 samples was studied, with a mean age of 71.5 years. 89% cases carried a diagnosis of primary open-angle glaucoma, while 11% carried a diagnosis of normal-tension glaucoma. In all cases, TM beams were observed, although the architecture was occasionally distorted due to tissue shearing and histologic processing. In one case, a periodic acid-Schiff (PAS)-positive membrane was observed. All other cases demonstrated tissue consistent with trabecular meshwork. Collagen IV staining was strongly positive in 100% of samples, concentrated around TM beams. Elastin staining was positive in only 44% of samples. Fibronectin was strongly present in all samples, while cochlin was present in varying degrees.
This is the first analysis of in vivo TM tissue obtained with the use of an ab interno glaucoma device. This study serves as a proof-of-concept, demonstrating that TM can be successfully isolated. Collagen IV deposition demonstrates its prevalence within TM. Elastin staining may have been intermittent, primarily concentrated in the corneoscleral TM. Fibronectin and cochlin staining demonstrate the possibilities of assaying TM. The case with a PAS-positive membrane suggests that Schwalbe’s line may have been breached. Such analysis has the potential to further our understanding of glaucoma, as it could assess for the presence of factors contributing to TM dysfunction. Secondary open-angle glaucomas could also be studied.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.
Trabecular meshwork from a goniotomy case stained with fibronectin (green) and cochlin (red). DAPI nuclear stain (blue) present. Magnification, 20X.
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