1
|
Mozzer A, Pitha I. Cyclic strain alters the transcriptional and migratory response of scleral fibroblasts to TGFβ. Exp Eye Res 2024; 244:109917. [PMID: 38697276 DOI: 10.1016/j.exer.2024.109917] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/06/2024] [Revised: 04/23/2024] [Accepted: 04/26/2024] [Indexed: 05/04/2024]
Abstract
In glaucoma, scleral fibroblasts are exposed to IOP-associated mechanical strain and elevated TGFβ levels. These stimuli, in turn, lead to scleral remodeling. Here, we examine the scleral fibroblast migratory and transcriptional response to these stimuli to better understand mechanisms of glaucomatous scleral remodeling. Human peripapillary scleral (PPS) fibroblasts were cultured on parallel grooves, treated with TGFβ (2 ng/ml) in the presence of vehicle or TGFβ signaling inhibitors, and exposed to uniaxial strain (1 Hz, 5%, 12-24 h). Axis of cellular orientation was determined at baseline, immediately following strain, and 24 h after strain cessation with 0° being completely aligned with grooves and 90° being perpendicular. Fibroblasts migration in-line and across grooves was assessed using a scratch assay. Transcriptional profiling of TGFβ-treated fibroblasts with or without strain was performed by RT-qPCR and pERK, pSMAD2, and pSMAD3 levels were measured by immunoblot. Pre-strain alignment of TGFβ-treated cells with grooves (6.2 ± 1.5°) was reduced after strain (21.7 ± 5.3°, p < 0.0001) and restored 24 h after strain cessation (9.5 ± 2.6°). ERK, FAK, and ALK5 inhibition prevented this reduction; however, ROCK, YAP, or SMAD3 inhibition did not. TGFβ-induced myofibroblast markers were reduced by strain (αSMA, POSTN, ASPN, MLCK1). While TGFβ-induced phosphorylation of ERK and SMAD2 was unaffected by cyclic strain, SMAD3 phosphorylation was reduced (p = 0.0004). Wound healing across grooves was enhanced by ROCK and SMAD3 inhibition but not ERK or ALK5 inhibition. These results provide insight into the mechanisms by which mechanical strain alters the cellular response to TGFβ and the potential signaling pathways that underlie scleral remodeling.
Collapse
Affiliation(s)
- Ann Mozzer
- Department of Ophthalmology, USA; Center for Nanomedicine, USA
| | - Ian Pitha
- Department of Ophthalmology, USA; Glaucoma Center of Excellence, The Johns Hopkins University School of Medicine, Baltimore, MD, 21287, USA.
| |
Collapse
|
2
|
Pitha I, Du L, Nguyen TD, Quigley H. IOP and glaucoma damage: The essential role of optic nerve head and retinal mechanosensors. Prog Retin Eye Res 2024; 99:101232. [PMID: 38110030 PMCID: PMC10960268 DOI: 10.1016/j.preteyeres.2023.101232] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2023] [Revised: 12/10/2023] [Accepted: 12/11/2023] [Indexed: 12/20/2023]
Abstract
There are many unanswered questions on the relation of intraocular pressure to glaucoma development and progression. IOP itself cannot be distilled to a single, unifying value, because IOP level varies over time, differs depending on ocular location, and can be affected by method of measurement. Ultimately, IOP level creates mechanical strain that affects axonal function at the optic nerve head which causes local extracellular matrix remodeling and retinal ganglion cell death - hallmarks of glaucoma and the cause of glaucomatous vision loss. Extracellular tissue strain at the ONH and lamina cribrosa is regionally variable and differs in magnitude and location between healthy and glaucomatous eyes. The ultimate targets of IOP-induced tissue strain in glaucoma are retinal ganglion cell axons at the optic nerve head and the cells that support axonal function (astrocytes, the neurovascular unit, microglia, and fibroblasts). These cells sense tissue strain through a series of signals that originate at the cell membrane and alter cytoskeletal organization, migration, differentiation, gene transcription, and proliferation. The proteins that translate mechanical stimuli into molecular signals act as band-pass filters - sensing some stimuli while ignoring others - and cellular responses to stimuli can differ based on cell type and differentiation state. Therefore, to fully understand the IOP signals that are relevant to glaucoma, it is necessary to understand the ultimate cellular targets of IOP-induced mechanical stimuli and their ability to sense, ignore, and translate these signals into cellular actions.
Collapse
Affiliation(s)
- Ian Pitha
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Center for Nanomedicine, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Glaucoma Center of Excellence, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Liya Du
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA
| | - Thao D Nguyen
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, MD, USA
| | - Harry Quigley
- Department of Ophthalmology, The Johns Hopkins University School of Medicine, Baltimore, MD, USA; Glaucoma Center of Excellence, The Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| |
Collapse
|
3
|
Korneva A, Kimball EC, Johnson TV, Quillen SE, Pease ME, Quigley HA, Nguyen TD. Comparison of the Biomechanics of the Mouse Astrocytic Lamina Cribrosa Between Glaucoma and Optic Nerve Crush Models. Invest Ophthalmol Vis Sci 2023; 64:14. [PMID: 38088825 PMCID: PMC10720758 DOI: 10.1167/iovs.64.15.14] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/20/2023] [Accepted: 11/14/2023] [Indexed: 12/17/2023] Open
Abstract
Purpose The strain response of the mouse astrocytic lamina (AL) to an ex vivo mechanical test was compared between two protocols: eyes that underwent sustained intraocular pressure (IOP) increase and eyes after optic nerve crush. Methods Chronic IOP elevation was induced by microbead injection or the optic nerve was crushed in mice with widespread green fluorescence. After 3 days or 6 weeks, eyes were inflation tested by a published method of two-photon fluorescence to image the AL. Digital volume correlation was used to calculate strains. Optic nerve axon damage was also evaluated. Results In the central AL but not the peripheral AL, four strains were greater in eyes at the 3-day glaucoma time point than control (P from 0.029 to 0.049, n = 8 eyes per group). Also, at this time point, five strains were greater in the central AL compared to the peripheral AL (P from 0.041 to 0.00003). At the 6-week glaucoma time point, the strains averaged across the specimen, in the central AL, and the peripheral AL were indistinguishable from the respective controls. Strains were not significantly different between controls and eyes 3 days or 6 weeks after crush (n = 8 and 16). Conclusions We found alterations in the ex vivo mechanical behavior in eyes from mice with experimental glaucoma but not in those with crushed optic nerves. The results of this study demonstrate that significant axon injury does not directly affect mechanical behavior of the astrocytic lamina.
Collapse
Affiliation(s)
- Arina Korneva
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Elizabeth C. Kimball
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Thomas V. Johnson
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Sarah E. Quillen
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Mary E. Pease
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Harry A. Quigley
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
| | - Thao D. Nguyen
- Glaucoma Center of Excellence, Wilmer Eye Institute, Johns Hopkins University School of Medicine, Baltimore, Maryland, United States
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland, United States
| |
Collapse
|
4
|
Bou Ghanem GO, Koktysh D, Baratta RO, Del Buono BJ, Schlumpf E, Wareham LK, Calkins DJ. Collagen Mimetic Peptides Promote Repair of MMP-1-Damaged Collagen in the Rodent Sclera and Optic Nerve Head. Int J Mol Sci 2023; 24:17031. [PMID: 38069354 PMCID: PMC10707085 DOI: 10.3390/ijms242317031] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/09/2023] [Revised: 11/20/2023] [Accepted: 11/28/2023] [Indexed: 12/18/2023] Open
Abstract
The structural and biomechanical properties of collagen-rich ocular tissues, such as the sclera, are integral to ocular function. The degradation of collagen in such tissues is associated with debilitating ophthalmic diseases such as glaucoma and myopia, which often lead to visual impairment. Collagen mimetic peptides (CMPs) have emerged as an effective treatment to repair damaged collagen in tissues of the optic projection, such as the retina and optic nerve. In this study, we used atomic force microscopy (AFM) to assess the potential of CMPs in restoring tissue stiffness in the optic nerve head (ONH), including the peripapillary sclera (PPS) and the glial lamina. Using rat ONH tissue sections, we induced collagen damage with MMP-1, followed by treatment with CMP-3 or vehicle. MMP-1 significantly reduced the Young's modulus of both the PPS and the glial lamina, indicating tissue softening. Subsequent CMP-3 treatment partially restored tissue stiffness in both the PPS and the glial lamina. Immunohistochemical analyses revealed reduced collagen fragmentation after MMP-1 digestion in CMP-3-treated tissues compared to vehicle controls. In summary, these results demonstrate the potential of CMPs to restore collagen stiffness and structure in ONH tissues following enzymatic damage. CMPs may offer a promising therapeutic avenue for preserving vision in ocular disorders involving collagen remodeling and degradation.
Collapse
Affiliation(s)
- Ghazi O. Bou Ghanem
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA;
| | - Dmitry Koktysh
- Vanderbilt Institute of Nanoscale Science and Engineering, Vanderbilt University, Nashville, TN 37212, USA
| | | | | | - Eric Schlumpf
- Stuart Therapeutics, Inc., Stuart, FL 34994, USA; (R.O.B.); (E.S.)
| | - Lauren K. Wareham
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA;
| | - David J. Calkins
- Vanderbilt Eye Institute, Department of Ophthalmology and Visual Sciences, Vanderbilt University Medical Center, Nashville, TN 37232, USA;
| |
Collapse
|
5
|
Korneva A, Kimball EC, Quillen S, Jefferys JL, Nawathe M, Ling YTT, Nguyen TD, Quigley HA. Mechanical strain in the mouse astrocytic lamina increases after exposure to recombinant trypsin. Acta Biomater 2023; 163:312-325. [PMID: 35196555 PMCID: PMC9391529 DOI: 10.1016/j.actbio.2022.02.023] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/28/2021] [Revised: 01/21/2022] [Accepted: 02/16/2022] [Indexed: 11/30/2022]
Abstract
The responses of astrocytes in the optic nerve head (ONH) to mechanical and biochemical stimuli are important to understanding the degeneration of retinal ganglion cell axons in glaucoma. The ONH in glaucoma is vulnerable to stress produced by the intraocular pressure (IOP). Notably, after three days of elevated IOP in a mouse model, the junctions between the astrocytic processes and the peripapillary sclera were altered and the structural compliance of the ONH increased. In order to simulate this aspect of glaucomatous remodeling, explanted mouse eyes were treated with TrypLE, a recombinant trypsin enzyme. Treatment with TrypLE caused the periphery of the astrocytic lamina to contract radially by 0.044 ± 0.038. Transmission electron microscopy showed that TrypLE caused a separation of the end-feet of the astrocyte processes from the basement membrane at the junction with the sclera. Inflation testing after treatment with TrypLE caused an increased strain response in the astrocytic lamina compared to the strain response before treatment. The greatest increase was in the radial Green-Lagrange strain, Err = 0.028 ± 0.009, which increased by 340%. The alterations in the microstructure and in the strain response of the astrocytic lamina reported in mouse experimental glaucoma were partially reproduced by experimental treatment of mouse eyes with TrypLE. The results herein suggest that separation of junctions between the astrocyte processes and the sclera may be instrumental in increasing the structural compliance of the ONH after a period of elevated IOP. STATEMENT OF SIGNIFICANCE: Astrocytes of the optic nerve of the eye spread out from edge to edge across the optic nerve in a region referred to as the astrocytic lamina. In an experimental model of glaucoma caused by elevated eye-pressure, there is disruption of the connections between astrocytes and the edge of the astrocytic lamina. We caused a similar event in the lamina by incubating explanted mouse eyes with an enzyme. Disruption of the astrocyte connections to the edge of their tissue caused the tissue to stretch more when we increased the eye-pressure, compared to the control tissue. This work is the first on the tissue of the optic nerve to demonstrate the importance of cell connections in preventing the over-stretching of the astrocytic lamina.
Collapse
Affiliation(s)
- Arina Korneva
- Glaucoma Center of Excellence, Johns Hopkins Wilmer Eye Institute, United States; Department of Ophthalmology, School of Medicine, Johns Hopkins University, Baltimore, MD 21218, United States.
| | - Elizabeth C Kimball
- Glaucoma Center of Excellence, Johns Hopkins Wilmer Eye Institute, United States.
| | - Sarah Quillen
- Glaucoma Center of Excellence, Johns Hopkins Wilmer Eye Institute, United States.
| | - Joan L Jefferys
- Glaucoma Center of Excellence, Johns Hopkins Wilmer Eye Institute, United States.
| | - Manasi Nawathe
- Department of Chemical and Biomolecular Engineering, Johns Hopkins University, Baltimore, MD 21218, United States.
| | - Yik Tung Tracy Ling
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, United States.
| | - Thao D Nguyen
- Department of Ophthalmology, School of Medicine, Johns Hopkins University, Baltimore, MD 21218, United States; Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, United States; Department of Materials Science, Johns Hopkins University, Baltimore, MD 21218, United States.
| | - Harry A Quigley
- Glaucoma Center of Excellence, Johns Hopkins Wilmer Eye Institute, United States; Department of Ophthalmology, School of Medicine, Johns Hopkins University, Baltimore, MD 21218, United States.
| |
Collapse
|
6
|
Abstract
Glaucoma is a progressive, age-related optic neuropathy, whereby the prevalence increases sharply over the age of 60 and is associated with increased systemic tissue stiffness. On a molecular basis, this is associated with increased deposition of collagen and loss of elastin structure, resulting in aberrant biomechanical compliance and reduced tissue elasticity. Increased tissue stiffness is a known driver of myofibroblast activation and persistence, especially in chronic cellular injuries via mechanotransduction pathways mediated by integrins and focal adhesion kinases. Evidence from histological and imaging studies plus force measurements of glaucomatous eyes show that several ocular tissues are stiffer than normal, healthy age-matched controls including the trabecular meshwork, Schlemm's canal, cornea, sclera and the lamina cribrosa. This is associated with increased extracellular matrix deposition and fibrosis. This review reports on the evidence to support the concept that glaucoma represents 'a stiff eye in a stiff body' and addresses potential mechanisms to attenuate this.
Collapse
Affiliation(s)
- Sarah Powell
- Department of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland.,Catherine McAuley Research Centre, University College Dublin, Dublin, Ireland
| | - Mustapha Irnaten
- Catherine McAuley Research Centre, University College Dublin, Dublin, Ireland
| | - Colm O'Brien
- Department of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland.,Catherine McAuley Research Centre, University College Dublin, Dublin, Ireland
| |
Collapse
|
7
|
Xia M, Zhang E, Yao F, Xia Z, Zhou M, Ran X, Xia X. Regional differences of the sclera in the ocular hypertensive rat model induced by circumlimbal suture. EYE AND VISION (LONDON, ENGLAND) 2023; 10:2. [PMID: 36597143 PMCID: PMC9811703 DOI: 10.1186/s40662-022-00319-w] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Figures] [Subscribe] [Scholar Register] [Received: 07/06/2022] [Accepted: 11/15/2022] [Indexed: 01/05/2023]
Abstract
PURPOSE To describe the regional differences of the sclera in ocular hypertension (OHT) models with the inappropriate extension of the ocular axis. METHODS To discover the regional differences of the sclera at the early stage, OHT models were established using circumlimbal suture (CS) or sclerosant injection (SI). Axial length (AL) was measured by ultrasound and magnetic resonance imaging. The glaucoma-associated distinction was determined by intraocular pressure (IOP) and retrograde tracing of retinal ganglion cells (RGCs). The central thickness of the ganglion cell complex (GCC) was measured by optical coherence tomography. RGCs and collagen fibrils were detected using a transmission electron microscope, furthermore, anti-alpha smooth muscle actin (αSMA) was determined in the early stage after the operation. RESULTS Compared with the control group, the eyes in OHT models showed an increased IOP (P < 0.001 in the CS group, P = 0.001 in the SI group), growing AL (P = 0.026 in the CS group, P = 0.043 in the SI group), reduction of central RGCs (P < 0.001 in the CS group, P = 0.017 in the SI group), thinning central GCC (P < 0.001 in the CS group), and a distinctive expression of αSMA in the central sclera in the early 4-week stage after the operation (P = 0.002 in the CS group). Compared with the SI group, the eye in the CS group showed a significantly increased AL (7.1 ± 0.4 mm, P = 0.031), reduction of central RGCs (2121.1 ± 87.2 cells/mm2, P = 0.001), thinning central GCC (71.4 ± 0.8 pixels, P = 0.015), and a distinctive expression of αSMA (P = 0.005). Additionally, ultrastructural changes in RGCs, scleral collagen fibers, and collagen crimp were observed in the different regions. Increased collagen volume fraction in the posterior segment of the eyeball wall (30.2 ± 3.1%, P = 0.022) was observed by MASSON staining in the CS group. CONCLUSION Regional differences of the sclera in the ocular hypertensive rat model induced by CS may provide a reference for further treatment of scleral-related eye disorders.
Collapse
Affiliation(s)
- Mingfang Xia
- grid.216417.70000 0001 0379 7164Eye Center of Xiangya Hospital, Central South University, Changsha, 410008 Hunan China ,grid.452223.00000 0004 1757 7615Hunan Key Laboratory of Ophthalmology, Changsha, 410008 Hunan China ,grid.216417.70000 0001 0379 7164National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008 Hunan China ,grid.469519.60000 0004 1758 070XDepartment of Ophthalmology, People’s Hospital of Ningxia Hui Autonomous Region, Yinchuan, 750004 Ningxia China
| | - Endong Zhang
- grid.216417.70000 0001 0379 7164Eye Center of Xiangya Hospital, Central South University, Changsha, 410008 Hunan China ,grid.452223.00000 0004 1757 7615Hunan Key Laboratory of Ophthalmology, Changsha, 410008 Hunan China ,grid.216417.70000 0001 0379 7164National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008 Hunan China
| | - Fei Yao
- grid.216417.70000 0001 0379 7164Eye Center of Xiangya Hospital, Central South University, Changsha, 410008 Hunan China ,grid.452223.00000 0004 1757 7615Hunan Key Laboratory of Ophthalmology, Changsha, 410008 Hunan China ,grid.216417.70000 0001 0379 7164National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008 Hunan China
| | - Zhaohua Xia
- grid.216417.70000 0001 0379 7164Eye Center of Xiangya Hospital, Central South University, Changsha, 410008 Hunan China ,grid.452223.00000 0004 1757 7615Hunan Key Laboratory of Ophthalmology, Changsha, 410008 Hunan China ,grid.216417.70000 0001 0379 7164National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008 Hunan China
| | - Mingmin Zhou
- grid.216417.70000 0001 0379 7164Eye Center of Xiangya Hospital, Central South University, Changsha, 410008 Hunan China ,grid.452223.00000 0004 1757 7615Hunan Key Laboratory of Ophthalmology, Changsha, 410008 Hunan China ,grid.216417.70000 0001 0379 7164National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008 Hunan China
| | - Xufang Ran
- grid.216417.70000 0001 0379 7164Eye Center of Xiangya Hospital, Central South University, Changsha, 410008 Hunan China ,grid.452223.00000 0004 1757 7615Hunan Key Laboratory of Ophthalmology, Changsha, 410008 Hunan China ,grid.216417.70000 0001 0379 7164National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008 Hunan China
| | - Xiaobo Xia
- grid.216417.70000 0001 0379 7164Eye Center of Xiangya Hospital, Central South University, Changsha, 410008 Hunan China ,grid.452223.00000 0004 1757 7615Hunan Key Laboratory of Ophthalmology, Changsha, 410008 Hunan China ,grid.216417.70000 0001 0379 7164National Clinical Research Center for Geriatric Disorders, Xiangya Hospital, Central South University, Changsha, 410008 Hunan China
| |
Collapse
|
8
|
Markov P, Zhu H, Boote C, Blain EJ. Delayed reorganisation of F-actin cytoskeleton and reversible chromatin condensation in scleral fibroblasts under simulated pathological strain. Biochem Biophys Rep 2022; 32:101338. [PMID: 36123992 PMCID: PMC9482111 DOI: 10.1016/j.bbrep.2022.101338] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/22/2022] [Revised: 08/25/2022] [Accepted: 08/27/2022] [Indexed: 11/06/2022] Open
Abstract
Mechanical loading regulates the functional capabilities of the ocular system, particularly in the sclera (‘white of the eye’) – the principal load-bearing tissue of the ocular globe. Resident fibroblasts of the scleral eye wall are continuously subjected to fluctuating mechanical strains arising from eye movements, cerebrospinal fluid pressure and, most influentially, intra-ocular pressure (IOP). Whilst fibroblasts are hypothesised to actively participate in scleral biomechanics, to date limited information has been reported on how the macroscopic stresses and strains are transmitted via their cytoskeletal networks. In this study, the effect of applying either a ‘physiological load’ (simulating healthy IOP) or a ‘pathological load’ (simulating an elevated glaucomatous IOP) to bovine scleral fibroblasts, as a model of human glaucoma, was conducted to characterise cytoskeletal organisation, chromatin condensation and cell dimensions using immunofluorescence confocal microscopy. Quantification of cell parameters and cytoskeletal element anisotropy were subsequently performed using FibrilTool, and chromatin condensation parameter assessment through a bespoke MATLAB script. The novel findings suggest that physiological load-induced F-actin rearrangement is transient, whereas pathological load, recapitulating in vivo glaucomatous IOP levels, had a reversible and inhibitory influence on remodelling of the cytoskeletal architecture and, further, induction of chromatin condensation. Ultimately, this could compromise cell behaviour. These findings could provide valuable insight into the mechanism(s) used by scleral fibroblasts to mechanically adapt to support biomechanical tissue integrity, and how it could be potentially modified for therapeutic avenues targeting mechanically mediated ocular pathologies such as glaucoma. Physiological strain induced a transient F-actin rearrangement in scleral fibroblasts. In contrast, pathological strain reversibly delayed F-actin rearrangement. Vimentin and β-tubulin networks were largely unaffected by strain regimens. Pathological strain reversibly increased chromatin condensation parameter. Pathological strain may induce ‘inhibition delay’ to confer cytoprotection.
Collapse
|
9
|
Elevated IOP Alters the Material Properties of Sclera and Lamina Cribrosa in Monkeys. DISEASE MARKERS 2022; 2022:5038847. [PMID: 36051361 PMCID: PMC9427265 DOI: 10.1155/2022/5038847] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 05/26/2022] [Revised: 07/02/2022] [Accepted: 07/25/2022] [Indexed: 12/02/2022]
Abstract
Objective Elevated intraocular pressure (IOP) has significant impacts on different stages in the progression of chronic glaucoma. In this study, we investigated changes in the material properties of sclera and lamina cribrosa (LC) in a nonhuman primate model with elevated IOP. Methods Normal adult Tibetan macaques were selected for the construction of elevated IOP model. After 40 days of stable maintenance on the ocular hypertension, the binocular eyeballs were obtained for the measurement of macroscopic parameters of the eyeballs. Posterior scleral tissue strips were obtained in circumferential and axial directions, and thickness was measured, respectively. Biomechanical parameters were obtained with stress relaxation, creep, and tensile test. The nanoindentation test was performed on the LC and scleral tissue around optic nerve head (ONH) to obtain compressive modulus. Results In the presence of elevated IOP, variations of the axial diameter of the eyeball were greater than those of the transverse diameter, and the mean scleral thickness around ONH was smaller in the experimental group than control group. The elastic modulus and stress relaxation modulus of sclera were larger, and the creep rate was lower in the experimental group than control group. In the control group, the elastic modulus and stress relaxation modulus of the circumferential sclera were larger in the axial direction, and creep rate was smaller. In the experimental group, there was no significant difference in biomechanical characteristics between the two directions. Compared to the control group, the compression modulus of the LC was smaller, and the compression modulus of sclera around ONH was larger in the experimental group. Conclusion Elevated IOP alters the viscoelasticity and anisotropy of sclera and LC. These may contribute to reduction of the organizational resistance to external forces and decline in the ability of self-recovery.
Collapse
|
10
|
Wang Y, Cao H. Corneal and Scleral Biomechanics in Ophthalmic Diseases: An Updated Review. MEDICINE IN NOVEL TECHNOLOGY AND DEVICES 2022. [DOI: 10.1016/j.medntd.2022.100140] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/18/2022] Open
|
11
|
Prediction of effective Lens position using anterior segment optical coherence tomography in Chinese subjects with angle closure. BMC Ophthalmol 2021; 21:454. [PMID: 34961542 PMCID: PMC8711180 DOI: 10.1186/s12886-021-02213-w] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/07/2021] [Accepted: 12/09/2021] [Indexed: 11/16/2022] Open
Abstract
Purpose To assess the accuracy of biometric parameters measured by anterior segment optical coherence tomography (AS-OCT) and partial coherence interferometry (PCI) in prediction of effective lens position (ELP) compared with previous formulas in PACG patients. Methods 121 PACG eyes were randomly divided into training set (85 eyes) and validation set (36 eyes) with same procedure including AS-OCT, PCI, phacoemulsification and IOL implantation surgery. Preoperative anterior chamber depth (pre-ACD), scleral spur depth (SSD), scleral spur width (SSW), lens vault (LV) and cornea thickness (CT) were measured from AS-OCT image. Axial length (AL) and corneal power (K) were measured by PCI. All the 7 parameters were analyzed by multiple linear regression in training set and a statistic regression formula was developed. In validation set, one-way ANOVA was applied to compare the new regression formula with Sanders-Retzlaff-Kraff theoretic (SRK/T), Holladay 1, Haigis, and a regression formula developed in previous study. Results The coefficient of determination (R2) of different parameter combinations are 0.19 (pre-ACD, AL), 0.25 (AL, K) and 0.49 (SSD, AL, SSW) in training set. In validation set, the correlation between predicted and measured ELP are: new formula (R2 = 0.50, P = 0.9947) Holladay 1 (R2 = 0.12, P < 0.0001), SRK/T (R2 = 0.11, P < 0.0001) and Haigis (R2 = 0.06, P < 0.0001). Conclusion Among 7 tested parameters, pre-ACD contribute little in ELP prediction. Formula consist of SSD, AL and SSW showed better accuracy than other formulas tested.
Collapse
|
12
|
Brown DM, Pardue MT, Ethier CR. A biphasic approach for characterizing tensile, compressive and hydraulic properties of the sclera. J R Soc Interface 2021; 18:20200634. [PMID: 33468024 PMCID: PMC7879763 DOI: 10.1098/rsif.2020.0634] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/06/2020] [Accepted: 12/15/2020] [Indexed: 11/12/2022] Open
Abstract
Measuring the biomechanical properties of the mouse sclera is of great interest: altered scleral properties are features of many common ocular pathologies, and the mouse is a powerful tool for studying genetic factors in disease, yet the small size of the mouse eye and its thin sclera make experimental measurements in the mouse difficult. Here, a poroelastic material model is used to analyse data from unconfined compression testing of both pig and mouse sclera, and the tensile modulus, compressive modulus and permeability of the sclera are obtained at three levels of compressive strain. Values for all three properties were comparable to previously reported values measured by tests specific for each property. The repeatability of the approach was evaluated using a test-retest experimental paradigm on pig sclera, and tensile stiffness and permeability measurements were found to be reasonably repeatable. The intrinsic material properties of the mouse sclera were measured for the first time. Tensile stiffness and permeability of the sclera in both species were seen to be dependent on the state of compressive strain. We conclude that unconfined compression testing of sclera, when analysed with poroelastic theory, is a powerful tool to phenotype mouse scleral changes in future genotype-phenotype association studies.
Collapse
Affiliation(s)
- Dillon M. Brown
- Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, 313 Ferst Drive, Atlanta, GA 30332, USA
- Atlanta Veterans Affairs Healthcare System, 1670 Clairmont Rd, Atlanta, GA, 30033, USA
| | - Machelle T. Pardue
- Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, 313 Ferst Drive, Atlanta, GA 30332, USA
- Atlanta Veterans Affairs Healthcare System, 1670 Clairmont Rd, Atlanta, GA, 30033, USA
| | - C. Ross Ethier
- Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, 313 Ferst Drive, Atlanta, GA 30332, USA
| |
Collapse
|
13
|
Korneva A, Kimball EC, Jefferys JL, Quigley HA, Nguyen TD. Biomechanics of the optic nerve head and peripapillary sclera in a mouse model of glaucoma. J R Soc Interface 2020; 17:20200708. [PMID: 33323053 PMCID: PMC7811579 DOI: 10.1098/rsif.2020.0708] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/01/2020] [Accepted: 11/17/2020] [Indexed: 01/09/2023] Open
Abstract
The deformation of the mouse astrocytic lamina (AL) and adjacent peripapillary sclera (PPS) was measured in response to elevated intraocular pressure. We subjected explanted mouse eyes to inflation testing, comparing control eyes to those 3 days and 6 weeks after induction of ocular hypertension (OHT) via ocular microbead injection. Laser scanning microscopy was used with second harmonic generation to image the collagenous PPS and two-photon fluorescence to image transgenic fluorescent astrocytes in the AL. Digital volume correlation was applied to calculate strains in the PPS and AL. The specimen-averaged strains were biaxial in the AL and PPS, with greater strain overall in the x- than y-direction in the AL and greater strain in the θ- than the r-direction in the PPS. Strains increased after 3-day OHT, with greater strain overall in the 3-day AL than control AL, and greater circumferential strain in the 3-day PPS than control PPS. In the 6-week OHT eyes, AL and PPS strains were similar overall to controls. This experimental glaucoma model demonstrated a dynamic change in the mechanical behaviour of the AL and PPS over time at the site of neuronal injury and remodelling in glaucoma.
Collapse
Affiliation(s)
- Arina Korneva
- Glaucoma Center of Excellence, Wilmer Eye Institute, John Hopkins University, Baltimore, MD, USA
| | - Elizabeth C. Kimball
- Glaucoma Center of Excellence, Wilmer Eye Institute, John Hopkins University, Baltimore, MD, USA
| | - Joan L. Jefferys
- Glaucoma Center of Excellence, Wilmer Eye Institute, John Hopkins University, Baltimore, MD, USA
| | - Harry A. Quigley
- Glaucoma Center of Excellence, Wilmer Eye Institute, John Hopkins University, Baltimore, MD, USA
| | - Thao D. Nguyen
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, MD 21218, USA
- Department of Ophthalmology, The Johns Hopkins University, Baltimore, MD 21218, USA
- Department of Materials Science, The Johns Hopkins University, Baltimore, MD 21218, USA
| |
Collapse
|
14
|
Moore J, Shu X, Lopes BT, Wu R, Abass A. Limbus misrepresentation in parametric eye models. PLoS One 2020; 15:e0236096. [PMID: 32970690 PMCID: PMC7514007 DOI: 10.1371/journal.pone.0236096] [Citation(s) in RCA: 8] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/03/2019] [Accepted: 06/29/2020] [Indexed: 11/20/2022] Open
Abstract
Purpose To assess the axial, radial and tangential limbus position misrepresentation when parametric models are used to represent the cornea and the sclera. Methods This retrospective study included 135 subjects aged 22 to 65 years (36.5 mean ±9.8 STD), 71 females and 64 males. Topography measurements were taken using an Eye Surface Profiler topographer and processed by a custom-built MATLAB code. Eye surfaces were freed from edge-effect artefacts and fitted to spherical, conic and biconic models. Results When comparing the radial position of the limbus, average errors of -0.83±0.19mm, -0.76±0.20mm and -0.69±0.20mm were observed within the right eye population for the spherical, conic and biconic models fitted up to 5mm. For the same fitting radius, the average fitting errors were -0.86±0.23mm, -0.78±0.23mm and -0.73±0.23mm for the spherical, conic and biconic models respectively within the left eye population. For the whole cornea fit, the average errors were -0.27±0.12mm and -0.28±0.13mm for the spherical models, -0.02±0.29mm and -0.05±0.27mm for the conic models, and -0.22±0.16mm and 0.24±0.17mm for the biconic models in the right and left eye populations respectively. Conclusions Through the use of spherical, conic and biconic parametric modelling methods, the eye’s limbus is being mislocated. Additionally, it is evident that the magnitude of fitting error associated with the sclera may be propagating through the other components of the eye. This suggests that a corneal nonparametric model may be necessary to improve the representation of the limbus.
Collapse
Affiliation(s)
- Joshua Moore
- Department of Mathematical Sciences, University of Liverpool, Liverpool, United Kingdom
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
| | - Xuhan Shu
- College of Physical Sciences, University of Guelph, Guelph, Canada
| | - Bernardo T. Lopes
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
- Department of Ophthalmology, Federal University of Sao Paulo, Sao Paulo, Brazil
| | - Richard Wu
- Department of Optometry, Central Taiwan University of Science and Technology, Taichung, Taiwan
- College of Optometry, Pacific University, Forest Grove, Oregon, United States of America
| | - Ahmed Abass
- School of Engineering, University of Liverpool, Liverpool, United Kingdom
- * E-mail:
| |
Collapse
|
15
|
Iomdina EN, Tikhomirova NK, Bessmertny AM, Serebryakova MV, Baksheeva VE, Zalevsky AO, Kotelin VI, Kiseleva OA, Kosakyan SM, Zamyatnin AA, Philippov PP, Zernii EY. Alterations in proteome of human sclera associated with primary open-angle glaucoma involve proteins participating in regulation of the extracellular matrix. Mol Vis 2020; 26:623-640. [PMID: 32913388 PMCID: PMC7479071] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 08/31/2020] [Indexed: 11/14/2022] Open
Abstract
Purpose Primary open-angle glaucoma (POAG) is a common ocular disease, associated with abnormalities in aqueous humor circulation and an increase in intraocular pressure (IOP), leading to progressive optical neuropathy and loss of vision. POAG pathogenesis includes alterations of the structural properties of the sclera, especially in the optic nerve head area, contributing to the degeneration of the retinal ganglion cells. Abnormal sclera biomechanics hinder adequate compensation of IOP fluctuations, thus aggravating POAG progression. The proteomic basis of biomechanical disorders in glaucomatous sclera remains poorly understood. This study is aimed at revealing alterations in major scleral proteins, associated with POAG, at different stages of the disease and with different IOP conditions. Methods Samples of sclera were collected from 67 patients with POAG during non-penetrating deep sclerectomy and from nine individuals without POAG. Scleral proteins were extracted with a strong lysis buffer, containing a combination of an ionic detergent, a chaotropic agent, and a disulfide reducing agent, and were separated using sodium dodecyl sulfate-polyacrylamide gel electrophoresis (SDS-PAGE). The major scleral proteins were selected, subjected to in-gel digestion, and identified using matrix-assisted laser desorption ionization-time of flight mass spectrometry (MALDI-TOF)/TOF mass spectrometry (MS), coupled with tandem mass spectrometry (MS/MS). The specific POAG-associated alterations of the selected proteins were analyzed with SDS-PAGE and confirmed with western blotting of the scleral extracts, using the respective antibodies. The group of POAG-associated proteins was analyzed using Gene Ontology and genome-wide association study enrichment and protein-protein interaction network prediction. Results A total of 11 proteins were identified, among which six proteins, namely, vimentin, angiopoietin-related protein 7, annexin A2, serum amyloid P component, serum albumin, and thrombospondin-4, were found to be upregulated in the sclera of patients with advanced and terminal POAG. In the early stages of the disease, thrombospondin-4 level was, on the contrary, reduced when compared with the control, whereas the concentration of vimentin varied, depending on the IOP level. Moreover, angiopoietin-related protein 7 manifested as two forms, exhibiting opposite behavior: The common 45 kDa form grew with the progression of POAG, whereas the 35 kDa (apparently non-glycosylated) form was absent in the control samples, appeared in patients with early POAG, and decreased in concentration over the course of the disease. Functional bioinformatics analysis linked the POAG-associated proteins with IOP alterations and predicted their secretion into extracellular space and their association with extracellular vesicles and a collagen-containing extracellular matrix. Conclusions POAG is accompanied by alterations of the scleral proteome, which represent a novel hallmark of the disease and can reflect pathological changes in scleral biochemistry and biomechanics. The potential mechanisms underlying these changes relate mainly to the structure of the extracellular matrix, protein glycosylation, and calcium binding, and may involve fibroblast cytoskeleton regulation, as well as oxidative and inflammatory responses.
Collapse
Affiliation(s)
- Elena N. Iomdina
- Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Natalya K. Tikhomirova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | | | - Marina V. Serebryakova
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Viktoriia E. Baksheeva
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Arthur O. Zalevsky
- Faculty of Bioengineering and Bioinformatics, Lomonosov Moscow State University, Moscow, Russia,Shemyakin and Ovchinnikov Institute of Bioorganic Chemistry of the Russian Academy of Sciences, Moscow, Russia,Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, Russia
| | | | - Olga A. Kiseleva
- Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Sbrui M. Kosakyan
- Helmholtz National Medical Research Center of Eye Diseases, Moscow, Russia
| | - Andrey A. Zamyatnin
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia,Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, Russia
| | - Pavel P. Philippov
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia
| | - Evgeni Yu. Zernii
- Belozersky Institute of Physico-Chemical Biology, Lomonosov Moscow State University, Moscow, Russia,Institute of Molecular Medicine, Sechenov First Moscow State Medical University, Moscow, Russia
| |
Collapse
|
16
|
Quillen S, Schaub J, Quigley H, Pease M, Korneva A, Kimball E. Astrocyte responses to experimental glaucoma in mouse optic nerve head. PLoS One 2020; 15:e0238104. [PMID: 32822415 PMCID: PMC7442264 DOI: 10.1371/journal.pone.0238104] [Citation(s) in RCA: 35] [Impact Index Per Article: 8.8] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2020] [Accepted: 08/10/2020] [Indexed: 12/20/2022] Open
Abstract
PURPOSE To delineate responses of optic nerve head astrocytes to sustained intraocular pressure (IOP) elevation in mice. METHODS We elevated IOP for 1 day to 6 weeks by intracameral microbead injection in 4 strains of mice. Astrocyte alterations were studied by transmission electron microscopy (TEM) including immunogold molecular localization, and by laser scanning microscopy (LSM) with immunofluorescence for integrin β1, α-dystroglycan, and glial fibrillary acidic protein (GFAP). Astrocyte proliferation and apoptosis were quantified by Ki67 and TUNEL labeling, respectively. RESULTS Astrocytes in normal optic nerve head expressed integrin β1 and α-dystroglycan by LSM and TEM immunogold labeling at electron dense junctional complexes that were found only on cell membrane zones bordering their basement membranes (BM) at the peripapillary sclera (PPS) and optic nerve head capillaries. At 1-3 days after IOP elevation, abnormal extracellular spaces appeared between astrocytes near PPS, and axonal vesical and mitochondrial accumulation indicated axonal transport blockade. By 1 week, abnormal spaces increased, new collagen formation occurred, and astrocytes separated from their BM, leaving cell membrane fragments. Electron dense junctional complexes separated or were absent at the BM. Astrocyte proliferation was modest during the first week, while only occasional apoptotic astrocytes were observed by TEM and TUNEL. CONCLUSIONS Astrocytes normally exhibit junctions with their BM which are disrupted by extended IOP elevation. Responses include reorientation of cell processes, new collagen formation, and cell proliferation.
Collapse
Affiliation(s)
- Sarah Quillen
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Julie Schaub
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Harry Quigley
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Mary Pease
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Arina Korneva
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Elizabeth Kimball
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| |
Collapse
|
17
|
Qiu C, Yao J, Zhang X, Zhang R, Sun X, Qian S. The Dynamic Scleral Extracellular Matrix Alterations in Chronic Ocular Hypertension Model of Rats. Front Physiol 2020; 11:682. [PMID: 32719611 PMCID: PMC7349004 DOI: 10.3389/fphys.2020.00682] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 12/30/2019] [Accepted: 05/26/2020] [Indexed: 11/23/2022] Open
Abstract
Intraocular pressure (IOP) generates stress and strains in the laminar cribrosa and sclera, which may affect the development and progression of glaucoma. Scleral stiffness and material components have changed under elevated IOP. However, the detailed changes of the components of the hypertensive sclera are not well understood. In this study, we aimed to investigate the changes of the main components in the scleral extracellular matrix (ECM), and matrix metalloproteinase 2 (MMP2) and their relationship with time under chronic elevated IOP in Sprague–Dawley rats. An ocular hypertension model was established in the right eyes by anterior chamber injection with 0.3% carbomer solution. The left eye was used as the contralateral control. Immunofluorescent imaging of the tissue frozen sections, Western blot analysis, and quantitative PCR (qPCR) were performed to detect the expressions of type I collagen (COL1), elastin, and MMP2 in the sclera. The ocular hypertension model was successfully established. As compared to the left eyes, the immunofluorescence imaging, Western blot analysis, and qPCR showed that COL1, elastin, and MMP2 were significantly increased in the right eyes at 1 week (all P < 0.05). At 2 weeks, COL1 in the right eyes tended to be lower than that in the left eyes, while elastin and MMP2 were still higher (all P < 0.05) in the right eyes. When the IOP was elevated for 4 weeks, both COL1 and MMP2 were lower than those in the left eyes (all P < 0.05), while elastin between the two eyes was similar (P > 0.05). Under this 4-week hypertensive state, COL1 and elastin were initially elevated at 1 week, and then obviously reduced from 2 to 4 weeks. Consistently, MMP2 was gradually increased, with a peak at 2 weeks, and then decreased at 4 weeks. In conclusion, the chronic elevated IOP induced dynamic scleral ECM alterations in rats in a pressure- and time-dependent manner. MMP2 may play an important role in the balance between ECM synthesis and degradation and could potentially be a novel target for glaucoma intervention.
Collapse
Affiliation(s)
- Chen Qiu
- Department of Ophthalmology and Vision Science, Eye and Ear, Nose, Throat Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia, Fudan University, Shanghai, China.,Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Jing Yao
- Department of Ophthalmology and Vision Science, Eye and Ear, Nose, Throat Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia, Fudan University, Shanghai, China.,Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Xi Zhang
- Department of Ophthalmology, Zhongshan Hospital of Fudan University, Shanghai, China
| | - Rong Zhang
- Department of Ophthalmology and Vision Science, Eye and Ear, Nose, Throat Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia, Fudan University, Shanghai, China.,Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| | - Xinghuai Sun
- Department of Ophthalmology and Vision Science, Eye and Ear, Nose, Throat Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia, Fudan University, Shanghai, China.,Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China.,State Key Laboratory of Medical Neurobiology, Institutes of Brain Science, Fudan University, Shanghai, China.,Shanghai Key Laboratory of Visual Impairment and Restoration, Fudan University, Shanghai, China
| | - Shaohong Qian
- Department of Ophthalmology and Vision Science, Eye and Ear, Nose, Throat Hospital, Shanghai Medical College, Fudan University, Shanghai, China.,NHC Key Laboratory of Myopia, Fudan University, Shanghai, China.,Laboratory of Myopia, Chinese Academy of Medical Sciences, Shanghai, China
| |
Collapse
|
18
|
Walker MK, Schornack MM, Vincent SJ. Anatomical and physiological considerations in scleral lens wear: Conjunctiva and sclera. Cont Lens Anterior Eye 2020; 43:517-528. [PMID: 32624363 DOI: 10.1016/j.clae.2020.06.005] [Citation(s) in RCA: 12] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/13/2020] [Revised: 06/17/2020] [Accepted: 06/18/2020] [Indexed: 12/20/2022]
Abstract
While scleral lenses have been fitted using diagnostic lenses or impression moulding techniques for over a century, recent advances in anterior segment imaging such as optical coherence tomography and corneo-scleral profilometry have significantly improved the current understanding of the anatomy of the anterior eye including the morphometry of the conjunctiva, sclera, and corneo-scleral junction, as well as the ocular surface shape and elevation. These technological advances in ocular imaging along with continual improvements and innovations in scleral lens design and manufacturing have led to a global increase in scleral lens prescribing. This review provides a comprehensive overview of the conjunctiva and sclera in the context of modern scleral lens practice, including anatomical variations in healthy and diseased eyes, the physiological impact of scleral lens wear, potential fitting challenges, and current approaches to lens modifications in order to minimise lens-induced complications and adverse ocular effects. Specific topics requiring further research are also discussed.
Collapse
Affiliation(s)
- Maria K Walker
- University of Houston College of Optometry, The Ocular Surface Institute, Houston, USA
| | | | - Stephen J Vincent
- Queensland University of Technology (QUT), Centre for Vision and Eye Research, School of Optometry and Vision Science, Contact Lens and Visual Optics Laboratory, Institute of Health and Biomedical Innovation, Queensland, Australia.
| |
Collapse
|
19
|
Lee EJ, Han JC, Park DY, Kee C. Long-term morphologic fundus and optic nerve head pattern of progressive myopia in congenital glaucoma distinguished by age at first surgery. Sci Rep 2020; 10:10041. [PMID: 32572115 PMCID: PMC7308308 DOI: 10.1038/s41598-020-67051-0] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/28/2019] [Accepted: 04/09/2020] [Indexed: 11/09/2022] Open
Abstract
The purpose of this study was to investigate the preservation of round optic nerve head (ONH) shape in myopic eyes of surgically treated congenital glaucoma patients, with regard to factors associated with intraocular pressure (IOP) elevation-induced peripapillary scleral (PPS) deformation. Using optical coherence tomography (OCT) on the ONH and macula, we identified myopic eyes with round ONH and internally oblique border tissue and those with non-round ONH. We investigated differences in clinical factors between the two groups. We included 51 eyes of 34 patients. Age at first surgery (2.8 vs. 15.2 months, P < 0.001) was significantly different between the two groups. Axial length was also significantly longer (P = 0.004) in the non-round group, but multiple logistic regression analysis revealed age as the only significant factor (P < 0.05) in ONH roundness. Interestingly, the round ONH group also had non-curved fundus morphology and a thick choroid, while the non-round ONH group showed diverse degrees of disc tilt and posterior pole curvature, and a thin choroid. In conclusion, in eyes with congenital glaucoma, age at first surgery, particularly when older than 6 months, was associated with round ONH and emmetropia-like fundus despite high myopia. The findings may indicate two different changes in the posterior sclera and the neural canal in response to the increased IOP.
Collapse
Affiliation(s)
- Eun Jung Lee
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Jong Chul Han
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Do Young Park
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea
| | - Changwon Kee
- Department of Ophthalmology, Samsung Medical Center, Sungkyunkwan University School of Medicine, Seoul, Korea.
| |
Collapse
|
20
|
Lin MH, Pope BD, Sasaki T, Keeley DP, Sherwood DR, Miner JH. Mammalian hemicentin 1 is assembled into tracks in the extracellular matrix of multiple tissues. Dev Dyn 2020; 249:775-788. [PMID: 32035013 DOI: 10.1002/dvdy.159] [Citation(s) in RCA: 10] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/15/2019] [Revised: 01/20/2020] [Accepted: 01/31/2020] [Indexed: 12/12/2022] Open
Abstract
BACKGROUND Hemicentins (HMCNs) are a family of extracellular matrix proteins first identified in Caenorhabditis elegans, with two orthologs (HMCN1 and 2) in vertebrates. In worms, HMCN is deposited at specific sites where it forms long, fine tracks that link two tissues by connecting adjacent basement membranes (BMs). By generating CRISPR/Cas9-mediated Hmcn1 and Hmcn2 knockout mice, we tested the hypothesis that HMCNs perform similar functions in mammals. RESULTS Hmcn1 -/- mice were viable and fertile. Using new, knockout mouse-validated HMCN1 antibodies, HMCN1 was detected in wild-type mice as fine tracks along the BM of hair and whisker follicles, in the sclera of the eyes, and in the lumen of some lymphoid conduits. It was also observed in the mesangial matrix of the kidney glomerulus. However, HMCN1 deficiency did not affect the functions of these tissues, including adherence of coat hairs and whiskers, the sieving function of lymphoid conduits, or the immune response to injected antigens. HMCN2 deficiency did not lead to any discernible phenotypes on its own or when combined with HMCN1 deficiency. CONCLUSION That Hmcn1 -/- , Hmcn2 -/- , and Hmcn1/2 double knockout mice did not display any overt phenotypes implicates compensation by other members of the fibulin family.
Collapse
Affiliation(s)
- Meei-Hua Lin
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Bill D Pope
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA
| | - Takako Sasaki
- Department of Biochemistry II, Oita University, Oita, Japan
| | - Daniel P Keeley
- Department of Biology, Regeneration Next, Duke University, Durham, North Carolina, USA
| | - David R Sherwood
- Department of Biology, Regeneration Next, Duke University, Durham, North Carolina, USA
| | - Jeffrey H Miner
- Division of Nephrology, Department of Medicine, Washington University School of Medicine, St. Louis, Missouri, USA.,Department of Cell Biology and Physiology, Washington University School of Medicine, St. Louis, Missouri, USA
| |
Collapse
|
21
|
Boote C, Sigal IA, Grytz R, Hua Y, Nguyen TD, Girard MJA. Scleral structure and biomechanics. Prog Retin Eye Res 2019; 74:100773. [PMID: 31412277 DOI: 10.1016/j.preteyeres.2019.100773] [Citation(s) in RCA: 130] [Impact Index Per Article: 26.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/04/2019] [Revised: 08/07/2019] [Accepted: 08/08/2019] [Indexed: 12/18/2022]
Abstract
As the eye's main load-bearing connective tissue, the sclera is centrally important to vision. In addition to cooperatively maintaining refractive status with the cornea, the sclera must also provide stable mechanical support to vulnerable internal ocular structures such as the retina and optic nerve head. Moreover, it must achieve this under complex, dynamic loading conditions imposed by eye movements and fluid pressures. Recent years have seen significant advances in our knowledge of scleral biomechanics, its modulation with ageing and disease, and their relationship to the hierarchical structure of the collagen-rich scleral extracellular matrix (ECM) and its resident cells. This review focuses on notable recent structural and biomechanical studies, setting their findings in the context of the wider scleral literature. It reviews recent progress in the development of scattering and bioimaging methods to resolve scleral ECM structure at multiple scales. In vivo and ex vivo experimental methods to characterise scleral biomechanics are explored, along with computational techniques that combine structural and biomechanical data to simulate ocular behaviour and extract tissue material properties. Studies into alterations of scleral structure and biomechanics in myopia and glaucoma are presented, and their results reconciled with associated findings on changes in the ageing eye. Finally, new developments in scleral surgery and emerging minimally invasive therapies are highlighted that could offer new hope in the fight against escalating scleral-related vision disorder worldwide.
Collapse
Affiliation(s)
- Craig Boote
- Structural Biophysics Research Group, School of Optometry & Vision Sciences, Cardiff University, UK; Ophthalmic Engineering & Innovation Laboratory (OEIL), Department of Biomedical Engineering, National University of Singapore, Singapore; Newcastle Research & Innovation Institute Singapore (NewRIIS), Singapore.
| | - Ian A Sigal
- Laboratory of Ocular Biomechanics, Department of Ophthalmology, University of Pittsburgh, USA
| | - Rafael Grytz
- Department of Ophthalmology & Visual Sciences, University of Alabama at Birmingham, USA
| | - Yi Hua
- Laboratory of Ocular Biomechanics, Department of Ophthalmology, University of Pittsburgh, USA
| | - Thao D Nguyen
- Department of Mechanical Engineering, Johns Hopkins University, USA
| | - Michael J A Girard
- Ophthalmic Engineering & Innovation Laboratory (OEIL), Department of Biomedical Engineering, National University of Singapore, Singapore; Singapore Eye Research Institute (SERI), Singapore National Eye Centre, Singapore
| |
Collapse
|
22
|
Nguyen C, Midgett D, Kimball E, Jefferys J, Nguyen TD, Schaub J, Pease M, Quigley H. Age-Related Changes in Quantitative Strain of Mouse Astrocytic Lamina Cribrosa and Peripapillary Sclera Using Confocal Microscopy in an Explant Model. Invest Ophthalmol Vis Sci 2019; 59:5157-5166. [PMID: 30372742 PMCID: PMC6516562 DOI: 10.1167/iovs.18-25111] [Citation(s) in RCA: 16] [Impact Index Per Article: 3.2] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023] Open
Abstract
Purpose The purpose of this study was to measure the full-field deformation response to IOP change in the peripapillary sclera (PPS) and astrocytic lamina cribrosa (ALC) of young and old mouse eyes ex vivo. Methods Thirty-eight transgenic reporter mice with green fluorescent protein–expressing astrocytes were studied at 2 to 4 months and 13 to 15 months old. The ALC and PPS of the explant eyes were imaged using laser scanning microscopy under controlled inflation from 10 to 30 mm Hg. Strains were estimated for the ALC and PPS from imaged volumes using digital volume correlation. Results ALC strains were significantly greater than zero nasal–temporally for both age groups (mean = 4.3% and 4.0%; each P ≤ 0.004) and significantly greater than zero in the inferior–superior direction for younger mice (P = 0.0004). Younger mice had larger ALC inferior–superior strains than older mice (P = 0.002). The ALC area and perimeter enlarged with inflation in both age groups, with a greater increase in younger than in older mice (all P ≤ 0.004). The ALC nasal–temporal diameter change was greater than inferior–superiorly, and younger mice had greater enlargement nasal–temporally than older. PPS maximum shear strain was greater in the older mice (P = 0.002). The axial lengths of older mice were 14% longer and the PPS was 16% thinner than younger mice (both P = 0.0003). Conclusions The behavior of the ALC in younger mice with inflation exhibited greater strains and enlargement of ALC area than older mice. Some strain measures in the PPS were greater in older mice, likely related to their longer axial length and thinner PPS.
Collapse
Affiliation(s)
- Cathy Nguyen
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute and the Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland, United States
| | - Dan Midgett
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute and the Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland, United States
| | - Elizabeth Kimball
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute and the Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland, United States
| | - Joan Jefferys
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute and the Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland, United States
| | - Thao D Nguyen
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute and the Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland, United States
| | - Julie Schaub
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute and the Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland, United States
| | - Mary Pease
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute and the Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland, United States
| | - Harry Quigley
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute and the Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland, United States
| |
Collapse
|
23
|
Pijanka JK, Markov PP, Midgett D, Paterson NG, White N, Blain EJ, Nguyen TD, Quigley HA, Boote C. Quantification of collagen fiber structure using second harmonic generation imaging and two-dimensional discrete Fourier transform analysis: Application to the human optic nerve head. JOURNAL OF BIOPHOTONICS 2019; 12:e201800376. [PMID: 30578592 PMCID: PMC6506269 DOI: 10.1002/jbio.201800376] [Citation(s) in RCA: 20] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/02/2018] [Revised: 12/13/2018] [Accepted: 12/19/2018] [Indexed: 05/17/2023]
Abstract
Second harmonic generation (SHG) microscopy is widely used to image collagen fiber microarchitecture due to its high spatial resolution, optical sectioning capabilities and relatively nondestructive sample preparation. Quantification of SHG images requires sensitive methods to capture fiber alignment. This article presents a two-dimensional discrete Fourier transform (DFT)-based method for collagen fiber structure analysis from SHG images. The method includes integrated periodicity plus smooth image decomposition for correction of DFT edge discontinuity artefact, avoiding the loss of peripheral image data encountered with more commonly used windowing methods. Outputted parameters are as follows: the collagen fiber orientation distribution, aligned collagen content and the degree of collagen fiber dispersion along the principal orientation. We demonstrate its application to determine collagen microstructure in the human optic nerve head, showing its capability to accurately capture characteristic structural features including radial fiber alignment in the innermost layers of the bounding sclera and a circumferential collagen ring in the mid-stromal tissue. Higher spatial resolution rendering of individual lamina cribrosa beams within the nerve head is also demonstrated. Validation of the method is provided in the form of correlative results from wide-angle X-ray scattering and application of the presented method to other fibrous tissues.
Collapse
Affiliation(s)
- Jacek K. Pijanka
- Structural Biophysics Group, School of Optometry and
Vision Sciences, Cardiff University, CF24 4HQ, Cardiff, UK
| | - Petar P. Markov
- Structural Biophysics Group, School of Optometry and
Vision Sciences, Cardiff University, CF24 4HQ, Cardiff, UK
| | - Dan Midgett
- Department of Mechanical Engineering, The Johns Hopkins
University, Baltimore, MD 21218, USA
- Department of Materials Science, The Johns Hopkins
University, Baltimore, MD 21218, USA
| | - Neil G. Paterson
- Diamond Light Source, Harwell Science and Innovation
Campus, Harwell, UK
| | - Nick White
- Vivat Scientia Bioimaging Labs, School of Optometry and
Visual Sciences, Cardiff University, CF24 4HQ, Cardiff, UK
| | - Emma J. Blain
- Arthritis Research UK Biomechanics and Bioengineering
Centre, Cardiff University, CF10 3AX, Cardiff, UK
| | - Thao D. Nguyen
- Department of Mechanical Engineering, The Johns Hopkins
University, Baltimore, MD 21218, USA
- Department of Materials Science, The Johns Hopkins
University, Baltimore, MD 21218, USA
| | - Harry A. Quigley
- Wilmer Ophthalmological Institute, School of Medicine, The
Johns Hopkins University, Baltimore, MD 21287, USA
| | - Craig Boote
- Structural Biophysics Group, School of Optometry and
Vision Sciences, Cardiff University, CF24 4HQ, Cardiff, UK
| |
Collapse
|
24
|
Effect of freezing and thawing on the biomechanical characteristics of porcine ocular tissues. J Biomech 2019; 87:93-99. [PMID: 30876736 DOI: 10.1016/j.jbiomech.2019.02.024] [Citation(s) in RCA: 5] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/11/2018] [Revised: 12/25/2018] [Accepted: 02/23/2019] [Indexed: 12/13/2022]
Abstract
PURPOSE To evaluate the effect of freezing and thawing on the biomechanical properties of ex-vivo porcine ocular tissue. METHODS Thirty-six porcine eyes (18 pairs) were obtained fresh from a local abattoir and split into two groups of nine pairs to study the effect of storage at -20 °C and -80 °C. A randomly-selected eye from each pair (Control Group, CG) was tested fresh while the fellow eyes were frozen for 14 days, either at -20 °C and -80 °C (Frozen Group, FG) before thawing and testing. Seventy-two strips were extracted from the corneas and scleras of eye globes and subjected to uniaxial tension tests under loads up to 1.0 N. Following five preconditioning cycles, the load and elongation data obtained experimentally were analysed to derive the tissue's stress-strain and tangent modulus-strain behaviour. RESULTS Corneal tissue subjected to freezing at -20 °C exhibited significant increases in tangent modulus (mechanical stiffness) by 13 ± 17% (p = 0.003) at 1% strain and 14 ± 12% (p < 0.001) at 2% strain. In contrast, the increases in corneal stiffness at -80 °C were insignificant (6 ± 14%, p = 0.099 at 1% strain, 6 ± 15%, p = 0.091 at 2% strain). The corresponding increases in tangent modulus in the sclera were all insignificant (for -20 °C: 4 ± 14%, p = 0.265 at 1% strain, 3 ± 9%, p = 0.186 at 2% strain; for -80 °C: 3 ± 18%, p = 0.537 at 1% strain and 3 ± 18%, p = 0.491 at 2% strain). CONCLUSIONS The study provided evidence that freezing and thawing led to insignificant changes in ocular tissue stiffness except in corneal tissue that was frozen at -20 °C.
Collapse
|
25
|
Markov PP, Eliasy A, Pijanka JK, Htoon HM, Paterson NG, Sorensen T, Elsheikh A, Girard MJ, Boote C. Bulk changes in posterior scleral collagen microstructure in human high myopia. Mol Vis 2018; 24:818-833. [PMID: 30713421 PMCID: PMC6334987] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/21/2018] [Accepted: 12/28/2018] [Indexed: 11/01/2022] Open
Abstract
Purpose We aimed to characterize any bulk changes in posterior scleral collagen fibril bundle architecture in human eyes with high myopia. Methods Wide-angle X-ray scattering (WAXS) was employed to map collagen orientation at 0.5 mm × 0.5 mm spatial intervals across the posterior sclera of seven non-myopic human eyes and three eyes with high myopia (>6D of refractive error). At each sampled point, WAXS provided thickness-averaged measures of the angular distribution of preferentially aligned collagen fibrils within the tissue plane and the anisotropic proportion (the ratio of preferentially aligned to total collagen scatter). Results Non-myopic specimens featured well-conserved microstructural features, including strong uniaxial collagen alignment along the extraocular muscle insertion sites of the mid-posterior sclera and a highly anisotropic annulus of collagen circumscribing the nerve head in the peripapillary sclera. All three myopic specimens exhibited notable alterations in the peripapillary sclera, including a partial loss of circumferential collagen alignment and a redistribution of the normally observed regional pattern of collagen anisotropic proportion. Linear mixed-model analysis indicated that the mean fiber angle deviation from the circumferential orientation in the peripapillary sclera of highly myopic eyes (23.9° ± 18.2) was statistically significantly higher than that of controls (17.9° ± 12.0; p<0.05). Conclusions Bulk alterations in the normal posterior scleral collagen microstructure occur in human eyes with high myopia. These changes could reflect remodeling of the posterior sclera during axial lengthening and/or a mechanical adaption to tissue stresses induced by fluid pressure or eye movements that may be exacerbated in enlarged eyes.
Collapse
Affiliation(s)
- Petar P. Markov
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
| | - Ashkan Eliasy
- Biomechanical Engineering Group, School of Engineering, University of Liverpool, Liverpool, UK
| | - Jacek K. Pijanka
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
| | - Hla M. Htoon
- Singapore Eye Research Institute (SERI), Singapore
| | - Neil G. Paterson
- Diamond Light Source, Harwell Science and Innovation Campus, Harwell, UK
| | - Thomas Sorensen
- Diamond Light Source, Harwell Science and Innovation Campus, Harwell, UK
| | - Ahmed Elsheikh
- Biomechanical Engineering Group, School of Engineering, University of Liverpool, Liverpool, UK,NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, UK,School of Biological Science and Biomedical Engineering, Beihang University, Beijing, China
| | - Michael J.A. Girard
- Singapore Eye Research Institute (SERI), Singapore,Ophthalmic Engineering & Innovation Laboratory (OEIL), Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Craig Boote
- Structural Biophysics Research Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK,Ophthalmic Engineering & Innovation Laboratory (OEIL), Department of Biomedical Engineering, National University of Singapore, Singapore
| |
Collapse
|
26
|
Kim YC, Hwang HS, Park HYL, Park CK. Transverse Separation of the Outer Retinal Layer at the Peripapillary in Glaucomatous Myopes. Sci Rep 2018; 8:12446. [PMID: 30127501 PMCID: PMC6102290 DOI: 10.1038/s41598-018-30523-5] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/22/2018] [Accepted: 08/01/2018] [Indexed: 11/10/2022] Open
Abstract
Glaucoma specialists often overlook the outer retinal changes because the glaucomatous optic neuropathy typically involves retinal nerve fiber layer (RNFL). By detailed inspection of the outer retina in myopic eyes, we observed a separation of the inner nuclear layer (INL) from the outer nuclear layer (ONL) at the peripapillary sclera (pp-sclera). Therefore, we conducted a retrospective observation of 108 eyes of 108 Korean subjects with myopia assessed by swept-source optical coherence tomography (SSOCT) and divided into normal and glaucomatous eyes. Mean subject age, refractive error and axial length difference between 2 groups were insignificant, respectively. To quantify the ONL-INL separation, straight-line distance from ONL endpoint to INL endpoint was measured at the center of the optic disc by SSOCT horizontal scan. The glaucomatous group had significantly large ONL-INL separation than the non-glaucomatous group (p = 0.027) but had no significant difference in INL – Anterior scleral canal opening (ASCO) separation. The width of ONL-INL separation were associated with β-peripapillary atrophy (β-PPA), degree of horizontal tilt of the optic disc and worse glaucomatous RNFL defect by Pearson’s correlation analysis (all p < 0.001, respectively). In conclusion, we demonstrate transverse separation of INL from ONL at the peripapillary region, which was significantly associated with glaucomatous optic nerve damage. These observations may be of interest to elucidate the role of PPA in glaucoma pathogenesis and a clinical index to take notice for myopic subjects.
Collapse
Affiliation(s)
- Yong Chan Kim
- Department of Ophthalmology, College of medicine, Chuncheon Sacred Heart Hospital, Hallym University, Chuncheon-si, Gangwon-do, Republic of Korea
| | - Ho Sik Hwang
- Department of Ophthalmology, College of medicine, Chuncheon Sacred Heart Hospital, Hallym University, Chuncheon-si, Gangwon-do, Republic of Korea
| | - Hae-Young Lopilly Park
- Department of Ophthalmology, College of medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea
| | - Chan Kee Park
- Department of Ophthalmology, College of medicine, Seoul St. Mary's Hospital, The Catholic University of Korea, Seoul, Republic of Korea.
| |
Collapse
|
27
|
Tehrani S, Delf RK, Cepurna WO, Davis L, Johnson EC, Morrison JC. In Vivo Small Molecule Delivery to the Optic Nerve in a Rodent Model. Sci Rep 2018. [PMID: 29535357 PMCID: PMC5849600 DOI: 10.1038/s41598-018-22737-4] [Citation(s) in RCA: 2] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/11/2022] Open
Abstract
Small molecule delivery to the optic nerve would allow for exploration of molecular and cellular pathways involved in normal physiology and optic neuropathies such as glaucoma, and provide a tool for screening therapeutics in animal models. We report a novel surgical method for small molecule drug delivery to the optic nerve head (ONH) in a rodent model. In proof-of-principle experiments, we delivered cytochalasin D (Cyt D; a filamentous actin inhibitor) to the junction of the superior optic nerve and globe in rats to target the actin-rich astrocytic cytoskeleton of the ONH. Cyt D delivery was quantified by liquid chromatography and mass spectrometry of isolated optic nerve tissue. One day after Cyt D delivery, anterior ONH filamentous actin bundle content was significantly reduced as assessed by fluorescent-tagged phalloidin labeling, relative to sham delivery. Anterior ONH nuclear counts and axon-specific beta-3 tubulin levels, as well as peripapillary retinal ganglion cell layer nuclear counts were not significantly altered after Cyt D delivery relative to sham delivery. Lastly, the surgical delivery technique caused minimal observable axon degeneration up to 10 days post-surgery. This small molecule delivery technique provides a new approach to studying optic neuropathies in in vivo rodent models.
Collapse
Affiliation(s)
- Shandiz Tehrani
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA.
| | - R Katherine Delf
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
| | - William O Cepurna
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
| | - Lauren Davis
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
| | - Elaine C Johnson
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
| | - John C Morrison
- Casey Eye Institute, Department of Ophthalmology, Oregon Health & Science University, Portland, OR, USA
| |
Collapse
|
28
|
Schaub JA, Kimball EC, Steinhart MR, Nguyen C, Pease ME, Oglesby EN, Jefferys JL, Quigley HA. Regional Retinal Ganglion Cell Axon Loss in a Murine Glaucoma Model. Invest Ophthalmol Vis Sci 2017; 58:2765-2773. [PMID: 28549091 PMCID: PMC5455173 DOI: 10.1167/iovs.17-21761] [Citation(s) in RCA: 23] [Impact Index Per Article: 3.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/26/2022] Open
Abstract
Purpose To determine if retinal ganglion cell (RGC) axon loss in experimental mouse glaucoma is uniform in the optic nerve. Methods Experimental glaucoma was induced for 6 weeks with a microbead injection model in CD1 (n = 78) and C57BL/6 (B6, n = 68) mice. From epoxy-embedded sections of optic nerve 1 to 2 mm posterior to the globe, total nerve area and regional axon density (axons/1600 μm2) were measured in superior, inferior, nasal, and temporal zones. Results Control eyes of CD1 mice have higher axon density and more total RGCs than control B6 mice eyes. There were no significant differences in control regional axon density in all mice or by strain (all P > 0.2, mixed model). Exposure to elevated IOP caused loss of RGC in both strains. In CD1 mice, axon density declined without significant loss of nerve area, while B6 mice had less density loss, but greater decrease in nerve area. Axon density loss in glaucoma eyes was not significantly greater in any region in either mouse strain (both P > 0.2, mixed model). In moderately damaged CD1 glaucoma eyes, and CD1 eyes with the greatest IOP elevation exposure, density loss differed by region (P = 0.05, P = 0.03, mixed model) with the greatest loss in the temporal and superior regions, while in severely injured B6 nerves superior loss was greater than inferior loss (P = 0.01, mixed model, Bonferroni corrected). Conclusions There was selectively greater loss of superior and temporal optic nerve axons of RGCs in mouse glaucoma at certain stages of damage. Differences in nerve area change suggest non-RGC responses differ between mouse strains.
Collapse
Affiliation(s)
- Julie A Schaub
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States
| | - Elizabeth C Kimball
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States
| | - Matthew R Steinhart
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States
| | - Cathy Nguyen
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States
| | - Mary E Pease
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States
| | - Ericka N Oglesby
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States
| | - Joan L Jefferys
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States
| | - Harry A Quigley
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States
| |
Collapse
|
29
|
Liu B, McNally S, Kilpatrick JI, Jarvis SP, O'Brien CJ. Aging and ocular tissue stiffness in glaucoma. Surv Ophthalmol 2017; 63:56-74. [PMID: 28666629 DOI: 10.1016/j.survophthal.2017.06.007] [Citation(s) in RCA: 98] [Impact Index Per Article: 14.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/08/2015] [Revised: 06/20/2017] [Accepted: 06/22/2017] [Indexed: 12/27/2022]
Abstract
Glaucoma is a progressive and chronic neurodegenerative disorder characterized by damage to the inner layers of the retina and deformation of the optic nerve head. The degeneration of retinal ganglion cells and their axons results in an irreversible loss of vision and is correlated with increasing age. Extracellular matrix changes related to natural aging generate a stiffer extracellular environment throughout the body. Altered age-associated ocular tissue stiffening plays a major role in a significant number of ophthalmic pathologies. In glaucoma, both the trabecular meshwork and the optic nerve head undergo extensive extracellular matrix remodeling, characterized by fibrotic changes associated with cellular and molecular events (including myofibroblast activation) that drive further tissue fibrosis and stiffening. Here, we review the literature concerning the role of age-related ocular stiffening in the trabecular meshwork, lamina cribrosa, sclera, cornea, retina, and Bruch membrane/choroid and discuss their potential role in glaucoma progression. Because both trabecular meshwork and lamina cribrosa cells are mechanosensitive, we then describe molecular mechanisms underlying tissue stiffening and cell mechanotransduction and how these cellular activities can drive further fibrotic changes within ocular tissues. An improved understanding of the interplay between age-related tissue stiffening and biological responses in the trabecular meshwork and optic nerve head could potentially lead to novel therapeutic strategies for glaucoma treatment.
Collapse
Affiliation(s)
- Baiyun Liu
- School of Physics, Conway Institute, University College Dublin, Dublin, Ireland; Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
| | - Sara McNally
- Department of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland
| | - Jason I Kilpatrick
- Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
| | - Suzanne P Jarvis
- School of Physics, Conway Institute, University College Dublin, Dublin, Ireland; Conway Institute of Biomolecular and Biomedical Research, University College Dublin, Dublin, Ireland
| | - Colm J O'Brien
- Department of Ophthalmology, Mater Misericordiae University Hospital, Dublin, Ireland; School of Medicine and Medical Science, University College Dublin, Dublin, Ireland.
| |
Collapse
|
30
|
Nguyen C, Midgett D, Kimball EC, Steinhart MR, Nguyen TD, Pease ME, Oglesby EN, Jefferys JL, Quigley HA. Measuring Deformation in the Mouse Optic Nerve Head and Peripapillary Sclera. Invest Ophthalmol Vis Sci 2017; 58:721-733. [PMID: 28146237 PMCID: PMC5295769 DOI: 10.1167/iovs.16-20620] [Citation(s) in RCA: 25] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022] Open
Abstract
Purpose To develop an ex vivo explant system using multiphoton microscopy and digital volume correlation to measure the full-field deformation response to intraocular pressure (IOP) change in the peripapillary sclera (PPS) and in the optic nerve head (ONH) astrocytic structure. Methods Green fluorescent protein (GFP)-glutamate transporter-GLT1 (GLT1/GFP) mouse eyes were explanted and imaged with a laser-scanning microscope under controlled inflation. Images were analyzed for regional strains and changes in astrocytic lamina and PPS shape. Astrocyte volume fraction in seven control GLT1/GFP mice was measured. The level of fluorescence of GFP fluorescent astrocytes was compared with glial fibrillary acidic protein (GFAP) labeled astrocytes using immunohistochemistry. Results The ONH astrocytic structure remained stable during 3 hours in explants. Control strain-globally, in the central one-half or two-thirds of the astrocytic lamina-was significantly greater in the nasal-temporal direction than in the inferior-superior or anterior-posterior directions (each P≤ 0.03, mixed models). The PPS opening (perimeter) in normal eye explants also became wider nasal-temporally than superior-inferiorly during inflation from 10 to 30 mm Hg (P = 0.0005). After 1 to 3 days of chronic IOP elevation, PPS area was larger than in control eyes (P = 0.035), perimeter elongation was 37% less than controls, and global nasal-temporal strain was significantly less than controls (P = 0.007). Astrocyte orientation was altered by chronic IOP elevation, with processes redirected toward the longitudinal axis of the optic nerve. Conclusions The explant inflation test measures the strain response of the mouse ONH to applied IOP. Initial studies indicate regional differences in response to both acute and chronic IOP elevation within the ONH region.
Collapse
Affiliation(s)
- Cathy Nguyen
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Baltimore, Maryland, United States
| | - Dan Midgett
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland, United States
| | - Elizabeth C Kimball
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Baltimore, Maryland, United States
| | - Matthew R Steinhart
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Baltimore, Maryland, United States
| | - Thao D Nguyen
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland, United States 3Department of Materials Science, Johns Hopkins University, Baltimore, Maryland, United States
| | - Mary E Pease
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Baltimore, Maryland, United States
| | - Ericka N Oglesby
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Baltimore, Maryland, United States
| | - Joan L Jefferys
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Baltimore, Maryland, United States
| | - Harry A Quigley
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Baltimore, Maryland, United States
| |
Collapse
|
31
|
Borrás T. A single gene connects stiffness in glaucoma and the vascular system. Exp Eye Res 2017; 158:13-22. [PMID: 27593913 PMCID: PMC6067113 DOI: 10.1016/j.exer.2016.08.022] [Citation(s) in RCA: 11] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/05/2016] [Revised: 08/26/2016] [Accepted: 08/31/2016] [Indexed: 12/13/2022]
Abstract
Arterial calcification results in arterial stiffness and higher systolic blood pressure. Arterial calcification is prevented by the high expression of the Matrix-Gla gene (MGP) in the vascular smooth muscle cells (VSMC) of the arteries' tunica media. Originally, MGP, a gene highly expressed in cartilage and VSMC, was found to be one of the top expressed genes in the trabecular meshwork. The creation of an Mgp-lacZ Knock-In mouse and the use of mouse genetics revealed that in the eye, Mgp's abundant expression is localized and restricted to glaucoma-associated tissues from the anterior and posterior segments. In particular, it is specifically expressed in the regions of the trabecular meshwork and of the peripapillary sclera that surrounds the optic nerve. Because stiffness in these tissues would significantly alter outflow facility and biomechanical scleral stress in the optic nerve head (ONH), we propose MGP as a strong candidate for the regulation of stiffness in glaucoma. MGP further illustrates the presence of a common function affecting key glaucomatous parameters in the front and back of the eye, and thus offers the possibility for a sole therapeutic target for the disease.
Collapse
Affiliation(s)
- Teresa Borrás
- Department of Ophthalmology, University of North Carolina School of Medicine, 4109C Neuroscience Research Building CB 7041, 105 Mason Farm Road, Chapel Hill, NC 27599-7041, USA.
| |
Collapse
|
32
|
Fialová S, Augustin M, Fischak C, Schmetterer L, Handschuh S, Glösmann M, Pircher M, Hitzenberger CK, Baumann B. Posterior rat eye during acute intraocular pressure elevation studied using polarization sensitive optical coherence tomography. BIOMEDICAL OPTICS EXPRESS 2017; 8:298-314. [PMID: 28101419 PMCID: PMC5231300 DOI: 10.1364/boe.8.000298] [Citation(s) in RCA: 5] [Impact Index Per Article: 0.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Received: 10/04/2016] [Revised: 12/01/2016] [Accepted: 12/12/2016] [Indexed: 05/05/2023]
Abstract
Polarization sensitive optical coherence tomography (PS-OCT) operating at 840 nm with axial resolution of 3.8 µm in tissue was used for investigating the posterior rat eye during an acute intraocular pressure (IOP) increase experiment. IOP was elevated in the eyes of anesthetized Sprague Dawley rats by cannulation of the anterior chamber. Three dimensional PS-OCT data sets were acquired at IOP levels between 14 mmHg and 105 mmHg. Maps of scleral birefringence, retinal nerve fiber layer (RNFL) retardation and relative RNFL/retina reflectivity were generated in the peripapillary area and quantitatively analyzed. All investigated parameters showed a substantial correlation with IOP. In the low IOP range of 14-45 mmHg only scleral birefringence showed statistically significant correlation. The polarization changes observed in the PS-OCT imaging study presented in this work suggest that birefringence of the sclera may be a promising IOP-related parameter to investigate.
Collapse
Affiliation(s)
- Stanislava Fialová
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Marco Augustin
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Corinna Fischak
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
- Department of Clinical Pharmacology, General Hospital and Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Leopold Schmetterer
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
- Department of Clinical Pharmacology, General Hospital and Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
- Singapore Eye Research Institute, The Academia, 20 College Road, Discovery Tower Level 6, 169856 Singapore, Republic of Singapore
- Lee Kong Chian School of Medicine, Nanyang Technological University, Novena Campus, 11 Mandalay Road, 308232 Singapore, Republic of Singapore
| | - Stephan Handschuh
- VetCore Facility for Research and Technology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210 Vienna, Austria
| | - Martin Glösmann
- VetCore Facility for Research and Technology, University of Veterinary Medicine Vienna, Veterinaerplatz 1, 1210 Vienna, Austria
| | - Michael Pircher
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Christoph K. Hitzenberger
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| | - Bernhard Baumann
- Center for Medical Physics and Biomedical Engineering, Medical University of Vienna, Waehringer Guertel 18-20, 1090 Vienna, Austria
| |
Collapse
|
33
|
Ho LC, Sigal IA, Jan NJ, Yang X, van der Merwe Y, Yu Y, Chau Y, Leung CK, Conner IP, Jin T, Wu EX, Kim SG, Wollstein G, Schuman JS, Chan KC. Non-invasive MRI Assessments of Tissue Microstructures and Macromolecules in the Eye upon Biomechanical or Biochemical Modulation. Sci Rep 2016; 6:32080. [PMID: 27561353 PMCID: PMC5000015 DOI: 10.1038/srep32080] [Citation(s) in RCA: 29] [Impact Index Per Article: 3.6] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/27/2016] [Accepted: 08/02/2016] [Indexed: 02/07/2023] Open
Abstract
The microstructural organization and composition of the corneoscleral shell (CSS) determine the biomechanical behavior of the eye, and are important in diseases such as glaucoma and myopia. However, limited techniques can assess these properties globally, non-invasively and quantitatively. In this study, we hypothesized that multi-modal magnetic resonance imaging (MRI) can reveal the effects of biomechanical or biochemical modulation on CSS. Upon intraocular pressure (IOP) elevation, CSS appeared hyperintense in both freshly prepared ovine eyes and living rat eyes using T2-weighted MRI. Quantitatively, transverse relaxation time (T2) of CSS increased non-linearly with IOP at 0-40 mmHg and remained longer than unloaded tissues after being unpressurized. IOP loading also increased fractional anisotropy of CSS in diffusion tensor MRI without apparent change in magnetization transfer MRI, suggestive of straightening of microstructural fibers without modification of macromolecular contents. Lastly, treatments with increasing glyceraldehyde (mimicking crosslinking conditions) and chondroitinase-ABC concentrations (mimicking glycosaminoglycan depletion) decreased diffusivities and increased magnetization transfer in cornea, whereas glyceraldehyde also increased magnetization transfer in sclera. In summary, we demonstrated the changing profiles of MRI contrast mechanisms resulting from biomechanical or biochemical modulation of the eye non-invasively. Multi-modal MRI may help evaluate the pathophysiological mechanisms in CSS and the efficacy of corneoscleral treatments.
Collapse
Affiliation(s)
- Leon C. Ho
- NeuroImaging Laboratory , University of Pittsburgh, Pittsburgh, PA, USA
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China
| | - Ian A. Sigal
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, PA, USA
| | - Ning-Jiun Jan
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - Xiaoling Yang
- NeuroImaging Laboratory , University of Pittsburgh, Pittsburgh, PA, USA
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
| | - Yolandi van der Merwe
- NeuroImaging Laboratory , University of Pittsburgh, Pittsburgh, PA, USA
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, PA, USA
| | - Yu Yu
- Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Hong Kong, China
| | - Ying Chau
- Department of Chemical and Biomolecular Engineering, Hong Kong University of Science and Technology, Hong Kong, China
- Division of Biomedical Engineering, Hong Kong University of Science and Technology, Hong Kong, China
| | - Christopher K. Leung
- University Eye Center, Hong Kong Eye Hospital, Hong Kong, China
- Department of Ophthalmology and Visual Sciences, The Chinese University of Hong Kong, Hong Kong, China
| | - Ian P. Conner
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, PA, USA
| | - Tao Jin
- NeuroImaging Laboratory , University of Pittsburgh, Pittsburgh, PA, USA
| | - Ed X. Wu
- Department of Electrical and Electronic Engineering, The University of Hong Kong, Hong Kong, China
| | - Seong-Gi Kim
- NeuroImaging Laboratory , University of Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, PA, USA
- Center for Neuroscience Imaging Research, Institute for Basic Science, Suwon, Korea
- Department of Biomedical Engineering, Sungkyunkwan University, Suwon, Korea
| | - Gadi Wollstein
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, PA, USA
| | - Joel S. Schuman
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, PA, USA
- Clinical and Translational Science Institute, University of Pittsburgh, Pittsburgh, PA, USA
| | - Kevin C. Chan
- NeuroImaging Laboratory , University of Pittsburgh, Pittsburgh, PA, USA
- UPMC Eye Center, Ophthalmology and Visual Science Research Center, Department of Ophthalmology, School of Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
- McGowan Institute for Regenerative Medicine, University of Pittsburgh, Pittsburgh, PA, USA
- Louis J. Fox Center for Vision Restoration, University of Pittsburgh, Pittsburgh, PA, USA
- Center for the Neural Basis of Cognition, University of Pittsburgh and Carnegie Mellon University, Pittsburgh, PA, USA
| |
Collapse
|
34
|
Voorhees AP, Grimm JL, Bilonick RA, Kagemann L, Ishikawa H, Schuman JS, Wollstein G, Sigal IA. What is a typical optic nerve head? Exp Eye Res 2016; 149:40-47. [PMID: 27339747 DOI: 10.1016/j.exer.2016.06.012] [Citation(s) in RCA: 9] [Impact Index Per Article: 1.1] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/27/2016] [Revised: 06/14/2016] [Accepted: 06/16/2016] [Indexed: 01/27/2023]
Abstract
Whereas it is known that elevated intraocular pressure (IOP) increases the risk of glaucoma, it is not known why optic nerve heads (ONHs) vary so much in sensitivity to IOP and how this sensitivity depends on the characteristics of the ONH such as tissue mechanical properties and geometry. It is often assumed that ONHs with uncommon or atypical sensitivity to IOP, high sensitivity in normal tension glaucoma or high robustness in ocular hypertension, also have atypical ONH characteristics. Here we address two specific questions quantitatively: Do atypical ONH characteristics necessarily lead to atypical biomechanical responses to elevated IOP? And, do typical biomechanical responses necessarily come from ONHs with typical characteristics. We generated 100,000 ONH numerical models with randomly selected values for the characteristics, all falling within literature ranges of normal ONHs. The models were solved to predict their biomechanical response to an increase in IOP. We classified ONH characteristics and biomechanical responses into typical or atypical using a percentile-based threshold, and calculated the fraction of ONHs for which the answers to the two questions were true and/or false. We then studied the effects of varying the percentile threshold. We found that when we classified the extreme 5% of individual ONH characteristics or responses as atypical, only 28% of ONHs with an atypical characteristic had an atypical response. Further, almost 29% of typical responses came from ONHs with at least one atypical characteristic. Thus, the answer to both questions is no. This answer held irrespective of the threshold for classifying typical or atypical. Our results challenge the assumption that ONHs with atypical sensitivity to IOP must have atypical characteristics. This finding suggests that the traditional approach of identifying risk factors by comparing characteristics between patient groups (e.g. ocular hypertensive vs. primary open angle glaucoma) may not be a sound strategy.
Collapse
Affiliation(s)
- A P Voorhees
- Department of Ophthalmology, UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - J L Grimm
- Department of Ophthalmology, UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - R A Bilonick
- Department of Ophthalmology, UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA
| | - L Kagemann
- Department of Ophthalmology, UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - H Ishikawa
- Department of Ophthalmology, UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - J S Schuman
- Department of Ophthalmology, UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; McGowan Institute for Regenerative Science, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA; Fox Center for Vision Restoration of UPMC and the University of Pittsburgh, Pittsburgh, PA, USA
| | - G Wollstein
- Department of Ophthalmology, UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - I A Sigal
- Department of Ophthalmology, UPMC Eye Center, Eye and Ear Institute, Ophthalmology and Visual Science Research Center, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; McGowan Institute for Regenerative Science, University of Pittsburgh School of Medicine, Pittsburgh, PA, USA; Department of Bioengineering, Swanson School of Engineering, University of Pittsburgh, Pittsburgh, PA, USA.
| |
Collapse
|
35
|
Boote C, Palko JR, Sorensen T, Mohammadvali A, Elsheikh A, Komáromy AM, Pan X, Liu J. Changes in posterior scleral collagen microstructure in canine eyes with an ADAMTS10 mutation. Mol Vis 2016; 22:503-17. [PMID: 27212875 PMCID: PMC4873561] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/05/2015] [Accepted: 05/15/2016] [Indexed: 11/25/2022] Open
Abstract
PURPOSE We aimed to characterize alterations in the posterior scleral collagen microstructure before detectable disease onset in a canine model of open-angle glaucoma caused by an ADAMTS10 mutation. METHODS Collagen orientation, anisotropy degree (proportion of preferentially aligned collagen), and relative density were measured at 0.4 mm spatial resolution using synchrotron wide-angle X-ray scattering. For statistical evaluation of structure parameters, regional averages of the peripapillary and mid-posterior sclera were compared between ADAMTS10 mutant (affected) dogs (n = 3) and age-matched (carrier) controls (n = 3). RESULTS No marked differences in the general pattern of preferential collagen fibril orientation were noted between the control and affected dogs. The peripapillary sclera of all specimens featured strongly aligned circumferential collagen ringing the optic nerve head. Collagen anisotropy was significantly reduced in the mid-posterior sclera of the affected dogs (carrier: 0.27±0.11; affected: 0.24±0.10; p = 0.032) but was not statistically significantly different in the peripapillary sclera (carrier: 0.46±0.15; affected: 0.45±0.17; p = 0.68). Collagen density was statistically significantly reduced in the affected dogs for the mid-posterior sclera (carrier: 28.1±9.14; affected: 18.3±5.12; p<0.0001) and the peripapillary sclera (carrier: 34.6±9.34; affected: 21.1±6.97; p = 0.0002). CONCLUSIONS Significant alterations in the posterior scleral collagen microstructure are present before the onset of clinical glaucoma in ADAMTS10 mutant dogs. A reduction in fibrous collagen density is likely an important contributory factor in the previously reported mechanical weakening of the sclera in this model. Baseline scleral abnormalities have the potential to interact with intraocular pressure (IOP) elevations in determining the course of glaucoma progression in animal models of the disease, and potentially in human glaucoma.
Collapse
Affiliation(s)
- Craig Boote
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, UK
| | - Joel R. Palko
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH
| | - Thomas Sorensen
- Diamond Light Source, Harwell Science and Innovation Campus, Harwell, UK
| | | | - Ahmed Elsheikh
- School of Engineering, University of Liverpool, Liverpool, UK,NIHR Biomedical Research Centre for Ophthalmology, Moorfields Eye Hospital NHS Foundation Trust and UCL Institute of Ophthalmology, UK
| | - András M. Komáromy
- Department of Small Animal Clinical Sciences, Michigan State University, East Lansing, MI,Department of Clinical Studies, School of Veterinary Medicine, University of Pennsylvania, Philadelphia, PA
| | - Xueliang Pan
- Center for Biostatistics, Department of Biomedical Informatics, The Ohio State University, Columbus, OH
| | - Jun Liu
- Department of Biomedical Engineering, The Ohio State University, Columbus, OH
| |
Collapse
|
36
|
Nguyen TD, Ethier CR. Biomechanical assessment in models of glaucomatous optic neuropathy. Exp Eye Res 2015; 141:125-38. [PMID: 26115620 PMCID: PMC4628840 DOI: 10.1016/j.exer.2015.05.024] [Citation(s) in RCA: 23] [Impact Index Per Article: 2.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/04/2015] [Revised: 05/20/2015] [Accepted: 05/31/2015] [Indexed: 01/26/2023]
Abstract
The biomechanical environment within the eye is of interest in both the regulation of intraocular pressure and the loss of retinal ganglion cell axons in glaucomatous optic neuropathy. Unfortunately, this environment is complex and difficult to determine. Here we provide a brief introduction to basic concepts of mechanics (stress, strain, constitutive relationships) as applied to the eye, and then describe a variety of experimental and computational approaches used to study ocular biomechanics. These include finite element modeling, direct experimental measurements of tissue displacements using optical and other techniques, direct experimental measurement of tissue microstructure, and combinations thereof. Thanks to notable technical and conceptual advances in all of these areas, we are slowly gaining a better understanding of how tissue biomechanical properties in both the anterior and posterior segments may influence the development of, and risk for, glaucomatous optic neuropathy. Although many challenging research questions remain unanswered, the potential of this body of work is exciting; projects underway include the coupling of clinical imaging with biomechanical modeling to create new diagnostic tools, development of IOP control strategies based on improved understanding the mechanobiology of the outflow tract, and attempts to develop novel biomechanically-based therapeutic strategies for preservation of vision in glaucoma.
Collapse
Affiliation(s)
- Thao D Nguyen
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - C Ross Ethier
- Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, USA; Department of Mechanical Engineering, Georgia Institute of Technology, USA; Institute of Biosciences and Bioengineering, Georgia Institute of Technology, USA; Department of Ophthalmology, Emory University, USA.
| |
Collapse
|
37
|
Glaucoma-related Changes in the Mechanical Properties and Collagen Micro-architecture of the Human Sclera. PLoS One 2015; 10:e0131396. [PMID: 26161963 PMCID: PMC4498780 DOI: 10.1371/journal.pone.0131396] [Citation(s) in RCA: 66] [Impact Index Per Article: 7.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2015] [Accepted: 06/01/2015] [Indexed: 12/13/2022] Open
Abstract
Objective The biomechanical behavior of the sclera determines the level of mechanical insult from intraocular pressure to the axons and tissues of the optic nerve head, as is of interest in glaucoma. In this study, we measure the collagen fiber structure and the strain response, and estimate the material properties of glaucomatous and normal human donor scleras. Methods Twenty-two posterior scleras from normal and diagnosed glaucoma donors were obtained from an eyebank. Optic nerve cross-sections were graded to determine the presence of axon loss. The specimens were subjected to pressure-controlled inflation testing. Full-field displacement maps were measured by digital image correlation (DIC) and spatially differentiated to compute surface strains. Maps of the collagen fiber structure across the posterior sclera of each inflated specimen were obtained using synchrotron wide-angle X-ray scattering (WAXS). Finite element (FE) models of the posterior scleras, incorporating a specimen-specific representation of the collagen structure, were constructed from the DIC-measured geometry. An inverse finite element analysis was developed to estimate the stiffness of the collagen fiber and inter-fiber matrix. Results The differences between glaucoma and non-glaucoma eyes were small in magnitude. Sectorial variations of degree of fiber alignment and peripapillary scleral strain significantly differed between normal and diagnosed glaucoma specimens. Meridional strains were on average larger in diagnosed glaucoma eyes compared with normal specimens. Non-glaucoma specimens had on average the lowest matrix and fiber stiffness, followed by undamaged glaucoma eyes, and damaged glaucoma eyes but the differences in stiffness were not significant. Conclusion The observed biomechanical and microstructural changes could be the result of tissue remodeling occuring in glaucoma and are likely to alter the mechanical environment of the optic nerve head and contribute to axonal damage.
Collapse
|
38
|
Quigley HA. The contribution of the sclera and lamina cribrosa to the pathogenesis of glaucoma: Diagnostic and treatment implications. PROGRESS IN BRAIN RESEARCH 2015; 220:59-86. [PMID: 26497785 DOI: 10.1016/bs.pbr.2015.04.003] [Citation(s) in RCA: 41] [Impact Index Per Article: 4.6] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 12/23/2022]
Abstract
Glaucoma, the second most common cause of world blindness, results from loss of retinal ganglion cells (RGC). RGC die as a consequence of injury to their axons, as they pass through the transition between the environment within the eye and that of the retrobulbar optic nerve, as they course to central visual centers. At the optic nerve head (ONH), axonal transport becomes abnormal, at least in part due to the effect of strain induced by intraocular pressure (IOP) on the sclera and ONH. Animal glaucoma models provide the ability to study how alterations in ocular connective tissues affect this pathological process. New therapeutic interventions are being investigated to mitigate glaucoma blindness by modifying the remodeling of ocular tissues in glaucoma. Some genetically altered mice are resistant to glaucoma damage, while treatment of the sclera with cross-linking agents makes experimental mouse glaucoma damage worse. Inhibition of transforming growth factor β activity is strikingly protective. Treatments that alter the response of ocular connective tissues to IOP may be effective in protecting those with glaucoma from vision loss.
Collapse
Affiliation(s)
- Harry A Quigley
- Glaucoma Center of Excellence, Wilmer Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
| |
Collapse
|
39
|
Borrás T, Smith MH, Buie LK. A Novel Mgp-Cre Knock-In Mouse Reveals an Anticalcification/Antistiffness Candidate Gene in the Trabecular Meshwork and Peripapillary Scleral Region. Invest Ophthalmol Vis Sci 2015; 56:2203-14. [PMID: 25711639 PMCID: PMC4406033 DOI: 10.1167/iovs.15-16460] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/15/2015] [Accepted: 02/14/2015] [Indexed: 11/24/2022] Open
Abstract
PURPOSE Soft tissue calcification is a pathological condition. Matrix Gla (MGP) is a potent mineralization inhibitor secreted by cartilage chondrocytes and arteries' vascular smooth muscle cells. Mgp knock-out mice die at 6 weeks due to massive arterial calcification. Arterial calcification results in arterial stiffness and higher systolic blood pressure. Intriguingly, MGP was highly abundant in trabecular meshwork (TM). Because tissue stiffness is relevant to glaucoma, we investigated which additional eye tissues use Mgp's function using knock-in mice. METHODS An Mgp-Cre-recombinase coding sequence (Cre) knock-in mouse, containing Mgp DNA plus an internal ribosomal entry site (IRES)-Cre-cassette was generated by homologous recombination. Founders were crossed with Cre-mediated reporter mouse R26R-lacZ. Their offspring expresses lacZ where Mgp is transcribed. Eyes from MgpCre/+;R26RlacZ/+ (Mgp-lacZ knock-in) and controls, 1 to 8 months were assayed for β-gal enzyme histochemistry. RESULTS As expected, Mgp-lacZ knock-in's TM was intensely blue. In addition, this mouse revealed high specific expression in the sclera, particularly in the peripapillary scleral region (ppSC). Ciliary muscle and sclera above the TM were also positive. Scleral staining was located immediately underneath the choroid (chondrocyte layer), began midsclera and was remarkably high in the ppSC. Cornea, iris, lens, ciliary body, and retina were negative. All mice exhibited similar staining patterns. All controls were negative. CONCLUSIONS Matrix Gla's restricted expression to glaucoma-associated tissues from anterior and posterior segments suggests its involvement in the development of the disease. Matrix Gla's anticalcification/antistiffness properties in the vascular tissue, together with its high TM and ppCS expression, place this gene as a strong candidate for TM's softness and sclera's stiffness regulation in glaucoma.
Collapse
Affiliation(s)
- Teresa Borrás
- Department of Ophthalmology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States
| | - Matthew H. Smith
- Department of Ophthalmology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States
| | - LaKisha K. Buie
- Department of Ophthalmology, University of North Carolina School of Medicine, Chapel Hill, North Carolina, United States
| |
Collapse
|