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Coroneo MT, Graterol-Nisi G, Maver E, Gillies RM. Aqueous Humor Circulation in the Era of Minimally Invasive Surgery for Glaucoma. Ann Biomed Eng 2024; 52:898-907. [PMID: 38155316 DOI: 10.1007/s10439-023-03427-3] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/03/2023] [Accepted: 12/11/2023] [Indexed: 12/30/2023]
Abstract
Glaucoma surgery with implantation of aqueous humor draining microstents may compromise long-term corneal health by disrupting aqueous humor circulation. The effect of stent numbers on this circulation was interrogated to determine the number of stents associated with minimal circulation disruption. An in vitro anterior eye model perfusion system was constructed with multiple exit ports. A 3-D model of the anterior eye was imported into ABAQUS CFD, analyzes were carried out for unsteady laminar flow and solved using Navier-Stokes equations. DT Vision Foundry was used to analyze velocity contour plot images. The field variable results output for the CFD model were fluid wall shear, fluid pressure and fluid velocity. In vitro, "aqueous" fluid flow is high through a single stent and "aqueous" stagnation is greatest in the quadrants 180° away. Increasing stent port numbers, results in an exponential decrease in the stagnant flow locations. High wall shear stress was seen in the single stent model and is markedly reduced after a second and subsequent stents are introduced. We identify two factors potentially contributing to corneal compromise post glaucoma drainage surgery: aqueous humor stagnation, remote to the stent site and higher exit flows imparting increased stent exit shear stress (particularly with a single stent). With 4 stents, there is minimal disruption of anterior chamber circulation (mimicking physiological conditions). Furthermore we propose that aqueous humor circulation disruption via the usual single-exit port approach disrupts aqueous humor circulation with long-term consequences for corneal health.
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Affiliation(s)
- Minas T Coroneo
- Ophthalmic Surgeons, 2 St Pauls St, Randwick, NSW, 2031, Australia.
- Department of Ophthalmology, Prince of Wales Hospital/University of New South Wales, Sydney, Australia.
| | | | - Eric Maver
- Ophthalmic Surgeons, 2 St Pauls St, Randwick, NSW, 2031, Australia
| | - R Mark Gillies
- Medical Device Research Australia Pty Ltd, Sydney, Australia
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2
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Ikegami K. Circadian rhythm of intraocular pressure. J Physiol Sci 2024; 74:14. [PMID: 38431563 PMCID: PMC10908160 DOI: 10.1186/s12576-024-00905-8] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2023] [Accepted: 02/04/2024] [Indexed: 03/05/2024]
Abstract
Intraocular pressure (IOP) plays a crucial role in glaucoma development, involving the dynamics of aqueous humor (AH). AH flows in from the ciliary body and exits through the trabecular meshwork (TM). IOP follows a circadian rhythm synchronized with the suprachiasmatic nucleus (SCN), the circadian pacemaker. The SCN resets peripheral clocks through sympathetic nerves or adrenal glucocorticoids (GCs). IOP's circadian rhythm is governed by circadian time signals, sympathetic noradrenaline (NE), and GCs, rather than the local clock. The activity of Na+/K+-ATPase in non-pigmented epithelial cells in the ciliary body can influence the nocturnal increase in IOP by enhancing AH inflow. Conversely, NE, not GCs, can regulate the IOP rhythm by suppressing TM macrophage phagocytosis and AH outflow. The activation of the β1-adrenergic receptor (AR)-mediated EPAC-SHIP1 signal through the ablation of phosphatidylinositol triphosphate may govern phagocytic cup formation. These findings could offer insights for better glaucoma management, such as chronotherapy.
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Affiliation(s)
- Keisuke Ikegami
- Laboratory of Regulation in Metabolism and Behavior, Faculty of Agriculture, Kyushu University, 744 Motooka, Nishi-Ku, Fukuoka, 819-0395, Japan.
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3
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Oltmann J, Morell M, Dakroub M, Verma-Fuehring R, Hillenkamp J, Loewen N. VEGF-A-induced changes in distal outflow tract structure and function. Graefes Arch Clin Exp Ophthalmol 2024; 262:537-543. [PMID: 37831170 PMCID: PMC10844149 DOI: 10.1007/s00417-023-06252-5] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2023] [Revised: 08/17/2023] [Accepted: 09/08/2023] [Indexed: 10/14/2023] Open
Abstract
PURPOSE To investigate changes in distal outflow tract vessels caused by VEGF-A and their impact on outflow. METHODS We compared VEGF-A perfused porcine anterior segments with and without trabecular meshwork (TM) to control eyes. In the first experiment (n=48), we analyzed live changes of the outflow tract with spectral-domain optical coherence tomography (SD-OCT) over 3 h and reconstructed them in 3D. In a second experiment (n=32), we measured the intraocular pressure (IOP) variation in response to VEGF-A over 48 h and computed the outflow facility. RESULTS VEGF-A increased the vessel volume of the distal outflow tract by 16.8±10.6% while control eyes remained unchanged (0.5±6.8%). Volume changes occurred within the first 100 min before plateauing at 140 min. VEGF-A enhanced the outflow facility in eyes without TM by 38.6±25.5% at 24 h as compared to controls (p<0.05). CONCLUSION VEGF-A dilated vessels of the distal outflow tract and increased the outflow facility even after TM removal, pointing to a regulatory mechanism independent of proximal structures.
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Affiliation(s)
- Jannis Oltmann
- Department of Ophthalmology, University Hospital Würzburg, Josef-Schneider-Straße 11, 97080, Würzburg, Germany
| | - Mark Morell
- Department of Ophthalmology, University Hospital Würzburg, Josef-Schneider-Straße 11, 97080, Würzburg, Germany
| | - Mohamad Dakroub
- Department of Ophthalmology, University Hospital Würzburg, Josef-Schneider-Straße 11, 97080, Würzburg, Germany
| | - Raoul Verma-Fuehring
- Department of Ophthalmology, University Hospital Würzburg, Josef-Schneider-Straße 11, 97080, Würzburg, Germany
| | - Jost Hillenkamp
- Department of Ophthalmology, University Hospital Würzburg, Josef-Schneider-Straße 11, 97080, Würzburg, Germany
| | - Nils Loewen
- Department of Ophthalmology, University Hospital Würzburg, Josef-Schneider-Straße 11, 97080, Würzburg, Germany.
- ARTEMIS Eye Centers of Frankfurt, Hanauer Landstr. 147, 60314, Frankfurt, Germany.
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Mohamed Y, Passaglia CL. Simulation of gravity- and pump-driven perfusion techniques for measuring outflow facility of ex vivo and in vivo eyes. PLoS One 2023; 18:e0294607. [PMID: 37988400 PMCID: PMC10662726 DOI: 10.1371/journal.pone.0294607] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2023] [Accepted: 11/03/2023] [Indexed: 11/23/2023] Open
Abstract
Aqueous humor dynamics are commonly assessed by infusing fluid into the eye and measuring intraocular pressure (IOP). From the pressure-flow relationship, conventional outflow facility is estimated to study glaucomatous processes that lower facility or identify therapeutics that enhance facility in hopes of restoring healthy IOP levels. The relative merits and limitations of constant flow (CF), gravity-driven constant pressure (CPg), and pump-driven constant pressure (CPp) infusion techniques were explored via simulations of a lumped parameter viscoelastic model of the eye. Model parameter values were based on published perfusion system properties and outflow facility data from rodents. Step increases in pressure or flow were simulated without and with IOP noise recorded from enucleated eyes, anesthetized animals, and conscious animals. Steady-state response levels were determined using published window and ratio criteria. Model simulations show that all perfusion techniques estimate facility accurately and that ocular fluid dynamics set a hard limit on how fast measurements can be taken. This limit can be approached with CPg and CPp systems by increasing their gain but not with CF systems, which invariably take longest to settle. Facility experiment duration is further lengthened by inclusion of IOP noise, and data filtering is needed for steady-state detection with in vivo noise. The ratio criterion was particularly affected because noise in the flow data is amplified by the higher gain of CPg and CPp systems. A recursive regression method is introduced, which can ignore large transient IOP fluctuations that interfere with steady-state detection by fitting incoming data to the viscoelastic eye model. The fitting method greatly speeds up data collection without loss of accuracy, which could enable outflow facility measurements in conscious animals. The model may be generalized to study response dynamics to fluid infusion in other viscoelastic compartments of the body and model insights extended to optimize experiment design.
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Affiliation(s)
- Youssef Mohamed
- Department of Medical Engineering, University of South Florida, Tampa, FL, United States of America
| | - Christopher L. Passaglia
- Department of Medical Engineering, University of South Florida, Tampa, FL, United States of America
- Department of Ophthalmology, University of South Florida, Tampa, FL, United States of America
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5
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Mimura M, Akagi T, Kohmoto R, Fujita Y, Sato Y, Ikeda T. Measurement of vitreous humor pressure in vivo using an optic fiber pressure sensor. Sci Rep 2023; 13:18233. [PMID: 37880357 PMCID: PMC10600124 DOI: 10.1038/s41598-023-45616-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2023] [Accepted: 10/21/2023] [Indexed: 10/27/2023] Open
Abstract
We conducted a study to assess the pressure difference between the aqueous and vitreous humors in rabbit eyes using a direct intraocular pressure (IOP) measurement method. A micro-optic-fiber pressure sensor was utilized for this purpose. Preliminary experiments with enucleated porcine eyes confirmed the sensor's accuracy in measuring both aqueous and vitreous humor pressure. The main study involved six healthy albino rabbits, where the sensor measured the pressure in the anterior chamber (aIOP) and posterior vitreous-cavity (pIOP). These measurements were compared to aIOP values obtained through rebound tonometry. Additionally, pre- and postoperative pressure comparisons were made after performing a vitrectomy. Results revealed a significant disparity between aqueous and vitreous humor pressures. Prior to vitrectomy, pIOP was 22.8 mmHg, over twice as high as aIOP (11.0 mmHg), but decreased to a similar level following the procedure. Comparison between the sensor measurements and rebound tonometry showed agreement in aIOP values. In conclusion, our study demonstrates that vitreous humor pressure is consistently higher than aqueous humor pressure, reaching the upper limit of normal IOP. Furthermore, vitrectomy effectively reduces pIOP, aligning it with aIOP. These findings contribute valuable insights into intraocular pressure dynamics and have implications for clinical interventions targeting ocular pressure regulation.
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Affiliation(s)
- Masashi Mimura
- Department of Ophthalmology, Osaka Medical College, Takatsuki-City, Osaka, Japan.
- Department of Ophthalmology, Hyogo Medical University, 1-1, Mukogawa-Cho, Nishinomiya-Shi, Hyogo , 663-8501, Japan.
- Department of Ophthalmology, Toho University Sakura Medical Center, Sakura-City, Chiba, Japan.
| | - Tadamichi Akagi
- Division of Ophthalmology and Visual Science, Niigata University Graduate School of Medical and Dental Sciences, Niigata, Japan
| | - Ryosuke Kohmoto
- Department of Ophthalmology, Osaka Medical College, Takatsuki-City, Osaka, Japan
| | - Yasushi Fujita
- Department of Ophthalmology, Osaka Medical College, Takatsuki-City, Osaka, Japan
| | - Yohei Sato
- Department of Ophthalmology, Osaka Medical College, Takatsuki-City, Osaka, Japan
| | - Tsunehiko Ikeda
- Department of Ophthalmology, Osaka Medical College, Takatsuki-City, Osaka, Japan
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6
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Ujiie N, Norden PR, Fang R, Beckmann L, Cai Z, Kweon J, Liu T, Tan C, Kuhn MS, Stamer WD, Aoto K, Quaggin SE, Zhang HF, Kume T. Differential roles of FOXC2 in the trabecular meshwork and Schlemm's canal in glaucomatous pathology. Life Sci Alliance 2023; 6:e202201721. [PMID: 37414529 PMCID: PMC10326420 DOI: 10.26508/lsa.202201721] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/12/2022] [Revised: 06/28/2023] [Accepted: 06/29/2023] [Indexed: 07/08/2023] Open
Abstract
Impaired development and maintenance of Schlemm's canal (SC) are associated with perturbed aqueous humor outflow and intraocular pressure. The angiopoietin (ANGPT)/TIE2 signaling pathway regulates SC development and maintenance, whereas the molecular mechanisms of crosstalk between SC and the neural crest (NC)-derived neighboring tissue, the trabecular meshwork (TM), are poorly understood. Here, we show NC-specific forkhead box (Fox)c2 deletion in mice results in impaired SC morphogenesis, loss of SC identity, and elevated intraocular pressure. Visible-light optical coherence tomography analysis further demonstrated functional impairment of the SC in response to changes in intraocular pressure in NC-Foxc2 -/- mice, suggesting altered TM biomechanics. Single-cell RNA-sequencing analysis identified that this phenotype is predominately characterized by transcriptional changes associated with extracellular matrix organization and stiffness in TM cell clusters, including increased matrix metalloproteinase expression, which can cleave the TIE2 ectodomain to produce soluble TIE2. Moreover, endothelial-specific Foxc2 deletion impaired SC morphogenesis because of reduced TIE2 expression, which was rescued by deleting the TIE2 phosphatase VE-PTP. Thus, Foxc2 is critical in maintaining SC identity and morphogenesis via TM-SC crosstalk.
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Affiliation(s)
- Naoto Ujiie
- Feinberg Cardiovascular and Renal Research Institute, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Pieter R Norden
- Feinberg Cardiovascular and Renal Research Institute, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Raymond Fang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
| | - Lisa Beckmann
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
| | - Zhen Cai
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
| | - Junghun Kweon
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
| | - Ting Liu
- Feinberg Cardiovascular and Renal Research Institute, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Can Tan
- Feinberg Cardiovascular and Renal Research Institute, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Megan S Kuhn
- Duke Eye Center, Duke University, Durham, NC, USA
| | | | - Kazushi Aoto
- Department of Biochemistry, Hamamatsu University School of Medicine, Hamamatsu, Japan
| | - Susan E Quaggin
- Feinberg Cardiovascular and Renal Research Institute, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Division of Nephrology and Hypertension, Northwestern University Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
| | - Hao F Zhang
- Department of Biomedical Engineering, Northwestern University, Evanston, IL, USA
- Department of Ophthalmology, Northwestern University, Chicago, IL, USA
| | - Tsutomu Kume
- Feinberg Cardiovascular and Renal Research Institute, Department of Medicine, Feinberg School of Medicine, Northwestern University, Chicago, IL, USA
- Department of Ophthalmology, Northwestern University, Chicago, IL, USA
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7
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McDowell CM, Kizhatil K, Elliott MH, Overby DR, van Batenburg-Sherwood J, Millar JC, Kuehn MH, Zode G, Acott TS, Anderson MG, Bhattacharya SK, Bertrand JA, Borras T, Bovenkamp DE, Cheng L, Danias J, De Ieso ML, Du Y, Faralli JA, Fuchshofer R, Ganapathy PS, Gong H, Herberg S, Hernandez H, Humphries P, John SWM, Kaufman PL, Keller KE, Kelley MJ, Kelly RA, Krizaj D, Kumar A, Leonard BC, Lieberman RL, Liton P, Liu Y, Liu KC, Lopez NN, Mao W, Mavlyutov T, McDonnell F, McLellan GJ, Mzyk P, Nartey A, Pasquale LR, Patel GC, Pattabiraman PP, Peters DM, Raghunathan V, Rao PV, Rayana N, Raychaudhuri U, Reina-Torres E, Ren R, Rhee D, Chowdhury UR, Samples JR, Samples EG, Sharif N, Schuman JS, Sheffield VC, Stevenson CH, Soundararajan A, Subramanian P, Sugali CK, Sun Y, Toris CB, Torrejon KY, Vahabikashi A, Vranka JA, Wang T, Willoughby CE, Xin C, Yun H, Zhang HF, Fautsch MP, Tamm ER, Clark AF, Ethier CR, Stamer WD. Consensus Recommendation for Mouse Models of Ocular Hypertension to Study Aqueous Humor Outflow and Its Mechanisms. Invest Ophthalmol Vis Sci 2022; 63:12. [PMID: 35129590 PMCID: PMC8842499 DOI: 10.1167/iovs.63.2.12] [Citation(s) in RCA: 19] [Impact Index Per Article: 9.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/03/2021] [Accepted: 12/08/2021] [Indexed: 01/07/2023] Open
Abstract
Due to their similarities in anatomy, physiology, and pharmacology to humans, mice are a valuable model system to study the generation and mechanisms modulating conventional outflow resistance and thus intraocular pressure. In addition, mouse models are critical for understanding the complex nature of conventional outflow homeostasis and dysfunction that results in ocular hypertension. In this review, we describe a set of minimum acceptable standards for developing, characterizing, and utilizing mouse models of open-angle ocular hypertension. We expect that this set of standard practices will increase scientific rigor when using mouse models and will better enable researchers to replicate and build upon previous findings.
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Affiliation(s)
- Colleen M. McDowell
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | | | - Michael H. Elliott
- University of Oklahoma Health Sciences Center, Oklahoma City, Oklahoma, United States
| | - Darryl R. Overby
- Department of Bioengineering, Imperial College London, United Kingdom
| | | | - J. Cameron Millar
- Department of Pharmacology & Neuroscience, and North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Markus H. Kuehn
- Department of Ophthalmology and Visual Sciences and Institute for Vision Research, The University of Iowa; Center for the Prevention and Treatment of Visual Loss, Veterans Affairs Medical Center, Iowa City, Iowa, United States
| | - Gulab Zode
- Department of Pharmacology & Neuroscience, and North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Ted S. Acott
- Ophthalmology and Biochemistry and Molecular Biology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Michael G. Anderson
- Department of Molecular Physiology and Biophysics and Department of Ophthalmology and Visual Sciences, The University of Iowa; Center for the Prevention and Treatment of Visual Loss, Veterans Affairs Medical Center, Iowa City, Iowa, United States
| | | | - Jacques A. Bertrand
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Terete Borras
- University of North Carolina at Chapel Hill, Chapel Hill, North Carolina, United States
| | | | - Lin Cheng
- Department of Ophthalmology and Visual Sciences, University of Iowa, Iowa City, Iowa, United States
| | - John Danias
- SUNY Downstate Health Sciences University, Brooklyn, New York, United States
| | - Michael Lucio De Ieso
- Department of Ophthalmology, Duke Eye Center, Duke University, Durham, North Carolina, United States
| | - Yiqin Du
- Department of Ophthalmology, University of Pittsburgh, Pennsylvania, United States
| | - Jennifer A. Faralli
- Department of Pathology and Laboratory Medicine, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Rudolf Fuchshofer
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
| | - Preethi S. Ganapathy
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, New York, United States
| | - Haiyan Gong
- Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Samuel Herberg
- Department of Ophthalmology and Visual Sciences, SUNY Upstate Medical University, Syracuse, New York, United States
| | | | - Peter Humphries
- Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - Simon W. M. John
- Department of Ophthalmology, Columbia University, New York, New York, United States
| | - Paul L. Kaufman
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Kate E. Keller
- Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Mary J. Kelley
- Department of Ophthalmology and Department of Integrative Biosciences, Oregon Health & Science University, Portland, Oregon, United States
| | - Ruth A. Kelly
- Ocular Genetics Unit, Smurfit Institute of Genetics, Trinity College Dublin, Dublin, Ireland
| | - David Krizaj
- Department of Ophthalmology, University of Utah School of Medicine, Salt Lake City, Utah, United States
| | - Ajay Kumar
- Department of Ophthalmology, University of Pittsburgh, Pennsylvania, United States
| | - Brian C. Leonard
- Department of Surgical and Radiological Sciences, University of California, Davis, Davis, California, United States
| | - Raquel L. Lieberman
- Department of Chemistry and Biochemistry, Georgia Institute of Technology, Atlanta, Georgia, United States
| | - Paloma Liton
- Department of Ophthalmology and Department of Pathology, Duke University, Durham, North Carolina, United States
| | - Yutao Liu
- Department of Cellular Biology and Anatomy, James & Jean Culver Vision Discovery Institute, Augusta University, Augusta, Georgia, United States
| | - Katy C. Liu
- Duke Eye Center, Duke Health, Durham, North Carolina, United States
| | - Navita N. Lopez
- Department of Neurobiology, University of Utah, Salt Lake City, Utah, United States
| | - Weiming Mao
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Timur Mavlyutov
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Fiona McDonnell
- Duke Eye Center, Duke Health, Durham, North Carolina, United States
| | - Gillian J. McLellan
- Department of Surgical Sciences and Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Philip Mzyk
- Department of Ophthalmology and Visual Sciences, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | - Andrews Nartey
- College of Optometry, University of Houston, Houston, Texas, United States
| | - Louis R. Pasquale
- Department of Ophthalmology, Icahn School of Medicine at Mount Sinai, New York, New York, United States
| | - Gaurang C. Patel
- Ophthalmology Research, Regeneron Pharmaceuticals, Tarreytown, New York, United States
| | | | - Donna M. Peters
- Department of Pathology and Laboratory Medicine, University of Wisconsin–Madison, Madison, Wisconsin, United States
| | | | - Ponugoti Vasantha Rao
- Department of Ophthalmology, Duke University School of Medicine, Durham, North Carolina, United States
| | - Naga Rayana
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Urmimala Raychaudhuri
- Department of Neurobiology, University of California, Irvine, Irvine, California, United States
| | - Ester Reina-Torres
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - Ruiyi Ren
- Department of Ophthalmology, Boston University School of Medicine, Boston, Massachusetts, United States
| | - Douglas Rhee
- Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Uttio Roy Chowdhury
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - John R. Samples
- Washington State University, Floyd Elson College of Medicine, Spokane, Washington, United States
| | | | - Najam Sharif
- Santen Inc., Emeryville, California, United States
| | - Joel S. Schuman
- Department of Ophthalmology and Department of Physiology and Neuroscience, NYU Grossman School of Medicine, NYU Langone Health, New York University, New York, New York, United States; Departments of Biomedical Engineering and Electrical and Computer Engineering, New York University Tandon School of Engineering, Brooklyn, New York, United States; Center for Neural Science, College of Arts and Science, New York University, New York, New York, United States
| | - Val C. Sheffield
- Department of Pediatrics and Department of Ophthalmology and Visual Sciences, University of Iowa Carver College of Medicine, Iowa City, Iowa, United States
| | - Cooper H. Stevenson
- Department of Pharmacology & Neuroscience, and North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Avinash Soundararajan
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | | | - Chenna Kesavulu Sugali
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Yang Sun
- Veterans Affairs Palo Alto Health Care System, Stanford University, Palo Alto, California, United States
| | - Carol B. Toris
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States; Department of Ophthalmology and Vision Sciences, The Ohio State University, Columbus, Ohio, United States
| | | | - Amir Vahabikashi
- Cell and Developmental Biology Department, Northwestern University, Chicago, Illinois, United States
| | - Janice A. Vranka
- Department of Ophthalmology, Casey Eye Institute, Oregon Health & Science University, Portland, Oregon, United States
| | - Ting Wang
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, Indiana, United States
| | - Colin E. Willoughby
- Genomic Medicine, Biomedical Sciences Research Institute, Ulster University, Coleraine, Northern Ireland, United Kingdom
| | - Chen Xin
- Beijing Institute of Ophthalmology, Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing, China
| | - Hongmin Yun
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States
| | - Hao F. Zhang
- Biomedical Engineering Department, Northwestern University, Evanston, Illinois, United States
| | - Michael P. Fautsch
- Biomedical Engineering Department, Northwestern University, Evanston, Illinois, United States
| | | | - Abbot F. Clark
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - C. Ross Ethier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology; Emory University School of Medicine, Emory University, Atlanta, Georgia, United States
| | - W. Daniel Stamer
- Duke Ophthalmology, Duke University, Durham, North Carolina, United States
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8
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Jasien JV, Read AT, van Batenburg-Sherwood J, Perkumas KM, Ethier CR, Stamer WD, Samuels BC. Anterior Segment Anatomy and Conventional Outflow Physiology of the Tree Shrew (Tupaia belangeri). Invest Ophthalmol Vis Sci 2022; 63:21. [PMID: 35040876 PMCID: PMC8764208 DOI: 10.1167/iovs.63.1.21] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2021] [Accepted: 10/26/2021] [Indexed: 11/24/2022] Open
Abstract
Purpose Rodent and primate models are commonly used in glaucoma research; however, both have their limitations. The tree shrew (Tupaia belangeri) is an emerging animal model for glaucoma research owing in part to having a human-like optic nerve head anatomy, specifically a collagenous load-bearing lamina. However, the anterior segment anatomy and function have not been extensively studied in the tree shrew. Thus, the purpose of this study was to provide the first detailed examination of the anterior segment anatomy and aqueous outflow facility in the tree shrew. Methods Aqueous outflow dynamics were measured in five ostensibly normal eyes from three tree shrews using the iPerfusion system over a range of pressures. Gross histological assessment and immunohistochemistry were performed to characterize anterior segment anatomy and to localize several key molecules related to aqueous outflow. Results Anterior segment anatomy in tree shrews is similar to humans, demonstrating a scleral spur, a multilayered trabecular meshwork and a circular Schlemm's canal with a single lumen. Average outflow facility was 0.193 µL/min/mm Hg (95% confidence interval, 0.153-0.244), and was stable over time. Outflow facility was more similar between contralateral eyes (approximately 5% average difference) than between eyes of different animals. No significant dependence of outflow facility on time or pressure was detected (pressure-flow nonlinearity parameter of 0.01 (95% % confidence interval, -0.29 to 0.31 CI µL/min/mm Hg). Conclusions These studies lend support to the usefulness of the tree shrew as a novel animal model in anterior segment glaucoma and pharmacology research. The tree shrew's cost, load-bearing collagenous lamina cribrosa, and lack of washout or anterior chamber deepening provides a distinct experimental and anatomic advantage over the current rodent and nonhuman primate models used for translational research.
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Affiliation(s)
- Jessica V. Jasien
- Vision Science Graduate Program, School of Optometry, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - A. Thomas Read
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
| | | | - Kristin M. Perkumas
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - C. Ross Ethier
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
| | - W. Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Brian C. Samuels
- Department of Ophthalmology and Visual Sciences, School of Medicine, University of Alabama at Birmingham, Birmingham, Alabama, United States
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9
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Hohberger B, Wörn M, Lämmer R, Mahajan A, Mardin C, Schötzer-Schrehardt U, Kunze R, Herrmann M, Wallukat G. Agonistic β2-Adrenergic Receptor Autoantibodies Characterize the Aqueous Humor of Patients With Primary and Secondary Open-Angle Glaucoma. Front Immunol 2021; 12:550236. [PMID: 34025634 PMCID: PMC8132703 DOI: 10.3389/fimmu.2021.550236] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/08/2020] [Accepted: 04/16/2021] [Indexed: 12/27/2022] Open
Abstract
Purpose Agonistic β2-adrenergic receptor autoantibodies (β2-agAAbs) were recently observed in sera of patients with ocular hypertension (OHT), primary (POAG), and secondary open-angle glaucoma (SOAG), yet not in healthy controls (HCs). It was the aim of the present study to investigate the presence of β2-agAAb in aqueous humor (AH) samples of OAG patients and to correlate these with the corresponding β2-agAAb serum data. Material and Methods Thirty-nine patients (21 male, 18 female) were recruited from the Department of Ophthalmology, University of Erlangen-Nürnberg: twenty-one POAG, 18 SOAG. Aqueous humor samples were collected during minimal invasive glaucoma surgery. Serum and AH samples were analyzed for β2-agAAb by a bioassay quantifying the beating rate of cultured cardiomyocyte (cut-off: 2 U). Results Thirty-six of 39 (92.3%) and 34 of 39 (87.2%) of OAG patients showed a β2-agAAb in their sera and AH samples, respectively. All β2-agAAb AH-positive OAG patients were also seropositive. We also observed a β2-agAAb seropositivity in 95 and 89% of patients with POAG and SOAG, respectively. Beta2-agAAbs were seen in 86% (POAG) and 78% (SOAG) of AH samples. The β2-agAAb adrenergic activity was increased in the AH of patients with POAG (6.5 ± 1.5 U) when compared with those with SOAG (4.1 ± 1.1 U; p = 0.004). Serum β2-agAAb adrenergic activity did not differ between the cohorts [POAG (4.5 ± 1.5 U); SOAG (4.6 ± 2.1 U; p=0.458)]. No correlation of the beating rates were observed between serum and AH samples for group and subgroup analyses. Conclusion The detection of β2-agAAb in systemic and local circulations supports the hypothesis of a direct functional impact of these agAAbs on ocular G-protein coupled receptors. The high prevalence of β2-agAAb in serum and AH samples of patients with POAG or SOAG suggests a common role of these AAbs in the etiopathogenesis of glaucoma, independent of open-angle glaucoma subtype.
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MESH Headings
- Adrenergic beta-2 Receptor Agonists/immunology
- Aged
- Aged, 80 and over
- Animals
- Aqueous Humor/immunology
- Aqueous Humor/physiology
- Autoantibodies/blood
- Autoantibodies/immunology
- Autoantibodies/pharmacology
- Cells, Cultured
- Female
- Glaucoma, Open-Angle/blood
- Glaucoma, Open-Angle/immunology
- Glaucoma, Open-Angle/physiopathology
- Humans
- Intraocular Pressure
- Male
- Middle Aged
- Myocytes, Cardiac/drug effects
- Myocytes, Cardiac/metabolism
- Myocytes, Cardiac/physiology
- Rats, Sprague-Dawley
- Receptors, Adrenergic, beta-2/metabolism
- Rats
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Affiliation(s)
- Bettina Hohberger
- Department of Ophthalmology, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany
| | - Max Wörn
- Department of Ophthalmology, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany
| | - Robert Lämmer
- Department of Ophthalmology, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany
| | - Aparna Mahajan
- Department of Internal Medicine III, Institute of Clinical Immunology and Rheumatology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Christian Mardin
- Department of Ophthalmology, Friedrich-Alexander-University of Erlangen-Nürnberg, Erlangen, Germany
| | | | - Rudolph Kunze
- Science office, Berlin-Buch, Campus Max Delbrück Center for Molecular Medicine, Berlin, Germany
| | - Martin Herrmann
- Department of Internal Medicine III, Institute of Clinical Immunology and Rheumatology, University of Erlangen-Nürnberg, Erlangen, Germany
| | - Gerd Wallukat
- Max Delbrück Center for Molecular Medicine, Berlin, Germany
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10
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Patel PD, Chen YL, Kasetti RB, Maddineni P, Mayhew W, Millar JC, Ellis DZ, Sonkusare SK, Zode GS. Impaired TRPV4-eNOS signaling in trabecular meshwork elevates intraocular pressure in glaucoma. Proc Natl Acad Sci U S A 2021; 118:e2022461118. [PMID: 33853948 PMCID: PMC8072326 DOI: 10.1073/pnas.2022461118] [Citation(s) in RCA: 22] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/03/2023] Open
Abstract
Primary Open Angle Glaucoma (POAG) is the most common form of glaucoma that leads to irreversible vision loss. Dysfunction of trabecular meshwork (TM) tissue, a major regulator of aqueous humor (AH) outflow resistance, is associated with intraocular pressure (IOP) elevation in POAG. However, the underlying pathological mechanisms of TM dysfunction in POAG remain elusive. In this regard, transient receptor potential vanilloid 4 (TRPV4) cation channels are known to be important Ca2+ entry pathways in multiple cell types. Here, we provide direct evidence supporting Ca2+ entry through TRPV4 channels in human TM cells and show that TRPV4 channels in TM cells can be activated by increased fluid flow/shear stress. TM-specific TRPV4 channel knockout in mice elevated IOP, supporting a crucial role for TRPV4 channels in IOP regulation. Pharmacological activation of TRPV4 channels in mouse eyes also improved AH outflow facility and lowered IOP. Importantly, TRPV4 channels activated endothelial nitric oxide synthase (eNOS) in TM cells, and loss of eNOS abrogated TRPV4-induced lowering of IOP. Remarkably, TRPV4-eNOS signaling was significantly more pronounced in TM cells compared to Schlemm's canal cells. Furthermore, glaucomatous human TM cells show impaired activity of TRPV4 channels and disrupted TRPV4-eNOS signaling. Flow/shear stress activation of TRPV4 channels and subsequent NO release were also impaired in glaucomatous primary human TM cells. Together, our studies demonstrate a central role for TRPV4-eNOS signaling in IOP regulation. Our results also provide evidence that impaired TRPV4 channel activity in TM cells contributes to TM dysfunction and elevated IOP in glaucoma.
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Affiliation(s)
- Pinkal D Patel
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107
| | - Yen-Lin Chen
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908
| | - Ramesh B Kasetti
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107
| | - Prabhavathi Maddineni
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107
| | - William Mayhew
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107
| | - J Cameron Millar
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107
| | - Dorette Z Ellis
- Department of Pharmaceutical Sciences, North Texas Eye Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107
| | - Swapnil K Sonkusare
- Robert M. Berne Cardiovascular Research Center, University of Virginia, Charlottesville, VA 22908;
- Molecular Physiology and Biological Physics, University of Virginia School of Medicine, Charlottesville, VA 22908
| | - Gulab S Zode
- Department of Pharmacology and Neuroscience, North Texas Eye Research Institute, University of North Texas Health Science Center at Fort Worth, Fort Worth, TX 76107;
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11
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Roy Chowdhury U, Bahler CK, Hann CR, Holman BH, Fautsch MP. Isolation and characterization of novel primary cells from the human distal outflow pathway. Sci Rep 2021; 11:4034. [PMID: 33597641 PMCID: PMC7890058 DOI: 10.1038/s41598-021-83558-6] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/29/2020] [Accepted: 02/01/2021] [Indexed: 12/01/2022] Open
Abstract
Ocular hypertension occurs due to increased resistance to aqueous humor removal through the conventional outflow pathway. Unlike the proximal region of the conventional outflow pathway, the distal region has not been well studied, mostly due to lack of model systems. Here we describe isolation and characterization of human primary vascular distal outflow pathway (VDOP) cells from the distal region of the conventional outflow pathway. Tissue from the distal region was isolated from human corneo-scleral rims, digested with collagenase type I (100 U/ml) and placed on gelatin coated plates to allow cellular growth in Dulbecco's Modified Eagle's Medium (low glucose) containing fetal bovine serum and antibiotic/antimycotic. VDOP cells showed consistent proliferation for up to 7 passages, retained endothelial-like nature of the parent tissues and showed a unique marker phenotype of Lectin+VEGFR2-CD34-NG2- that was distinct from neighboring trabecular meshwork (Lectin+VEGFR2-CD34-NG2+) and Schlemm's canal (Lectin+VEGFR2+CD34+NG2+) cells. Dexamethasone treated VDOP cells did not express myocilin and did not form cross-linked actin networks, in contrast to trabecular meshwork cells. These data show that VDOP cells are unique to the distal outflow region and can be used as a viable in vitro model system to understand the biology of the distal outflow pathway and intraocular pressure regulation.
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Affiliation(s)
- Uttio Roy Chowdhury
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA.
| | - Cindy K Bahler
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Cheryl R Hann
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Bradley H Holman
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
| | - Michael P Fautsch
- Department of Ophthalmology, Mayo Clinic, 200 First Street SW, Rochester, MN, 55905, USA
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12
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Stankowska DL, Millar JC, Kodati B, Behera S, Chaphalkar RM, Nguyen T, Nguyen KT, Krishnamoorthy RR, Ellis DZ, Acharya S. Nanoencapsulated hybrid compound SA-2 with long-lasting intraocular pressure-lowering activity in rodent eyes. Mol Vis 2021; 27:37-49. [PMID: 33633438 PMCID: PMC7883929] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/06/2020] [Accepted: 01/14/2021] [Indexed: 11/30/2022] Open
Abstract
Purpose Glaucoma is a neurodegenerative disease of the eye with an estimated prevalence of more than 111.8 million patients worldwide by 2040, with at least 6 to 8 million projected to become bilaterally blind. Clinically, the current method of slowing glaucomatous vision loss is to reduce intraocular pressure (IOP). In this manuscript, we describe the in vitro cytoprotective and in vivo long lasting IOP-lowering activity of the poly D, L-lactic-co-glycolic acid (PLGA) nanoparticle-encapsulated hybrid compound SA-2, possessing nitric oxide (NO) donating and superoxide radical scavenging functionalities. Methods Previously characterized primary human trabecular meshwork (hTM) cells were used for the study. hTM cells were treated with SA-2 (100 µM, 200 µM, and 1,000 µM), SA-2 PLGA-loaded nanosuspension (SA-2 NPs, 0.1%), or vehicle for 30 min. Cyclic guanosine monophosphate (cGMP) and super oxide dismutase (SOD) levels were analyzed using commercial kits. In another experiment, hTM cells were pretreated with tert-butyl hydrogen peroxide (TBHP, 300 µM) for 30 min followed by treatment with escalating doses of SA-2 for 24 h, and CellTiter 96 cell proliferation assay was performed. For the biodistribution study, the cornea, aqueous humor, vitreous humor, retina, choroid, and sclera were collected after 1 h of administration of a single eye drop (30 μl) of SA-2 NPs (1% w/v) formulated in PBS to rat (n = 6) eyes. Compound SA-2 was quantified using high performance liquid chromatography /mass spectrometry (HPLC/MS). For the IOP-lowering activity study, a single SA-2 NPs (1%) eye drop was instilled in normotensive rats eyes and in the IOP-elevated rat eyes (n = 3/group, in the Morrison model of glaucoma), or Ad5TGFβ2-induced ocular hypertensive (OHT) mouse eyes (n = 5/group). IOP was measured at various time points up to 72 h, and the experiment was repeated in triplicate. Mouse aqueous humor outflow facility was determined with multiple flow-rate infusion and episcleral venous pressure estimated with manometry. Results SA-2 upregulated cGMP levels (six- to ten-fold) with an half maximal effective concentration (EC50) of 20.3 µM in the hTM cells and simultaneously upregulated (40-fold) the SOD enzyme when compared with the vehicle-treated hTM cells. SA-2 also protected hTM cells from TBHP-induced decrease in cell survival with an EC50 of 0.38 µM. A single dose of slow-release SA-2 NPs (1% w/v) delivered as an eye drop significantly lowered IOP (by 30%) in normotensive and OHT rodent eyes after 3 h post-dose, with the effect lasting up to 72 h. A statistically significant increase in aqueous outflow facility and a decrease in episcleral venous pressure was observed in rodents at this dose at 54 h. Conclusions Hybrid compound SA-2 upregulated cGMP in hTM cells, increased outflow facility and decreased IOP in rodent models of OHT. Compound SA-2 possessing an antioxidant moiety provided additive cytoprotective activity to oxidatively stressed hTM cells by scavenging reactive oxygen species (ROS) and increasing SOD enzyme activity. Additionally, the PLGA nanosuspension formulation (SA-2 NPs) provided longer duration of IOP-lowering activity (up to 3 days) in comparison with the free non-encapsulated SA-2 drug. The data have implications for developing novel, non-prostaglandin therapeutics for IOP-lowering and cytoprotective effects with the possibility of an eye drop dosing regimen of once every 3 days for patients with glaucoma.
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Affiliation(s)
- Dorota L Stankowska
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX
| | - J Cameron Millar
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX
| | - Bindu Kodati
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX
| | - Sumita Behera
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX
| | - Renuka M Chaphalkar
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX
| | - Tam Nguyen
- Department of Bioengineering, The University of Texas at Arlington, Arlington, TX
| | - Kytai T Nguyen
- Department of Bioengineering, The University of Texas at Arlington, Arlington, TX
| | - Raghu R Krishnamoorthy
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX
| | - Dorette Z Ellis
- Department of Pharmaceutical Sciences, College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX
| | - Suchismita Acharya
- Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, TX
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, TX
- Department of Pharmaceutical Sciences, College of Pharmacy, University of North Texas Health Science Center, Fort Worth, TX
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13
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Khokhar S, Bhayana AA, Vashistha V, Azad SV. Novel sign to check wound leak intraoperatively: 'Bloody Seidel's'. BMJ Case Rep 2020; 13:e239486. [PMID: 33148564 PMCID: PMC7643487 DOI: 10.1136/bcr-2020-239486] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Accepted: 10/14/2020] [Indexed: 11/04/2022] Open
Affiliation(s)
- Sudarshan Khokhar
- Ophthalmology, Dr Rajendra Prasad Centre for Ophthalmic Sciences, AIl India Institute of Medical Sciences, New Delhi, India
| | - Amber Amar Bhayana
- Ophthalmology, Dr Rajendra Prasad Centre for Ophthalmic Sciences, AIl India Institute of Medical Sciences, New Delhi, India
| | - Vimal Vashistha
- Ophthalmology, Dr Rajendra Prasad Centre for Ophthalmic Sciences, AIl India Institute of Medical Sciences, New Delhi, India
| | - Shorya Vardhan Azad
- Ophthalmology, Dr Rajendra Prasad Centre for Ophthalmic Sciences, AIl India Institute of Medical Sciences, New Delhi, India
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14
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Akiyama G, Saraswathy S, Bogarin T, Pan X, Barron E, Wong TT, Kaneko MK, Kato Y, Hong Y, Huang AS. Functional, structural, and molecular identification of lymphatic outflow from subconjunctival blebs. Exp Eye Res 2020; 196:108049. [PMID: 32387381 PMCID: PMC7328765 DOI: 10.1016/j.exer.2020.108049] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2020] [Revised: 04/05/2020] [Accepted: 04/27/2020] [Indexed: 01/26/2023]
Abstract
The purpose of this study is to evaluate outflow pathways from subconjunctival blebs and to identify their identity. Post-mortem porcine (n = 20), human (n = 1), and bovine (n = 1) eyes were acquired, and tracers (fluorescein, indocyanine green, or fixable/fluorescent dextrans) were injected into the subconjunctival space to create raised blebs where outflow pathways were visualized qualitatively and quantitatively. Rodents with fluorescent reporter transgenes were imaged for structural comparison. Concurrent optical coherence tomography (OCT) was obtained to study the structural nature of these pathways. Using fixable/fluorescent dextrans, tracers were trapped to the bleb outflow pathway lumen walls for histological visualization and molecular identification using immunofluorescence against lymphatic and blood vessel markers. Bleb outflow pathways could be observed using all tracers in all species. Quantitative analysis showed that the nasal quadrant had more bleb-related outflow pathways compared to the temporal quadrant (nasal: 1.9±0.3 pathways vs. temporal: 0.7±0.2 pathways; p = 0.003). However, not all blebs resulted in an outflow pathway (0-pathways = 18.2%; 1-pathway = 36.4%; 2-pathways = 38.6%; and 3-pathways = 6.8%). Outflow signal was validated as true luminal pathways using optical coherence tomography and histology. Bicuspid valves were identified in the direction of flow in porcine eyes. Immunofluorescence of labeled pathways demonstrated a lymphatic (Prox-1 and podoplanin) but not a blood vessel (CD31) identity. Therefore, subconjunctival bleb outflow occurs in discrete luminal pathways. They are lymphatic as assessed by structural identification of valves and molecular identification of lymphatic markers. Better understanding of lymphatic outflow may lead to improved eye care for glaucoma surgery and ocular drug delivery.
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Affiliation(s)
- Goichi Akiyama
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA; Jikei School of Medicine, Tokyo, Japan
| | - Sindhu Saraswathy
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Thania Bogarin
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Xiaojing Pan
- Qingdao Eye Hospital, Shandong Eye Institute, Shandong First Medical University, Qingdao, China
| | - Ernesto Barron
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Tina T Wong
- Singapore National Eye Center and Singapore Research Institute, Singapore, Singapore
| | - Mika K Kaneko
- Tohoku University Graduate School of Medicine, Miyagi, Japan
| | - Yukinari Kato
- Tohoku University Graduate School of Medicine, Miyagi, Japan; New Industry Creation Hatchery Center, Tohoku University, Miyagi, Japan
| | - Young Hong
- Division of Plastic and Reconstructive Surgery, Department of Surgery, Norris Comprehensive Cancer Center Keck School of Medicine, University of Southern California, Los Angeles, CA, USA
| | - Alex S Huang
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
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15
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Saraswathy S, Bogarin T, Barron E, Francis BA, Tan JCH, Weinreb RN, Huang AS. Segmental differences found in aqueous angiographic-determined high - and low-flow regions of human trabecular meshwork. Exp Eye Res 2020; 196:108064. [PMID: 32439396 DOI: 10.1016/j.exer.2020.108064] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2019] [Revised: 05/04/2020] [Accepted: 05/05/2020] [Indexed: 01/28/2023]
Abstract
This work sought to compare aqueous angiographic segmental patterns with bead-based methods which directly visualize segmental trabecular meshwork (TM) tracer trapping. Additionally, segmental protein expression differences between aqueous angiographic-derived low- and high-outflow human TM regions were evaluated. Post-mortem human eyes (One Legacy and San Diego eye banks; n = 15) were perfused with fluorescent tracers (fluorescein [2.5%], indocyanine green [0.4%], and/or fluorescent microspheres). After angiographic imaging (Spectralis HRA+OCT; Heidelberg Engineering), peri-limbal low- and high-angiographic flow regions were marked. Aqueous angiographic segmental outflow patterns were similar to fluorescent microsphere TM trapping segmental patterns. TM was dissected from low- and high-flow areas and processed for immunofluorescence or Western blot and compared. Versican expression was relatively elevated in low-flow regions while MMP3 and collagen VI were relatively elevated in high-flow regions. TGF-β2, thrombospondin-1, TGF-β receptor1, and TGF-β downstream proteins such as α-smooth muscle actin were relatively elevated in low-flow regions. Additionally, fibronectin (FN) levels were unchanged, but the EDA isoform (FN-EDA) that is associated with fibrosis was relatively elevated in low-flow regions. These results show that segmental aqueous angiographic patterns are reflective of underlying TM molecular characteristics and demonstrate increased pro-fibrotic activation in low-flow regions. Thus, we provide evidence that aqueous angiography outflow visualization, the only tracer outflow imaging method available to clinicians, is in part representative of TM biology.
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Affiliation(s)
- Sindhu Saraswathy
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Thania Bogarin
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Ernesto Barron
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Brian A Francis
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - James C H Tan
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA
| | - Robert N Weinreb
- Hamilton Glaucoma Center, Shiley Eye Institute, Viterbi Family Department of Ophthalmology University of California, San Diego, CA, USA
| | - Alex S Huang
- Doheny Eye Institute and Department of Ophthalmology, David Geffen School of Medicine at UCLA, Los Angeles, CA, USA.
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16
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Loewen RT, Waxman S, Wang C, Atta S, Chen S, Watkins SC, Watson AM, Loewen NA. 3D-Reconstruction of the human conventional outflow system by ribbon scanning confocal microscopy. PLoS One 2020; 15:e0232833. [PMID: 32421732 PMCID: PMC7233539 DOI: 10.1371/journal.pone.0232833] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/23/2019] [Accepted: 04/22/2020] [Indexed: 11/19/2022] Open
Abstract
PURPOSE The risk for glaucoma is driven by the microanatomy and function of the anterior segment. We performed a computation-intense, high-resolution, full-thickness ribbon-scanning confocal microscopy (RSCM) of the outflow tract of two human eyes. We hypothesized this would reveal important species differences when compared to existing data of porcine eyes, an animal that does not spontaneously develop glaucoma. METHODS After perfusing two human octogenarian eyes with lectin-fluorophore conjugate and optical clearance with benzyl alcohol benzyl benzoate (BABB), anterior segments were scanned by RSCM and reconstructed in 3D for whole-specimen rendering. Morphometric analyses of the outflow tract were performed for the trabecular meshwork (TM), limbal, and perilimbal outflow structures and compared to existing porcine data. RESULTS RSCM provided high-resolution data for IMARIS-based surface reconstruction of outflow tract structures in 3D. Different from porcine eyes with an abundance of highly interconnected, narrow, and short collector channels (CCs), human eyes demonstrated fewer CCs which had a 1.5x greater cross-sectional area (CSA) and 2.6x greater length. Proximal CC openings at the level of Schlemm's canal (SC) had a 1.3x larger CSA than distal openings into the scleral vascular plexus (SVP). CCs were 10.2x smaller in volume than the receiving SVP vessels. Axenfeld loops, projections of the long ciliary nerve, were also visualized. CONCLUSION In this high-resolution, volumetric RSCM analysis, human eyes had far fewer outflow tract vessels than porcine eyes. Human CCs spanned several clock-hours and were larger than in porcine eyes. These species differences may point to factors downstream of the TM that increase our vulnerability to glaucoma.
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Affiliation(s)
- Ralitsa T. Loewen
- Department of Ophthalmology, University of Würzburg, Würzburg, Germany
| | - Susannah Waxman
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Chao Wang
- Department of Ophthalmology, University of Würzburg, Würzburg, Germany
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Cellular Biology, Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Sarah Atta
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Si Chen
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, China
| | - Simon C. Watkins
- Department of Cellular Biology, Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Alan M. Watson
- Department of Cellular Biology, Center for Biologic Imaging, University of Pittsburgh, Pittsburgh, Pennsylvania, United States of America
| | - Nils A. Loewen
- Department of Ophthalmology, University of Würzburg, Würzburg, Germany
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Zhou Y, Xia X, Yang E, Wang Y, Marra KG, Ethier CR, Schuman JS, Du Y. Adipose-derived stem cells integrate into trabecular meshwork with glaucoma treatment potential. FASEB J 2020; 34:7160-7177. [PMID: 32259357 PMCID: PMC7254553 DOI: 10.1096/fj.201902326r] [Citation(s) in RCA: 14] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/25/2019] [Revised: 02/24/2020] [Accepted: 03/23/2020] [Indexed: 12/13/2022]
Abstract
The trabecular meshwork (TM) is an ocular tissue that maintains intraocular pressure (IOP) within a physiologic range. Glaucoma patients have reduced TM cellularity and, frequently, elevated IOP. To establish a stem cell-based approach to restoring TM function and normalizing IOP, human adipose-derived stem cells (ADSCs) were induced to differentiate to TM cells in vitro. These ADSC-TM cells displayed a TM cell-like genotypic profile, became phagocytic, and responded to dexamethasone stimulation, characteristic of TM cells. After transplantation into naive mouse eyes, ADSCs and ADSC-TM cells integrated into the TM tissue, expressed TM cell markers, and maintained normal IOP, outflow facility, and extracellular matrix. Cell migration and affinity results indicated that the chemokine pair CXCR4/SDF1 may play an important role in ADSC-TM cell homing. Our study demonstrates the possibility of applying autologous or allogeneic ADSCs and ADSC-TM cells as a potential treatment to restore TM structure and function in glaucoma.
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Affiliation(s)
- Yi Zhou
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA 15213
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, China 410008
- Co-first author
| | - Xiaobo Xia
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, China 410008
- Co-first author
| | - Enzhi Yang
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA 15213
| | - Yiwen Wang
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA 15213
- Department of Ophthalmology, Xiangya Hospital, Central South University, Changsha, Hunan, China 410008
| | - Kacey G. Marra
- Departments of Plastic Surgery and Bioengineering, University of Pittsburgh, Pittsburgh, PA 15213
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15213
| | - C. Ross Ethier
- Department of Biomedical Engineering, Georgia Institute of Technology & Emory University, Atlanta, GA 30332
| | - Joel S. Schuman
- Department of Ophthalmology, New York University School of Medicine, New York, NY 10016
| | - Yiqin Du
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA 15213
- Department of Developmental Biology, University of Pittsburgh, Pittsburgh, PA 15213
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA 15213
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Abstract
PURPOSE OF REVIEW Most microinvasive glaucoma surgery (MIGS) procedures bypass outflow resistance residing proximally in the trabecular meshwork and inner wall of Schlemm's canal. A novel procedure combining trabeculotomy with viscodilation adds to this by also addressing distal resistance of the canal and collector channel ostia. This review examines the development and evidence for both trabeculotomy and canaloplasty separately and the combination in a single procedure. RECENT FINDINGS Recent aqueous angiography studies have confirmed the segmental nature of outflow through Schlemm's canal highlighting the need to address distal outflow pathway resistance. Combined trabeculotomy and viscodilation ab interno is a novel approach with a new purpose-designed device (OMNI Surgical System) becoming available to surgeons in early 2018. Recent results as both a standalone and combined with cataract procedure demonstrate significant intraocular pressure reductions with an average 41% reduction from baseline in the pseudophakic group. SUMMARY Targeting both distal as well as proximal points of outflow resistance in the conventional pathway may prove to be a highly efficacious MIGS modality. Additional large prospective studies are currently ongoing to confirm these preliminary results.
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Affiliation(s)
- Jaime E. Dickerson
- Sight Sciences Inc., Menlo Park, California
- North Texas Eye Research Institute, University of North Texas Health Science Center, Fort Worth, Texas
| | - Reay H. Brown
- Sight Sciences Inc., Menlo Park, California
- Atlanta Ophthalmology Associates, Atlanta, Georgia, USA
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Zhao YB, Chen B, Li D. Optimization of surgical protocol for laser iridotomy based on the numerical simulation of aqueous flow. Math Biosci Eng 2019; 16:7405-7420. [PMID: 31698619 DOI: 10.3934/mbe.2019370] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 06/10/2023]
Abstract
Primary angle-closure glaucoma (PACG) is a major cause of blindness worldwide, with a particularly high prevalence in Asian populations. Laser iridotomy (LI) has been the standard therapeutic modality for treating PACG to avoid blindness. However, the complex structure of the eyeball, the aqueous fluidity, and the limitation of detecting equipment will cause difficulty in surgery and the probability of complications. Numerical simulation was conducted to investigate aqueous humor (AH) flow under different physiological structures before and after laser surgery. When the anterior chamber depth decreases from 2.8 mm to 2.0 mm (caused by angle-closure glaucoma), the maximum velocity of natural convection is doubled, and the pressure difference between the posterior and anterior chambers increases by 20%. Therefore, a shallow anterior chamber depth is crucial for the accurate investigation of glaucoma. Pupil block sharply increases the intraocular pressure (IOP). When the gap between the lens and iris decreases from 10 μm to 0.5 μm, P between the posterior and anterior chambers is approximately 37 times higher than before, thereby damaging intraocular tissues. LI can effectively reduce the IOP caused by pupil block, but the velocity of AH after operation is 40 times the normal condition, and the increased corneal shear stress could lead to corneal damage, which can be solved by adjusting the incident angle of laser beam On the basis of the allowable angle range of surgical equipment and the effect of different incident angles on the cornea and iris, the optimum angle of laser drilling is 45°.
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Affiliation(s)
- Yi Bo Zhao
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shanxi, China
| | - Bin Chen
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shanxi, China
| | - Dong Li
- State Key Laboratory of Multiphase Flow in Power Engineering, Xi'an Jiaotong University, Xi'an, Shanxi, China
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20
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Schwerk B, Harder L, Windhövel C, Hewicker-Trautwein M, Wagner A, Bach JP, Voigt LC, Hinze U, Chichkov B, Haferkamp H, Lubatschowski H, Nikolic S, Nolte I. Comparison of two prototypes of a magnetically adjustable glaucoma implant in rabbits. PLoS One 2019; 14:e0215316. [PMID: 30973952 PMCID: PMC6459522 DOI: 10.1371/journal.pone.0215316] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2018] [Accepted: 03/30/2019] [Indexed: 01/03/2023] Open
Abstract
Glaucoma drainage devices are used in surgical glaucoma therapy. Success of controlling the intraocular pressure is limited due to fibrous implant encapsulation and fibrin coating on the implant which lead to drainage obstructions. An innovative implant with a magnetically adjustable valve was developed. The valve opening of the implant should eliminate inflammatory products from the outflow area and affect fibrous tissue formation to achieve a sufficient long-term aqueous humour outflow. Lifting of this valve should disturb cell adhesion by exerting mechanical forces. Before testing this hypothesis, the flow characteristics of glaucoma drainage devices, especially the outflow resistance by regular IOP, should be considered in a pilot study, as they are important in preventing too low postoperative intraocular pressure known as ocular hypotony. Therefore, two prototypes of the innovative implant differing in their valve area design were examined regarding their flow characteristics in a limited animal experiment lasting two weeks. Ten healthy New Zealand White rabbits were divided into two groups (A & B) with different implanted prototypes. Daily, tonometry and direct ophthalmoscopy were performed to assess the intraocular pressure and the inflammatory reaction of the eye. After two weeks, the rabbits were euthanised to evaluate the initially histological inflammatory reaction to the implant. In group A, one case of hypotony emerged. When considering the entire observation period, a highly statistically significant difference between the intraocular pressure in the operated eye and that in the control eye was detected in group A (p < 0.0001) in contrast to group B (p = 0.0063). The postoperative inflammatory signs decreased within two weeks. Histologically, a typical but low level foreign body reaction with macrophages and lymphocytes as well as mild to moderate fibrosis was seen after the short experimental period. Based on our tonometric results, prototype B seems to be the system of choice for further research assessing its long-term function and biocompatibility.
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Affiliation(s)
- Birthe Schwerk
- Small Animal Clinic, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
- * E-mail: (IN); (BS)
| | - Lisa Harder
- Small Animal Clinic, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Claudia Windhövel
- Small Animal Clinic, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | | | - Anna Wagner
- Institute for Pathology, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Jan-Peter Bach
- Small Animal Clinic, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Lena Carolin Voigt
- Clinic for Small Mammals, Reptiles and Birds, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
| | - Ulf Hinze
- Institute of Quantum Optics, Gottfried Wilhelm Leibniz University Hannover, Hannover, Germany
| | - Boris Chichkov
- Institute of Quantum Optics, Gottfried Wilhelm Leibniz University Hannover, Hannover, Germany
| | - Heinz Haferkamp
- Gottfried Wilhelm Leibniz University Hannover, Hannover, Germany
| | | | | | - Ingo Nolte
- Small Animal Clinic, University of Veterinary Medicine Hannover, Foundation, Hannover, Germany
- * E-mail: (IN); (BS)
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Tanna AP, Johnson M. Rho Kinase Inhibitors as a Novel Treatment for Glaucoma and Ocular Hypertension. Ophthalmology 2018; 125:1741-1756. [PMID: 30007591 PMCID: PMC6188806 DOI: 10.1016/j.ophtha.2018.04.040] [Citation(s) in RCA: 147] [Impact Index Per Article: 24.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/13/2018] [Revised: 04/24/2018] [Accepted: 04/30/2018] [Indexed: 01/11/2023] Open
Abstract
In an elegant example of bench-to-bedside research, a hypothesis that cells in the outflow pathway actively regulate conventional outflow resistance was proposed in the 1990s and systematically pursued, exposing novel cellular and molecular mechanisms of intraocular pressure (IOP) regulation. The critical discovery that pharmacologic manipulation of the cytoskeleton of outflow pathway cells decreased outflow resistance placed a spotlight on the Rho kinase pathway that was known to regulate the cytoskeleton. Ultimately, a search for Rho kinase inhibitors led to the discovery of several molecules of therapeutic interest, leaving us today with 2 new ocular hypotensive agents approved for clinical use: ripasudil in Japan and netarsudil in the United States. These represent members of the first new class of clinically useful ocular hypotensive agents since the US Food and Drug Administration approval of latanoprost in 1996. The development of Rho kinase inhibitors as a class of medications to lower IOP in patients with glaucoma and ocular hypertension represents a triumph in translational research. Rho kinase inhibitors are effective alone or when combined with other known ocular hypotensive medications. They also offer the possibility of neuroprotective activity, a favorable impact on ocular blood flow, and even an antifibrotic effect that may prove useful in conventional glaucoma surgery. Local adverse effects, however, including conjunctival hyperemia, subconjunctival hemorrhages, and cornea verticillata, are common. Development of Rho kinase inhibitors targeted to the cells of the outflow pathway and the retina may allow these agents to have even greater clinical impact. The objectives of this review are to describe the basic science underlying the development of Rho kinase inhibitors as a therapy to lower IOP and to summarize the results of the clinical studies reported to date. The neuroprotective and vasoactive properties of Rho kinase inhibitors, as well as the antifibrotic properties, of these agents are reviewed in the context of their possible role in the medical and surgical treatment of glaucoma.
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Affiliation(s)
- Angelo P Tanna
- Department of Ophthalmology, Northwestern University Feinberg School of Medicine, Chicago, Illinois.
| | - Mark Johnson
- Department of Ophthalmology, Northwestern University Feinberg School of Medicine, Chicago, Illinois; Department of Biomedical Engineering, Northwestern University, Evanston, Illinois; Department of Mechanical Engineering, Northwestern University, Evanston, Illinois
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Andrés-Guerrero V, García-Feijoo J. Nitric oxide-donating compounds for IOP lowering in glaucoma. Arch Soc Esp Oftalmol (Engl Ed) 2018; 93:290-299. [PMID: 29580758 DOI: 10.1016/j.oftal.2018.02.004] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Received: 11/07/2017] [Revised: 02/01/2018] [Accepted: 02/02/2018] [Indexed: 06/08/2023]
Abstract
INTRODUCTION An elevated intraocular pressure (IOP) remains the main risk factor for progression of glaucoma upon which we can efficiently act. Pharmacological strategies to reduce IOP are directed towards the reduction of aqueous humour (AH) production and/or the increase in AH drainage through the uveoscleral pathway. However, there are no drugs currently available as first-line treatment to increase AH outflow primarily via the conventional route. Ocular nitric oxide (NO) production takes place in AH outflow pathways and in the ciliary muscle, modulating the cellular response to elevated IOP. METHODS This review describes the mechanism of action of endogenous NO and NO-donating compounds that are under research. It includes information regarding pre-clinical and clinical studies previously conducted with these compounds, discussing their role and therapeutic potential in the pharmacological treatment of ocular hypertension in glaucoma. RESULTS The topical ocular administration of NO-donating compounds significantly lowered IOP and maintained it in animal models of glaucoma and subjects with ocular hypertension. CONCLUSIONS The mechanism of action of these compounds is novel and scientific evidence that shows promising results. However, there is a need for more comprehensive studies to assess long-term safety and tolerability in order to properly evaluate their use in chronic therapies.
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Affiliation(s)
- V Andrés-Guerrero
- Servicio de Oftalmología, Instituto de Investigación Sanitaria San Carlos (IdISSC), Hospital Clínico San Carlos. Red de Enfermedades Oculares OftaRed, Instituto de Salud Carlos III, Madrid, España.
| | - J García-Feijoo
- Servicio de Oftalmología, Instituto de Investigación Sanitaria San Carlos (IdISSC), Hospital Clínico San Carlos. Red de Enfermedades Oculares OftaRed, Instituto de Salud Carlos III, Madrid, España; Departamento de Oftalmología y ORL, Instituto de Investigaciones Oftalmológicas Ramón Castroviejo, Facultad de Medicina, Universidad Complutense de Madrid, Madrid, España
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23
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Marques-Neves C, Martins-Baptista A, Boto JP, Delgado E, Silva-Carvalho L, Rocha I. Intraocular Pressure Variability in the Anesthetized Rat: A Spectral Analysis. Eur J Ophthalmol 2018; 14:381-6. [PMID: 15506599 DOI: 10.1177/112067210401400504] [Citation(s) in RCA: 7] [Impact Index Per Article: 1.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/17/2022]
Abstract
Purpose Intraocular pressure (IOP) is a measure of the balance between the inflow and outflow of the aqueous humor, being in close relationship with the venous ocular blood flow. But the influence of the autonomic nervous system upon this variable is not well understood. One of the most frequently used mathematical tools for the evaluation of the autonomic nervous system in the frequency domain is the fast Fourier algorithm (FFT) applied to the analysis of heart rate (HR) and arterial blood pressure (BP). For these variables, a power spectrum has been built showing the major bands: very low frequency, lower frequency, and higher frequency (HF). The range of these bands depends on the animal species. In this study, the authors used FFT to analyze the variability of IOP in anesthetized rats. Methods BP and electrocardiogram were acquired at 2 KHz in all animals before and following muscle blockade and artificial ventilation at the same frequency as the spontaneous ventilation. Also, in this last condition, IOP was recorded before and after the application of atropine in the eye. Results Results show three bands in the IOP spectrum, a similar profile to those observed in the HR and BP spectra, with HF band modified after atropine application Discussion The discussion calls attention to the influence of the autonomic nervous system on IOP and suggests the possibility of clinical application of this methodology on diagnosis and therapeutic efficacy.
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Affiliation(s)
- C Marques-Neves
- Instituto de Fisiologia, Faculdade de Medicina de Lisboa, Lisbon--Portugal
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24
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Chan JCW, Choy BNK, Chan OCC, Li KKW. Early intraocular pressure change after peripheral iridotomy with ultralow fluence pattern scanning laser and Nd:YAG laser in primary angle-closure suspect: Kowloon East Pattern Scanning Laser Study Report No. 3. Graefes Arch Clin Exp Ophthalmol 2017; 256:363-369. [PMID: 29218423 DOI: 10.1007/s00417-017-3860-1] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/09/2017] [Revised: 10/11/2017] [Accepted: 11/28/2017] [Indexed: 11/29/2022] Open
Abstract
PURPOSE Our purpose was to assess the early intraocular pressure (IOP) changes of ultralow fluence laser iridotomy using pattern scanning laser followed by neodymium:yttrium-aluminum-gamet (Nd:YAG) laser. METHODS This is a prospective interventional study. Thirty-three eyes of 33 adult Chinese primary angle-closure suspect subjects were recruited for prophylactic laser peripheral iridotomy. Sequential laser peripheral iridotomy was performed using pattern scanning laser followed by Nd:YAG laser. Visual acuity (VA) and IOP were measured before treatment, at 1 h, 1 day, 1 week, 1 month, 3 months and 6 months after laser. Laser energy used and complications were documented. Corneal endothelial cell count was examined at baseline and 6 months. Patency of the iridotomy was assessed at each follow-up visit. RESULTS All subjects achieved patent iridotomy in a single session. The mean energy used was 0.335+/-0.088 J for the pattern scanning laser, and 4.767+/-5.780 mJ for the Nd:YAG laser. The total mean energy was 0.339+/-0.089 J. None of the eyes developed a clinically significant IOP spike (≥ 8 mmHg) at 1 h and 1 day after laser use. Only four eyes developed higher IOP at 1 h and all were ≤3 mmHg compared to baseline. The mean IOP was 13.8+/-2.5 mmHg at 1 h and 11.5+/-2.2 mmHg at 1 day, both were significantly lower than baseline (15.8+/-2.1 mmHg) (P < 0.001). Mean VA (logMAR) was similar at 1 h post laser compared to baseline (0.23 vs 0.26). There was also no statistically significant difference in mean VA at other follow-up visits compared to baseline. Peripheral iridotomy closure was encountered in two (6.1%) eyes, one at 1 month and another at 6 months follow-up. There were no complications including hyphema, peripheral anterior synechia formation nor prolonged inflammation throughout the follow-up period. There was no significant loss in corneal endothelial cell counts at 6 months (2255+/-490) compared to baseline (2303+/-386) (P = 0.347). CONCLUSIONS Sequential LPI using an ultralow fluence pattern scanning laser, followed by a Nd:YAG laser, is safe and efficacious, and produces no IOP spike in dark irides of primary angle-closure suspects. Further studies to investigate its role in the treatment of other angle-closure conditions are warranted.
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Affiliation(s)
- Jeffrey Chi Wang Chan
- Department of Ophthalmology, United Christian Hospital, 130 Hip Wo Street, Kowloon, Hong Kong
- Department of Ophthalmology, Tseung Kwan O Hospital, Tseung Kwan O, Hong Kong
| | - Bonnie Nga Kwan Choy
- Department of Ophthalmology, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong
| | - Orlando Chia Chieh Chan
- Department of Ophthalmology, United Christian Hospital, 130 Hip Wo Street, Kowloon, Hong Kong
| | - Kenneth Kai Wang Li
- Department of Ophthalmology, United Christian Hospital, 130 Hip Wo Street, Kowloon, Hong Kong.
- Department of Ophthalmology, Tseung Kwan O Hospital, Tseung Kwan O, Hong Kong.
- Department of Ophthalmology, LKS Faculty of Medicine, The University of Hong Kong, Pokfulam, Hong Kong.
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Madekurozwa M, Reina-Torres E, Overby DR, Sherwood JM. Direct measurement of pressure-independent aqueous humour flow using iPerfusion. Exp Eye Res 2017; 162:129-138. [PMID: 28720436 PMCID: PMC5587799 DOI: 10.1016/j.exer.2017.07.008] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/24/2017] [Revised: 05/16/2017] [Accepted: 07/14/2017] [Indexed: 10/19/2022]
Abstract
Reduction of intraocular pressure is the sole therapeutic target for glaucoma. Intraocular pressure is determined by the dynamics of aqueous humour secretion and outflow, which comprise several pressure-dependent and pressure-independent mechanisms. Accurately quantifying the components of aqueous humour dynamics is essential in understanding the pathology of glaucoma and the development of new treatments. To better characterise aqueous humour dynamics, we propose a method to directly measure pressure-independent aqueous humour flow. Using the iPerfusion system, we directly measure the flow into the eye when the pressure drop across the pressure-dependent pathways is eliminated. Using this approach we address i) the magnitude of pressure-independent flow in ex vivo eyes, ii) whether we can accurately measure an artificially imposed pressure-independent flow, and iii) whether the presence of a pressure-independent flow affects our ability to measure outflow facility. These studies are conducted in mice, which are a common animal model for aqueous humour dynamics. In eyes perfused with a single cannula, the average pressure-independent flow was 1 [-3, 5] nl/min (mean [95% confidence interval]) (N = 6). Paired ex vivo eyes were then cannulated with two needles, connecting the eye to both iPerfusion and a syringe pump, which was used to impose a known pressure-independent flow of 120 nl/min into the experimental eye only. The measured pressure-independent flow was then 121 [117, 125] nl/min (N = 7), indicating that the method could measure pressure-independent flow with high accuracy. Finally, we showed that the artificially imposed pressure-independent flow did not affect our ability to measure facility, provided that the pressure-dependence of facility and the true pressure-independent flow were accounted for. The present study provides a robust method for measurement of pressure-independent flow, and demonstrates the importance of accurately quantifying this parameter when investigating pressure-dependent flow or outflow facility.
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Affiliation(s)
| | | | - Darryl R Overby
- Dept. of Bioengineering, Imperial College London, London SW7 2AZ, UK.
| | - Joseph M Sherwood
- Dept. of Bioengineering, Imperial College London, London SW7 2AZ, UK
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Abstract
Ab externo Schlemm's canal (SC) surgery (e.g., viscocanalostomy and canaloplasty) is a valuable alternative to glaucoma filtration surgery. It targets the abnormally high resistance to outflow in the trabecular meshwork (TM) and reestablishes the physiologic outflow system. In viscocanalostomy, viscoelastic substance is injected to dilate SC, which in turn leads to microdisruptions of the inner wall. In canaloplasty, the additional intracanalicular stent (suture or Stegmann Canal Expander®) keeps the canal patent and enhances the circumferential flow. A prerequisite for these procedures to work is the integrity of the distal outflow system, which can be evaluated by 2 clinical tests before surgery: provocative gonioscopy with blood reflux, and fluorescein channelography. Ab externo SC surgery is suitable for open-angle glaucoma, but also for angle closure glaucoma in combination with cataract extraction. Intraocular pressure reduction to the mid-teens for viscocanalostomy and to the lower-teens for canaloplasty can be expected. The majority of complications seen in filtering surgery are largely eliminated by the nonpenetrating and bleb-independent approach. Postoperative care is minimal as no bleb management such as needling is required, and hypotony-related complications are largely avoided by the intrinsic resistance of the physiologic outflow system. With its efficacy and high safety profile, ab externo SC surgery will continue to play an increasing role and will change the current concept of glaucoma surgery towards earlier intervention. Surgeons will be well advised to implement these antimetabolite-free procedures into their armamentarium to meet the expectations of the demanding glaucoma patient.
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Abstract
Detailed characterizations of ocular biometrics and parameters of aqueous humor dynamics are lacking in primary angle closure suspect (PACS) patients. This study aims to characterize these parameters and compare them with age-matched healthy volunteers.Elderly healthy volunteers (60.6 ± 7.2 years of age, mean ± SD, n = 28) and PACS patients (64.1 ± 11.6 years, n = 30) completed the study. Parameters investigated were axial length (AXL), anterior chamber depth (ACD), anterior chamber volume (ACV), central cornea thickness (CCT), intraocular pressure (IOP), aqueous flow (Fa), outflow facility (C), episcleral venous pressure (EVP), and uveoscleral outflow (Fu). Comparisons and correlations were made between and within groups.In healthy volunteers, ocular biometric parameters, IOP, and EVP correlated very well between the 2 eyes of each individual, but Fa, C, and Fu were not significantly correlated. Biometric parameters of the PACS group significantly (P < 0.001) differed from those of the healthy controls: AXL (23.31 ± 1.03 mm [PACS] vs 22.39 ± 1.04 mm [Control]; mean ± SD), ACD (2.44 ± 0.33 mm [PACS] vs 1.86 ± 0.25 mm [Control]), ACV (136.0 ± 36.1 μL [PACS] vs 81.4 ± 21.8 μL [Control]), CCT (526.9 ± 37.0 μm [PACS] vs 556.1 ± 28.4 μm [Control]). There was no significant change in IOP, Fa, C, EVP, or Fu between Control and PACS. Furthermore, IOP showed no significant correlations with AXL, ACD, ACV, CCT, or C in both groups.The PACS eyes had a shorter AXL, a shallower ACD, and a smaller ACV, but a thicker CCT. Despite these morphological changes, the PACS eyes did not have any significant changes in IOP, and aqueous humor dynamics parameters. This is consistent with the findings that IOP did not show significant correlations with biometrics, or C.
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Affiliation(s)
- Li Guo
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine
- Bengbu Medical College, Bengbu, Anhui Province, P.R. China
| | - Yuan Deng
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine
| | - Li Fang
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine
| | - Chaoqi Liu
- Department of Ophthalmology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai
| | - Tao Guo
- Department of Ophthalmology, Shanghai Ninth People's Hospital, Shanghai JiaoTong University School of Medicine
- Department of Ophthalmology, Shanghai Tenth People's Hospital, Tongji University School of Medicine, Shanghai
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28
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Kazemi A, McLaren JW, Lin SC, Toris CB, Gulati V, Moroi SE, Sit AJ. Comparison of Aqueous Outflow Facility Measurement by Pneumatonography and Digital Schiøtz Tonography. Invest Ophthalmol Vis Sci 2017; 58:204-210. [PMID: 28114581 PMCID: PMC5256680 DOI: 10.1167/iovs.16-20754] [Citation(s) in RCA: 18] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2016] [Accepted: 10/24/2016] [Indexed: 11/24/2022] Open
Abstract
Purpose It is not known if outflow facilities measured by pneumatonography and Schiøtz tonography are interchangeable. In this study we compared outflow facility measured by pneumatonography to outflow facility measured by digital Schiøtz tonography. Methods Fifty-six eyes from 28 healthy participants, ages 41 to 68 years, were included. Intraocular pressure (IOP) was measured in the sitting and supine positions with a pneumatonometer. With the subject in the supine position, IOP was recorded for 2 minutes by using a pneumatonometer with a 10-g weight and for 4 minutes by using a custom digital Schiøtz tonometer. Outflow facility was determined from the changes in pressure and intraocular volume and a standard assumed ocular rigidity coefficient for each instrument, respectively, and by using an ocular rigidity coefficient calculated by measuring pressure without and with a weight added to the pneumatonometer tip. Results The outflow facility was 0.29 ± 0.09 μL/min/mm Hg by Schiøtz tonography and 0.24 ± 0.08 μL/min/mm Hg by pneumatonography (P < 0.001) when using the standard assumed constant ocular rigidity coefficient. Mean calculated ocular rigidity coefficient was 0.028 ± 0.01 μL-1, and outflow facility determined by using this coefficient was 0.23 ± 0.08 μL/min/mm Hg by Schiøtz tonography and 0.21 ± 0.07 μL/min/mm Hg by pneumatonography (P = 0.003). Outflow facilities measured by the two devices were correlated when the ocular rigidity was assumed (r = 0.60, P < 0.001) or calculated (r = 0.70, P < 0.001). Conclusions Outflow facilities measured by pneumatonography were correlated with those measured by Schiøtz tonography, but Schiøtz tonography reported approximately 10% to 20% higher facilities when using the standard method. When ocular rigidity was determined for each eye, differences were smaller. Measurements from these devices cannot be compared directly.
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Affiliation(s)
- Arash Kazemi
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - Jay W. McLaren
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - Shuai-Chun Lin
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
| | - Carol B. Toris
- Department of Ophthalmology and Visual Sciences, Case Western Reserve University, Cleveland, Ohio, United States
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States
| | - Vikas Gulati
- Department of Ophthalmology and Visual Sciences, University of Nebraska Medical Center, Omaha, Nebraska, United States
| | - Sayoko E. Moroi
- Department of Ophthalmology and Visual Sciences, University of Michigan, Ann Arbor, Michigan, United States
| | - Arthur J. Sit
- Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, United States
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Rodrigues IA, Alaghband P, Beltran Agullo L, Galvis E, Jones S, Husain R, Lim KS. Aqueous outflow facility after phacoemulsification with or without goniosynechialysis in primary angle closure: a randomised controlled study. Br J Ophthalmol 2016; 101:879-885. [PMID: 28400374 DOI: 10.1136/bjophthalmol-2016-309556] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.9] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2016] [Revised: 09/22/2016] [Accepted: 09/27/2016] [Indexed: 11/03/2022]
Abstract
BACKGROUND Goniosynechialysis (GSL) to remove peripheral anterior synechiae (PAS) alongside standard cataract surgery has potential theoretical advantages, Published randomised trials, however, have not shown conclusive functional benefits and aqueous outflow changes following GSL are unknown. This study aimed to compare electronic Shiøtz tonographic aqueous outflow facility (TOF) following phacoemulsification with or without GSL in patients with primary angle closure (PAC) and PAC glaucoma. Secondary outcomes were changes in intraocular pressure (IOP) and use of glaucoma medications. METHODS Prospective randomised pilot study of 26 patients on glaucoma medication, with ≥90° PAS and significant lens opacity. Patients were randomised 1:1 to receive phacoemulsification with intraocular lens (IOL) implantation only (phaco) or phacoemulsification with IOL plus GSL (phaco-GSL). RESULTS Fourteen patients were randomised to phaco-GSL and 12 to phaco alone. TOF increased with phaco-GSL from 0.099±0.07 μL/min/mm Hg to 0.194±0.07, μL/min/mm Hg, p=0.0006, while the phaco group showed no significant change. IOP reduced in both groups, but reduced significantly more following phaco-GSL (46.0%) compared with phaco alone (27.6%, p=0.04). Medication use and extent of PAS only reduced with phaco-GSL, from 0.923±0.86 to 0.384±0.18 medications, p=0.0279, and from 249.2±83.4 to 110.8±53.9° PAS, 6 months postoperatively. No serious adverse events occurred in either group. CONCLUSIONS Eyes randomised to both surgical groups had similar and good outcomes at 6 months in this pilot study. However, only eyes undergoing GSL combined with standard phacoemulsification had significantly increased TOF, reduced glaucoma medication dependence and PAS postoperatively. GSL should therefore be considered in such patients. TRIAL REGISTRATION NUMBER NCT00719290, Results.
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Affiliation(s)
- Ian A Rodrigues
- Department of Ophthalmology, St Thomas' Hospital, London, UK
| | - Pouya Alaghband
- Department of Ophthalmology, St Thomas' Hospital, London, UK
| | | | | | - Stephanie Jones
- Department of Ophthalmology, St Thomas' Hospital, London, UK
| | - Rahat Husain
- Department of Ophthalmology, St Thomas' Hospital, London, UK
| | - K Sheng Lim
- Department of Ophthalmology, St Thomas' Hospital, London, UK
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30
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Xin C, Johnstone M, Wang N, Wang RK. OCT Study of Mechanical Properties Associated with Trabecular Meshwork and Collector Channel Motion in Human Eyes. PLoS One 2016; 11:e0162048. [PMID: 27598990 PMCID: PMC5012558 DOI: 10.1371/journal.pone.0162048] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/12/2016] [Accepted: 08/16/2016] [Indexed: 11/25/2022] Open
Abstract
We report the use of a high-resolution optical coherence tomography (OCT) imaging platform to identify and quantify pressure-dependent aqueous outflow system (AOS) tissue relationships and to infer mechanical stiffness through examination of tissue properties in ex vivo human eyes. Five enucleated human eyes are included in this study, with each eye prepared with four equal-sized quadrants, each encompassing 90 degrees of the limbal circumference. In radial limbal segments perfusion pressure within Schlemm’s canal (SC) is controlled by means of a perfusion cannula inserted into the canal lumen, while the other end of the cannula leads to a reservoir at a height that can control the pressure in the cannula. The OCT system images the sample with a spatial resolution of about 5 μm from the trabecular meshwork (TM) surface. Geometric parameters are quantified from the 2D OCT images acquired from the sample subjected to controlled changes in perfusion pressures; parameters include area and height of the lumen of SC, collector channel entrances (CCE) and intrascleral collector channels (ISCC). We show that 3D OCT imaging permits the identification of 3-D relationships of the SC, CCE and ISCC lumen dimensions. Collagen flaps or leaflets are found at CCE that are attached or hinged at only one end, whilst the flaps are connected to the TM by cylindrical structures spanning SC. Increasing static SC pressures resulted in SC lumen enlargement with corresponding enlargement of the CCE and ISCC lumen. Pressure-dependent SC lumen area and height changes are significant at the 0.01 levels for ANOVA, and at the 0.05 for both polynomial curves and Tukey paired comparisons. Dynamic measurements demonstrate a synchronous increase in SC, CCE and ISCC lumen height in response to pressure changes from 0 to 10, 30 or 50 mm Hg, respectively, and the response time is within the 50-millisecond range. From the measured SC volume and corresponding IOP values, we demonstrate that an elastance curve can be developed to infer the mechanical stiffness of the TM by means of quantifying pressure-dependent SC volume changes over a 2 mm radial region of SC. Our study finds pressure-dependent motion of the TM that corresponds to collagen leaflet configuration motion at CCE; the synchronous tissue motion also corresponds with synchrony of SC and CCE lumen dimension changes.
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Affiliation(s)
- Chen Xin
- Departments of Bioengineering, University of Washington, Seattle, Washington, 98195, United States of America
- Beijing TongRen Eye Center, Beijing TongRen Hospital, Capital Medical University, Beijing, 100730, China
- Department of Ophthalmology, Beijing AnZhen Hospital, Capital Medical University, Beijing, 100029, China
| | - Murray Johnstone
- Department of Ophthalmology, University of Washington, Seattle, Washington, 98104, United States of America
| | - Ningli Wang
- Beijing TongRen Eye Center, Beijing TongRen Hospital, Capital Medical University, Beijing, 100730, China
| | - Ruikang K. Wang
- Departments of Bioengineering, University of Washington, Seattle, Washington, 98195, United States of America
- Department of Ophthalmology, University of Washington, Seattle, Washington, 98104, United States of America
- * E-mail:
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31
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Fujimoto T, Inoue T, Maki K, Inoue-Mochita M, Tanihara H. Vascular Endothelial Growth Factor-A Increases the Aqueous Humor Outflow Facility. PLoS One 2016; 11:e0161332. [PMID: 27584577 PMCID: PMC5008796 DOI: 10.1371/journal.pone.0161332] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/03/2016] [Accepted: 08/03/2016] [Indexed: 12/18/2022] Open
Abstract
PURPOSE Anti-vascular endothelial growth factor (VEGF) antibody therapy is an effective treatment for ocular angiogenesis. Although the intraocular pressure of some patients increases after anti-VEGF therapy, the effects of VEGF-A on the aqueous humor outflow pathway remain unknown. This study investigated the effects of VEGF-A on the aqueous humor outflow pathway. METHODS We used human recombinant VEGF121 and VEGF165. Trabecular meshwork (TM) and Schlemm's canal endothelial (SCE) cells were isolated from the eyes of cynomolgus monkeys. Expression of mRNA coding four VEGF receptors, VEGFR1 (FLT1), VEGFR2 (KDR), neuropilin-1, and neuropilin-2, was examined by RT-PCR. To evaluate the permeability of cell monolayers, we measured transendothelial electrical resistance (TEER). The outflow facility was measured in perfused porcine anterior segment organ cultures treated with 30 ng/mL VEGF121 for 48 h. RESULTS Four VEGF-A-related receptor mRNAs were expressed in TM and SCE cells. The TEER of TM cells was not significantly affected by VEGF121 or VEGF165 treatment. In contrast, the TEER of SCE cells was significantly lower 48 h after treatment with 30 ng/mL VEGF121 to 69.4 ± 12.2% of baseline (n = 10), which was a significant difference compared with the control (P = 0.0001). VEGF165 (30 ng/mL) decreased the TEER of SCE cells at 48 h after treatment to 72.3 ± 14.1% compared with the baseline (n = 10), which was not a significant difference compared with the control (P = 0.0935). Ki8751, a selective VEGFR2 inhibitor, completely suppressed the effect of VEGF121 on SCE cell permeability, although ZM306416, a selective VEGFR1 inhibitor, did not affect the VEGF121-induced decrease in TEER. Perfusion with 30 ng/mL of VEGF121 for 48 h significantly increased the outflow facility compared with the control (47.8 ± 28.5%, n = 5, P = 0.013). CONCLUSIONS These results suggest that VEGF-A may regulate the conventional aqueous outflow of SCE cells through VEGFR2.
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Affiliation(s)
- Tomokazu Fujimoto
- Department of Ophthalmology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Toshihiro Inoue
- Department of Ophthalmology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
- * E-mail:
| | - Kei Maki
- Department of Ophthalmology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Miyuki Inoue-Mochita
- Department of Ophthalmology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
| | - Hidenobu Tanihara
- Department of Ophthalmology, Faculty of Life Sciences, Kumamoto University, Kumamoto, Japan
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32
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Kuehn MH, Lipsett KA, Menotti-Raymond M, Whitmore SS, Scheetz TE, David VA, O'Brien SJ, Zhao Z, Jens JK, Snella EM, Ellinwood NM, McLellan GJ. A Mutation in LTBP2 Causes Congenital Glaucoma in Domestic Cats (Felis catus). PLoS One 2016; 11:e0154412. [PMID: 27149523 PMCID: PMC4858209 DOI: 10.1371/journal.pone.0154412] [Citation(s) in RCA: 22] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/29/2015] [Accepted: 03/31/2016] [Indexed: 01/18/2023] Open
Abstract
The glaucomas are a group of diseases characterized by optic nerve damage that together represent a leading cause of blindness in the human population and in domestic animals. Here we report a mutation in LTBP2 that causes primary congenital glaucoma (PCG) in domestic cats. We identified a spontaneous form of PCG in cats and established a breeding colony segregating for PCG consistent with fully penetrant, autosomal recessive inheritance of the trait. Elevated intraocular pressure, globe enlargement and elongated ciliary processes were consistently observed in all affected cats by 8 weeks of age. Varying degrees of optic nerve damage resulted by 6 months of age. Although subtle lens zonular instability was a common feature in this cohort, pronounced ectopia lentis was identified in less than 10% of cats examined. Thus, glaucoma in this pedigree is attributed to histologically confirmed arrest in the early post-natal development of the aqueous humor outflow pathways in the anterior segment of the eyes of affected animals. Using a candidate gene approach, significant linkage was established on cat chromosome B3 (LOD 18.38, θ = 0.00) using tightly linked short tandem repeat (STR) loci to the candidate gene, LTBP2. A 4 base-pair insertion was identified in exon 8 of LTBP2 in affected individuals that generates a frame shift that completely alters the downstream open reading frame and eliminates functional domains. Thus, we describe the first spontaneous and highly penetrant non-rodent model of PCG identifying a valuable animal model for primary glaucoma that closely resembles the human disease, providing valuable insights into mechanisms underlying the disease and a valuable animal model for testing therapies.
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Affiliation(s)
- Markus H. Kuehn
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Koren A. Lipsett
- Laboratory of Genomic Diversity, National Cancer Institute, Frederick, Maryland, United States of America
- Department of Chemistry, Gettysburg College, Gettysburg, Pennsylvania, United States of America
| | - Marilyn Menotti-Raymond
- Laboratory of Genomic Diversity, National Cancer Institute, Frederick, Maryland, United States of America
| | - S. Scott Whitmore
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Todd E. Scheetz
- Department of Ophthalmology and Visual Sciences, Carver College of Medicine, University of Iowa, Iowa City, Iowa, United States of America
| | - Victor A. David
- Laboratory of Genomic Diversity, National Cancer Institute, Frederick, Maryland, United States of America
- Basic Research Laboratory, National Cancer Institute, Frederick, Maryland, United States of America
| | - Stephen J. O'Brien
- Laboratory of Genomic Diversity, National Cancer Institute, Frederick, Maryland, United States of America
- Theodosius Dobzhansky Center for Genome Bioinformatics, St. Petersburg State University, St. Petersburg, Russia
- Oceanographic Center, Nova Southeastern University, Fort Lauderdale, Florida, United States of America
| | - Zhongyuan Zhao
- Department of Chemistry, Gettysburg College, Gettysburg, Pennsylvania, United States of America
| | - Jackie K. Jens
- Department of Animal Science, Iowa State University, Ames, Iowa, United States of America
| | - Elizabeth M. Snella
- Department of Animal Science, Iowa State University, Ames, Iowa, United States of America
| | - N. Matthew Ellinwood
- Department of Animal Science, Iowa State University, Ames, Iowa, United States of America
- Department of Veterinary Clinical Sciences, Iowa State University, Ames, Iowa, United States of America
| | - Gillian J. McLellan
- Department of Ophthalmology and Visual Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- Department of Surgical Sciences, University of Wisconsin-Madison, Madison, Wisconsin, United States of America
- McPherson Eye Research Institute, Madison, Wisconsin, United States of America
- * E-mail:
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33
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Li G, Mukherjee D, Navarro I, Ashpole NE, Sherwood JM, Chang J, Overby DR, Yuan F, Gonzalez P, Kopczynski CC, Farsiu S, Stamer WD. Visualization of conventional outflow tissue responses to netarsudil in living mouse eyes. Eur J Pharmacol 2016; 787:20-31. [PMID: 27085895 DOI: 10.1016/j.ejphar.2016.04.002] [Citation(s) in RCA: 75] [Impact Index Per Article: 9.4] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/04/2016] [Revised: 03/10/2016] [Accepted: 04/04/2016] [Indexed: 12/23/2022]
Abstract
Visual impairment due to glaucoma currently impacts 70 million people worldwide. While disease progression can be slowed or stopped with effective lowering of intraocular pressure, current medical treatments are often inadequate. Fortunately, three new classes of therapeutics that target the diseased conventional outflow tissue responsible for ocular hypertension are in the final stages of human testing. The rho kinase inhibitors have proven particularly efficacious and additive to current therapies. Unfortunately, non-contact technology that monitors the health of outflow tissue and its response to conventional outflow therapy is not available clinically. Using optical coherence tomographic (OCT) imaging and novel segmentation software, we present the first demonstration of drug effects on conventional outflow tissues in living eyes. Topical netarsudil (formerly AR-13324), a rho kinase/ norepinephrine transporter inhibitor, affected both proximal (trabecular meshwork and Schlemm's Canal) and distal portions (intrascleral vessels) of the mouse conventional outflow tract. Hence, increased perfusion of outflow tissues was reliably resolved by OCT as widening of the trabecular meshwork and significant increases in cross-sectional area of Schlemm's canal following netarsudil treatment. These changes occurred in conjunction with increased outflow facility, increased speckle variance intensity of outflow vessels, increased tracer deposition in conventional outflow tissues and decreased intraocular pressure. This is the first report using live imaging to show real-time drug effects on conventional outflow tissues and specifically the mechanism of action of netarsudil in mouse eyes. Advancements here pave the way for development of a clinic-friendly OCT platform for monitoring glaucoma therapy.
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Affiliation(s)
- Guorong Li
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA
| | - Dibyendu Mukherjee
- Department of Biomedical Engineering, Duke University, Durham, NC 27710, USA
| | - Iris Navarro
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA
| | - Nicole E Ashpole
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA
| | - Joseph M Sherwood
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - Jinlong Chang
- Department of Biomedical Engineering, Duke University, Durham, NC 27710, USA
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London SW7 2AZ, United Kingdom
| | - Fan Yuan
- Department of Biomedical Engineering, Duke University, Durham, NC 27710, USA
| | - Pedro Gonzalez
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA
| | | | - Sina Farsiu
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA; Department of Biomedical Engineering, Duke University, Durham, NC 27710, USA
| | - W Daniel Stamer
- Department of Ophthalmology, Duke University, Durham, NC 27710, USA; Department of Biomedical Engineering, Duke University, Durham, NC 27710, USA.
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Abstract
An acoustic tonometer that measures shifts in resonance frequencies associated with intraocular pressure (IOP) could provide an opportunity for a type of tonometer that can be operated at home or worn by patients. However, there is insufficient theoretical background, especially with respect to the uncertainty in operating frequency ranges and the unknown relationships between IOPs and resonance frequencies. The purpose of this paper is to develop a frequency function for application in an acoustic tonometer. A linear wave theory is used to derive an explicit frequency function, consisting of an IOP and seven other physiological parameters. In addition, impulse response experiments are performed to measure the natural frequencies of porcine eyes to validate the provided function. From a real-time detection perspective, explicitly providing a frequency function can be the best way to set up an acoustic tonometer. The theory shows that the resonance oscillation of the eyeball is mainly dominated by liquid inside the eyeball. The experimental validation demonstrates the good prediction of IOPs and resonance frequencies. The proposed explicit frequency function supports further modal analysis not only of the dynamics of eyeballs, but also of the natural frequencies, for further development of the acoustic tonometer.
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Affiliation(s)
- Po-Jen Shih
- Department of Civil and Environmental Engineering, National University of Kaohsiung, Kaohsiung, Taiwan
| | - Yi-Ren Guo
- Department of Civil and Environmental Engineering, National University of Kaohsiung, Kaohsiung, Taiwan
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35
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Zouache MA, Eames I, Samsudin A. Allometry and Scaling of the Intraocular Pressure and Aqueous Humour Flow Rate in Vertebrate Eyes. PLoS One 2016; 11:e0151490. [PMID: 26990431 PMCID: PMC4798774 DOI: 10.1371/journal.pone.0151490] [Citation(s) in RCA: 10] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/09/2015] [Accepted: 02/29/2016] [Indexed: 11/23/2022] Open
Abstract
In vertebrates, intraocular pressure (IOP) is required to maintain the eye into a shape allowing it to function as an optical instrument. It is sustained by the balance between the production of aqueous humour by the ciliary body and the resistance to its outflow from the eye. Dysregulation of the IOP is often pathological to vision. High IOP may lead to glaucoma, which is in man the second most prevalent cause of blindness. Here, we examine the importance of the IOP and rate of formation of aqueous humour in the development of vertebrate eyes by performing allometric and scaling analyses of the forces acting on the eye during head movement and the energy demands of the cornea, and testing the predictions of the models against a list of measurements in vertebrates collated through a systematic review. We show that the IOP has a weak dependence on body mass, and that in order to maintain the focal length of the eye, it needs to be an order of magnitude greater than the pressure drop across the eye resulting from gravity or head movement. This constitutes an evolutionary constraint that is common to all vertebrates. In animals with cornea-based optics, this constraint also represents a condition to maintain visual acuity. Estimated IOPs were found to increase with the evolution of terrestrial animals. The rate of formation of aqueous humour was found to be adjusted to the metabolic requirements of the cornea, scaling as Vac(0.67), where Vac is the volume of the anterior chamber. The present work highlights an interdependence between IOP and aqueous flow rate crucial to ocular function that must be considered to understand the evolution of the dioptric apparatus. It should also be taken into consideration in the prevention and treatment of glaucoma.
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Affiliation(s)
- Moussa A. Zouache
- Institute of Ophthalmology, University College London, London, United Kingdom
| | - Ian Eames
- Department of Mechanical Engineering, University College London, London, United Kingdom
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36
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Guo J, Zhang H, Wang J. [Numerical Simulation of Heat Transfer in the Human Anterior Chamber at Different Corneal Temperatures]. Sheng Wu Yi Xue Gong Cheng Xue Za Zhi 2015; 32:1191-1195. [PMID: 27079085] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/05/2023]
Abstract
A three-dimensional (3D) model of human anterior chamber is reconstructed to explore the effect of different corneal temperatures on the heat transfer in the chamber. Based on the optical coherence tomography imaging of the volunteers with normal anterior chamber, a 3D anterior chamber model was reconstructed by the method of UG parametric design. Numerical simulation of heat transfer and aqueous humor flow in the whole anterior chamber were analyzed by the finite volume methods at different corneal temperatures. The results showed that different corneal temperatures had obvious influence on the temperature distribution and the aqueous flow in the anterior chamber. The temperature distribution is linear and axial symmetrical around the pupillary axis. As the temperature difference increases, the symmetry becomes poorer. Aqueous floated along the warm side and sank along the cool side which forms a vortexing flow. Its velocity increased with the addition of temperature difference. Heat fluxes of cornea, lens and iris were mainly affected by the aqueous velocity. The higher the velocity, the bigger more absolute value of the above-mentioned heat fluxes became. It is practicable to perform the numerical simulation of anterior chamber by the optical coherence tomography imaging. The results are useful for studying the important effect of corneal temperature on the heat transfer and aqueous humor dynamics in the anterior chamber.
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Abstract
In order to understand the pathophysiology, select optimal therapeutic options for patients and provide clients with honest expectations for cases of canine glaucoma, clinicians should be familiar with a rational understanding of the functional anatomy of the ocular structures involved in this group of diseases. The topographical extension and the structural and humoral complexity of the regions involved with the production and the outflow of aqueous humor undergo numerous changes with aging and disease. Therefore, the anatomy relative to the fluid dynamics of aqueous has become a pivotal yet flexible concept to interpret the different phenotypes of glaucoma.
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Affiliation(s)
- Stefano Pizzirani
- Ophthalmology, Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, 200 Westboro Road, North Grafton, MA 01536, USA.
| | - Haiyan Gong
- Ophthalmology and Anatomy and Neurobiology, Boston University School of Medicine, 72 East Concord Street, L905, Boston, MA 02118, USA
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Stothert AR, Fontaine SN, Sabbagh JJ, Dickey CA. Targeting the ER-autophagy system in the trabecular meshwork to treat glaucoma. Exp Eye Res 2015; 144:38-45. [PMID: 26302411 DOI: 10.1016/j.exer.2015.08.017] [Citation(s) in RCA: 34] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/10/2015] [Revised: 07/23/2015] [Accepted: 08/18/2015] [Indexed: 12/19/2022]
Abstract
A major drainage network involved in aqueous humor dynamics is the conventional outflow pathway, which is gated by the trabecular meshwork (TM). The TM acts as a molecular sieve, providing resistance to aqueous outflow, which is responsible for regulating intraocular pressure (IOP). If the TM is damaged, aqueous outflow is impaired, IOP increases and glaucoma can manifest. Mutations in the MYOC gene cause hereditary primary open-angle glaucoma (POAG) by promoting the abnormal amyloidosis of the myocilin protein in the endoplasmic reticulum (ER), leading to ER stress-induced TM cell death. Myocilin accumulation is observed in approximately 70-80% of all glaucoma cases suggesting that environmental or other genetic factors may also promote myocilin toxicity. For example, simply preventing myocilin glycosylation is sufficient to promote its abnormal accretion. These myocilin amyloids are unique as there are no other known pathogenic proteins that accumulate within the ER of TM cells and cause toxicity. Moreover, this pathogenic accumulation only kills TM cells, despite expression of this protein in other cell types, suggesting that another modifier exclusive to the TM participates in the proteotoxicity of myocilin. ER autophagy (reticulophagy) is one of the pathways essential for myocilin clearance that can be impacted dramatically by aging and other environmental factors such as nutrition. This review will discuss the link between myocilin and autophagy, evaluating the role of this degradation pathway in glaucoma as well as its potential as a therapeutic target.
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Affiliation(s)
- Andrew R Stothert
- Department of Molecular Medicine, Byrd Alzheimer's Research Institute, University of South Florida, Tampa, FL 33613, USA
| | - Sarah N Fontaine
- Department of Molecular Medicine, Byrd Alzheimer's Research Institute, University of South Florida, Tampa, FL 33613, USA
| | - Jonathan J Sabbagh
- Department of Molecular Medicine, Byrd Alzheimer's Research Institute, University of South Florida, Tampa, FL 33613, USA
| | - Chad A Dickey
- Department of Molecular Medicine, Byrd Alzheimer's Research Institute, University of South Florida, Tampa, FL 33613, USA.
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Liton PB. The autophagic lysosomal system in outflow pathway physiology and pathophysiology. Exp Eye Res 2015; 144:29-37. [PMID: 26226231 DOI: 10.1016/j.exer.2015.07.013] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/30/2015] [Revised: 07/06/2015] [Accepted: 07/22/2015] [Indexed: 12/19/2022]
Abstract
Malfunction of the trabecular meshwork (TM)/schlemm's canal (SC) conventional outflow pathway is associated with elevated intraocular pressure (IOP) and, therefore, increased risk of developing glaucoma, a potentially blinding disease affecting more than 70 million people worldwide. This TM/SC tissue is subjected to different types of stress, including mechanical, oxidative, and phagocytic stress. Long-term exposure to these stresses is believed to lead to a progressive accumulation of damaged cellular and tissue structures causing permanent alterations in the tissue physiology, and contribute to the pathologic increase in aqueous humor (AH) outflow resistance. Autophagy is emerging as an essential cellular survival mechanism against a variety of stressors. In addition to performing basal functions, autophagy acts as a cellular survival pathway and represents an essential mechanism by which organisms can adapt to acute stress conditions and repair stress-induced damage. A decline in autophagy has been observed in most tissues with aging and has been considered responsible, at least in part, for the accumulation of damaged cellular components in almost all tissues of aging organisms. Dysfunction in the autophagy pathway is associated with several human diseases, from infectious diseases to cancer and neurodegeneration. In this review, we will summarize our current knowledge of the emerging roles of autophagy in outflow tissue physiology and pathophysiology, including novel evidence suggesting compromised autophagy in the glaucomatous outflow pathway.
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Affiliation(s)
- Paloma B Liton
- Duke University, Department of Ophthalmology, Durham, NC, USA.
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40
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Rich W. External fistulisation of the canal of Schlemm and Nd-YAG laser trabeculotomy. Dev Ophthalmol 2015; 11:132-5. [PMID: 3839467 DOI: 10.1159/000411101] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [MESH Headings] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 01/07/2023]
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41
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Braakman ST, Read AT, Chan DWH, Ethier CR, Overby DR. Colocalization of outflow segmentation and pores along the inner wall of Schlemm's canal. Exp Eye Res 2015; 130:87-96. [PMID: 25450060 PMCID: PMC4305530 DOI: 10.1016/j.exer.2014.11.008] [Citation(s) in RCA: 48] [Impact Index Per Article: 5.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2014] [Accepted: 11/12/2014] [Indexed: 11/30/2022]
Abstract
All aqueous humor draining through the conventional outflow pathway must cross the endothelium of Schlemm's canal (SC), likely by passing through micron-sized transendothelial pores. SC pores are non-uniformly distributed along the inner wall endothelium, but it is unclear how the distribution of pores relates to the non-uniform or segmental distribution of aqueous humor outflow through the trabecular meshwork. It is hypothesized that regions in the juxtacanalicular tissue (JCT) with higher local outflow should coincide with regions of greater inner wall pore density compared to JCT regions with lower outflow. Three pairs of non-glaucomatous human donor eyes were perfused at 8 mmHg with fluorescent tracer nanospheres to decorate local patterns of outflow segmentation through the JCT. The inner wall was stained for CD31 and/or vimentin and imaged en face using confocal and scanning electron microscopy (SEM). Confocal and SEM images were spatially registered to examine the spatial relationship between inner wall pore density and tracer intensity in the underlying JCT. For each eye, tracer intensity, pore density (n) and pore diameter (D) (for both transcellular "I" and paracellular "B" pores) were measured in 4-7 regions of interest (ROIs; 50 × 150 μm each). Analysis of covariance was used to examine the relationship between tracer intensity and pore density, as well as the relationship between tracer intensity and three pore metrics (nD, nD(2) and nD(3)) that represent the local hydraulic conductivity of the outflow pathway as predicted by various hydrodynamic models. Tracer intensity in the JCT correlated positively with local pore density when considering total pores (p = 0.044) and paracellular B pores on their own (p = 0.016), but not transcellular I-pores on their own (p = 0.54). Local hydraulic conductivity as predicted by the three hydrodynamic models all showed a significant positive correlation with tracer intensity when considering total pores and B-pores (p < 0.0015 and p < 10(-4)) but not I-pores (p > 0.38). These data suggest that aqueous humor passes through micron-sized pores in the inner wall endothelium of SC. Paracellular B-pores appear to have a dominant contribution towards transendothelial filtration across the inner wall relative to transcellular I-pores. Impaired pore formation, as previously described in glaucomatous SC cells, may thereby contribute to greater outflow heterogeneity, outflow obstruction, and IOP elevation in glaucoma.
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Affiliation(s)
- Sietse T Braakman
- Department of Bioengineering, Imperial College London, London, United Kingdom
| | - A Thomas Read
- Department of Ophthalmology and Vision Sciences, University of Toronto, Canada
| | - Darren W-H Chan
- Department of Ophthalmology and Vision Sciences, University of Toronto, Canada
| | - C Ross Ethier
- Department of Bioengineering, Imperial College London, London, United Kingdom; Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, USA
| | - Darryl R Overby
- Department of Bioengineering, Imperial College London, London, United Kingdom.
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42
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de Miranda AP, Silva CB, Mimica LMJ, Moscovici BK, Malavazzi GR, Hida RY. In vitro antimicrobial analysis of aqueous humor after topical application of moxifloxacin hydrochloride 0.5%. J Cataract Refract Surg 2014; 41:135-9. [PMID: 25532640 DOI: 10.1016/j.jcrs.2014.11.010] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/14/2014] [Revised: 04/06/2014] [Accepted: 04/11/2014] [Indexed: 11/15/2022]
Abstract
PURPOSE To evaluate the in vitro antimicrobial activity of aqueous humor in patients who had preoperative topical application of moxifloxacin hydrochloride 0.5%. SETTING Department of Ophthalmology, Santa Casa de Misericórdia de São Paulo, Brazil. DESIGN Comparative case series. METHODS Twenty-nine eyes from 29 cataract surgery patients were included in this study. In the study group (n = 15 eyes), 3 topical applications of moxifloxacin hydrochloride 0.5% were administered preoperatively; in the control group (n = 14 eyes), no topical applications were administered. Aqueous humor samples were collected and stored in sterile microtubes at -80°C until analysis. Antimicrobial analysis was performed using standard strains with standard sterile filter paper disks. Inhibition halos were measured in millimeters, and both bactericidal and bacteriostatic effects were analyzed. RESULTS Inhibition halos were observed on most of the study group plates except those with Streptococcus pneumoniae: Escherichia coli (13.93 mm ± 0.64 [SD]), Klebsiella pneumoniae (10.63 ± 0.61 mm), Staphylococcus aureus (7.47 ± 0.68 mm), and S epidermidis (4.20 ± 3.33 mm) The differences between the mean inhibition halo diameters were statistically significant (P < .0001) in all samples. No bactericidal effect was observed against any of the microorganisms studied. CONCLUSIONS After topical application of moxifloxacin 0.5%, aqueous humor showed bacteriostatic effect against E coli, K pneumoniae, S aureus, and S epidermidis. No bactericidal effect was observed against any of the microorganisms evaluated. No antimicrobial effect against S pneumoniae was observed. FINANCIAL DISCLOSURE No author has a financial or proprietary interest in any material or method mentioned.
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Affiliation(s)
- Aline P de Miranda
- From the Department of Ophthalmology (de Miranda, Moscovici, Malavazzi, Hida), Ocular Tissue Bank (Hida), the Department of Microbiology (Silva, Mimica), Santa Casa de Misericórdia de São Paulo, and the Department of Ophthalmology (Hida), University of São Paulo, São Paulo, Brazil
| | - Cely B Silva
- From the Department of Ophthalmology (de Miranda, Moscovici, Malavazzi, Hida), Ocular Tissue Bank (Hida), the Department of Microbiology (Silva, Mimica), Santa Casa de Misericórdia de São Paulo, and the Department of Ophthalmology (Hida), University of São Paulo, São Paulo, Brazil
| | - Lycia M J Mimica
- From the Department of Ophthalmology (de Miranda, Moscovici, Malavazzi, Hida), Ocular Tissue Bank (Hida), the Department of Microbiology (Silva, Mimica), Santa Casa de Misericórdia de São Paulo, and the Department of Ophthalmology (Hida), University of São Paulo, São Paulo, Brazil
| | - Bernardo K Moscovici
- From the Department of Ophthalmology (de Miranda, Moscovici, Malavazzi, Hida), Ocular Tissue Bank (Hida), the Department of Microbiology (Silva, Mimica), Santa Casa de Misericórdia de São Paulo, and the Department of Ophthalmology (Hida), University of São Paulo, São Paulo, Brazil
| | - Gustavo R Malavazzi
- From the Department of Ophthalmology (de Miranda, Moscovici, Malavazzi, Hida), Ocular Tissue Bank (Hida), the Department of Microbiology (Silva, Mimica), Santa Casa de Misericórdia de São Paulo, and the Department of Ophthalmology (Hida), University of São Paulo, São Paulo, Brazil
| | - Richard Y Hida
- From the Department of Ophthalmology (de Miranda, Moscovici, Malavazzi, Hida), Ocular Tissue Bank (Hida), the Department of Microbiology (Silva, Mimica), Santa Casa de Misericórdia de São Paulo, and the Department of Ophthalmology (Hida), University of São Paulo, São Paulo, Brazil.
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Park DY, Lee J, Park I, Choi D, Lee S, Song S, Hwang Y, Hong KY, Nakaoka Y, Makinen T, Kim P, Alitalo K, Hong YK, Koh GY. Lymphatic regulator PROX1 determines Schlemm's canal integrity and identity. J Clin Invest 2014; 124:3960-74. [PMID: 25061877 DOI: 10.1172/jci75392] [Citation(s) in RCA: 117] [Impact Index Per Article: 11.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 05/30/2014] [Indexed: 12/30/2022] Open
Abstract
Schlemm's canal (SC) is a specialized vascular structure in the eye that functions to drain aqueous humor from the intraocular chamber into systemic circulation. Dysfunction of SC has been proposed to underlie increased aqueous humor outflow (AHO) resistance, which leads to elevated ocular pressure, a factor for glaucoma development in humans. Here, using lymphatic and blood vasculature reporter mice, we determined that SC, which originates from blood vessels during the postnatal period, acquires lymphatic identity through upregulation of prospero homeobox protein 1 (PROX1), the master regulator of lymphatic development. SC expressed lymphatic valve markers FOXC2 and integrin α9 and exhibited continuous vascular endothelial-cadherin (VE-cadherin) junctions and basement membrane, similar to collecting lymphatics. SC notably lacked luminal valves and expression of the lymphatic endothelial cell markers podoplanin and lymphatic vessel endothelial hyaluronan receptor 1 (LYVE-1). Using an ocular puncture model, we determined that reduced AHO altered the fate of SC both during development and under pathologic conditions; however, alteration of VEGF-C/VEGFR3 signaling did not modulate SC integrity and identity. Intriguingly, PROX1 expression levels linearly correlated with SC functionality. For example, PROX1 expression was reduced or undetectable under pathogenic conditions and in deteriorated SCs. Collectively, our data indicate that PROX1 is an accurate and reliable biosensor of SC integrity and identity.
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Aspelund A, Tammela T, Antila S, Nurmi H, Leppänen VM, Zarkada G, Stanczuk L, Francois M, Mäkinen T, Saharinen P, Immonen I, Alitalo K. The Schlemm's canal is a VEGF-C/VEGFR-3-responsive lymphatic-like vessel. J Clin Invest 2014; 124:3975-86. [PMID: 25061878 DOI: 10.1172/jci75395] [Citation(s) in RCA: 157] [Impact Index Per Article: 15.7] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2014] [Accepted: 05/30/2014] [Indexed: 12/21/2022] Open
Abstract
In glaucoma, aqueous outflow into the Schlemm's canal (SC) is obstructed. Despite striking structural and functional similarities with the lymphatic vascular system, it is unknown whether the SC is a blood or lymphatic vessel. Here, we demonstrated the expression of lymphatic endothelial cell markers by the SC in murine and zebrafish models as well as in human eye tissue. The initial stages of SC development involved induction of the transcription factor PROX1 and the lymphangiogenic receptor tyrosine kinase VEGFR-3 in venous endothelial cells in postnatal mice. Using gene deletion and function-blocking antibodies in mice, we determined that the lymphangiogenic growth factor VEGF-C and its receptor, VEGFR-3, are essential for SC development. Delivery of VEGF-C into the adult eye resulted in sprouting, proliferation, and growth of SC endothelial cells, whereas VEGF-A obliterated the aqueous outflow system. Furthermore, a single injection of recombinant VEGF-C induced SC growth and was associated with trend toward a sustained decrease in intraocular pressure in adult mice. These results reveal the evolutionary conservation of the lymphatic-like phenotype of the SC, implicate VEGF-C and VEGFR-3 as critical regulators of SC lymphangiogenesis, and provide a basis for further studies on therapeutic manipulation of the SC with VEGF-C in glaucoma treatment.
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Iomdina EN, Kiseleva OA, Svetikova LA, Liubimov GA, Moiseeva IN, Shteĭn AA. [New algorithm of aqueous humor dynamics assessment in glaucoma]. Vestn Oftalmol 2014; 130:8-13. [PMID: 25306716] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/04/2023]
Abstract
The purpose of the study was to develop a new algorithm of aqueous humor dynamics assessment in glaucomatous eyes, which would take into account the shape of the tonographic curve and individual elastic properties of the corneoscleral capsule. Basic ophthalmic examination supplemented with tonography and differentiated tonometry was performed on 33 patients with primary open-angle glaucoma (POAG), 8 POAG suspects, and 9 healthy controls. Obtained data were processed in accordance with the developed algorithm. A new formula for calculating the coefficient of outflow facility and several additional parameters describing the condition of aqueous pathways were proposed. In POAG patients these parameters significantly differed from those in healthy controls.
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46
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Abstract
Schlemm's canal is an important structure of the conventional aqueous humor outflow pathway and is critically involved in regulating the intraocular pressure. In this study, we report a novel finding that prospero homeobox protein 1 (Prox-1), the master control gene for lymphatic development, is expressed in Schlemm's canal. Moreover, we provide a novel in vivo method of visualizing Schlemm's canal using a transgenic mouse model of Prox-1-green fluorescent protein (GFP). The anatomical location of Prox-1+ Schlemm's canal was further confirmed by in vivo gonioscopic examination and ex vivo immunohistochemical analysis. Additionally, we show that the Schlemm's canal is distinguishable from typical lymphatic vessels by lack of lymphatic vessel endothelial hyaluronan receptor (LYVE-1) expression and absence of apparent sprouting reaction when inflammatory lymphangiogenesis occurred in the cornea. Taken together, our findings offer new insights into Schlemm's canal and provide a new experimental model for live imaging of this critical structure to help further our understanding of the aqueous humor outflow. This may lead to new avenues toward the development of novel therapeutic intervention for relevant diseases, most notably glaucoma.
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Affiliation(s)
- Tan N. Truong
- Graduate Group in Vision Science, University of California, Berkeley, California, United States of America
- Center for Eye Disease and Development, Program in Vision Science and School of Optometry, University of California, Berkeley, California, United States of America
| | - Hannah Li
- Center for Eye Disease and Development, Program in Vision Science and School of Optometry, University of California, Berkeley, California, United States of America
| | - Young-Kwon Hong
- Department of Surgery and Department of Biochemistry and Molecular Biology, Norris Comprehensive Cancer Center, Keck School of Medicine, University of Southern California, Los Angeles, California, United States of America
| | - Lu Chen
- Graduate Group in Vision Science, University of California, Berkeley, California, United States of America
- Center for Eye Disease and Development, Program in Vision Science and School of Optometry, University of California, Berkeley, California, United States of America
- The Francis I. Proctor Foundation for Research in Ophthalmology, University of California San Francisco, San Francisco, California, United States of America
- Schepens Eye Research Institute, Massachusetts Eye and Ear Infirmary, Harvard Medical School, Boston, Massachusetts, United States of America
- * E-mail: .
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47
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Muniesa MJ, González S, Buetas P, López S, Sánchez C, Matias-Guiu X. [Evaluation of conjunctival epithelium of filtering blebs by impression cytology]. ACTA ACUST UNITED AC 2014; 89:216-21. [PMID: 24814379 DOI: 10.1016/j.oftal.2013.07.004] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/15/2012] [Revised: 06/29/2013] [Accepted: 07/02/2013] [Indexed: 11/19/2022]
Abstract
PURPOSE To study the ocular surface in filtering blebs using impression cytology, comparing the bleb side and areas outside the bleb edges. METHODS Twelve filtering blebs of 8 patients were included: 4 cases of trabeculectomy without mitomycin C (MMC), 6 cases of trabeculectomy with MMC, and 2 cases of non-penetrating glaucoma surgery. Impression cytology specimens were taken from filtering blebs as well as outside the bleb area. A classification scale from 0 to 3 was used to describe the distribution of epithelial cells and the density of goblet cells. Grade 0 indicated cohesive epithelial cells and abundant goblet cells; and the grade 3 indicated loss of epithelial cohesion and absence of goblet cells. RESULTS The mean grade of cytology in filtering blebs was 2.4 ± 0.9, and in the outside bleb area of 0.8 ± 0.3 (P<.001). These differences were independent of the use of MMC (P=.48). The large majority (83%) of filtering blebs showed a decrease in epithelial cohesion and absence of goblet cells. Outside the bleb area, 100% of the cases had cohesive epithelial cells with different grades of goblet cells. CONCLUSION The conjunctival epithelium overlying the filtering blebs showed significant changes that consisted of increased intercellular spaces and loss of goblet cells. These increased intercellular spaces could explain the trans-epithelial pathway of aqueous humor. The least amount of mucin due to loss of goblet cells could contribute to increase the risk of infection in filtering blebs.
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Affiliation(s)
- M J Muniesa
- Departamento de Oftalmología, Hospital Universitari Arnau de Vilanova, Lérida, España; Institut de Recerca Biomèdica de Lleida (IRB Lleida), Lérida, España.
| | - S González
- Institut de Recerca Biomèdica de Lleida (IRB Lleida), Lérida, España; Departamento de Patología y Genética Molecular, Hospital Universitari Arnau de Vilanova, Lérida, España
| | - P Buetas
- Institut de Recerca Biomèdica de Lleida (IRB Lleida), Lérida, España; Departamento de Patología y Genética Molecular, Hospital Universitari Arnau de Vilanova, Lérida, España
| | - S López
- Institut de Recerca Biomèdica de Lleida (IRB Lleida), Lérida, España; Departamento de Patología y Genética Molecular, Hospital Universitari Arnau de Vilanova, Lérida, España
| | - C Sánchez
- Departamento de Oftalmología, Hospital Universitari Arnau de Vilanova, Lérida, España; Institut de Recerca Biomèdica de Lleida (IRB Lleida), Lérida, España
| | - X Matias-Guiu
- Institut de Recerca Biomèdica de Lleida (IRB Lleida), Lérida, España; Departamento de Patología y Genética Molecular, Hospital Universitari Arnau de Vilanova, Lérida, España
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48
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Fan M, Dai P. [The application of computer modeling in ophthalmologic investigation]. Sheng Wu Yi Xue Gong Cheng Xue Za Zhi 2013; 30:1350-1353. [PMID: 24645624] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [What about the content of this article? (0)] [Abstract] [MESH Headings] [Subscribe] [Scholar Register] [Indexed: 06/03/2023]
Abstract
It is very difficult to measure the human eye properties directly, such as the accommodation mechanism, intraocular pressure distribution, the dynamics of aqueous humor flow and the bio-heat transfer in human eyes. Modeling and simulation may, therefore, play an increasingly important role in the ophthalmologic investigation. The major computer modeling methods, including geometric modeling, physical modeling and mathematical modeling, are introduced in this paper. Modeling and simulation anatomy properties and physiological properties of eye tissues, such as the cornea, aqueous humor and crystalline lens, vitreous, optic nerve head, sclera, are analyzed in the order from global to local, from front to back, from outside to inside. Finally, the problems of computer modeling in ophthalmologic investigation are discussed, and the development trends of the future are pointed out.
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Kumar S, Shah S, Tang HM, Smith M, Borrás T, Danias J. Tissue plasminogen activator in trabecular meshwork attenuates steroid induced outflow resistance in mice. PLoS One 2013; 8:e72447. [PMID: 23977299 PMCID: PMC3747096 DOI: 10.1371/journal.pone.0072447] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.1] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/20/2013] [Accepted: 07/16/2013] [Indexed: 11/18/2022] Open
Abstract
Tissue plasminogen activator, a serine protease encoded by the PLAT gene is present in the trabecular meshwork (TM) and other ocular tissues and has been reported to be downregulated by treatment with steroids in vitro. Steroids are known to cause changes in outflow facility of aqueous humor in many species. In the present study, we tested whether overexpression of PLAT can prevent and/or reverse the outflow facility of mouse eyes treated with steroids. Animals received bilateral injection with 20 µl of triamcinolone acetonide (TA) (40 mg/ml) suspension subconjunctivally to induce outflow facility changes. Some animals received unilateral intracameral injection with 2 µl of adenoviral suspension [3-4 x 10(12) virus genomes per milliliter (vg/ml)] carrying sheep PLAT cDNA (AdPLAT) either concurrently with TA injection or one week after TA injection, whereas others received bilateral intracameral injection with 2 µl of adenoviral suspension (9 x 10(12) vg/ml) carrying no transgene (AdNull) concurrently with TA injection. Animals were sacrificed one week after AdPLAT or AdNull treatment. Endogenous mRNA expression levels of mouse PAI-1 and MMP-2, -9 and -13 were also measured using qRT-PCR. Outflow facility one week after AdPLAT administration was increased by 60% and 63% respectively for animals that had not or had been pretreated with steroids. Overexpression of PLAT significantly upregulated expression of PAI-1, MMP-2, -9 and -13 compared to the levels found in TA only treated eyes. These findings suggest that overexpression of PLAT in TM of mouse eyes can both prevent and reverse the decrease in outflow facility caused by steroid treatment and is associated with upregulation of MMPs.
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Affiliation(s)
- Sandeep Kumar
- Department of Cell Biology, SUNY Downstate Medical Center, Brooklyn, New York, United States of America
- Department of Ophthalmology, SUNY Downstate Medical Center and the SUNY Eye Institute, Brooklyn, New York, United States of America
- * E-mail:
| | - Shaily Shah
- Department of Ophthalmology, SUNY Downstate Medical Center and the SUNY Eye Institute, Brooklyn, New York, United States of America
- Mount Sinai School of Medicine, New York, New York, United States of America
| | - Hai Michael Tang
- Department of Cell Biology, SUNY Downstate Medical Center, Brooklyn, New York, United States of America
| | - Matthew Smith
- Department of Ophthalmology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - Teresa Borrás
- Department of Ophthalmology, University of North Carolina, Chapel Hill, North Carolina, United States of America
| | - John Danias
- Department of Cell Biology, SUNY Downstate Medical Center, Brooklyn, New York, United States of America
- Department of Ophthalmology, SUNY Downstate Medical Center and the SUNY Eye Institute, Brooklyn, New York, United States of America
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50
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Barton MD, Trembly BS. Measurement of the anisotropic thermal conductivity of the porcine cornea. Exp Eye Res 2013; 115:216-23. [PMID: 23933570 DOI: 10.1016/j.exer.2013.07.029] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [What about the content of this article? (0)] [Affiliation(s)] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2013] [Revised: 06/28/2013] [Accepted: 07/29/2013] [Indexed: 11/19/2022]
Abstract
Accurate thermal models for the cornea of the eye support the development of thermal techniques for reshaping the cornea and other scientific purposes. Heat transfer in the cornea must be quantified accurately so that a thermal treatment does not destroy the endothelial layer, which cannot regenerate, and yet is responsible for maintaining corneal transparency. We developed a custom apparatus to measure the thermal conductivity of ex vivo porcine corneas perpendicular to the surface and applied a commercial apparatus to measure thermal conductivity parallel to the surface. We found that corneal thermal conductivity is 14% anisotropic at the normal state of corneal hydration. Small numbers of ex vivo feline and human corneas had a thermal conductivity perpendicular to the surface that was indistinguishable from the porcine corneas. Aqueous humor from ex vivo porcine, feline, and human eyes had a thermal conductivity nearly equal to that of water. Including the anisotropy of corneal thermal conductivity will improve the predictive power of thermal models of the eye.
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Affiliation(s)
- Michael D Barton
- Thayer School of Engineering, Dartmouth College, 14 Engineering Drive, Hanover, NH 03755, USA.
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