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Czerpak CA, Quigley HA, Nguyen TD. Long-term Remodeling Response in the Lamina Cribrosa Years after Intraocular Pressure Lowering by Suturelysis after Trabeculectomy. Ophthalmol Glaucoma 2024; 7:298-307. [PMID: 38272391 PMCID: PMC11127792 DOI: 10.1016/j.ogla.2024.01.003] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/02/2023] [Revised: 11/15/2023] [Accepted: 01/17/2024] [Indexed: 01/27/2024]
Abstract
OBJECTIVE To measure the remodeling of the lamina cribrosa (LC) years after intraocular pressure (IOP) lowering by suturelysis. DESIGN Cohort study. PARTICIPANTS Glaucoma patients were imaged 20 minutes after laser suturelysis after trabeculectomy surgery and at their follow-up appointment 1 to 4 years later (16 image pairs; 15 persons). INTERVENTION Noninvasive OCT imaging of the eye. MAIN OUTCOME MEASURES Deformation calculated by correlating OCT scans of the LC immediately after IOP lowering by suturelysis and those acquired years later (defined as remodeling strain). RESULTS The LC anterior border moved 60.9 ± 54.6 μm into the eye (P = 0.0007), and the LC exhibited regions of large local stretch in the anterior-posterior direction on long-term, maintained IOP lowering, resulting in a mean anterior-posterior remodeling strain of 14.0% ± 21.3% (P = 0.02). This strain and the LC border movement was 14 times and 124 times larger, respectively, than the direct response to IOP lowering by suturelysis. A larger anterior LC border movement was associated with greater mean anterior-posterior remodeling strain (P = 0.004). A thinner retinal nerve fiber layer at suturelysis was also associated with greater mean anterior-posterior remodeling strain at follow-up (P = 0.05). Worsening visual field indexes during follow-up were associated with a greater mean circumferential remodeling strain (P = 0.02), due to regions of large local circumferential stretch of the LC. Eyes with a more compliant LC torsional shear strain response at lysis were associated with worse mean deviation at follow-up (P = 0.03). CONCLUSIONS Strains and LC border position changes measured years after IOP lowering are far larger than the immediate response to IOP lowering and indicate dramatic remodeling of the LC anatomical structure caused by IOP lowering and glaucoma progression. The remodeling strains indicate substantial local stretch in the anterior-posterior direction and are associated with movement of the LC anterior border into the eye. Eyes with greater direct strain response to IOP lowering, greater glaucoma damage at suturelysis, and greater worsening of visual field at follow-up experienced greater remodeling. TRIAL REGISTRATION ClinicalTrials.gov Identifier: NCT03267849. FINANCIAL DISCLOSURE(S) Proprietary or commercial disclosure may be found in the Footnotes and Disclosures at the end of this article.
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Affiliation(s)
- Cameron A Czerpak
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland.
| | - Harry A Quigley
- Wilmer Ophthalmological Institute, School of Medicine, The Johns Hopkins University, Baltimore, Maryland
| | - Thao D Nguyen
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland; Wilmer Ophthalmological Institute, School of Medicine, The Johns Hopkins University, Baltimore, Maryland
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Claudel H, Bastelica P, Hamard P, Labbé A, Baudouin C. [Biomechanics of the lamina cribrosa: A determining factor in glaucomatous neuropathy. A review of the literature]. J Fr Ophtalmol 2023; 46:1087-1098. [PMID: 37827943 DOI: 10.1016/j.jfo.2023.05.026] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/12/2023] [Revised: 04/27/2023] [Accepted: 05/09/2023] [Indexed: 10/14/2023]
Abstract
Glaucoma is a chronic optic neuropathy characterized by progressive sclero-laminar remodeling. The main factor at the origin of these deformations is the intraocular pressure (IOP), the effect of which varies according to the biomechanical properties of the individual lamina cribrosa (LC). In this environment, the LC represents a malleable zone of weakness within a rigid corneoscleral shell. It is a dynamic structure whose movements play a key role in the pathogenesis of glaucoma: displacing it posteriorly, in addition to contributing to the characteristic appearance of glaucomatous cupping, would increase constriction on the nerve fibers and the laminar capillaries. Often incorrectly considered permanent in adults, these deformations have a certain degree of reversibility, which is currently better characterized thanks to progress in imaging techniques. The occurrence of anterior displacement and laminar thickening following a reduction in IOP could thus constitute a good prognostic factor by reducing mechanical stress on this region. These changes would tend to reduce laminar pore tortuosity and shear forces, which are probably key mechanisms of axonal loss in glaucoma.
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Affiliation(s)
- H Claudel
- Service 3, centre hospitalier national d'ophtalmologie des Quinze-Vingts, IHU FOReSIGHT, 28, rue de Charenton, 75012 Paris, France.
| | - P Bastelica
- Service 3, centre hospitalier national d'ophtalmologie des Quinze-Vingts, IHU FOReSIGHT, 28, rue de Charenton, 75012 Paris, France
| | - P Hamard
- Service 3, centre hospitalier national d'ophtalmologie des Quinze-Vingts, IHU FOReSIGHT, 28, rue de Charenton, 75012 Paris, France
| | - A Labbé
- Service 3, centre hospitalier national d'ophtalmologie des Quinze-Vingts, IHU FOReSIGHT, 28, rue de Charenton, 75012 Paris, France; Institut de la vision, IHU FOReSIGHT, Sorbonne université, 17, rue Moreau, 75012 Paris, France; Hôpital Ambroise-Paré, AP-HP, université de Versailles Saint-Quentin-en-Yvelines, 9, avenue Charles-De-Gaulle, 92100 Boulogne Billancourt, France; Direction de l'hospitalisation et des soins, Inserm, centre d'investigation clinique 1423, centre hospitalier national d'ophtalmologie des Quinze-Vingts, IHU FOReSIGHT, 28, rue de Charenton, 75012 Paris, France
| | - C Baudouin
- Service 3, centre hospitalier national d'ophtalmologie des Quinze-Vingts, IHU FOReSIGHT, 28, rue de Charenton, 75012 Paris, France; Institut de la vision, IHU FOReSIGHT, Sorbonne université, 17, rue Moreau, 75012 Paris, France; Hôpital Ambroise-Paré, AP-HP, université de Versailles Saint-Quentin-en-Yvelines, 9, avenue Charles-De-Gaulle, 92100 Boulogne Billancourt, France; Direction de l'hospitalisation et des soins, Inserm, centre d'investigation clinique 1423, centre hospitalier national d'ophtalmologie des Quinze-Vingts, IHU FOReSIGHT, 28, rue de Charenton, 75012 Paris, France
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Kwok S, Ma Y, Pan X, Liu J. Three-Dimensional Ultrasound Elastography Detects Age-Related Increase in Anterior Peripapillary Sclera and Optic Nerve Head Compression During IOP Elevation. Invest Ophthalmol Vis Sci 2023; 64:16. [PMID: 37289169 PMCID: PMC10257341 DOI: 10.1167/iovs.64.7.16] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/01/2023] [Accepted: 05/18/2023] [Indexed: 06/09/2023] Open
Abstract
Purpose High-frequency ultrasound elastography offers a tool to resolve the complex and heterogeneous deformation through the full thickness of the optic nerve head (ONH) and peripapillary sclera (PPS). Using this tool, we quantified the three-dimensional deformation of the ONH and PPS in human donor eyes and evaluated age-associated changes. Methods The ONH and PPS in 15 human donor globes were imaged with a 50-MHz ultrasound probe while increasing intraocular pressure (IOP) from 15 to 30 mm Hg. Tissue displacements were obtained using correlation-based ultrasound speckle tracking. Three-dimensional spherical strains (radial, circumferential, meridional, and respective shear strains) were calculated for the ONH and PPS volumes segmented from three-dimensional ultrasound images. Age-related trends of different strains in each region of interest were explored. Results The dominant form of IOP-induced deformation in the ONH and PPS was radial compression. High-magnitude localized out-of-plane shear strains were also observed in both regions. Most strains were concentrated in the anterior one-half of the ONH and PPS. The magnitude of radial and volumetric strains increased with age in the anterior ONH and anterior PPS, indicating greater radial compression and volume loss during IOP elevation in older age. Conclusions The age-associated increase of radial compression, the predominant form of IOP-induced deformation in anterior ONH and PPS, may underlie age-associated glaucoma risk. High-frequency ultrasound elastography offers a useful tool to quantify all types of deformation comprehensively in all regions of ONH and PPS, which may improve our understanding of the biomechanical factors contributing to glaucoma risk.
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Affiliation(s)
- Sunny Kwok
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, United States
| | - Yanhui Ma
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, United States
- Department of Ophthalmology and Visual Sciences, The Ohio State University, Columbus, Ohio, United States
| | - Xueliang Pan
- Department of Biomedical Informatics, The Ohio State University, Columbus, Ohio, United States
| | - Jun Liu
- Department of Biomedical Engineering, The Ohio State University, Columbus, Ohio, United States
- Department of Ophthalmology and Visual Sciences, The Ohio State University, Columbus, Ohio, United States
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Czerpak CA, Kashaf MS, Zimmerman BK, Quigley HA, Nguyen TD. The Strain Response to Intraocular Pressure Decrease in the Lamina Cribrosa of Patients with Glaucoma. Ophthalmol Glaucoma 2023; 6:11-22. [PMID: 35863747 PMCID: PMC9849479 DOI: 10.1016/j.ogla.2022.07.005] [Citation(s) in RCA: 5] [Impact Index Per Article: 5.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/17/2022] [Revised: 07/11/2022] [Accepted: 07/12/2022] [Indexed: 01/27/2023]
Abstract
OBJECTIVE To measure biomechanical strains in the lamina cribrosa (LC) of living human eyes with intraocular pressure (IOP) lowering. DESIGN Cohort study. PARTICIPANTS Patients with glaucoma underwent imaging before and after laser suturelysis after trabeculectomy surgery (29 image pairs; 26 persons). INTERVENTION Noninvasive imaging of the eye. MAIN OUTCOME MEASURES Strains in optic nerve head tissue and changes in depths of the anterior border of the LC. RESULTS Intraocular pressure decreases caused the LC to expand in thickness in the anterior-posterior strain (Ezz = 0.94 ± 1.2%; P = 0.00020) and contract in radius in the radial strain (Err = - 0.19 ± 0.33%; P = 0.0043). The mean LC depth did not significantly change with IOP lowering (1.33 ± 6.26 μm; P = 0.26). A larger IOP decrease produced a larger, more tensile Ezz (P < 0.0001), greater maximum principal strain (Emax; P < 0.0001), and greater maximum shear strain (Γmax; P < 0.0001). The average LC depth change was associated with the Γmax and radial-circumferential shear strain (Erθ; P < 0.02) but was not significantly related to tensile or compressive strains. An analysis by clock hour showed that in temporal clock hours 3 to 6, a more anterior LC movement was associated with a more positive Emax, and in clock hours 3, 5, and 6, it was associated with a more positive Γmax. At 10 o'clock, a more posterior LC movement was related to a more positive Emax (P < 0.004). Greater compliance (strain/ΔIOP) of Emax (P = 0.044), Γmax (P = 0.052), and Erθ (P = 0.018) was associated with a thinner retinal nerve fiber layer. Greater compliance of Emax (P = 0.041), Γmax (P = 0.021), Erθ (P = 0.024), and in-plane shear strain (Erz; P = 0.0069) was associated with more negative mean deviations. Greater compliance of Γmax (P = 0.055), Erθ (P = 0.040), and Erz (P = 0.015) was associated with lower visual field indices. CONCLUSIONS With IOP lowering, the LC moves either into or out of the eye but, on average, expands in thickness and contracts in radius. Shear strains are nearly as substantial as in-plane strains. Biomechanical strains are more compliant in eyes with greater glaucoma damage. This work was registered at ClinicalTrials.gov as NCT03267849.
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Affiliation(s)
- Cameron A Czerpak
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland.
| | - Michael Saheb Kashaf
- Wilmer Ophthalmological Institute, School of Medicine, The Johns Hopkins University, Baltimore, Maryland
| | - Brandon K Zimmerman
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland
| | - Harry A Quigley
- Wilmer Ophthalmological Institute, School of Medicine, The Johns Hopkins University, Baltimore, Maryland
| | - Thao D Nguyen
- Department of Mechanical Engineering, The Johns Hopkins University, Baltimore, Maryland; Wilmer Ophthalmological Institute, School of Medicine, The Johns Hopkins University, Baltimore, Maryland
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Ramm L, Herber R, Lorenz G, Jasper CS, Pillunat LE, Pillunat KR. Evaluation of corneal biomechanical properties using the ocular response analyzer and the dynamic Scheimpflug-Analyzer Corvis ST in high pressure and normal pressure open-angle glaucoma patients. PLoS One 2023; 18:e0281017. [PMID: 36701409 PMCID: PMC9879466 DOI: 10.1371/journal.pone.0281017] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/25/2022] [Accepted: 01/12/2023] [Indexed: 01/27/2023] Open
Abstract
PURPOSE To characterize differences in corneal biomechanics in high (HPG) and normal pressure (NPG) primary open-angle glaucoma, and its association to disease severity. METHODS Corneal biomechanical properties were measured using the Ocular Response Analyzer (ORA) and the dynamic Scheimpflug-Analyzer Corvis ST (CST). Disease severity was functionally assessed by automated perimetry (Humphrey field analyzer) and structurally with the Heidelberg Retina Tomograph. To avoid a possible falsification by intraocular pressure, central corneal thickness and age, which strongly influence ORA and CST measurements, group matching was performed. Linear mixed models and generalized estimating equations were used to consider inter-eye correlation. RESULTS Following group matching, 60 eyes of 38 HPG and 103 eyes of 60 NPG patients were included. ORA measurement revealed a higher CRF in HPG than in NPG (P < 0.001). Additionally, the CST parameter integrated radius (P < 0.001) was significantly different between HPG and NPG. The parameter SSI (P < 0.001) representing corneal stiffness was higher in HPG than in NPG. Furthermore, regression analysis revealed associations between biomechanical parameters and indicators of disease severity. In HPG, SSI correlated to RNFL thickness. In NPG, dependencies between biomechanical readings and rim area, MD, and PSD were shown. CONCLUSION Significant differences in corneal biomechanical properties were detectable between HPG and NPG patients which might indicate different pathophysiological mechanisms underlying in both entities. Moreover, biomechanical parameters correlated to functional and structural indices of diseases severity. A reduced corneal deformation measured by dynamic methods was associated to advanced glaucomatous damage.
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Affiliation(s)
- Lisa Ramm
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Robert Herber
- Faculty of Medicine Carl Gustav Carus, Department of Ophthalmology, TU Dresden, Dresden, Germany
- * E-mail:
| | - Georg Lorenz
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Carolin S. Jasper
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Lutz E. Pillunat
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
| | - Karin R. Pillunat
- Department of Ophthalmology, University Hospital Carl Gustav Carus, TU Dresden, Dresden, Germany
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Guan C, Pease ME, Quillen S, Ling YTT, Li X, Kimball E, Johnson TV, Nguyen TD, Quigley HA. Quantitative Microstructural Analysis of Cellular and Tissue Remodeling in Human Glaucoma Optic Nerve Head. Invest Ophthalmol Vis Sci 2022; 63:18. [PMID: 36269186 PMCID: PMC9617510 DOI: 10.1167/iovs.63.11.18] [Citation(s) in RCA: 4] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/15/2022] [Accepted: 09/23/2022] [Indexed: 12/02/2022] Open
Abstract
Purpose To measure quantitatively changes in lamina cribrosa (LC) cell and connective tissue structure in human glaucoma eyes. Methods We studied 27 glaucoma and 19 age-matched non-glaucoma postmortem eyes. In 25 eyes, LC cross-sections were examined by confocal and multiphoton microscopy to quantify structures identified by anti-glial fibrillary acidic protein (GFAP), phalloidin-labeled F-actin, nuclear 4',6-diamidino-2-phenylindole (DAPI), and by second harmonic generation imaging of LC beams. Additional light and transmission electron microscopy were performed in 21 eyes to confirm features of LC remodeling, including immunolabeling by anti-SOX9 and anti-collagen IV. All glaucoma eyes had detailed clinical histories of open-angle glaucoma status, and degree of axon loss was quantified in retrolaminar optic nerve cross-sections. Results Within LC pores, the proportionate area of both GFAP and F-actin processes was significantly lower in glaucoma eyes than in controls (P = 0.01). Nuclei were rounder (lower median aspect ratio) in glaucoma specimens (P = 0.02). In models assessing degree of glaucoma damage, F-actin process width was significantly wider in glaucoma eyes with more damage (P = 0.024), average LC beam width decreased with worse glaucoma damage (P = 0.042), and nuclear count per square millimeter rose with worse damage (P = 0.019). The greater cell count in LC pores represented 92.3% astrocytes by SOX9 labeling. The results are consistent with replacement of axons in LC pores by basement membrane labeled by anti-collagen IV and in-migrating astrocytes. Conclusions Alteration in LC structure in glaucoma involves migration of astrocytes into axonal bundles, change in astrocyte orientation and processes, production of basement membrane material, and thinning of connective tissue beams.
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Affiliation(s)
- Carolyn Guan
- Wilmer Ophthalmological Institute, School of Medicine, The Johns Hopkins University, Baltimore, Maryland, United States
| | - Mary Ellen Pease
- Wilmer Ophthalmological Institute, School of Medicine, The Johns Hopkins University, Baltimore, Maryland, United States
| | - Sarah Quillen
- Wilmer Ophthalmological Institute, School of Medicine, The Johns Hopkins University, Baltimore, Maryland, United States
| | - Yik Tung Tracy Ling
- Departments of Mechanical Engineering and Materials Science & Engineering, The Johns Hopkins University, Baltimore, Maryland, United States
| | - Ximin Li
- Department of Biostatistics, The Bloomberg School of Public Health, The Johns Hopkins University, Baltimore, Maryland, United States
| | - Elizabeth Kimball
- Wilmer Ophthalmological Institute, School of Medicine, The Johns Hopkins University, Baltimore, Maryland, United States
| | - Thomas V. Johnson
- Wilmer Ophthalmological Institute, School of Medicine, The Johns Hopkins University, Baltimore, Maryland, United States
| | - Thao D. Nguyen
- Wilmer Ophthalmological Institute, School of Medicine, The Johns Hopkins University, Baltimore, Maryland, United States
- Departments of Mechanical Engineering and Materials Science & Engineering, The Johns Hopkins University, Baltimore, Maryland, United States
| | - Harry A. Quigley
- Wilmer Ophthalmological Institute, School of Medicine, The Johns Hopkins University, Baltimore, Maryland, United States
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Dillinger AE, Weber GR, Mayer M, Schneider M, Göppner C, Ohlmann A, Shamonin M, Monkman GJ, Fuchshofer R. CCN2/CTGF—A Modulator of the Optic Nerve Head Astrocyte. Front Cell Dev Biol 2022; 10:864433. [PMID: 35493079 PMCID: PMC9047870 DOI: 10.3389/fcell.2022.864433] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/28/2022] [Accepted: 03/18/2022] [Indexed: 12/14/2022] Open
Abstract
In primary open-angle glaucoma (POAG), a neurodegenerative disease of the optic nerve (ON) and leading cause of blindness, the optic nerve head (ONH) undergoes marked structural extracellular matrix (ECM) changes, which contribute to its permanent deformation and to degeneration of ON axons. The remodeling process of the ECM causes changes in the biomechanical properties of the ONH and the peripapillary sclera, which is accompanied by an increased reactivity of the resident astrocytes. The molecular factors involved in the remodeling process belong to the Transforming growth factor (TGF)-β superfamily, especially TGF-β2. In previous publications we showed that TGF-β2 induced ECM alterations are mediated by Cellular Communication Network Factor (CCN)2/Connective Tissue Growth Factor (CTGF) and recently we showed that CCN2/CTGF is expressed by astrocytes of the ON under normal conditions. In this study we wanted to get a better understanding of the function of CCN2/CTGF under normal and pathologic conditions. To this end, we analyzed the glial lamina and peripapillary sclera of CCN2/CTGF overexpressing mice and studied the effect of CCN2/CTGF and increasing substratum stiffness on murine ON astrocytes in vitro. We observed enhanced astrocyte reactivity in the ONH, increased ECM protein synthesis in the peripapillary sclera and increased Ccn2/Ctgf expression in the ONH during the pathologic development in situ. CCN2/CTGF treatment of primary murine ON astrocytes induced a higher migration rate, and increase of ECM proteins including fibronectin, elastin and collagen type III. Furthermore, the astrocytes responded to stiffer substratum with increased glial fibrillary acidic protein, vimentin, actin and CCN2/CTGF synthesis. Finally, we observed the reinforced appearance of CCN2/CTGF in the lamina cribrosa of glaucomatous patients. We conclude that reactive changes in ONH astrocytes, induced by the altered biomechanical characteristics of the region, give rise to a self-amplifying process that includes increased TGF-β2/CCN2/CTGF signaling and leads to the synthesis of ECM molecules and cytoskeleton proteins, a process that in turn augments the stiffness at the ONH. Such a scenario may finally result in a vicious circle in the pathogenesis of POAG. The transgenic CTGF-overexpressing mouse model might be an optimal model to study the chronic pathological POAG changes in the ONH.
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Affiliation(s)
- Andrea E. Dillinger
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
| | - Gregor R. Weber
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
| | - Matthias Mayer
- Faculty of Electrical Engineering and Information Technology, Ostbayerische Technische Hochschule Regensburg, Regensburg, Germany
| | - Magdalena Schneider
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
| | - Corinna Göppner
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
| | - Andreas Ohlmann
- Department of Ophthalmology, University Hospital, Ludwig-Maximilians-University Munich, Munich, Germany
| | - Mikhail Shamonin
- Faculty of Electrical Engineering and Information Technology, Ostbayerische Technische Hochschule Regensburg, Regensburg, Germany
| | - Gareth J. Monkman
- Faculty of Electrical Engineering and Information Technology, Ostbayerische Technische Hochschule Regensburg, Regensburg, Germany
| | - Rudolf Fuchshofer
- Institute of Human Anatomy and Embryology, University of Regensburg, Regensburg, Germany
- *Correspondence: Rudolf Fuchshofer,
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Abstract
PURPOSE OF REVIEW Biomechanics is an important aspect of the complex family of diseases known as the glaucomas. Here, we review recent studies of biomechanics in glaucoma. RECENT FINDINGS Several tissues have direct and/or indirect biomechanical roles in various forms of glaucoma, including the trabecular meshwork, cornea, peripapillary sclera, optic nerve head/sheath, and iris. Multiple mechanosensory mechanisms and signaling pathways continue to be identified in both the trabecular meshwork and optic nerve head. Further, the recent literature describes a variety of approaches for investigating the role of tissue biomechanics as a risk factor for glaucoma, including pathological stiffening of the trabecular meshwork, peripapillary scleral structural changes, and remodeling of the optic nerve head. Finally, there have been advances in incorporating biomechanical information in glaucoma prognoses, including corneal biomechanical parameters and iridial mechanical properties in angle-closure glaucoma. SUMMARY Biomechanics remains an active aspect of glaucoma research, with activity in both basic science and clinical translation. However, the role of biomechanics in glaucoma remains incompletely understood. Therefore, further studies are indicated to identify novel therapeutic approaches that leverage biomechanics. Importantly, clinical translation of appropriate assays of tissue biomechanical properties in glaucoma is also needed.
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Affiliation(s)
- Babak N. Safa
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta GA, USA
| | - Cydney A. Wong
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta GA, USA
| | - Jungmin Ha
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta GA, USA
| | - C. Ross Ethier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta GA, USA
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Park SA, Komáromy AM. Biomechanics of the optic nerve head and sclera in canine glaucoma: A brief review. Vet Ophthalmol 2021; 24:316-325. [PMID: 34402566 DOI: 10.1111/vop.12923] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/18/2020] [Revised: 06/04/2021] [Accepted: 07/25/2021] [Indexed: 01/17/2023]
Abstract
Glaucoma is a leading cause of irreversible blindness, a progressive optic neuropathy with retinal ganglion cell (RGC) death beginning in the optic nerve head (ONH). A primary risk factor for developing glaucoma is elevated intraocular pressure (IOP). Reducing IOP is the only treatment proven to be effective at delaying disease progression. Nevertheless, even when patients have their IOP reduced, the majority of them continue to lose vision. There are, in both humans and dogs, significant interindividual variabilities in susceptibilities to IOP-induced optic nerve damage. Vision loss progresses much more slowly in Beagles with open-angle glaucoma (OAG) caused by ADAMTS10 mutation. This can be attributed to the mutation-related altered ocular biomechanical properties. The principal site of optic nerve (ON) damage in glaucoma is the ONH. It is suggested that the biomechanical properties of the ONH and the surrounding peripapillary sclera (PPS) contribute to glaucoma development and progression. As far as the beneficial biomechanical properties of the ONH and PPS for a decreased susceptibility and slow progression of glaucoma, data are inconsistent and conflicting. Recent biomechanical studies on beagles with ADAMTS10 mutation demonstrated that the mutant dogs have mechanically weak posterior sclera. This weakness was associated with a reduced collagen density and a lower proportion of insoluble collagen. These changes, observed before glaucoma development, were considered intrinsic characteristics caused by the mutation rather than a secondary effect of IOP elevation. Further studies of ADAMTS10-OAG may elucidate the effects of altered biomechanical properties of ONH and PPS in determining the glaucoma progression.
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Affiliation(s)
- Shin Ae Park
- Department of Veterinary Clinical Sciences, College of Veterinary Medicine, Purdue University, West Lafayette, Indiana, USA
| | - András M Komáromy
- Department of Small Animal Clinical Sciences, College of Veterinary Medicine, Michigan State University, East Lansing, Michigan, USA
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Changes in ocular morphology after cataract surgery in open angle glaucoma patients. Sci Rep 2021; 11:12203. [PMID: 34108591 PMCID: PMC8190274 DOI: 10.1038/s41598-021-91740-z] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2020] [Accepted: 05/28/2021] [Indexed: 02/05/2023] Open
Abstract
The purpose of this study was to evaluate intraocular pressure (IOP) pre- and postoperatively, together with anterior chamber angle (ACA) parameters and biometrical results in cataract patients with or without open angle glaucoma (OAG). The prospective observational case-control study included 15 eyes with cataract and OAG in the glaucoma group and 25 eyes with only cataract in control group. Examination included full ophthalmic evaluation, IOP, ocular biometry and anterior segment optical coherence tomography measuring ACA pre- and 6 months postoperatively. OAG patients had a larger absolute IOP reduction compared to control group. Anterior chamber depth (ACD) and ACA width significantly increased in both groups. The OAG group had a tendency of narrower ACA preoperatively, but overall ACA parameters did not differ in either group pre- and postoperatively. The ACD change after surgery correlated with ACA parameters in the control group, but not in OAG group. Axial length was shorter postoperatively in the control group, but remained similar in the OAG group. Absolute IOP reduction was more pronounced in cataract patients with OAG than in cataract patients without glaucoma. ACD and ACA postoperatively increased in both groups and AL shortening was observed in non-OAG in cataract group.
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Girkin CA, Belghith A, Bowd C, Medeiros FA, Weinreb RN, Liebmann JM, Proudfoot JA, Zangwill LM, Fazio MA. Racial Differences in the Rate of Change in Anterior Lamina Cribrosa Surface Depth in the African Descent and Glaucoma Evaluation Study. Invest Ophthalmol Vis Sci 2021; 62:12. [PMID: 33844828 PMCID: PMC8039570 DOI: 10.1167/iovs.62.4.12] [Citation(s) in RCA: 4] [Impact Index Per Article: 1.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/24/2022] Open
Abstract
Purpose The purpose of this study was to determine if the rate of change in the depth of the surface of the lamina cribrosa due to glaucomatous remodeling differs between glaucoma patients of African descent (AD) and European descent (ED). Methods There were 1122 images taken longitudinally over an average of 3 years (range = 0.9-4.1 years) from 122 patients with glaucoma followed in the African Descent and Glaucoma Evaluation Study (ADAGES) and Diagnostic Intervention and Glaucoma Study (DIGS) were automatically segmented to compute anterior lamina cribrosa surface depth (ALCSD). The rate of ALCSD change was compared across racial groups after adjusting for baseline characteristics known to be associated with ALCSD or disease progression (visual field, ALCSD, corneal thickness, optic disk size, and age). Results After adjusting for all other covariates, the ED group had significantly greater ALCSD posterior migration (deepening) than the AD group (difference = 2.57 µm/year, P = 0.035). There was a wider range of ALCSD change in the ED compared with the AD group, and more individuals had greater magnitude of both deepening and shallowing. No other covariates measured at baseline had independent effects on the longitudinal changes in ALCSD (baseline visual field severity, baseline ALCSD, corneal thickness, Bruch's membrane opening [BMO] area, or age). Conclusions Glaucomatous remodeling of the lamina cribrosa differs between AD and ED patients with glaucoma. Unlike the cross-sectional associations seen with aging, in which a deeper ALCSD was seen with age in the ED group, glaucomatous remodeling in this longitudinal study resulted in more posterior migration of ALCSD in ED compared to AD patients.
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Affiliation(s)
- Christopher A Girkin
- Department of Ophthalmology and Visual Science, School of Medicine, The University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Akram Belghith
- Hamilton Glaucoma Center, Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, California, United States
| | - Christopher Bowd
- Hamilton Glaucoma Center, Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, California, United States
| | - Felipe A Medeiros
- Duke Eye Center and Department of Ophthalmology, Duke University, Durham, North Carolina, United States
| | - Robert N Weinreb
- Hamilton Glaucoma Center, Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, California, United States
| | - Jeffrey M Liebmann
- Bernard and Shirlee Brown Glaucoma Research Laboratory, Edward S. Harkness Eye Institute, Columbia University Medical Center, New York, New York, United States
| | - James A Proudfoot
- Hamilton Glaucoma Center, Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, California, United States
| | - Linda M Zangwill
- Hamilton Glaucoma Center, Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, California, United States
| | - Massimo A Fazio
- Department of Ophthalmology and Visual Science, School of Medicine, The University of Alabama at Birmingham, Birmingham, Alabama, United States.,Hamilton Glaucoma Center, Shiley Eye Institute, Viterbi Family Department of Ophthalmology, University of California San Diego, La Jolla, California, United States.,Department of Biomedical Engineering, School of Engineering, The University of Alabama at Birmingham, Birmingham, Alabama, United States
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12
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Role of radially aligned scleral collagen fibers in optic nerve head biomechanics. Exp Eye Res 2020; 199:108188. [PMID: 32805265 DOI: 10.1016/j.exer.2020.108188] [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: 06/24/2020] [Revised: 07/22/2020] [Accepted: 08/06/2020] [Indexed: 01/04/2023]
Abstract
Collagen fibers organized circumferentially around the canal in the peripapillary sclera are thought to provide biomechanical support to the sensitive tissues within the optic nerve head (ONH). Recent studies have demonstrated the existence of a family of fibers in the innermost sclera organized radially from the scleral canal. Our goal was to determine the role of these radial fibers in the sensitivity of scleral canal biomechanics to acute increases in intraocular pressure (IOP). Following the same general approach of previous parametric sensitivity studies, we created nonlinear generic finite element models of a posterior pole with various combinations of radial and circumferential fibers at an IOP of 0 mmHg. We then simulated the effects of normal and elevated IOP levels (15 and 30 mmHg). We monitored four IOP-induced geometric changes: peripapillary sclera stretch, scleral canal displacement, lamina cribrosa displacement, and scleral canal expansion. In addition, we examined the radial (maximum tension) and through-thickness (maximum compression) strains within the ONH tissues. Our models predicted that: 1) radial fibers reduced the posterior displacement of the lamina, especially at elevated IOP; 2) radial fibers reduced IOP-induced radial strain within the peripapillary sclera and retinal tissue; and 3) a combination of radial and circumferential fibers maintained strains within the ONH at a level similar to those conferred by circumferential fibers alone. In conclusion, radial fibers provide support for the posterior globe, additional to that provided by circumferential fibers. Most importantly, a combination of both fiber families can better protect ONH tissues from excessive IOP-induced deformation than either alone.
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13
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Nakazawa T, Fukuchi T. What is glaucomatous optic neuropathy? Jpn J Ophthalmol 2020; 64:243-249. [PMID: 32394134 DOI: 10.1007/s10384-020-00736-1] [Citation(s) in RCA: 19] [Impact Index Per Article: 4.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/27/2019] [Accepted: 02/14/2020] [Indexed: 10/24/2022]
Abstract
Glaucomatous optic neuropathy (GON) is the pathohistological feature of glaucoma in the optic nerve. The pathogenesis of GON has been hypothesized, to either originate from compromised mechanical conditions at the lamina cribrosa or as associated with pathological vascular involvement. From a historical perspective, glaucoma is the degeneration of retinal ganglion cells (RGC) due to the elevation of intraocular pressure (IOP). The consensus of glaucoma treatment is generally accepted as sufficient IOP reduction. Is there an additional option to treat GON from the perspective of the vascular theory? In this section, two distinguished leaders in glaucoma research advance their views and discuss the current opinions surrounding the two theories regarding the causes of GON in primary open angle glaucoma (POAG) and normal tension glaucoma (NTG).
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Affiliation(s)
- Toru Nakazawa
- Department of Ophthalmology, Tohoku University Graduate School of Medicine, Sendai, Japan.
| | - Takeo Fukuchi
- Division of Opthalmology and Visual Science, Graduated School of Medical and Dental Sciences, Niigata University, Niigata, Japan.
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14
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Midgett DE, Jefferys JL, Quigley HA, Nguyen TD. The inflation response of the human lamina cribrosa and sclera: Analysis of deformation and interaction. Acta Biomater 2020; 106:225-241. [PMID: 32044458 PMCID: PMC8340454 DOI: 10.1016/j.actbio.2020.01.049] [Citation(s) in RCA: 26] [Impact Index Per Article: 6.5] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/21/2019] [Revised: 01/28/2020] [Accepted: 01/30/2020] [Indexed: 11/23/2022]
Abstract
This study investigated the inflation response of the lamina cribrosa (LC) and adjacent peripapillary sclera (PPS) in post-mortem human eyes with no history of glaucoma. The posterior sclera of 13 human eyes from 7 donors was subjected to controlled pressurization between 5-45 mmHg. A laser-scanning microscope (LSM) was used to image the second harmonic generation (SHG) response of collagen and the two-photon fluorescent (TPF) response of elastin within the volume of the LC and PPS at each pressure. Image volumes were analyzed using digital volume correlation (DVC) to calculate the three-dimensional (3D) deformation field between pressures. The LC exhibited larger radial strain, Err, and maximum principal strain, Emax, (p < 0.0001) and greater posterior displacement (p=0.0007) compared to the PPS between 5-45 mmHg, but had similar average circumferential strain, Eθθ, and maximum shear strain, Γmax. The Emax and Γmax were highest near the LC-PPS interface and lowest in the nasal quadrant of both tissues. Larger LC area was associated with smaller Emax in the peripheral LC and larger Emax in the central LC (p ≤ 0.01). The Emax, Γmax, and Eθθ in the inner PPS increased with increasing strain in adjacent LC regions (p ≤ 0.001). Smaller strains in the PPS were associated with a larger difference in the posterior displacement between the PPS and central LC (p < 0.0001 for Emax and Err), indicating that a stiffer pressure-strain response of the PPS is associated with greater posterior bowing of the LC. STATEMENT OF SIGNIFICANCE: Glaucoma causes vision loss through progressive damage of the retinal ganglion axons at the lamina cribrosa (LC), a connective tissue structure that supports the axons as they pass through the eye wall. It is hypothesized that strains caused by intraocular pressure may initiate this damage and that these strains are modulated by the combined deformation of the LC and adjacent peripapillary sclera (PPS). In this study we present a method to measure the pressure-induced 3D displacement and strain field in the LC and PPS simultaneously. Regional strain variation in the LC and PPS was investigated and compared and strains were analyzed for associations with age, LC area, LC strain magnitude, and LC posterior motion relative to the PPS.
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Affiliation(s)
- Dan E Midgett
- Department of Biomedical Engineering, Yale University, New Haven, CT 06520, USA.
| | - Joan L Jefferys
- Wilmer Ophthalmological Institute, School of Medicine, The Johns Hopkins University, Baltimore, MD 21287, USA
| | - Harry A Quigley
- Wilmer Ophthalmological Institute, School of Medicine, The Johns Hopkins University, Baltimore, MD 21287, USA
| | - 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.
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15
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Tun TA, Atalay E, Baskaran M, Nongpiur ME, Htoon HM, Goh D, Cheng CY, Perera SA, Aung T, Strouthidis NG, Girard MJA. Association of Functional Loss With the Biomechanical Response of the Optic Nerve Head to Acute Transient Intraocular Pressure Elevations. JAMA Ophthalmol 2019; 136:184-192. [PMID: 29302683 DOI: 10.1001/jamaophthalmol.2017.6111] [Citation(s) in RCA: 15] [Impact Index Per Article: 3.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/14/2022]
Abstract
Importance The acute biomechanical response of the optic nerve head (ONH) to intraocular pressure (IOP) elevations may serve as a biomarker for the development and progression of glaucoma. Objective To evaluate the association between visual field loss and the biomechanical response of the ONH to acute transient IOP elevations. Design, Setting, and Participants In this observational study, 91 Chinese patients (23 with primary open-angle glaucoma [POAG], 45 with primary angle-closure glaucoma, and 23 without glaucoma) were recruited from September 3, 2014, through February 2, 2017. Optical coherence tomography scans of the ONH were acquired at baseline and at 2 sequential IOP elevations (0.64 N and then 0.90 N, by applying forces to the anterior sclera using an ophthalmodynamometer). In each optical coherence tomography volume, lamina cribrosa depth (LCD) and minimum rim width (MRW) were calculated. The mean deviation (MD) and the visual field index (VFI), as assessed by automated perimetry, were correlated with IOP-induced changes of LCD and MRW globally and sectorially. Main Outcomes and Measures The LCD, MRW, MD, and VFI. Results Among the 91 patients, 39 (42.9%) were women; the mean (SD) age was 65.48 (7.23) years. In POAG eyes, a greater change in LCD (anterior displacement) was associated with worse MD and VFI (R = -0.64; 95% CI, -0.97 to -0.31; P = .001; and R = -0.57; 95% CI, -0.94 to -0.19; P = .005, respectively) at the first IOP elevation, and a greater reduction in MRW was also associated with worse MD and VFI (first IOP elevation: R = -0.48; 95% CI, -0.86 to -0.09; P = .02; and R = -0.57; 95% CI, -0.94 to -0.20; P = .004, respectively; second IOP elevation: R = -0.56; 95% CI, -0.98 to -0.13; P = .01; and R = -0.60; 95% CI, -1.03 to -0.17; P = .008, respectively), after adjusting for age, sex, and baseline IOP. A correlation was found between the reduction in MRW in the inferior-temporal sector and the corresponding visual field cluster in POAG eyes at the second elevation (ρ = -0.55; 95% CI, -0.78 to -0.18; P = .006). Conclusions and Relevance The biomechanical response of the ONH to acute IOP elevations was associated with established visual field loss in POAG eyes, but not in primary angle-closure glaucoma eyes. This suggests that ONH biomechanics may be related to glaucoma severity in POAG and that the 2 glaucoma subgroups exhibit inherently different biomechanical properties.
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Affiliation(s)
- Tin A Tun
- Singapore Eye Research Institute and Singapore National Eye Centre, Singapore.,Ophthalmic Engineering and Innovation Laboratory, Department of Biomedical Engineering, National University of Singapore, Singapore
| | - Eray Atalay
- Singapore Eye Research Institute and Singapore National Eye Centre, Singapore.,Eskisehir Osmangazi University Faculty of Medicine, Eskisehir, Turkey
| | - Mani Baskaran
- Singapore Eye Research Institute and Singapore National Eye Centre, Singapore.,Duke-National University of Singapore Medical School, Singapore
| | - Monisha E Nongpiur
- Singapore Eye Research Institute and Singapore National Eye Centre, Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Hla M Htoon
- Singapore Eye Research Institute and Singapore National Eye Centre, Singapore.,Duke-National University of Singapore Medical School, Singapore
| | - David Goh
- Singapore Eye Research Institute and Singapore National Eye Centre, Singapore
| | - Ching-Yu Cheng
- Singapore Eye Research Institute and Singapore National Eye Centre, Singapore.,Duke-National University of Singapore Medical School, Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Shamira A Perera
- Singapore Eye Research Institute and Singapore National Eye Centre, Singapore.,Duke-National University of Singapore Medical School, Singapore
| | - Tin Aung
- Singapore Eye Research Institute and Singapore National Eye Centre, Singapore.,Duke-National University of Singapore Medical School, Singapore.,Department of Ophthalmology, Yong Loo Lin School of Medicine, National University of Singapore, Singapore
| | - Nicholas G Strouthidis
- Singapore Eye Research Institute and Singapore National Eye Centre, Singapore.,Discipline of Clinical Ophthalmology and Eye Health, University of Sydney, Sydney, Australia.,National Institute for Health Research Biomedical Research Centre, Moorfields Eye Hospital National Health Service Foundation Trust and University College London Institute of Ophthalmology, London, United Kingdom
| | - Michaël J A Girard
- Singapore Eye Research Institute and Singapore National Eye Centre, Singapore.,Ophthalmic Engineering and Innovation Laboratory, Department of Biomedical Engineering, National University of Singapore, Singapore
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16
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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.
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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
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17
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A Protective Eye Shield Reduces Limbal Strain and Its Variability During Simulated Sleep in Adults With Glaucoma. J Glaucoma 2019; 27:77-86. [PMID: 29194205 DOI: 10.1097/ijg.0000000000000826] [Citation(s) in RCA: 3] [Impact Index Per Article: 0.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/26/2022]
Abstract
PURPOSE To determine the effect of wearing a protective eye shield (mask) on limbal strain magnitude and variability in glaucoma eyes when sleeping with 1 side of the face down (FD) against a pillow. METHODS A prospective, randomized, interventional trial was conducted at the Wilmer Eye Institute with 36 glaucoma patients. A contact lens sensor measured limbal strain (output in equivalent millivolts) during intervals of up to 60 minutes in lateral decubitus, FD, and supine positions. Eighteen subjects wore a mask during 1 of 2 FD intervals, with randomized assignment of the interval. Data from additional trials with no mask were included in some analyses. In addition, some facial-feature dimensions from 3D scanned images of 23 subjects were compared with limbal strain data. RESULTS Wearing a mask trends toward a reduced mean change in contact lens sensor output (limbal strain) on moving to a FD positions [+34.1 mVeq, P=0.01 reduced by -22.3 mVeq, P=0.09 (n=36)]. Mask wearing reduced variability in strain while FD [-22.8 mVeq, P=0.04 (n=18)]. In eyes with past progressive visual field loss, the effect of the mask reduced mean strain change when moving to FD [-44.8 mVeq, P=0.02 (n=31)]. Longer corneal apex to nose-tip and to temple lengths were associated with reduced variability while FD [P=0.02 and 0.04, respectively (n=23)]. Treating both lengths as confounding factors increased statistical significance, particularly for analysis of the no-mask change in strain data moving to and from the FD position [P=0.004 to 0.002 and P=0.03 to 0.01 (n=23)]. CONCLUSION AND RELEVANCE Wearing a mask reduced limbal strain and variation in limbal strain during simulated FD sleep, particularly in eyes with past field worsening, as did some facial features.
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18
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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.
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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
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19
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Krzyżanowska-Berkowska P, Czajor K, Helemejko I, Iskander DR. Relationship between the rate of change in lamina cribrosa depth and the rate of retinal nerve fiber layer thinning following glaucoma surgery. PLoS One 2018; 13:e0206040. [PMID: 30399148 PMCID: PMC6219770 DOI: 10.1371/journal.pone.0206040] [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: 01/14/2018] [Accepted: 10/05/2018] [Indexed: 11/18/2022] Open
Abstract
PURPOSE To assess whether lamina cribrosa depth (LCD) reduction and the rate of change in LCD over time (ΔLCD/Δt) is associated with retinal nerve fiber layer (RNFL) thickness and the rate of RNFL thinning over time (ΔRNFL/Δt) to test the hypothesis that, in a long term, RNFL thinning occurs irrespectively to the displacement of the lamina cribrosa following glaucoma surgery. METHODS Twenty-nine primary open-angle glaucoma patients underwent glaucoma surgery. Sixteen patients underwent trabeculectomy and 13 patients undertook non-penetrating deep sclerectomy. Images of optic nerve head using spectral-domain optical coherence tomography (SD-OCT) with enhanced depth imaging technology were obtained preoperatively, at one-, three-, six-month and follow-up postoperative visit from 12 to 29 months after surgery (1pv, 3pv, 6pv, and FUpv, respectively). Correspondingly, measurements of the circumpapillary RNFL thickness were acquired. RESULTS Intraocular pressure decreased from 24.0±8.9 to 10.9±3.9mmHg at 6pv (P<0.001) and to 12.7±4.4mmHg at FUpv (P<0.001). LCD was reduced from 465.3±136.4μm to 402.9±126.4μm at 1pv (P<0.001) and maintained similar position at 6pv (394.3±118.4μm; P = 0.170 with respect to 1pv). A significant decrease in the LCD was noted at FUpv (342.8±90.3μm, P<0.001) with respect to 6pv. RNFL thickness increased significantly to 64.9±19.8μm at 1pv (P = 0.005) and subsequently decreased to baseline level at 3pv. Further statistically significant decrease in RNFL thickness with respect to previous visit was found at 6pv and at FUpv (56.4±15.6μm and 55.0±14.0μm, P = 0.023 and P = 0.045, respectively). A thinner RNFL thickness at FUpv was not related to the LCD at FUpv (P = 0.129) but was correlated with ΔLCD/Δt at FUpv (P = 0.003). The ΔRNFL/Δt at FUpv was statistically significantly correlated with ΔLCD/Δt at FUpv (P<0.001). CONCLUSIONS This is the first study that considers direct correlation between the rate of change in LCD with the rate of RNFL thinning over time. A thinner RNFL thickness following glaucoma surgery was associated with the rate of LCD reduction, not with position of the lamina cribrosa at the FUpv.
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Affiliation(s)
| | - Karolina Czajor
- Department of Ophthalmology, Wroclaw Medical University, Wroclaw, Poland
| | - Iwona Helemejko
- Department of Ophthalmology, Wroclaw Medical University, Wroclaw, Poland
| | - D Robert Iskander
- Department of Biomedical Engineering, Faculty of Fundamental Problems of Technology, Wroclaw University of Science and Technology, Wroclaw, Poland
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20
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Structural features of eyelid connective tissue in patients with primary open-angle glaucoma. Int Ophthalmol 2018; 39:2005-2014. [PMID: 30315390 DOI: 10.1007/s10792-018-1035-7] [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: 07/10/2018] [Accepted: 10/04/2018] [Indexed: 10/28/2022]
Abstract
PURPOSE To study the connective tissue (CT) structure of upper eyelid skin of primary open-angle glaucoma (POAG) patients. PATIENTS AND METHODS Forty-seven patients aged 47-91 expecting blepharoplasty formed 3 groups: group 1 [16 subjects without POAG, median age 55 years (interquartile range 54-55.5)], group 2 [12 subjects without POAG, median age 73 (72-76.5)], and group 3 [(19 subjects with POAG, median age 74 (70-80.5)]. Age differences between groups 1 and 2 and groups 1 and 3 are significant (p < 0.05). Thermodynamic parameters of skin samples taken during blepharoplasty: Endothermic peak ([Formula: see text], °C) and denaturation enthalpy ([Formula: see text], J/g of dry weight) were determined using differential scanning calorimetry. RESULTS [Formula: see text] and [Formula: see text] in groups 1-3 were, respectively, 8.41 (7.42-10.25) and 66.55 (59.9-66.7); 7.10 (5.76-10.17) and 67.35 (67.0-68.03); 11.40 (9.0-14.9) and 67.70 (67.05-68.45). [Formula: see text] differences between groups 1 and 2 are significant (p < 0.05), and Spearman's correlation between the age and [Formula: see text] is direct, medium (R = 0.638) and significant. [Formula: see text] in group 3 is significantly higher than in group 2. [Formula: see text] and [Formula: see text] in patients without POAG (groups 1 and 2) and those with POAG (group 3) are, respectively, 7.79 (6.9-10.17) and 66.6 (61.2-67,3); 11.40 (9.0-14.9); 67.7 (67.05-68.45); the respective differences are significant. CONCLUSION Patients without POAG show a significant increase in [Formula: see text] with age, while [Formula: see text] slightly decreases. In POAG, [Formula: see text] is significantly higher and [Formula: see text] tends to grow, which may indicate structural changes in eyelid CT (collagen accumulation and cross-linking level rise). Since the upper lid is unaffected by increasing IOP directly, the changes may be viewed as manifestations of systemic CT pathology.
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21
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Gross JC, Harris A, Siesky BA, Sacco R, Shah A, Guidoboni G. Mathematical modeling for novel treatment approaches to open-angle glaucoma. EXPERT REVIEW OF OPHTHALMOLOGY 2017. [DOI: 10.1080/17469899.2017.1383896] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Submit a Manuscript] [Subscribe] [Scholar Register] [Indexed: 10/18/2022]
Affiliation(s)
- Josh C Gross
- Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Alon Harris
- Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Brent A Siesky
- Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Riccardo Sacco
- Dipartimento di Matematica, Politecnico di Milano, Milano, Italy
| | - Aaditya Shah
- Eugene and Marilyn Glick Eye Institute, Indiana University School of Medicine, Indianapolis, IN, USA
| | - Giovanna Guidoboni
- Department of Mathematical Sciences, Indiana University Purdue University Indianapolis, Indianapolis, IN, USA
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Abstract
The choroid is part of the uveal tract and is a heavily vascularized bed that also contains connective tissue and melanin pigment. Given the role of the choroidal vasculature in the blood supply of the anterior laminar and prelaminar regions of the optic nerve head, the peripapillary choroid might be a relevant target for investigation in patients with glaucoma. The purpose of this paper is to critically review the current understanding of potential role of the choroid in the pathogenesis of glaucomatous damage.
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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.
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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
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Coudrillier B, Campbell IC, Read AT, Geraldes DM, Vo NT, Feola A, Mulvihill J, Albon J, Abel RL, Ethier CR. Effects of Peripapillary Scleral Stiffening on the Deformation of the Lamina Cribrosa. Invest Ophthalmol Vis Sci 2017; 57:2666-77. [PMID: 27183053 PMCID: PMC4874475 DOI: 10.1167/iovs.15-18193] [Citation(s) in RCA: 56] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/08/2023] Open
Abstract
Purpose Scleral stiffening has been proposed as a treatment for glaucoma to protect the lamina cribrosa (LC) from excessive intraocular pressure–induced deformation. Here we experimentally evaluated the effects of moderate stiffening of the peripapillary sclera on the deformation of the LC. Methods An annular sponge, saturated with 1.25% glutaraldehyde, was applied to the external surface of the peripapillary sclera for 5 minutes to stiffen the sclera. Tissue deformation was quantified in two groups of porcine eyes, using digital image correlation (DIC) or computed tomography imaging and digital volume correlation (DVC). In group A (n = 14), eyes were subjected to inflation testing before and after scleral stiffening. Digital image correlation was used to measure scleral deformation and quantify the magnitude of scleral stiffening. In group B (n = 5), the optic nerve head region was imaged using synchrotron radiation phase-contrast microcomputed tomography (PC μCT) at an isotropic spatial resolution of 3.2 μm. Digital volume correlation was used to compute the full-field three-dimensional deformation within the LC and evaluate the effects of peripapillary scleral cross-linking on LC biomechanics. Results On average, scleral treatment with glutaraldehyde caused a 34 ± 14% stiffening of the peripapillary sclera measured at 17 mm Hg and a 47 ± 12% decrease in the maximum tensile strain in the LC measured at 15 mm Hg. The reduction in LC strains was not due to cross-linking of the LC. Conclusions Peripapillary scleral stiffening is effective at reducing the magnitude of biomechanical strains within the LC. Its potential and future utilization in glaucoma axonal neuroprotection requires further investigation.
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Affiliation(s)
- Baptiste Coudrillier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
| | - Ian C Campbell
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States 2Atlanta VA Medical Center, Decatur, Georgia, United States
| | - A Thomas Read
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
| | - Diogo M Geraldes
- Biomechanics Group, Department of Mechanical Engineering, Imperial College London, London, United Kingdom
| | - Nghia T Vo
- Diamond Light Source, Didcot, United Kingdom
| | - Andrew Feola
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
| | - John Mulvihill
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States
| | - Julie Albon
- Optic Nerve Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, United Kingdom 6Cardiff Institute of Tissue Engineering and Repair, Cardiff University, Cardiff, Wales, United Kingdom
| | - Richard L Abel
- Department of Surgery and Cancer, Imperial College, London, United Kingdom
| | - C Ross Ethier
- Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States 2Atlanta VA Medical Center, Decatur, Georgia, United States
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25
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Fazio MA, Johnstone JK, Smith B, Wang L, Girkin CA. Displacement of the Lamina Cribrosa in Response to Acute Intraocular Pressure Elevation in Normal Individuals of African and European Descent. Invest Ophthalmol Vis Sci 2017; 57:3331-9. [PMID: 27367500 PMCID: PMC4961061 DOI: 10.1167/iovs.15-17940] [Citation(s) in RCA: 53] [Impact Index Per Article: 7.6] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/13/2022] Open
Abstract
Purpose To assess if the in vivo mechanical displacement of the anterior laminar cribrosa surface (ALCS) as a response of an acute elevation in intraocular pressure (IOP) differs in individuals of European (ED) and African descent (AD). Methods Spectral-domain optical coherence tomography (SDOCT) scans were obtained from 24 eyes of 12 individuals of AD and 18 eyes of 9 individuals of ED at their normal baseline IOP and after 60 seconds IOP elevation using ophthalmodynamometry. Change in depth (displacement) of the LC and to the prelaminar tissue (PLT) were computed in association with the change (delta) in IOP (Δ IOP), race, age, corneal thickness, corneal rigidity (ocular response analyzer [ORA]), and axial. Results In the ED group for small IOP elevations (Δ IOP < 12 mm Hg), the ALCS initially displaced posteriorly but for larger increase of IOP an anterior displacement of the lamina followed. Inversely, in the AD group the ALCS did not show a significant posterior displacement for small Δ IOP, while for larger IOP increases the ALCS significantly displaced posteriorly. Posterior displacement of the lamina cribrosa (LC) was also significantly correlated with longer axial length, higher corneal thickness, and ORA parameters. Prelaminar tissue posteriorly displaced for any magnitude of Δ IOP, in both groups. Conclusions The African descent group demonstrated a greater acute posterior bowing of the LC after adjustment for age, axial length, Bruch's membrane opening (BMO) area, and ORA parameters. Greater PLT posterior displacement was also seen in the AD group with increasing IOP, which was tightly correlated with the displacement of the LC.
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Affiliation(s)
- Massimo A Fazio
- Department of Ophthalmology University of Alabama at Birmingham, Birmingham, Alabama, United States 2Department of Biomedical Engineering, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - John K Johnstone
- Department of Computer and Information Sciences, University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Brandon Smith
- Department of Ophthalmology University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Lan Wang
- Department of Ophthalmology University of Alabama at Birmingham, Birmingham, Alabama, United States
| | - Christopher A Girkin
- Department of Ophthalmology University of Alabama at Birmingham, Birmingham, Alabama, United States
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Murphy ML, Pokrovskaya O, Galligan M, O'Brien C. Corneal hysteresis in patients with glaucoma-like optic discs, ocular hypertension and glaucoma. BMC Ophthalmol 2017; 17:1. [PMID: 28068950 PMCID: PMC5223406 DOI: 10.1186/s12886-016-0396-9] [Citation(s) in RCA: 36] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2016] [Accepted: 12/16/2016] [Indexed: 12/14/2022] Open
Abstract
Background To compare corneal hysteresis (CH) measurements between patients with glaucoma, ocular hypertension (OHT) and glaucoma-like optic discs (GLD)- defined as a cup to disc ratio greater than or equal to 0.6 with normal intraocular pressure (IOP) and visual fields. The secondary aim was to investigate whether corneal resistance factor (CRF) and central corneal thickness (CCT) differ between patient groups. Methods In this cross sectional study a total of 123 patients (one eye each) were recruited from a glaucoma outpatient department to undergo ocular response analyser (ORA) testing and ultrasound pachymetry as well as clinical examination. A One-way Analysis of Covariance (ANCOVA) was conducted to evaluate the mean difference in CH between the three diagnostic groups (glaucoma, OHT and GLD) correcting for potential confounding factors, IOP and age. Analysis was repeated for CRF and CCT. Results There was a significant difference in mean CH across the three diagnosis groups; F(2, 115) = 96.95; p < 0.001. Mean CH significantly higher for GLD compared to glaucoma (mean difference 1.83, p < 0.001), and significantly higher for OHT compared to glaucoma (mean difference 2.35, p < 0.001). Mean CH was slightly lower in patients with GLD than those with OHT but this difference was not statistically significant. A similar pattern was seen when the analysis was repeated for CRF and CCT. Conclusions Higher CH in GLD and OHT compared to glaucoma suggests increased viscoelasticity of ocular tissues may have a protective role against glaucoma.
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Affiliation(s)
- Melissa L Murphy
- School of Medicine and Medical Sciences, Mater Misericordiae University Hospital, Eccles Street Dublin 7, Dublin, Ireland.
| | - Olya Pokrovskaya
- School of Medicine and Medical Sciences, Mater Misericordiae University Hospital, Eccles Street Dublin 7, Dublin, Ireland
| | - Marie Galligan
- School of Medicine and Medical Sciences, Mater Misericordiae University Hospital, Eccles Street Dublin 7, Dublin, Ireland
| | - Colm O'Brien
- School of Medicine and Medical Sciences, Mater Misericordiae University Hospital, Eccles Street Dublin 7, Dublin, Ireland
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Sharpe GP, Danthurebandara VM, Vianna JR, Alotaibi N, Hutchison DM, Belliveau AC, Shuba LM, Nicolela MT, Chauhan BC. Optic Disc Hemorrhages and Laminar Disinsertions in Glaucoma. Ophthalmology 2016; 123:1949-56. [PMID: 27432205 DOI: 10.1016/j.ophtha.2016.06.001] [Citation(s) in RCA: 35] [Impact Index Per Article: 4.4] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/23/2016] [Revised: 06/01/2016] [Accepted: 06/01/2016] [Indexed: 11/25/2022] Open
Abstract
PURPOSE To determine whether structural abnormalities of the lamina cribrosa explain the presence of optic disc hemorrhages, we determined the spatial concordance between disc hemorrhages and laminar disinsertions from the sclera. DESIGN Prospective noninterventional study. PARTICIPANTS From open-angle glaucoma patients followed up prospectively, we identified 52 eyes of 46 open-angle glaucoma patients with optic disc hemorrhage (ODH+ group) in at least 1 optic disc photograph during follow-up. We also identified 52 control eyes of 46 glaucoma patients in whom no disc hemorrhage was detected (ODH- group). METHODS Enhanced depth imaging optical coherence tomography of the optic nerve head (24 radial scans) was performed. The scans were de-identified and a trained observer masked to all clinical information determined the presence of laminar disinsertions in each of the 48 positions with a confidence score of 1 (least certain) to 5 (most certain). Only disinsertions with a score of 3 or more were included in the analysis. MAIN OUTCOME MEASURES Frequency and spatial concordance between disc hemorrhages and laminar disinsertions. RESULTS The median age, visual field mean deviation, and follow-up period of the ODH+ and ODH- groups was 77.5 and 70.8 years, -5.20 and -4.70 dB, and 10.4 and 9.9 years, respectively. There were 84 hemorrhages recorded in the ODH+ group. There were laminar disinsertions in 50 eyes (96%) in the ODH+ group and in 27 eyes (52%) in the ODH- group, with 2 or more disinsertions in 30 eyes (58%) and 5 eyes (10%), respectively. Most hemorrhages and disinsertions were located in the inferotemporal and superotemporal sectors. However, in individual patients, only 33 of the ODHs (39%) were located within a laminar disinsertion. CONCLUSIONS Laminar disinsertions occurred twice as frequently in eyes with ODHs; however, in individual patients, the spatial concordance between ODHs and laminar disinsertions was poor.
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Affiliation(s)
- Glen P Sharpe
- Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Canada
| | | | - Jayme R Vianna
- Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Canada
| | - Noor Alotaibi
- Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Canada
| | - Donna M Hutchison
- Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Canada
| | - Anne C Belliveau
- Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Canada
| | - Lesya M Shuba
- Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Canada
| | - Marcelo T Nicolela
- Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Canada
| | - Balwantray C Chauhan
- Department of Ophthalmology and Visual Sciences, Dalhousie University, Halifax, Canada.
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Jones HJ, Girard MJ, White N, Fautsch MP, Morgan JE, Ethier CR, Albon J. Quantitative analysis of three-dimensional fibrillar collagen microstructure within the normal, aged and glaucomatous human optic nerve head. J R Soc Interface 2016; 12:rsif.2015.0066. [PMID: 25808336 PMCID: PMC4424682 DOI: 10.1098/rsif.2015.0066] [Citation(s) in RCA: 28] [Impact Index Per Article: 3.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/12/2022] Open
Abstract
The aim of this study was to quantify connective tissue fibre orientation and alignment in young, old and glaucomatous human optic nerve heads (ONH) to understand ONH microstructure and predisposition to glaucomatous optic neuropathy. Transverse (seven healthy, three glaucomatous) and longitudinal (14 healthy) human ONH cryosections were imaged by both second harmonic generation microscopy and small angle light scattering (SALS) in order to quantify preferred fibre orientation (PFO) and degree of fibre alignment (DOFA). DOFA was highest within the peripapillary sclera (ppsclera), with relatively low values in the lamina cribrosa (LC). Elderly ppsclera DOFA was higher than that in young ppsclera (p < 0.00007), and generally higher than in glaucoma ppsclera. In all LCs, a majority of fibres had preferential orientation horizontally across the nasal–temporal axis. In all glaucomatous LCs, PFO was significantly different from controls in a minimum of seven out of 12 LC regions (p < 0.05). Additionally, higher fibre alignment was observed in the glaucomatous inferior–temporal LC (p < 0.017). The differences between young and elderly ONH fibre alignment within regions suggest that age-related microstructural changes occur within the structure. The additional differences in fibre alignment observed within the glaucomatous LC may reflect an inherent susceptibility to glaucomatous optic neuropathy, or may be a consequence of ONH remodelling and/or collapse.
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Affiliation(s)
- H J Jones
- Optic Nerve Group, Cardiff Centre for Vision Science, Cardiff University, Cardiff, UK Bioimaging Labs, Cardiff University, Cardiff, UK Cardiff Institute for Tissue Engineering and Repair, Cardiff University, Cardiff, UK
| | - M J Girard
- In vivo Biomechanics Laboratory, Department of Biomedical Engineering, National University of Singapore, Singapore Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
| | - N White
- Cardiff Institute for Tissue Engineering and Repair, Cardiff University, Cardiff, UK
| | - M P Fautsch
- Department of Ophthalmology, Mayo Clinic, Rochester, NY, USA
| | - J E Morgan
- Optic Nerve Group, Cardiff Centre for Vision Science, Cardiff University, Cardiff, UK
| | - C R Ethier
- Georgia Institute of Technology and Emory, University School of Medicine, Atlanta, GA, USA Department of Bioengineering, Imperial College, London, UK
| | - J Albon
- Optic Nerve Group, Cardiff Centre for Vision Science, Cardiff University, Cardiff, UK Bioimaging Labs, Cardiff University, Cardiff, UK Cardiff Institute for Tissue Engineering and Repair, Cardiff University, Cardiff, UK
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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.
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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.
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30
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Quigley HA, Pitha IF, Welsbie DS, Nguyen C, Steinhart MR, Nguyen TD, Pease ME, Oglesby EN, Berlinicke CA, Mitchell KL, Kim J, Jefferys JJ, Kimball EC. Losartan Treatment Protects Retinal Ganglion Cells and Alters Scleral Remodeling in Experimental Glaucoma. PLoS One 2015; 10:e0141137. [PMID: 26505191 PMCID: PMC4624713 DOI: 10.1371/journal.pone.0141137] [Citation(s) in RCA: 46] [Impact Index Per Article: 5.1] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/20/2015] [Accepted: 10/05/2015] [Indexed: 12/20/2022] Open
Abstract
Purpose To determine if oral losartan treatment decreases the retinal ganglion cell (RGC) death caused by experimental intraocular pressure (IOP) elevation in mice. Methods We produced IOP increase in CD1 mice and performed unilateral optic nerve crush. Mice received oral losartan, spironolactone, enalapril, or no drug to test effects of inhibiting angiotensin receptors. IOP was monitored by Tonolab, and blood pressure was monitored by tail cuff device. RGC loss was measured in masked axon counts and RGC bodies by β-tubulin labeling. Scleral changes that could modulate RGC injury were measured including axial length, scleral thickness, and retinal layer thicknesses, pressure-strain behavior in inflation testing, and study of angiotensin receptors and pathways by reverse transcription polymerase chain reaction, Western blot, and immunohistochemistry. Results Losartan treatment prevented significant RGC loss (median loss = 2.5%, p = 0.13), while median loss with water, spironolactone, and enalapril treatments were 26%, 28% and 43%; p < 0.0001). The lower RGC loss with losartan was significantly less than the loss with spironolactone or enalapril (regression model p = 0.001; drug treatment group term p = 0.01). Both losartan and enalapril significantly lowered blood pressure (p< 0.001), but losartan was protective, while enalapril led to worse than water-treated RGC loss. RGC loss after crush injury was unaffected by losartan treatment (difference from control p = 0.9). Survival of RGC in cell culture was not prolonged by sartan treatment. Axonal transport blockade after 3 day IOP elevations was less in losartan-treated than in control glaucoma eyes (p = 0.007). Losartan inhibited effects of glaucoma, including reduction in extracellular signal-related kinase activity and modification of glaucoma-related changes in scleral thickness and creep under controlled IOP. Conclusions The neuroprotective effect of losartan in mouse glaucoma is associated with adaptive changes in the sclera expressed at the optic nerve head.
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Affiliation(s)
- Harry A. Quigley
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
- * E-mail:
| | - Ian F. Pitha
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Derek S. Welsbie
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Cathy Nguyen
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Matthew R. Steinhart
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Thao D. Nguyen
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Mary Ellen Pease
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Ericka N. Oglesby
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Cynthia A. Berlinicke
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Katherine L. Mitchell
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Jessica Kim
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Joan J. Jefferys
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
| | - Elizabeth C. Kimball
- The Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States of America
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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.
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Affiliation(s)
- Harry A Quigley
- Glaucoma Center of Excellence, Wilmer Institute, Johns Hopkins University School of Medicine, Baltimore, MD, USA.
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Coudrillier B, Pijanka J, Jefferys J, Sorensen T, Quigley HA, Boote C, Nguyen TD. Effects of age and diabetes on scleral stiffness. J Biomech Eng 2015; 137:2196535. [PMID: 25751456 DOI: 10.1115/1.4029986] [Citation(s) in RCA: 31] [Impact Index Per Article: 3.4] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/16/2014] [Indexed: 02/05/2023]
Abstract
The effects of diabetes on the collagen structure and material properties of the sclera are unknown but may be important to elucidate whether diabetes is a risk factor for major ocular diseases such as glaucoma. This study provides a quantitative assessment of the changes in scleral stiffness and collagen fiber alignment associated with diabetes. Posterior scleral shells from five diabetic donors and seven non-diabetic donors were pressurized to 30 mm Hg. Three-dimensional surface displacements were calculated during inflation testing using digital image correlation (DIC). After testing, each specimen was subjected to wide-angle X-ray scattering (WAXS) measurements of its collagen organization. Specimen-specific finite element models of the posterior scleras were generated from the experimentally measured geometry. An inverse finite element analysis was developed to determine the material properties of the specimens, i.e., matrix and fiber stiffness, by matching DIC-measured and finite element predicted displacement fields. Effects of age and diabetes on the degree of fiber alignment, matrix and collagen fiber stiffness, and mechanical anisotropy were estimated using mixed effects models accounting for spatial autocorrelation. Older age was associated with a lower degree of fiber alignment and larger matrix stiffness for both diabetic and non-diabetic scleras. However, the age-related increase in matrix stiffness was 87% larger in diabetic specimens compared to non-diabetic controls and diabetic scleras had a significantly larger matrix stiffness (p = 0.01). Older age was associated with a nearly significant increase in collagen fiber stiffness for diabetic specimens only (p = 0.06), as well as a decrease in mechanical anisotropy for non-diabetic scleras only (p = 0.04). The interaction between age and diabetes was not significant for all outcomes. This study suggests that the age-related increase in scleral stiffness is accelerated in eyes with diabetes, which may have important implications in glaucoma.
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Murphy-Ullrich JE, Downs JC. The Thrombospondin1-TGF-β Pathway and Glaucoma. J Ocul Pharmacol Ther 2015; 31:371-5. [PMID: 26352161 DOI: 10.1089/jop.2015.0016] [Citation(s) in RCA: 14] [Impact Index Per Article: 1.6] [Reference Citation Analysis] [Abstract] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/25/2023] Open
Abstract
Glaucoma is characterized by abnormal remodeling of the extracellular matrix (ECM) in the trabecular meshwork and in the connective tissue beams of the lamina cribrosa (LC) at the optic nerve head (ONH), which is associated with axonal damage. Mechanical strain can stimulate ECM remodeling and increased expression of matricellular proteins. Thrombospondins 1 and 2 are induced by cyclic mechanical strain in the eye in both the trabecular meshwork and in the LC region of the ONH. TGF-betas 1 and 2 are increased in glaucoma and play a role in the pathologic remodeling of the ECM in the eye in glaucoma. In this study, we address the role of thrombospondin1 as a regulator of latent TGF-beta activation and discuss the potential therapeutic use of antagonists of the thrombospondin1-TGF-beta pathway for treatment of glaucoma.
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Affiliation(s)
- Joanne E Murphy-Ullrich
- 1 Department of Pathology, University of Alabama at Birmingham , Birmingham, Alabama.,2 Department of Cell Developmental and Integrative Biology, University of Alabama at Birmingham , Birmingham, Alabama.,3 Department of Ophthalmology, University of Alabama at Birmingham , Birmingham, Alabama
| | - J Crawford Downs
- 3 Department of Ophthalmology, University of Alabama at Birmingham , Birmingham, Alabama.,4 Department of Biomedical Engineering, University of Alabama at Birmingham , Birmingham, Alabama
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Girard MJA, Dupps WJ, Baskaran M, Scarcelli G, Yun SH, Quigley HA, Sigal IA, Strouthidis NG. Translating ocular biomechanics into clinical practice: current state and future prospects. Curr Eye Res 2015; 40:1-18. [PMID: 24832392 PMCID: PMC4233020 DOI: 10.3109/02713683.2014.914543] [Citation(s) in RCA: 72] [Impact Index Per Article: 8.0] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/17/2022]
Abstract
Biomechanics is the study of the relationship between forces and function in living organisms and is thought to play a critical role in a significant number of ophthalmic disorders. This is not surprising, as the eye is a pressure vessel that requires a delicate balance of forces to maintain its homeostasis. Over the past few decades, basic science research in ophthalmology mostly confirmed that ocular biomechanics could explain in part the mechanisms involved in almost all major ophthalmic disorders such as optic nerve head neuropathies, angle closure, ametropia, presbyopia, cataract, corneal pathologies, retinal detachment and macular degeneration. Translational biomechanics in ophthalmology, however, is still in its infancy. It is believed that its use could make significant advances in diagnosis and treatment. Several translational biomechanics strategies are already emerging, such as corneal stiffening for the treatment of keratoconus, and more are likely to follow. This review aims to cultivate the idea that biomechanics plays a major role in ophthalmology and that the clinical translation, lead by collaborative teams of clinicians and biomedical engineers, will benefit our patients. Specifically, recent advances and future prospects in corneal, iris, trabecular meshwork, crystalline lens, scleral and lamina cribrosa biomechanics are discussed.
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Affiliation(s)
- Michaël J A Girard
- In Vivo Biomechanics Laboratory, Department of Biomedical Engineering, National University of Singapore , Singapore
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Pyne JD, Genovese K, Casaletto L, Vande Geest JP. Sequential-digital image correlation for mapping human posterior sclera and optic nerve head deformation. J Biomech Eng 2014; 136:021002. [PMID: 24337344 DOI: 10.1115/1.4026224] [Citation(s) in RCA: 15] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/02/2013] [Accepted: 12/12/2013] [Indexed: 01/26/2023]
Abstract
Optic nerve head (ONH) deformations may be involved in the onset or further development of glaucoma, including in patients with relatively normal intraocular pressures (IOPs). Characterizing posterior scleral deformations over physiological pressures may provide a better understanding of how changes in IOP lead to changes in the mechanical environment of the ONH and possibly retinal ganglion cell death. Pressure inflation measurement test protocols are commonly used to measure deformation of the peripapillary sclera with full-field noncontact optical methods. The purpose of this work was to develop and validate a new sequential 3D digital image correlation (S-DIC) approach for quantification of posterior scleral pressure induced deformation that improves z (in-depth) resolution of the DIC measurement without losing in-plane sensitivity, while also being able to contour and map deformations of the complex-shaped ONH. Our approach combines two orthogonal axes of parallax with standard 3D DIC methods using a single high-resolution camera. The enhanced capabilities of S-DIC with respect to standard 3D DIC has been demonstrated by carrying out a complete benchmark for shape, deformation, and strain measurement on an object of known complex geometry. Our S-DIC method provided a reconstruction accuracy of 0.17% and an uncertainty in z-position measurement of 8 μm. The developed methodology has also been applied to a human posterior scleral shell, including the full peripapillary sclera and optic nerve. The relatively inexpensive S-DIC approach may provide new information on the biomechanical deformations of the optic nerve head and, thus, the death of retinal ganglion cells in primary open angle glaucoma.
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Kimball EC, Nguyen C, Steinhart MR, Nguyen TD, Pease ME, Oglesby EN, Oveson BC, Quigley HA. Experimental scleral cross-linking increases glaucoma damage in a mouse model. Exp Eye Res 2014; 128:129-40. [PMID: 25285424 PMCID: PMC4254118 DOI: 10.1016/j.exer.2014.08.016] [Citation(s) in RCA: 66] [Impact Index Per Article: 6.6] [Reference Citation Analysis] [Abstract] [Key Words] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/11/2014] [Revised: 07/21/2014] [Accepted: 08/07/2014] [Indexed: 12/12/2022]
Abstract
The purpose of this study was to assess the effect of a scleral cross-linking agent on susceptibility to glaucoma damage in a mouse model.CD1 mice underwent 3 subconjunctival injections of 0.5 M glyceraldehyde (GA) in 1 week, then had elevated intraocular pressure (IOP) induced by bead injection. Degree of cross-linking was measured by enzyme-linked immunosorbent assay (ELISA), scleral permeability was measured by fluorescence recovery after photobleaching (FRAP), and the mechanical effects of GA exposure were measured by inflation testing. Control mice had buffer injection or no injection in 2 separate glaucoma experiments. IOP was monitored by Tonolab and retinal ganglion cell (RGC) loss was measured by histological axon counting. To rule out undesirable effects of GA, we performed electroretinography and detailed histology of the retina. GA exposure had no detectable effects on RGC number, retinal structure or function either histologically or electrophysiologically. GA increased cross-linking of sclera by 37% in an ELISA assay, decreased scleral permeability (FRAP, p = 0.001), and produced a steeper pressure-strain behavior by in vitro inflation testing. In two experimental glaucoma experiments, GA-treated eyes had greater RGC axon loss from elevated IOP than either buffer-injected or control eyes, controlling for level of IOP exposure over time (p = 0.01, and 0.049, multivariable regression analyses). This is the first report that experimental alteration of the sclera, by cross-linking, increases susceptibility to RGC damage in mice.
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Affiliation(s)
- Elizabeth C Kimball
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, MD, USA.
| | - Cathy Nguyen
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Matthew R Steinhart
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Thao D Nguyen
- The Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, USA
| | - Mary E Pease
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Ericka N Oglesby
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Brian C Oveson
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, MD, USA
| | - Harry A Quigley
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, MD, USA
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Pijanka JK, Kimball EC, Pease ME, Abass A, Sorensen T, Nguyen TD, Quigley HA, Boote C. Changes in scleral collagen organization in murine chronic experimental glaucoma. Invest Ophthalmol Vis Sci 2014; 55:6554-64. [PMID: 25228540 DOI: 10.1167/iovs.14-15047] [Citation(s) in RCA: 38] [Impact Index Per Article: 3.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022] Open
Abstract
PURPOSE The organization of scleral collagen helps to determine the eye's biomechanical response to intraocular pressure (IOP), and may therefore be important in glaucoma. This study provides a quantitative assessment of changes in scleral collagen fibril organization in bead-induced murine experimental glaucoma. METHODS Wide-angle X-ray scattering was used to study the effect of bead-induced glaucoma on posterior scleral collagen organization in one eye of 12 CD1 mice, with untreated fellow eyes serving as controls. Three collagen parameters were measured: the local preferred fibril directions, the degree of collagen anisotropy, and the total fibrillar collagen content. RESULTS The mouse sclera featured a largely circumferential orientation of fibrillar collagen with respect to the optic nerve head canal. Localized alteration to fibril orientations was evident in the inferior peripapillary sclera of bead-treated eyes. Collagen anisotropy was significantly (P<0.05) reduced in bead-treated eyes in the superior peripapillary (Treated: 43±8%; CONTROL 49±6%) and midposterior (Treated: 39±4%; CONTROL 43±4%) sclera, and in the peripapillary region overall (Treated: 43±6%; CONTROL 47±3%). No significant differences in total collagen content were found between groups. CONCLUSIONS Spatial changes in collagen fibril anisotropy occur in the posterior sclera of mice with bead-induced chronic IOP elevation and axonal damage. These results support the idea that dynamic changes in scleral form and structure play a role in the development of experimental glaucoma in mice, and potentially in human glaucoma.
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Affiliation(s)
- Jacek K Pijanka
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | - Elizabeth C Kimball
- 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
| | - Ahmed Abass
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
| | | | - Thao D Nguyen
- Department of Mechanical Engineering, Johns Hopkins University, Baltimore, Maryland, United States
| | - Harry A Quigley
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University, Baltimore, Maryland, United States
| | - Craig Boote
- Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom
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Sanfilippo PG, Grimm JL, Flanagan JG, Lathrop KL, Sigal IA. Application of Elliptic Fourier analysis to describe the lamina cribrosa shape with age and intraocular pressure. Exp Eye Res 2014; 128:1-7. [PMID: 25193035 DOI: 10.1016/j.exer.2014.08.013] [Citation(s) in RCA: 4] [Impact Index Per Article: 0.4] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/15/2014] [Revised: 07/18/2014] [Accepted: 08/22/2014] [Indexed: 11/29/2022]
Abstract
The lamina cribrosa (LC) plays an important biomechanical role in the optic nerve head (ONH). We developed a statistical shape model of the LC and tested if the shape varies with age or IOP. The ONHs of 18 donor eyes (47-91 years, mean 76 years) fixed at either 5 or 50 mmHg of IOP were sectioned, stained, and imaged under a microscope. A 3D model of each ONH was reconstructed and the outline of the vertical sagittal section closest to the geometric center of the LC extracted. The outline shape was described using Elliptic Fourier analysis, and principal components analysis (PCA) employed to identify the primary modes of LC shape variation. Linear mixed effect models were used to determine if the shape measurements were associated with age or IOP. The analysis revealed several modes of shape variation: thickness and depth directly (PC 1), or inversely (PC 2) related, and superior-inferior asymmetry (PC 3). Only PC 3 was associated with IOP, with higher IOP correlating with greater curvature of the LC superiorly compared to inferiorly. Our analysis enabled a concise and complete characterization of LC shape, revealing variations without defining them a priori. No association between LC shape and age was found for the relatively old population studied. Superior-inferior asymmetry of LC shape was associated with IOP, with more asymmetry at higher IOP. Increased IOP was not associated with LC thickness or depth.
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Affiliation(s)
- P G Sanfilippo
- Centre for Eye Research Australia, Royal Victorian Eye and Ear Hospital, University of Melbourne, Melbourne, Australia
| | - J L Grimm
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA
| | - J G Flanagan
- Department of Ophthalmology and Vision Science, University of Toronto, Toronto, ON, Canada; School of Optometry and Vision Science, University of Waterloo, Waterloo, ON, Canada
| | - K L Lathrop
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA
| | - I A Sigal
- Department of Ophthalmology, University of Pittsburgh, Pittsburgh, PA, USA; Department of Bioengineering, University of Pittsburgh, Pittsburgh, PA, USA.
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Steinhart MR, Cone-Kimball E, Nguyen C, Nguyen TD, Pease ME, Chakravarti S, Oglesby EN, Quigley HA. Susceptibility to glaucoma damage related to age and connective tissue mutations in mice. Exp Eye Res 2013; 119:54-60. [PMID: 24368172 DOI: 10.1016/j.exer.2013.12.008] [Citation(s) in RCA: 19] [Impact Index Per Article: 1.7] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/12/2013] [Revised: 11/14/2013] [Accepted: 12/13/2013] [Indexed: 12/16/2022]
Abstract
The purpose of this research was to study the effects of age and genetic alterations in key connective tissue proteins on susceptibility to experimental glaucoma in mice. We used mice haploinsufficient in the elastin gene (EH) and mice without both alleles of the fibromodulin gene (FM KO) and their wild type (WT) littermates of B6 and CD1 strains, respectively. FM KO mice were tested at two ages: 2 months and 12 months. Intraocular pressure (IOP) was measured by Tonolab tonometer, axial lengths and widths measured by digital caliper post-enucleation, and chronic glaucoma damage was measured using a bead injection model and optic nerve axon counts. IOP in EH mice was not significantly different from WT, but FM KO were slightly lower than their controls (p = 0.04). Loss of retinal ganglion cell (RGC) axons was somewhat, but not significantly greater in young EH and younger or older FM KO strains than in age-matched controls (p = 0.48, 0.34, 0.20, respectively, multivariable regression adjusting for IOP exposure). Older CD1 mice lost significantly more RGC axons than younger CD1 (p = 0.01, multivariable regression). The CD1 mouse strain showed age-dependence of experimental glaucoma damage to RGC in the opposite, and more expected, direction than in B6 mice in which older mice are more resistant to damage. Genetic alteration in two genes that are constituents of sclera, fibromodulin and elastin do not significantly affect RGC loss.
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Affiliation(s)
- Matthew R Steinhart
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Departments of Ophthalmology, Baltimore, MD, United States
| | - Elizabeth Cone-Kimball
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Departments of Ophthalmology, Baltimore, MD, United States
| | - Cathy Nguyen
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Departments of Ophthalmology, Baltimore, MD, United States
| | - Thao D Nguyen
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Mechanical Engineering, Johns Hopkins University, Baltimore, MD, United States
| | - Mary E Pease
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Departments of Ophthalmology, Baltimore, MD, United States
| | - Shukti Chakravarti
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Departments of Ophthalmology, Baltimore, MD, United States
| | - Ericka N Oglesby
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Departments of Ophthalmology, Baltimore, MD, United States
| | - Harry A Quigley
- Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Departments of Ophthalmology, Baltimore, MD, United States.
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40
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Status and perspectives of neuroprotective therapies in glaucoma: the European Glaucoma Society White Paper. Cell Tissue Res 2013; 353:347-54. [PMID: 23712457 DOI: 10.1007/s00441-013-1637-3] [Citation(s) in RCA: 9] [Impact Index Per Article: 0.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/26/2013] [Accepted: 04/12/2013] [Indexed: 12/12/2022]
Abstract
Glaucoma, a chronic progressive neuropathy and the most frequent cause of irreversible blindness worldwide, is commonly treated by medication or surgery aimed at lowering intraocular pressure. In view of the limited therapeutic options, the European Glaucoma Society (EGS) sponsored two Think Tank Meetings with the goal of assessing the current status and the overall perspectives for neuroprotective treatment strategies in glaucoma. The results of the meetings are summarized in this EGS White Paper.
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