Browsing by Author "Johnstone, Murray A."

Now showing 1 - 2 of 2
  • Thumbnail Image
    Item
    A Novel Technique Identifies Valve-Like Pathways Entering and Exiting Schlemm's Canal in Macaca nemestrina Primates With Similarities to Human Pathways
    (Frontiers Media, 2022-07-04) Martin, Elizabeth A.; Johnstone, Murray A.; Ophthalmology, School of Medicine
    Purpose: The aim of the study was 1) to describe a novel combination of techniques that permit immunohistochemistry imaging of Schlemm's canal inlet (SIV) and outlet (SOV) valve-like structures, 2) to identify tissue-level SIV adhesive relationships linking the trabecular meshwork (TM) to hinged collagen leaflets at the Schlemm's canal (SC) external wall, and 3) to determine whether the SIV lumen wall's adhesive vascular markers are similar to those of the SC inner wall endothelium. Materials and Methods: Anterior segments of 16 M. nemestrina primates underwent immunohistochemistry (IHC) labeling. We perfused fluorescent microspheres into 12 of the eyes. Limbal tissues were divided into quadrants, viscoelastic introduced into SC, tissues fixed, immunohistochemistry performed, radial segments cut, tissues clarified, and confocal microscopy performed. Finally, we generated ImageJ 3D projections encompassing the TM, SC, and distal pathways. Results: IHC imaging identified 3D relationships between SIV, collector channel ostia, collector channels (CC), SOV, and intrascleral channels. Imaging depth increased 176.9%, following clarification (p < 0.0001). Imaging demonstrated CD31, collagen type 1 and 4 in the walls of the SIV lumen and more distal pathways. In eight eyes, 384 segments were examined, 447 SIV identified, and 15.4% contained microspheres. Conclusion: Our technique's imaging depth permitted the identification of SIV linkage between the TM and SOV. We found comparable cell-cell adhesion molecules (CD31) and basement membrane components in the SC inner wall and SIV lumen walls. Recent OCT studies have suggested that SIV tensional relationships may control CC entrance dimensions that regulate distal resistance. Cellular adhesive properties sustain SIV tensional relationships. These SIV cell-cell and cell-basement membrane properties warrant further study because abnormalities could be a factor in the IOP elevation of glaucoma.
  • Thumbnail Image
    Item
    Consensus Recommendations for Studies of Outflow Facility and Intraocular Pressure Regulation Using Ex Vivo Perfusion Approaches
    (Association for Research in Vision and Ophthalmology, 2024) Acott, Ted S.; Fautsch, Michael P.; Mao, Weiming; Ethier, C. Ross; Huang, Alex S.; Kelley, Mary J.; Aga, Mini; Bhattacharya, Sanjoy K.; Borras, Terete; Bovenkamp, Diane; Chowdhury, Uttio Roy; Clark, Abbot F.; Dibas, Mohammed I.; Du, Yiqin; Elliott, Michael H.; Faralli, Jennifer A.; Gong, Haiyan; Herberg, Samuel; Johnstone, Murray A.; Kaufman, Paul L.; Keller, Kate E.; Kelly, Ruth A.; Krizaj, David; Kuehn, Markus H.; Li, Hoi Lam; Lieberman, Raquel; Lin, Shan C.; Liu, Yutao; McDonnell, Fiona S.; McDowell, Colleen M.; McLellan, Gillian J.; Mzyk, Philip; Nair, Kayarat Saidas; Overby, Darryl R.; Peters, Donna M.; Raghunathan, VijayKrishna; Rao, Ponugoti Vasantha; Roddy, Gavin W.; Sharif, Najam A.; Shim, Myoung Sup; Sun, Yang; Thomson, Benjamin R.; Toris, Carol B.; Willoughby, Colin E.; Zhang, Hao F.; Freddo, Thomas F.; Fuchshofer, Rudolf; Hill, Kamisha R.; Karimi, Alireza; Kizhatil, Krishnakumar; Kopcyznski, Casey C.; Liton, Paloma; Patel, Gaurang; Peng, Michael; Pattabiraman, Padmanabhan P.; Prasanna, Ganesh; Reina-Torres, Ester; Samples, E. Griffen; Samples, John R.; Steel, Cynthia L.; Strohmaier, Clemens A.; Subramanian, Preeti; Sugali, Chenna Kesavulu; van Batenburg-Sherwood, Joseph; Wong, Cydney; Youngblood, Hannah; Zode, Gulab S.; White, Elizabeth; Stamer, W. Daniel; Ophthalmology, School of Medicine
    Intraocular pressure (IOP) elevation is the primary risk factor and currently the main treatable factor for progression of glaucomatous optic neuropathy. In addition to direct clinical and living animal in vivo studies, ex vivo perfusion of anterior segments and whole eyes is a key technique for studying conventional outflow function as it is responsible for IOP regulation. We present well-tested experimental details, protocols, considerations, advantages, and limitations of several ex vivo model systems for studying IOP regulation. These include: (1) perfused whole globes, (2) stationary anterior segment organ culture, (3) perfused human anterior segment organ culture, (4) perfused animal anterior segment organ culture, (5) perfused human corneal rims, and (6) perfused human anterior segment wedges. These methods, with due consideration paid to their strengths and limitations, comprise a set of very strong tools for extending our understanding of IOP regulation.