A method to determine the mechanical properties of the retina based on an experiment in vivo

Qian, Xiuqing; Zhang, Kunya; Liu, Zhicheng

doi:10.3233/bme-151316

Cited by 10 publications

(13 citation statements)

References 40 publications

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“…The majority of inverse FE studies on ocular biomechanics have focused on the corneoscleral tunic in ex vivo models [50][51][52]. However, Qian et al [53] applied inverse FE analysis to assess biomechanical properties of the choroid and retina in vivo. The authors injected saline into the anterior chamber of a cat eye while monitoring pressure using a pressure transducer.…”

Section: Finite and Inverse Finite Element Modellingmentioning

confidence: 99%

Biomechanical properties of retina and choroid: a comprehensive review of techniques and translational relevance

Ferrara

Lugano

Sandinha

et al. 2021

Eye

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Studying the biomechanical properties of biological tissue is crucial to improve our understanding of disease pathogenesis. The biomechanical characteristics of the cornea, sclera and the optic nerve head have been well addressed with an extensive literature and an in-depth understanding of their significance whilst, in comparison, knowledge of the retina and choroid is relatively limited. Knowledge of these tissues is important not only to clarify the underlying pathogenesis of a wide variety of retinal and vitreoretinal diseases, including age-related macular degeneration, hereditary retinal dystrophies and vitreoretinal interface diseases but also to optimise the surgical handling of retinal tissues and, potentially, the design and properties of implantable retinal prostheses and subretinal therapies. Our aim with this article is to comprehensively review existing knowledge of the biomechanical properties of retina, internal limiting membrane (ILM) and the Bruch’s membrane–choroidal complex (BMCC), highlighting the potential implications for clinical and surgical practice. Prior to this we review the testing methodologies that have been used both in vitro, and those starting to be used in vivo to aid understanding of their results and significance.

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Section: Finite and Inverse Finite Element Modellingmentioning

confidence: 99%

Biomechanical properties of retina and choroid: a comprehensive review of techniques and translational relevance

Ferrara

Lugano

Sandinha

et al. 2021

Eye

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“…Material properties of the different regions of the numerical model. cornea [17] limbal region [17] anterior sclera [17] equatorial region [17] posterior sclera [17] retina [36] gelatin The experimental results show that in tests with eye rotation up to 5°, the displacement monitored in the vitreous did not exceed 4°in the transient state and 3.2°in the steady state in all tests. The corresponding maximum displacements in tests with 10°maximum rotation were 6.5°in the transient state and 4.2°in the steady state.…”

Section: Inverse Analysismentioning

confidence: 80%

“…The cornea, limbus, retina and sclera of all specimens were assumed to follow the stress-strain behaviour reported in the literature for porcine eyes [17,36]. Following earlier research, the eye model components were assumed to comply with Ogden's hyperelastic strain energy function [37] with the material parameters listed in table 1 [38] W ¼…”

Section: Materials Propertiesmentioning

confidence: 99%

Experimental evaluation of the viscoelasticity of porcine vitreous

Aboulatta

Abass

Makarem

et al. 2021

J. R. Soc. Interface.

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This study aims to estimate the material properties of the porcine vitreous while testing it in close to its natural physiological conditions. Eighteen porcine eyes were tested within 48 h post-mortem. A custom-built computer-controlled test rig was designed to support, load and monitor the behaviour of eye globes while being subjected to dynamic rotation cycles mimicking saccade eye movement. Specimens were glued to the base of a container, surrounded by gelatin, frozen and cut in half to expose the vitreous. After thawing, the container was subjected to concentric dynamic rotations of up to 5°, 10° or 15°, while taking 50 MP photos of the specimen every 2 ms. The images were analysed by a digital image correlation algorithm to trace the movement of marked points on the vitreous surface with different radii from the centre of the posterior chamber. The initial camera image was used in building a finite-element model of the test set-up, which was used in an inverse analysis exercise to estimate the material properties of the vitreous. Angular displacements of the monitored points were up to 3.3°, 4.1° and 3.9° in response to eye rotations of 5°, 10° and 15°, respectively. With the experimental relationships between eye rotation and angular displacements used as target behaviour, the inverse analysis exercise estimated the initial shear modulus, the long-term shear modulus and the viscoelastic decay constant of the porcine vitreous as 2.10 ± 0.15 Pa, 0.50 ± 0.04 Pa and 1.20 ± 0.09 s −1 , respectively. Consideration of the viscoelasticity of the vitreous was essential to represent its experimental behaviour. Testing the vitreous in close to its normal physiological conditions produced estimations of the initial shear modulus and long-term shear modulus that were, respectively, smaller and larger than reported values (Zimberlin et al . 2010 Soft Matter 6, 3632–3635. ( doi:10.1039/b925407b ), Liu et al . 2013 J. Biomech. 46, 1321–7. ( doi:10.1016/j.jbiomech.2013.02.006) , Rossi et al . 2011 Invest. Ophthalmol. Vis. Sci. 52, 3994–4002. ( doi:10.1167/iovs.10-6477 )).

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“…28 These factors could be the reason behind the wide range of reported retinal stiffness values. Qian et al 31 extracted the cat's retinal stiffness in vivo by combining OCT technique with IFEM. They reported a shear modulus of 75.9 kPa, which is similar to our results (64.2 ± 36.1 kPa).…”

Section: Discussionmentioning

confidence: 99%

In Vivo Measurements of Prelamina and Lamina Cribrosa Biomechanical Properties in Humans

Zhang

Beotra

Baskaran

et al. 2020

Invest. Ophthalmol. Vis. Sci.

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To develop and use a custom virtual fields method (VFM) to assess the biomechanical properties of human prelamina and lamina cribrosa (LC) in vivo. METHODS. Clinical data of 20 healthy, 20 ocular hypertensive (OHT), 20 primary openangle glaucoma, and 16 primary angle-closure glaucoma eyes were analyzed. For each eye, the intraocular pressure (IOP) and optical coherence tomography (OCT) images of the optic nerve head (ONH) were acquired at the normal state and after acute IOP elevation. The IOP-induced deformation of the ONH was obtained from the OCT volumes using a three-dimensional tracking algorithm and fed into the VFM to extract the biomechanical properties of the prelamina and the LC in vivo. Statistical measurements and P values from the Mann-Whitney-Wilcoxon tests were reported. RESULTS. The average shear moduli of the prelamina and the LC were 64.2 ± 36.1 kPa and 73.1 ± 46.9 kPa, respectively. The shear moduli of the prelamina of healthy subjects were significantly lower than those of the OHT subjects. Comparisons between healthy and glaucoma subjects could not be made robustly due to a small sample size. CONCLUSIONS. We have developed a methodology to assess the biomechanical properties of human ONH tissues in vivo and provide preliminary comparisons in healthy and OHT subjects. Our proposed methodology may be of interest for glaucoma management.

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A method to determine the mechanical properties of the retina based on an experiment in vivo

Cited by 10 publications

References 40 publications

Biomechanical properties of retina and choroid: a comprehensive review of techniques and translational relevance

Biomechanical properties of retina and choroid: a comprehensive review of techniques and translational relevance

Experimental evaluation of the viscoelasticity of porcine vitreous

In Vivo Measurements of Prelamina and Lamina Cribrosa Biomechanical Properties in Humans

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