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Glaucoma: HELP
Articles by Baptiste Coudrillier
Based on 8 articles published since 2010
(Why 8 articles?)
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Between 2010 and 2020, Baptiste Coudrillier wrote the following 8 articles about Glaucoma.
 
+ Citations + Abstracts
1 Review Biomechanics of the posterior eye: a critical role in health and disease. 2014

Campbell, Ian C / Coudrillier, Baptiste / Ross Ethier, C. · ·J Biomech Eng · Pubmed #24356942.

ABSTRACT: The posterior eye is a complex biomechanical structure. Delicate neural and vascular tissues of the retina, choroid, and optic nerve head that are critical for visual function are subjected to mechanical loading from intraocular pressure, intraocular and extraorbital muscles, and external forces on the eye. The surrounding sclera serves to counteract excessive deformation from these forces and thus to create a stable biomechanical environment for the ocular tissues. Additionally, the eye is a dynamic structure with connective tissue remodeling occurring as a result of aging and pathologies such as glaucoma and myopia. The material properties of these tissues and the distribution of stresses and strains in the posterior eye is an area of active research, relying on a combination of computational modeling, imaging, and biomechanical measurement approaches. Investigators are recognizing the increasing importance of the role of the collagen microstructure in these material properties and are undertaking microstructural measurements to drive microstructurally-informed models of ocular biomechanics. Here, we review notable findings and the consensus understanding on the biomechanics and microstructure of the posterior eye. Results from computational and numerical modeling studies and mechanical testing of ocular tissue are discussed. We conclude with some speculation as to future trends in this field.

2 Article Deformation of the Lamina Cribrosa and Optic Nerve Due to Changes in Cerebrospinal Fluid Pressure. 2017

Feola, Andrew J / Coudrillier, Baptiste / Mulvihill, John / Geraldes, Diogo M / Vo, Nghia T / Albon, Julie / Abel, Richard L / Samuels, Brian C / Ethier, C Ross. ·Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, United States. · Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, United States 2Exponent, Inc., Menlo Park, California, United States. · Department of Biomedical Engineering, Georgia Institute of Technology/Emory University, Atlanta, Georgia, United States 3School of Engineering/Bernal Institute, University of Limerick, Limerick, Ireland. · Biomechanics Group, Department of Mechanical Engineering, Imperial College London, London, United Kingdom. · Diamond Light Source, Didcot, United Kingdom. · Optic Nerve Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, Wales, United Kingdom 7Cardiff Institute of Tissue Engineering and Repair, Cardiff University, Cardiff, Wales, United Kingdom. · Department of Surgery and Cancer, Imperial College, London, United Kingdom. · Department of Ophthalmology, University of Alabama at Birmingham, Birmingham, Alabama, United States. ·Invest Ophthalmol Vis Sci · Pubmed #28389675.

ABSTRACT: Purpose: Cerebrospinal fluid pressure (CSFp) changes are involved or implicated in various ocular conditions including glaucoma, idiopathic intracranial hypertension, and visual impairment and intracranial pressure syndrome. However, little is known about the effects of CSFp on lamina cribrosa and retrolaminar neural tissue (RLNT) biomechanics, potentially important in these conditions. Our goal was to use an experimental approach to visualize and quantify the deformation of these tissues as CSFp increased. Methods: The posterior eye and RLNT of porcine eyes (n = 3) were imaged using synchrotron radiation phase-contrast micro-computed tomography (PC μCT) at an intraocular pressure of 15 mm Hg and CSFps of 4, 10, 20, and 30 mm Hg. Scans of each tissue region were acquired at each CSFp step and analyzed using digital volume correlation to determine 3-dimensional tissue deformations. Results: Elevating CSFp increased the strain in the lamina cribrosa and RLNT of all three specimens, with the largest strains occurring in the RLNT. Relative to the baseline CSFp of 4 mm Hg, at 30 mm Hg, the lamina cribrosa experienced a mean first and third principal strain of 4.4% and -3.5%, respectively. The corresponding values for the RLNT were 9.5% and -9.1%. Conclusions: CSFp has a significant impact on the strain distributions within the lamina cribrosa and, more prominently, within the RLNT. Elevations in CSFp were positively correlated with increasing deformations in each region and may play a role in ocular pathologies linked to changes in CSFp.

3 Article Effects of Peripapillary Scleral Stiffening on the Deformation of the Lamina Cribrosa. 2016

Coudrillier, Baptiste / Campbell, Ian C / Read, A Thomas / Geraldes, Diogo M / Vo, Nghia T / Feola, Andrew / Mulvihill, John / Albon, Julie / Abel, Richard L / Ethier, C Ross. ·Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, Atlanta, Georgia, United States. · 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. · Biomechanics Group, Department of Mechanical Engineering, Imperial College London, London, United Kingdom. · Diamond Light Source, Didcot, United Kingdom. · 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. · Department of Surgery and Cancer, Imperial College, London, United Kingdom. ·Invest Ophthalmol Vis Sci · Pubmed #27183053.

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.

4 Article Glaucoma-related Changes in the Mechanical Properties and Collagen Micro-architecture of the Human Sclera. 2015

Coudrillier, Baptiste / Pijanka, Jacek K / Jefferys, Joan L / Goel, Adhiraj / Quigley, Harry A / Boote, Craig / Nguyen, Thao D. ·Department of Biomedical Engineering, Georgia Institute of Technology, Atlanta, GA, United States of America. · Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom. · Glaucoma Center of Excellence, Wilmer Ophthalmological Institute, Johns Hopkins University School of Medicine, Baltimore, MD, United States of America. · Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD, United States of America. ·PLoS One · Pubmed #26161963.

ABSTRACT: OBJECTIVE: The biomechanical behavior of the sclera determines the level of mechanical insult from intraocular pressure to the axons and tissues of the optic nerve head, as is of interest in glaucoma. In this study, we measure the collagen fiber structure and the strain response, and estimate the material properties of glaucomatous and normal human donor scleras. METHODS: Twenty-two posterior scleras from normal and diagnosed glaucoma donors were obtained from an eyebank. Optic nerve cross-sections were graded to determine the presence of axon loss. The specimens were subjected to pressure-controlled inflation testing. Full-field displacement maps were measured by digital image correlation (DIC) and spatially differentiated to compute surface strains. Maps of the collagen fiber structure across the posterior sclera of each inflated specimen were obtained using synchrotron wide-angle X-ray scattering (WAXS). Finite element (FE) models of the posterior scleras, incorporating a specimen-specific representation of the collagen structure, were constructed from the DIC-measured geometry. An inverse finite element analysis was developed to estimate the stiffness of the collagen fiber and inter-fiber matrix. RESULTS: The differences between glaucoma and non-glaucoma eyes were small in magnitude. Sectorial variations of degree of fiber alignment and peripapillary scleral strain significantly differed between normal and diagnosed glaucoma specimens. Meridional strains were on average larger in diagnosed glaucoma eyes compared with normal specimens. Non-glaucoma specimens had on average the lowest matrix and fiber stiffness, followed by undamaged glaucoma eyes, and damaged glaucoma eyes but the differences in stiffness were not significant. CONCLUSION: The observed biomechanical and microstructural changes could be the result of tissue remodeling occuring in glaucoma and are likely to alter the mechanical environment of the optic nerve head and contribute to axonal damage.

5 Article Automated segmentation of the lamina cribrosa using Frangi's filter: a novel approach for rapid identification of tissue volume fraction and beam orientation in a trabeculated structure in the eye. 2015

Campbell, Ian C / Coudrillier, Baptiste / Mensah, Johanne / Abel, Richard L / Ethier, C Ross. ·Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 315 Ferst Drive NW, Atlanta, GA 30332, USA Atlanta VA Medical Center, 1670 Clairmont Road, Decatur, GA 30033, USA. · Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 315 Ferst Drive NW, Atlanta, GA 30332, USA. · MSk Laboratory, Department of Surgery and Cancer, Faculty of Medicine, Imperial College London, London W6 8RP, UK. · Wallace H. Coulter Department of Biomedical Engineering, Georgia Institute of Technology and Emory University, 315 Ferst Drive NW, Atlanta, GA 30332, USA Atlanta VA Medical Center, 1670 Clairmont Road, Decatur, GA 30033, USA ross.ethier@bme.gatech.edu. ·J R Soc Interface · Pubmed #25589572.

ABSTRACT: The lamina cribrosa (LC) is a tissue in the posterior eye with a complex trabecular microstructure. This tissue is of great research interest, as it is likely the initial site of retinal ganglion cell axonal damage in glaucoma. Unfortunately, the LC is difficult to access experimentally, and thus imaging techniques in tandem with image processing have emerged as powerful tools to study the microstructure and biomechanics of this tissue. Here, we present a staining approach to enhance the contrast of the microstructure in micro-computed tomography (micro-CT) imaging as well as a comparison between tissues imaged with micro-CT and second harmonic generation (SHG) microscopy. We then apply a modified version of Frangi's vesselness filter to automatically segment the connective tissue beams of the LC and determine the orientation of each beam. This approach successfully segmented the beams of a porcine optic nerve head from micro-CT in three dimensions and SHG microscopy in two dimensions. As an application of this filter, we present finite-element modelling of the posterior eye that suggests that connective tissue volume fraction is the major driving factor of LC biomechanics. We conclude that segmentation with Frangi's filter is a powerful tool for future image-driven studies of LC biomechanics.

6 Article Studies of scleral biomechanical behavior related to susceptibility for retinal ganglion cell loss in experimental mouse glaucoma. 2013

Nguyen, Cathy / Cone, Frances E / Nguyen, Thao D / Coudrillier, Baptiste / Pease, Mary E / Steinhart, Matthew R / Oglesby, Ericka N / Jefferys, Joan L / Quigley, Harry A. ·Glaucoma Center of Excellence, Wilmer Eye Institute at Johns Hopkins University, Baltimore, Maryland, USA. ·Invest Ophthalmol Vis Sci · Pubmed #23404116.

ABSTRACT: PURPOSE: To study anatomical changes and mechanical behavior of the sclera in mice with experimental glaucoma by comparing CD1 to B6 mice. METHODS: Chronic experimental glaucoma for 6 weeks was produced in 2- to 4-month-old CD1 (43 eyes) and B6 mice (42 eyes) using polystyrene bead injection into the anterior chamber with 126 control CD1 and 128 control B6 eyes. Intraocular pressure (IOP) measurements were made with the TonoLab at baseline and after bead injection. Axial length and scleral thickness were measured after sacrifice in the CD1 and B6 animals and compared to length data from 78 eyes of DBA/2J mice. Inflation testing of posterior sclera was conducted, and circumferential and meridional strain components were determined from the displacement response. RESULTS: Experimental glaucoma led to increases in axial length and width by comparison to fellow eyes (6% in CD1 and 10% in B6; all P < 0.03). While the peripapillary sclera became thinner in both mouse types with glaucoma, the remainder of the sclera uniformly thinned in CD1, but thickened in B6. Peripapillary sclera in CD1 controls had significantly greater temporal meridional strain than B6 and had differences in the ratios of meridional to effective circumferential strain from B6 mice. In both CD1 and B6 mice, exposure to chronic IOP elevation resulted in stiffer pressure-strain responses for both the effective circumferential and meridional strains (multivariable regression model, P = 0.01-0.03). CONCLUSIONS: Longer eyes, greater scleral strain in some directions at baseline, and generalized scleral thinning after glaucoma were characteristic of CD1 mice that have greater tendency to retinal ganglion cell damage than B6 mice. Increased scleral stiffness after glaucoma exposure in mice mimics findings in monkey and human glaucoma eyes.

7 Article Quantitative mapping of collagen fiber orientation in non-glaucoma and glaucoma posterior human sclerae. 2012

Pijanka, Jacek K / Coudrillier, Baptiste / Ziegler, Kimberly / Sorensen, Thomas / Meek, Keith M / Nguyen, Thao D / Quigley, Harry A / Boote, Craig. ·Structural Biophysics Group, School of Optometry and Vision Sciences, Cardiff University, Cardiff, United Kingdom. ·Invest Ophthalmol Vis Sci · Pubmed #22786908.

ABSTRACT: PURPOSE: The posterior sclera has a major biomechanical influence on the optic nerve head, and may therefore be important in glaucoma. Scleral material properties are influenced significantly by collagen fiber architecture. Here we quantitatively map fiber orientation in non-glaucoma and glaucoma posterior human sclerae. METHODS: Wide-angle x-ray scattering quantified fiber orientation at 0.5-mm intervals across seven non-glaucoma post-mortem human sclerae, and five sclerae with glaucoma history and confirmed axon loss. Multiphoton microscopy provided semiquantitative depth-profiling in the peripapillary sclera. RESULTS: Midposterior fiber orientation was either uniaxial (one preferred direction) or biaxial (two directions). The peripapillary sclera was characterized by a ring of fibers located mainly in the mid-/outer stromal depth and encompassing ∼50% of the total tissue thickness. Fiber anisotropy was 37% higher in the peripapillary sclera compared with midposterior, varied up to 4-fold with position around the scleral canal, and was consistently lowest in the superior-nasal quadrant. Mean fiber anisotropy was significantly lower in the superior-temporal (P < 0.01) and inferior-nasal (P < 0.05) peripapillary scleral quadrants in glaucoma compared with non-glaucoma eyes. CONCLUSIONS: The collagen fiber architecture of the posterior human sclera is highly anisotropic and inhomogeneous. Regional differences in peripapillary fiber anisotropy between non-glaucoma and glaucoma eyes may represent adaptive changes in response to elevated IOP and/or glaucoma, or baseline structural properties that associate with predisposition to glaucomatous axon damage. Quantitative fiber orientation data will benefit numerical eye models aimed at predicting the sclera's influence on nerve head biomechanics, and thereby its possible role in glaucoma.

8 Article Biomechanics of the human posterior sclera: age- and glaucoma-related changes measured using inflation testing. 2012

Coudrillier, Baptiste / Tian, Jing / Alexander, Stephen / Myers, Kristin M / Quigley, Harry A / Nguyen, Thao D. ·Department of Mechanical Engineering, Johns Hopkins University, Baltimore, MD 21218, USA. ·Invest Ophthalmol Vis Sci · Pubmed #22395883.

ABSTRACT: PURPOSE: The objective of this study was to measure the biomechanical response of the human posterior sclera in vitro and to estimate the effects of age and glaucoma. METHODS: Scleral specimens from 22 donors with no history of glaucoma and 11 donors with a history of glaucoma were excised 3 mm posterior to the equator and affixed to an inflation chamber. Optic nerve cross-sections were graded to determine the presence of axon loss. The time-dependent inflation response was measured in a series of pressure-controlled load-unload tests to 30 mm Hg and creep tests to 15 and 30 mm Hg. Circumferential and meridional strains were computed from the digital image correlation displacements, and midposterior stresses were determined from pressure and deformed geometry. RESULTS: Among normal specimens, older age was predictive of a stiffer response and a thinner sclera. In the age group 75 to 93, diagnosed glaucoma eyes with axon damage were thicker than normal eyes. Both damaged and undamaged glaucoma eyes had a different strain response in the peripapillary sclera characterized by a stiffer meridional response. Undamaged glaucoma eyes had slower circumferential creep rates in the peripapillary sclera than normal eyes. Glaucoma eyes were not different from normal eyes in stresses and strains in the midposterior sclera. CONCLUSIONS: The observed differences in the biomechanical response of normal and glaucoma sclera may represent baseline properties that contribute to axon damage, or may be characteristics that result from glaucomatous disease.