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Finite element analysis and preliminary experiments to study the effects of high myopia in macular degeneration.

机译：有限元分析和初步实验研究高度近视对黄斑变性的影响。

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摘要

Axial myopia is characterized by an elongation of the eye and defocusing of the image formed on the macula (central retina). The elongation in high myopia stretches the retina, which can cause hemorrhage, atrophy and the formation of new blood vessels in the macula and underlying tissue. This process leads to scarring, blurring and even loss of useful central vision.;A modeling approach has been developed to study the effect of deformed geometry, material properties and intraocular pressure on the pathology of myopic macular degeneration. 2-D axisymmetric and three dimensional finite element models of a myopic eye were generated to study the induced stress and integrity of the retinal layers. Cases of linear, bilinear and hyper-elastic Mooney-Rivlin material behavior were examined for the retina and linear and hyper-elastic Ogden (n=1) material model for the choroid. Mechanical tests were performed to mechanical material properties of bovine choroid membrane along with a traditional uniaxial tensile test. The modulus of elasticity for the bovine choroid averaged 0.2 +/- 0.08 MPa. Direct measurements enable the use of more realistic material properties during modeling. The finite element models showed maximum radial and circumferential stress in the region of the macula in each model. Maximum radial and circumferential tensile strains of 11% were observed in the macular region. Such high strains indicate that this region would be most vulnerable to mechanical changes occurring in axial myopia. Increased tensile strain (stretching of the retina) could lead to reduction of the density of photoreceptor cells, hemorrhage and formation of cracks in the macular region making it favorable for new blood vessels to grow in this region. Formation of these vessels can lead to bleeding; the result of which is scarring and loss of vision.;Thus the finite element modeling proves to be an effective method to study the mechanics involved in axial myopia, providing a mechanical explanation for the pathology of myopic macular degeneration.
机译：轴向近视的特征在于眼睛的伸长和在黄斑（中央视网膜）上形成的图像的散焦。高度近视眼的伸长会拉伸视网膜，这可能导致出血，萎缩以及黄斑和下层组织中新血管的形成。该过程导致有用的中央视线形成疤痕，模糊甚至丧失。;已经开发出一种建模方法来研究变形的几何形状，材料特性和眼内压对近视性黄斑变性的病理学的影响。生成了近视眼的二维轴对称和三维有限元模型，以研究诱导的应力和视网膜层的完整性。检查了线性，双线性和超弹性Mooney-Rivlin材料行为的案例，并检查了脉络膜的线性和超弹性Ogden（n = 1）材料模型。对牛脉络膜的机械材料性能进行了机械测试，同时进行了传统的单轴拉伸测试。牛脉络膜的弹性模量平均为0.2 +/- 0.08 MPa。直接测量可以在建模过程中使用更逼真的材料属性。有限元模型在每个模型中都显示出在黄斑区域最大的径向和周向应力。在黄斑区观察到最大径向和周向拉伸应变为11％。如此高的应变表明该区域最容易受到轴向近视眼中发生的机械变化的影响。拉伸应变的增加（视网膜的拉伸）可能导致感光细胞密度降低，出血以及黄斑区域裂缝的形成，从而有利于新血管在该区域的生长。这些血管的形成会导致出血；因此，有限元建模被证明是研究轴性近视的相关力学的有效方法，为近视性黄斑变性的病理学提供了力学解释。

著录项

  • 作者

    Bendre, Aneesh Ajay.;

  • 作者单位

    Northeastern University.;

  • 授予单位 Northeastern University.;
  • 学科 Health Sciences Ophthalmology.;Engineering Mechanical.
  • 学位 M.S.
  • 年度 2009
  • 页码 77 p.
  • 总页数 77
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类 机械、仪表工业;
  • 关键词

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