Simulation of Active Eye Motion Using Finite Element Modelling

Karami, Abbas; Eghtesad, Mohammad

doi:10.1590/1679-78254016

Cited by 2 publications

(1 citation statement)

References 26 publications

(48 reference statements)

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“…While these efforts shed much light on the vitreous behaviour, and the fact that some methods subjected the tissue to non-physiological conditions led to a wide variation in the shear relaxation modulus reported in the literature. Saccadic eye movement has been modelled in several studies [24][25][26]; David et al [27] investigated the vitreous behaviour due to eye movement. They only compared between a numerical and analytical model of the vitreous.…”

Section: Introductionmentioning

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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Section: Introductionmentioning

confidence: 99%

Experimental evaluation of the viscoelasticity of porcine vitreous

Aboulatta

Abass

Makarem

et al. 2021

J. R. Soc. Interface.

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Finite element model of ocular adduction with unconstrained globe translation

Jafari,

Park,

et al. 2024

Biomech Model Mechanobiol

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Details of the anatomy and behavior of the structures responsible for human eye movements have been extensively elaborated since the first modern biomechanical models were introduced. Based on these findings, a finite element model of human ocular adduction is developed based on connective anatomy and measured optic nerve (ON) properties, as well as active contractility of bilaminar extraocular muscles (EOMs), but incorporating the novel feature that globe translation is not otherwise constrained so that realistic kinematics can be simulated. Anatomy of the hemisymmetric model is defined by magnetic resonance imaging. The globe is modeled as suspended by anatomically realistic connective tissues, orbital fat, and contiguous ON. The model incorporates a material subroutine that implements active EOM contraction based on fiber twitch characteristics. Starting from the initial condition of 26° adduction, the medial rectus (MR) muscle was commanded to contract as the lateral rectus (LR) relaxed. We alternatively modeled absence or presence of orbital fat. During pursuit-like adduction from 26 to 32°, the globe translated 0.52 mm posteriorly and 0.1 mm medially with orbital fat present, but 1.2 mm posteriorly and 0.1 mm medially without fat. Maximum principal strains in the optic disk and peripapillary reached 0.05–0.06, and von-Mises stress 96 kPa. Tension in the MR orbital layer was ~ 24 g-force after 6° adduction, but only ~ 3 gm-f in the whole LR. This physiologically plausible simulation of EOM activation in an anatomically realistic globe suspensory system demonstrates that orbital connective tissues and fat are integral to the biomechanics of adduction, including loading by the ON.

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Simulation of Active Eye Motion Using Finite Element Modelling

Cited by 2 publications

References 26 publications

Experimental evaluation of the viscoelasticity of porcine vitreous

Experimental evaluation of the viscoelasticity of porcine vitreous

Finite element model of ocular adduction with unconstrained globe translation

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