Finite Element Model of Ocular Adduction by Active Extraocular Muscle Contraction

Jafari, Somaye; Lü, Yongtao; Park, Joseph; Demer, Joseph L.

doi:10.1167/iovs.62.1.1

Cited by 17 publications

(16 citation statements)

References 54 publications

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“…Likewise, Shin et al [ 9 ] studied ONH stresses and strains during 6° adduction vs multiple levels of IOP in an FE model, concluding that adduction produces far greater mechanical stress and strain than does IOP elevation. A recent FE study performed by Jafari et al [ 10 ], in which a 6° ocular rotation was generated, has also confirmed these findings. Thus, as a result, it has been hypothesized that eye movements could also contribute to the development of glaucomatous optic neuropathy [ 8 , 9 , 11 , 12 ].…”

Section: Introductionsupporting

confidence: 55%

“…The classic physiopathology theory of glaucoma poses that an increase in intraocular pressure (IOP) would lead to compression of the axons at the lamina cribrosa (LC) with consequent ischemia and axoplasmic flow blockage, and hence the death of RGC [ 2 ]. However, although high IOP is recognized as the most important risk factor for glaucoma [ 3 ], this is not the only mechanical load experienced by the optic nerve, as it is also influenced by cerebrospinal fluid pressure [ 4 , 5 ], IOP fluctuations [ 6 ], vascular pulsatility [ 7 ], and eye movements [ [8] , [9] , [10] , [11] , [12] , [13] , [14] , [15] , [16] , [17] , [18] , [19] , [20] ], among other factors.…”

Section: Introductionmentioning

confidence: 99%

“…On the other hand, eye anatomy has typically been reconstructed variably in FE studies. As a result, different eye regions and tissues have been included and excluded in posterior ocular models [ [8] , [9] , [10] , [11] , [12] , [31] , [32] , [33] , [34] , [35] , [36] , [37] ]. Biologically the eye is comprised of three tunics, namely: fibrous (cornea and sclera), vascular (iris, ciliary body, and choroid), and nervous (retina), and it is located within the orbit and surrounded by fat [ 38 ].…”

Section: Introductionmentioning

confidence: 99%

“…Nevertheless, some ocular models have not included the choroid [ [8] , [9] , [10] , 12 , 31 , 32 , 34 , 36 , 37 ], and some others neither the nervous tunic [ 9 , 10 , 12 , 33 ]. Besides that, the retina has usually been regarded as an extension of the prelaminar tissue [ 40 ] and adipose tissue has not been commonly incorporated.…”

Section: Introductionmentioning

confidence: 99%

See 3 more Smart Citations

The impact of horizontal eye movements versus intraocular pressure on optic nerve head biomechanics: A tridimensional finite element analysis study

Sarmiento

Montaño²,

Rodríguez³

2023

Heliyon

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Section: Introductionsupporting

confidence: 55%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

See 2 more Smart Citations

The impact of horizontal eye movements versus intraocular pressure on optic nerve head biomechanics: A tridimensional finite element analysis study

Sarmiento

Montaño²,

Rodríguez³

2023

Heliyon

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“…Clearly, other sources of stress on the ON besides IOP deserve consideration. We [1][2][3]11,[35][36][37] and others 16,[38][39][40] have suggested that eye movements could constitute another important source of mechanical damage to the ON.…”

mentioning

confidence: 99%

Finite element modeling of effects of tissue property variation on human optic nerve tethering during adduction

Park

Shin

Demer

2022

Sci Rep

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Tractional tethering by the optic nerve (ON) on the eye as it rotates towards the midline in adduction is a significant ocular mechanical load and has been suggested as a cause of ON damage induced by repetitive eye movements. We designed an ocular finite element model (FEM) simulating 6° incremental adduction beyond the initial configuration of 26° adduction that is the observed threshold for ON tethering. This FEM permitted sensitivity analysis of ON tethering using observed material property variations in measured hyperelasticity of the anterior, equatorial, posterior, and peripapillary sclera; and the ON and its sheath. The FEM predicted that adduction beyond the initiation of ON tethering concentrates stress and strain on the temporal side of the optic disc and peripapillary sclera, the ON sheath junction with the sclera, and retrolaminar ON neural tissue. However, some unfavorable combinations of tissue properties within the published ranges imposed higher stresses in these regions. With the least favorable combinations of tissue properties, adduction tethering was predicted to stress the ON junction and peripapillary sclera more than extreme conditions of intraocular and intracranial pressure. These simulations support the concept that ON tethering in adduction could induce mechanical stresses that might contribute to ON damage.

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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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Finite Element Model of Ocular Adduction by Active Extraocular Muscle Contraction

Cited by 17 publications

References 54 publications

The impact of horizontal eye movements versus intraocular pressure on optic nerve head biomechanics: A tridimensional finite element analysis study

The impact of horizontal eye movements versus intraocular pressure on optic nerve head biomechanics: A tridimensional finite element analysis study

Finite element modeling of effects of tissue property variation on human optic nerve tethering during adduction

Finite element model of ocular adduction with unconstrained globe translation

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