SIMULATING THE EFFECTS OF ELEVATED INTRAOCULAR PRESSURE ON OCULAR STRUCTURES USING A GLOBAL FINITE ELEMENT MODEL OF THE HUMAN EYE

2017 ◽  
Vol 17 (02) ◽  
pp. 1750038 ◽  
Author(s):  
PEISHAN DAI ◽  
YALI ZHAO ◽  
HANWEI SHENG ◽  
LING LI ◽  
JING WU ◽  
...  
Keyword(s):  
Finite Element ◽  
Intraocular Pressure ◽  
Element Model ◽  
Global Model ◽  
Eye Model ◽  
Human Eye ◽  
Anterior Eye Segment ◽  
Elevated Intraocular Pressure ◽  
Biomechanical Responses ◽  
Iop Elevation

Elevated intraocular pressure (IOP) may be the primary risk factor to the development of glaucoma. Finite element (FE) modeling is commonly considered as an effective method to quantitatively analyze pathogenesis of glaucoma. Recent researches focus on establishing partial human eye models. A refined global human eye model was developed using ANSYS software to investigate the correlation between IOP elevation and biomechanical responses. First, the pressure transferring process according to IOP elevation in the whole eye was analyzed to simulate the effects of IOP elevation on glaucoma. Then, the biomechanical responses of the anterior eye segment under various pressure differences between the anterior and posterior chambers (AC and PC) were analyzed to simulate posterior nonadhesion of iris and posterior synechia. This global eye model not only simulated the responses of elevated IOP on ocular structures, but also revealed the process of pressure transferring among each tissue from the anterior eye segment to the optic nerve head (ONH) region. The local mechanical characteristics of the ocular structures obtained from the global model agreed with previous findings. This global model may shed light on the studies of multifactorial glaucoma.

scholarly journals Frequency spectrum of the human head–neck to mechanical vibrations

2017 ◽  
Vol 37 (3) ◽  
pp. 611-618 ◽  
Author(s):  
Bin Yang ◽  
Zheng Shi ◽  
Qun Wang ◽  
Feng Xiao ◽  
Tong-Tong Gu ◽  
...  
Keyword(s):  
Finite Element ◽  
Frequency Spectrum ◽  
Mechanical Vibration ◽  
Three Dimensional ◽  
Human Head ◽  
Element Model ◽  
Mode Shapes ◽  
Joint Disorder ◽  
Biomechanical Responses ◽  
Head Neck

This study is based on a real finite element human head–neck model and concentrates on its numerical vibration characteristic. Frequency spectrum and mode shapes of the finite element model of human head–neck under mechanical vibration have been calculated. These vibration characteristics are in good agreement with the previous studies. The simulated fundamental frequency of 35.25 Hz is fairly similar to the published documents, and rarely reported modal responses such as “mastication” and flipping of nasal lateral cartilages modes, however, are introduced by our three-dimensional modal analysis. These additional modes may be of interest to surgeons or clinicians who are specialized in temporomandibular or rhinoplasty joint disorder. Modal validation in terms of modal shapes proposes a necessity for elaborate modeling to identify each individual part’s extra frequencies. Furthermore, it also studies the influence of damping on resonant frequencies and biomechanical responses. It is discovered that damping has an inverse proportionality between damping effect on natural frequency and that on biomechanical responses.

Improved Correlation of Measured and Predicted Hysteresis Loops in a Multiaxial Fretting Fatigue Test Rig for Spline Couplings

2007 ◽  
Vol 7-8 ◽  
pp. 37-42
Author(s):  
D. Houghton ◽  
P.M. Wavish ◽  
Edward J. Williams ◽  
Sean B. Leen
Keyword(s):  
Finite Element ◽  
Finite Element Model ◽  
Fatigue Test ◽  
Hysteresis Loops ◽  
Element Model ◽  
Fretting Fatigue ◽  
Global Model ◽  
Test Rig ◽  
Force Displacement

This paper investigates the comparison of the measured and predicted force-displacement loops of a multiaxial representative fretting fatigue test rig for aeroengine spline couplings. A local finite element model of the fretting specimen and the fretting bridge is outlined. A more extensive model of the fretting test rig is then introduced. This global model also includes the loading structures. The model captures the compliance of the fretting test rig and improves the correlation of the observed hysteresis. This method allows the slip amplitude at the contacts to be quantified.

Large Scale Voxel-Based Finite Element Modeling of Normal and Early Glaucomatous Monkey Lamina Cribrosa

2008 ◽  
Author(s):  
Sanjay Kodiyalam ◽  
Michael D. Roberts ◽  
Ian A. Sigal ◽  
Richard T. Hart ◽  
Claude F. Burgoyne ◽  
...  
Keyword(s):  
Finite Element ◽  
Intraocular Pressure ◽  
Connective Tissue ◽  
Large Scale ◽  
Lamina Cribrosa ◽  
Posterior Pole ◽  
Stress And Strain ◽  
Structural Support ◽  
Elevated Intraocular Pressure ◽  
Related Stress

Glaucoma is a leading cause of blindness worldwide. Some of the chief clinical hallmarks of glaucoma are the permanent posterior cupping of the optic nerve head, in the posterior pole of the eye, and the accompanying damage to the lamina cribrosa — the fenestrated structure of connective tissue spanning the scleral canal that provides structural support to the axon bundles passing through it. While elevated intraocular pressure (IOP) is associated with this disease, its role remains unclear. It has been hypothesized that IOP-related stress and strain within the laminar connective tissue (LCT) underlie the onset and progression of glaucoma [1] and that they may be used to predict the location of axonal insult and the pattern of damage within the LCT.

Finite Element Analysis of the Human Eye for a Range of Intraocular Pressure

2020 ◽  
pp. 173-181
Author(s):  
R. Vivek Suganthan ◽  
S. Meenatchi Sundaram ◽  
S. Ve Ramesh ◽  
Thomas Rinu ◽  
R. Pai ◽  
...  
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Intraocular Pressure ◽  
Element Analysis ◽  
Human Eye

Finite Element Analysis of a Close Head Axonal Injury Model: Relating Brain Tissue Biomechanics to Skull Deformation

2008 ◽  
Author(s):  
Haojie Mao ◽  
Liying Zhang ◽  
King H. Yang ◽  
Albert I. King ◽  
J’ozsef Pál ◽  
...  
Keyword(s):  
Finite Element ◽  
Compressive Strain ◽  
Axonal Injury ◽  
Element Model ◽  
Element Analysis ◽  
Injury Model ◽  
Weight Drop ◽  
Biomechanical Responses ◽  
Histological Results ◽  
The Impact

Biomechanical responses of a rat brain in a new weight-drop model were investigated by comparing histological results against finite element model predictions. This graded axonal injury rat model differed from others because of its utilization of intact skull without global angular motion to confound data analyses. Results demonstrated that the maximum principal strain and the compressive strain along the impact direction best correlated the experimentally observed injury locations while the shear strain did not have positive correlation.

scholarly journals A Water Balloon Eye Model for Teaching about the Human Eye

2020 ◽  
Vol 82 (5) ◽  
pp. 341-343
Author(s):  
Kwok-chi Lau
Keyword(s):  
Intraocular Pressure ◽  
Eye Model ◽  
Human Eye ◽  
Convex Lens

A physical eye model made of a water balloon and a convex lens is described. It can be used to model how an image is formed in the eye as well as shortsightedness and farsightedness. The model is unique in featuring a fluid-filled “eyeball” with “intraocular pressure,” making it a useful tool for teaching about accommodation and glaucoma. Instructional ideas for the model are suggested.

FINITE ELEMENT ANALYSIS OF THE MECHANICAL CHARACTERISTICS OF GLAUCOMA

2016 ◽  
Vol 16 (04) ◽  
pp. 1650060 ◽  
Author(s):  
PEISHAN DAI ◽  
HAN HAN ◽  
YALI ZHAO ◽  
MIN FAN
Keyword(s):  
Finite Element Analysis ◽  
Finite Element ◽  
Optic Nerve ◽  
Finite Element Model ◽  
Mechanical Characteristics ◽  
Element Model ◽  
Finite Element Method Result ◽  
Element Analysis ◽  
Human Eye ◽  
Geometry Model

Purpose: Construct a finite element model of the human eye to quantitatively analyze the mechanical characteristics of the human eye, especially the glaucoma damage process of the optic nerve head (ONH). Method: First, the geometry model of the human eye with nonuniform thickness was established based on a reasonable hypothesis and assumptions. Because the ONH is an important factor for glaucoma, we refine the structure of the ONH with lamina cribrosa. Then, mesh division was applied for finite element analysis. To simplify the complexity of the analysis, the materials of the model were assumed to be isotropic linear elastic materials, and physical properties such as Young’s modulus and Poisson’s ratio were set according to published literature. Next, proper constraints and loads were applied to the model and solved with a finite element method. Result: A finite element model of the human eye was created to simulate the mechanical characteristics of the eye structures under high intraocular pressure (IOP). The ONH depressed 1.057[Formula: see text]mm under 0.009[Formula: see text]MPa pressure to simulate high IOP. Conclusion: The constructed model is able to quantitatively simulate excavation of the optic disc and damage of the optic nerve. The result proved Houcheng Liang’s hypothesis about the ONH damage mechanism in glaucoma.

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