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Harvey DH, Sugali CK, Mao W. Glucocorticoid-Induced Ocular Hypertension and Glaucoma. Clin Ophthalmol 2024; 18:481-505. [PMID: 38379915 PMCID: PMC10878139 DOI: 10.2147/opth.s442749] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/01/2023] [Accepted: 01/22/2024] [Indexed: 02/22/2024] Open
Abstract
Glucocorticoid (GC) therapy is indicated in many diseases, including ocular diseases. An important side-effect of GC therapy is GC-induced ocular hypertension (GIOHT), which may cause irreversible blindness known as GC-induced glaucoma (GIG). Here, we reviewed the pathological changes that contribute to GIOHT including in the trabecular meshwork and Schlemm's canal at cellular and molecular levels. We also discussed the clinical aspects of GIOHT/GIG including disease prevalence, risk factors, the type of GCs, the route of GC administration, and management strategies.
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Affiliation(s)
- Devon Hori Harvey
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
- Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Chenna Kesavulu Sugali
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
- Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Weiming Mao
- Department of Ophthalmology, Indiana University School of Medicine, Indianapolis, IN, USA
- Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Biochemistry & Molecular Biology, Indiana University School of Medicine, Indianapolis, IN, USA
- Department of Pharmacology and Toxicology, Indiana University School of Medicine, Indianapolis, IN, USA
- Stark Neurosciences Research Institute, Indiana University School of Medicine, Indianapolis, IN, USA
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2
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He C, Ye P, Zhang X, Esmaeili E, Li Y, Lü P, Cai C. The Role of TGF-β Signaling in Saphenous Vein Graft Failure after Peripheral Arterial Disease Bypass Surgery. Int J Mol Sci 2023; 24:10381. [PMID: 37373529 DOI: 10.3390/ijms241210381] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/05/2023] [Revised: 06/11/2023] [Accepted: 06/16/2023] [Indexed: 06/29/2023] Open
Abstract
Saphenous vein bypass grafting is an effective technique used to treat peripheral arterial disease (PAD). However, restenosis is the major clinical challenge for the graft vessel among people with PAD postoperation. We hypothesize that there is a common culprit behind arterial occlusion and graft restenosis. To investigate this hypothesis, we found TGF-β, a gene specifically upregulated in PAD arteries, by bioinformatics analysis. TGF-β has a wide range of biological activities and plays an important role in vascular remodeling. We discuss the molecular pathway of TGF-β and elucidate its mechanism in vascular remodeling and intimal hyperplasia, including EMT, extracellular matrix deposition, and fibrosis, which are the important pathways contributing to stenosis. Additionally, we present a case report of a patient with graft restenosis linked to the TGF-β pathway. Finally, we discuss the potential applications of targeting the TGF-β pathway in the clinic to improve the long-term patency of vein grafts.
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Affiliation(s)
- Changhuai He
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Pin Ye
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Xuecheng Zhang
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Elham Esmaeili
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Yiqing Li
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Ping Lü
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
| | - Chuanqi Cai
- Department of Vascular Surgery, Union Hospital, Tongji Medical College, Huazhong University of Science and Technology, Wuhan 430022, China
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3
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Shim MS, Liton PB. The physiological and pathophysiological roles of the autophagy lysosomal system in the conventional aqueous humor outflow pathway: More than cellular clean up. Prog Retin Eye Res 2022; 90:101064. [PMID: 35370083 PMCID: PMC9464695 DOI: 10.1016/j.preteyeres.2022.101064] [Citation(s) in RCA: 9] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/02/2021] [Revised: 03/09/2022] [Accepted: 03/25/2022] [Indexed: 10/18/2022]
Abstract
During the last few years, the autophagy lysosomal system is emerging as a central cellular pathway with roles in survival, acting as a housekeeper and stress response mechanism. Studies by our and other labs suggest that autophagy might play an essential role in maintaining aqueous humor outflow homeostasis, and that malfunction of autophagy in outflow pathway cells might predispose to ocular hypertension and glaucoma pathogenesis. In this review, we will collect the current knowledge and discuss the molecular mechanisms by which autophagy does or might regulate normal outflow pathway tissue function, and its response to different types of stressors (oxidative stress and mechanical stress). We will also discuss novel roles of autophagy and lysosomal enzymes in modulation of TGFβ signaling and ECM remodeling, and the link between dysregulated autophagy and cellular senescence. We will examine what we have learnt, using pre-clinical animal models about how dysregulated autophagy can contribute to disease and apply that to the current status of autophagy in human glaucoma. Finally, we will consider and discuss the challenges and the potential of autophagy as a therapeutic target for the treatment of ocular hypertension and glaucoma.
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Affiliation(s)
- Myoung Sup Shim
- Duke University, Department of Ophthalmology, Durham, NC, 27705, USA
| | - Paloma B Liton
- Duke University, Department of Ophthalmology, Durham, NC, 27705, USA.
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MacDonald WW, Swaminathan SS, Heo JY, Castillejos A, Hsueh J, Liu BJ, Jo D, Du A, Lee H, Kang MH, Rhee DJ. Effect of SPARC Suppression in Mice, Perfused Human Anterior Segments, and Trabecular Meshwork Cells. Invest Ophthalmol Vis Sci 2022; 63:8. [PMID: 35671048 PMCID: PMC9187959 DOI: 10.1167/iovs.63.6.8] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/15/2023] Open
Abstract
Purpose Secreted protein, acidic and rich in cysteine (SPARC) elevates intraocular pressure (IOP), increases certain structural extracellular matrix (ECM) proteins in the juxtacanalicular trabecular meshwork (JCT), and decreases matrix metalloproteinase (MMP) protein levels in trabecular meshwork (TM) endothelial cells. We investigated SPARC as a potential target for lowering IOP. We hypothesized that suppressing SPARC will decrease IOP, decrease structural JCT ECM proteins, and alter the levels of MMPs and/or their inhibitors. Methods A lentivirus containing short hairpin RNA of human SPARC suppressed SPARC in mouse eyes and perfused cadaveric human anterior segments with subsequent IOP measurements. Immunohistochemistry determined structural correlates. Human TM cell cultures were treated with SPARC suppressing lentivirus. Quantitative reverse transcriptase polymerase chain reaction (PCR), immunoblotting, and zymography determined total RNA, relative protein levels, and MMP enzymatic activity, respectively. Results Suppressing SPARC decreased IOP in mouse eyes and perfused human anterior segments by approximately 20%. Histologically, this correlated to a decrease in collagen I, IV, and VI in both the mouse TM and human JCT regions; in the mouse, fibronectin was also decreased but not in the human. In TM cells, collagen I and IV, fibronectin, MMP-2, and tissue inhibitor of MMP-1 were decreased. Messenger RNA of the aforementioned genes was not changed. Plasminogen activator inhibitor 1 (PAI-1) was upregulated in vitro by quantitative PCR and immunoblotting. MMP-1 activity was reduced in vitro by zymography. Conclusions Suppressing SPARC decreased IOP in mice and perfused cadaveric human anterior segments corresponding to qualitative structural changes in the JCT ECM, which do not appear to be the result of transcription regulation.
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Affiliation(s)
- William W MacDonald
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Swarup S Swaminathan
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States.,Department of Ophthalmology, Bascom Palmer Eye Institute, Miami, Florida, United States
| | - Jae Young Heo
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Alexandra Castillejos
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States.,Department of Ophthalmology, Massachusetts Eye & Ear Infirmary, Boston, Massachusetts, United States
| | - Jessica Hsueh
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Brian J Liu
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Diane Jo
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Annie Du
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Hyunpil Lee
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Min Hyung Kang
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
| | - Douglas J Rhee
- Department of Ophthalmology & Visual Sciences, University Hospitals, Case Western Reserve University School of Medicine, Cleveland, Ohio, United States
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Pumphrey SA, Zitek-Morrison E, Pizzirani S, Meola DM. Evaluation of matrix metalloproteinases and tissue inhibitors of metalloproteinases in aqueous humor of dogs with versus without naturally occurring primary angle-closure glaucoma. Am J Vet Res 2021; 83:245-255. [PMID: 34936570 DOI: 10.2460/ajvr.21.04.0062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/20/2022]
Abstract
OBJECTIVE To compare concentrations of matrix metalloproteinases (MMPs) and tissue inhibitors of metalloproteinases (TIMPs) in aqueous humor from ophthalmologically normal dogs and dogs with naturally occurring primary angle-closure glaucoma (cPACG). SAMPLE Aqueous humor samples from 12 eyes with cPACG and 18 ophthalmologically normal eyes of dogs. PROCEDURES A multiplex fluorescence-based ELISA was used to measure concentrations of MMP-1, MMP-2, MMP-3, MMP-8, MMP-9, MMP-10, MMP-13, TIMP-1, TIMP-2, and TIMP-4. Results for eyes with versus without cPACG were compared. RESULTS Significantly higher mean concentrations of MMP-1 (45% higher), MMP-2 (55% higher), MMP-3 (39% higher), MMP-8 (79% higher), MMP-9 (29% higher), MMP-10 (60% higher), TIMP-1 (63% higher), and TIMP-2 (136% higher) were detected in aqueous humor from eyes with cPACG, compared with ophthalmologically normal eyes. CLINICAL RELEVANCE MMPs and TIMPs have pivotal roles in extracellular matrix turnover and homeostasis in the outflow pathways of the eye. Results of the present study documented higher concentrations of MMPs and TIMPs in aqueous humor samples from dog eyes with late-stage cPACG. Although, to our knowledge, TIMPs have not previously been evaluated in the context of cPACG, the markedly higher concentration of TIMPs in eyes with cPACG suggested that inhibition of proteolysis and extracellular matrix turnover might be a factor in the development of glaucoma in susceptible individuals. However, because the present study used samples from dogs with late-stage cPACG, further work is required to characterize the temporal relationship between MMP and TIMP concentration changes and onset or progression of disease.
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Affiliation(s)
- Stephanie A Pumphrey
- Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA
| | - Emily Zitek-Morrison
- Department of Population and Quantitative Health Sciences, UMass Chan Medical School, University of Massachusetts, Worcester, MA
| | - Stefano Pizzirani
- Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA
| | - Dawn M Meola
- Department of Clinical Sciences, Cummings School of Veterinary Medicine, Tufts University, North Grafton, MA
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Gindina S, Barron AO, Hu Y, Dimopoulos A, Danias J. Tissue plasminogen activator rescues steroid-induced outflow facility reduction via non-enzymatic action. Mol Vis 2021; 27:691-705. [PMID: 35002214 PMCID: PMC8684809] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/31/2020] [Accepted: 12/05/2021] [Indexed: 11/23/2022] Open
Abstract
PURPOSE Tissue plasminogen activator (tPA) prevents steroid-induced reduction in aqueous humor outflow facility; however, its mechanism of action at the trabecular meshwork (TM) remains unclear. Enzymatic and non-enzymatic domains allow tPA to function as both an enzyme and a cytokine. This study sought to determine whether cytokine activity is sufficient to rescue steroid-induced outflow facility reduction. METHODS Outflow facility was measured in C57BL/6J mice following triamcinolone acetonide exposure and either transfection of the TM using adenoviral vectors, encoding for enzymatically active and inactive tPA, or administration of the respective proteins. Protein injections were also administered to tPA deficient (PlatKO) and Mmp-9 deficient (Mmp-9KO) mice to determine the potential to rescue reductions in outflow facility and determine downstream mechanisms. Gene expression of matrix metalloproteinases (Mmp-2, -9, and -13) was measured in angle ring tissues containing the TM. RESULTS Enzymatically active and inactive tPA (either produced after TM transfection or after direct administration) were equally effective in attenuating steroid-induced outflow facility reduction in C57BL/6J mice. They were also equally effective in rescuing outflow reduction in PlatKO mice and causing enhanced expression of matrix metalloproteinases. However, both enzymatically active and enzymatically inactive tPA did not improve outflow reduction in Mmp-9KO mice or increase the baseline outflow facility in naïve C57BL/6J mice. CONCLUSIONS tPA enzymatic activity is not necessary in the regulation of aqueous humor outflow. tPA can increase the expression of matrix metalloproteinases in a cytokine-mediated fashion. This cascade of events may eventually lead to extracellular matrix remodeling at the TM, which reverses outflow facility reduction caused by steroids.
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Affiliation(s)
- Sofya Gindina
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY,Department of Ophthalmology, SUNY Downstate Health Sciences University, Brooklyn, NY
| | - Arturo O. Barron
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY,Department of Ophthalmology, SUNY Downstate Health Sciences University, Brooklyn, NY
| | - Yan Hu
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY,Department of Ophthalmology, SUNY Downstate Health Sciences University, Brooklyn, NY
| | - Antonios Dimopoulos
- Department of Ophthalmology, SUNY Downstate Health Sciences University, Brooklyn, NY
| | - John Danias
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY,Department of Ophthalmology, SUNY Downstate Health Sciences University, Brooklyn, NY
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Mody AA, Millar JC, Clark AF. ID1 and ID3 are Negative Regulators of TGFβ2-Induced Ocular Hypertension and Compromised Aqueous Humor Outflow Facility in Mice. Invest Ophthalmol Vis Sci 2021; 62:3. [PMID: 33938911 PMCID: PMC8107646 DOI: 10.1167/iovs.62.6.3] [Citation(s) in RCA: 9] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/19/2023] Open
Abstract
Purpose In POAG, elevated IOP remains the major risk factor in irreversible vision loss. Increased TGFβ2 expression in POAG aqueous humor and in the trabecular meshwork (TM) amplifies extracellular matrix (ECM) deposition and reduces ECM turnover in the TM, leading to a decreased aqueous humor (AH) outflow facility and increased IOP. Inhibitor of DNA binding proteins (ID1 and ID3) inhibit TGFβ2-induced fibronectin and PAI-1 production in TM cells. We examined the effects of ID1 and ID3 gene expression on TGFβ2-induced ocular hypertension and decreased AH outflow facility in living mouse eyes. Methods IOP and AH outflow facility changes were determined using a mouse model of Ad5-hTGFβ2C226S/C288S-induced ocular hypertension. The physiological function of ID1 and ID3 genes were evaluated using Ad5 viral vectors to enhance or knockdown ID1/ID3 gene expression in the TM of BALB/cJ mice. IOP was measured in conscious mice using a Tonolab impact tonometer. AH outflow facilities were determined by constant flow infusion in live mice. Results Over-expressing ID1 and ID3 significantly blocked TGFβ2-induced ocular hypertension (P < 0.0001). Although AH outflow facility was significantly decreased in TGFβ2-transduced eyes (P < 0.04), normal outflow facility was preserved in eyes injected concurrently with ID1 or ID3 along with TGFβ2. Knockdown of ID1 or ID3 expression exacerbated TGFβ2-induced ocular hypertension. Conclusions Increased expression of ID1 and ID3 suppressed both TGFβ2-elevated IOP and decreased AH outflow facility. ID1 and/or ID3 proteins thus may show promise as future candidates as IOP-lowering targets in POAG.
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Affiliation(s)
- Avani A Mody
- North Texas Eye Research Institute, Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - J Cameron Millar
- North Texas Eye Research Institute, Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, United States
| | - Abbot F Clark
- North Texas Eye Research Institute, Department of Pharmacology and Neuroscience, University of North Texas Health Science Center, Fort Worth, Texas, United States
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Gindina S, Hu Y, Barron AO, Qureshi Z, Danias J. Tissue plasminogen activator attenuates outflow facility reduction in mouse model of juvenile open angle glaucoma. Exp Eye Res 2020; 199:108179. [PMID: 32739292 DOI: 10.1016/j.exer.2020.108179] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/06/2020] [Revised: 06/19/2020] [Accepted: 07/29/2020] [Indexed: 12/12/2022]
Abstract
Tissue plasminogen activator (tPA) has been shown to prevent steroid-induced reduction in aqueous humor outflow facility via an upregulation in matrix metalloproteinase (Mmp) expression. The purpose of this study was to determine whether tPA can rescue outflow facility reduction in the Tg-MYOCY437H mouse model, which replicates human juvenile open angle glaucoma. Outflow facility was measured in Tg-MYOCY437H mice following: periocular steroid exposure and intraocular protein treatment with enzymatically active or enzymatically inactive tPA. Effects of tPA on outflow facility were compared to those of animals treated with topical sodium phenylbutarate (PBA), a modulator of endoplasmic reticulum stress. Gene expression of fibrinolytic pathway components (Plat, Plau, and Pai-1) and matrix metalloproteinases (Mmp-2, -9, and -13) was determined in angle ring tissues containing the trabecular meshwork. Tg-MYOCY437H mice did not display further outflow facility reduction following steroid exposure. Enzymatically active and enzymatically inactive tPA were equally effective in attenuating outflow facility reduction in Tg-MYOCY437H mice and caused enhanced expression of matrix metalloproteinases (Mmp-9 and Mmp-13). tPA was equally effective to topical PBA treatment in ameliorating outflow facility reduction in Tg-MYOCY437H mice. Both treatments were associated with an upregulation in Mmp-9 expression while tPA also upregulated Mmp-13 expression. tPA increases the expression of matrix metalloproteinases and may cause extracellular matrix remodeling at the trabecular meshwork, which results in reversal of outflow facility reduction in Tg-MYOCY437H mice.
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Affiliation(s)
- Sofya Gindina
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA; Department of Ophthalmology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA.
| | - Yan Hu
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA; Department of Ophthalmology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Arturo O Barron
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA; Department of Ophthalmology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - Zain Qureshi
- Department of Ophthalmology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
| | - John Danias
- Department of Cell Biology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA; Department of Ophthalmology, SUNY Downstate Health Sciences University, Brooklyn, NY, USA
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Chen W, Hu T, Xu Q, Chen Z, Zhang H, Wang J. Acute Effects of Intraocular Pressure-Induced Changes in Schlemm's Canal Morphology on Outflow Facility in Healthy Human Eyes. Invest Ophthalmol Vis Sci 2020; 61:36. [PMID: 32716504 PMCID: PMC7425758 DOI: 10.1167/iovs.61.8.36] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose To estimate the outflow facility coefficient (C) as a function of Schlemm's canal cross-sectional area (SCAR) in healthy subjects using noninvasive oculopression tonometry (OPT). Methods In 25 healthy volunteers, intraocular pressure (IOP) decay values were recorded by a ophthalmodynamometer, with a fixed external force (0.15 N) on the inferior-temporal eyelid, every 10 seconds, for four minutes, and again after a 30-minute rest. Schlemm's canal profile images and IOP were obtained pre-procedurally (baseline), immediately (T0), and at 1-minute intervals post-procedurally (T1, T2, T3, and T4). C was calculated for different IOPs. The SCAR, coronal, and the meridional diameter of Schlemm's canal were calculated. Results Mean C0 for the maximum IOP was 0.020 ± 0.017 µL/min/mm Hg; mean C was 0.018 ± 0.0071 and 0.058 ± 0.0146 µL/min/mm Hg at 40 and 20 mm Hg, respectively. C was nonlinearly dependent on the IOP (R2 = 0.945). The SCAR was 5440 ± 3140.82, 3947.6 ± 2246.8, and 5375.7 ± 2662.7 µm2 at baseline, T0, and T4, respectively. The coronal diameter of SC decreased significantly from the baseline (33.02 ± 11.3 µm) to T0 (26.6 ± 9.37 µm) and recovered at T4 (32.3 ± 9.53 µm). The SCAR and IOP correlated significantly throughout (R2 = 0.9944; P < 0.001). C0 significantly correlated with the SCAR at baseline and with changes in the SCAR and IOP from T0 to T4. Conclusions Schlemm's canal dimensions are responsible for the IOP-dependent mechanical forces, and these changes appear to directly affect outflow facility.
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