Biomechanical model of human cornea based on stromal microstructure

Studer, H; Larrea, Xabier; Riedwyl, Hansjörg; Büchler, Philippe

doi:10.1016/j.jbiomech.2009.11.021

Cited by 88 publications

(76 citation statements)

References 28 publications

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“…Since collagen organization in collagen hydrogels is random, tissue-indentation testing was used to measure the stiffening of collagen regardless of orientation. As shown in a past study, 42 extensiometry with unidirectional tensile measurements of materials with random collagen fibers orientation only assess the collagen fibers parallel to the stretching direction. On the other hand, indentation testing is more convenient when using thin collagen hydrogels as used in the current experiment.…”

Section: Discussionmentioning

confidence: 98%

Nonlinear optical collagen cross-linking and mechanical stiffening: a possible photodynamic therapeutic approach to treating corneal ectasia

et al. 2013

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Abstract. In this study we test the hypothesis that nonlinear optical (NLO) multiphoton photoactivation of riboflavin using a focused femtosecond (FS) laser light can be used to induce cross-linking (CXL) and mechanically stiffen collagen as a potential clinical therapy for the treatment of keratoconus and corneal ectasia. Riboflavin-soaked, compressed collagen hydrogels are cross-linked using a FS laser tuned to 760 nm and set to either 100 mW (NLO CXL I) or 150 mW (NLO CXL II) of laser power. FS pulses are focused into the hydrogel using a 0.75 NA objective lens, and the hydrogel is three-dimensionally scanned. Measurement of hydrogel stiffness by indentation testing show that the calculated elastic modulus (E) values are significantly increased over twofold following NLO CXL I and II compared with baseline values (P < 0.05). Additionally, no significant differences are detected between NLO CXL and single photon, UVA CXL (P > 0.05). This data suggests that NLO CXL has a comparable effect to conventional UVA CXL in mechanically stiffening collagen and may provide a safe and effective approach to localize CXL at different regions and depths within the cornea. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Discussionmentioning

confidence: 98%

Nonlinear optical collagen cross-linking and mechanical stiffening: a possible photodynamic therapeutic approach to treating corneal ectasia

et al. 2013

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“…This model has been applied to the cornea by Studer et al [5]. The model parameters a and b have been identified using corneal inflation experimental data and optimal values found to be a ¼ 30 kPa and b ¼ 75 [44].…”

Section: Fibril and Shear Elasticitymentioning

confidence: 99%

“…However, no fully three-dimensional and comprehensive model has yet been presented. It is noteworthy that current finite-element-based models for structural analysis of the cornea treat the interfibrillar fluid as an incompressible or nearly incompressible elastic solid [3][4][5][6]. While this approach is convenient, it cannot describe swelling behaviour or (steady-state) bulk compressibility.…”

Section: Introductionmentioning

confidence: 99%

A structural model for thein vivohuman cornea including collagen-swelling interaction

Cheng

Petsche

Pinsky

2015

J. R. Soc. Interface.

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A structural model of the in vivo cornea, which accounts for tissue swelling behaviour, for the three-dimensional organization of stromal fibres and for collagen-swelling interaction, is proposed. Modelled as a binary electrolyte gel in thermodynamic equilibrium, the stromal electrostatic free energy is based on the mean-field approximation. To account for active endothelial ionic transport in the in vivo cornea, which modulates osmotic pressure and hydration, stromal mobile ions are shown to satisfy a modified Boltzmann distribution. The elasticity of the stromal collagen network is modelled based on three-dimensional collagen orientation probability distributions for every point in the stroma obtained by synthesizing X-ray diffraction data for azimuthal angle distributions and second harmonicgenerated image processing for inclination angle distributions. The model is implemented in a finite-element framework and employed to predict free and confined swelling of stroma in an ionic bath. For the in vivo cornea, the model is used to predict corneal swelling due to increasing intraocular pressure (IOP) and is adapted to model swelling in Fuchs' corneal dystrophy. The biomechanical response of the in vivo cornea to a typical LASIK surgery for myopia is analysed, including tissue fluid pressure and swelling responses. The model provides a new interpretation of the corneal active hydration control (pump-leak) mechanism based on osmotic pressure modulation. The results also illustrate the structural necessity of fibre inclination in stabilizing the corneal refractive surface with respect to changes in tissue hydration and IOP.

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“…Many different biomechanical models have been presented in the literature to model cornea behavior [12,11,15,19,20,22]. Most previous works measured the elastic constants of those models using ex-vivo human corneas from an eye bank [23,6].…”

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confidence: 99%

A new methodology for the in vivo estimation of the elastic constants that characterize the patient-specific biomechanical behavior of the human cornea

Lago

Rupérez

Martínez‐Martínez

et al. 2015

Journal of Biomechanics

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Elsevier Lago, MA.; Rupérez Moreno, MJ.; Martínez Martínez, F.; Monserrat Aranda, C.; Larra, E.; Gueell, JL.; Peris-Martinez, C. (2015). A new methodology for the in vivo estimation of the elastic constants that characterize the patient-specific biomechanical behavior of the human cornea. Journal of Biomechanics. 48(1): 38-43. doi:10.1016/j.jbiomech.2014.11.009. A new methodology for the in-vivo estimation of the elastic constants that characterize the patient-specific biomechanical behavior of the human cornea AbstractThis work presents a methodology for the in-vivo characterization of the complete biomechanical behavior of the human cornea of each patient. Specifically, the elastic constants of a hyperelastic, second-order Ogden model were estimated for 24 corneas corresponding to 12 patients. The finite element method was applied to simulate the deformation of human corneas due to non-contact tonometry, and an iterative search controlled by a genetic heuristic was used to estimate the elastic parameters that most closely approximates the simulated deformation to the real one. The results from a synthetic experiment showed that these parameters can be estimated with an error of about 5%. The results of 24 in-vivo corneas showed an overlap of about 90% between simulation and real deformed cornea and a modified Hausdorff distance of 25µm, which indicates the great accuracy of the proposed methodology.

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Biomechanical model of human cornea based on stromal microstructure

Cited by 88 publications

References 28 publications

Nonlinear optical collagen cross-linking and mechanical stiffening: a possible photodynamic therapeutic approach to treating corneal ectasia

Nonlinear optical collagen cross-linking and mechanical stiffening: a possible photodynamic therapeutic approach to treating corneal ectasia

A structural model for thein vivohuman cornea including collagen-swelling interaction

A new methodology for the in vivo estimation of the elastic constants that characterize the patient-specific biomechanical behavior of the human cornea

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