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Intraocular pressure measurements using vibration based non-contact tonometry.

机译：使用基于振动的非接触眼压计进行眼压测量。

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摘要

Glaucoma is a group of diseases of the optic nerve that can lead to blindness and is generally characterized by an increase of intraocular pressure (IOP). Early detection of glaucoma is important because, in many cases, the disease can be successfully treated in its early stages. Monitoring of the IOP is the most common way to detect glaucoma. In this study, the correlation between intraocular pressure (IOP) and the vibration characteristics of the eye is investigated through a series of finite element and experimental modal analyses. Cadaver pig eyes were used in this investigation, due to their similarity in size and structural properties to human eyes. Finite element analysis was performed using a three dimensional shell model to examine the correlation between IOP and vibration characteristics of eyes. Experimental modal analysis was then carried out using a hammer and an accelerometer to acquire the vibration parameters by performing the spectral analysis. The IOP of eye was controlled and gradually changed using a manometer system. The comparison between the finite element model and the experimental results shows a good correlation: an increase in IOP also increased the natural frequencies. Therefore, vibration characteristics can be used to estimate a change in IOP. The correlations between different physical parameters of the eye and IOP were also investigated through a series of regression analyses.;Based on the premise that IOP is correlated to natural frequency, a non-contact vibration based tonometer is designed and tested. A design analysis identified three critical systems in a vibration based tonometer: the excitation of the eye, the measurement of the input signal, and the measurement of the output signal. This approach is applied to develop a non-contact EMA technique for tonometry purposes. Proof of concept of this non-contact EMA technique was explored by exciting a cantilever beam using a collimated air impulse controlled by a solenoid valve. The reflected airwave from the beam surface was measured by a microphone array. The experimental tests demonstrate the effectiveness of the proposed methodology to both accurately and cost-effectively measure structural dynamics in translational and rotational degrees. This method is also assessed on cadaver pig eyes at different IOPs and showed a good correlation between the dynamics and IOPs. This study provides a basis for the development of a vibration based portable tonometer for which patients can self-monitor their IOPs to prevent vision loss.
机译：青光眼是一组会导致失明的视神经疾病，通常以眼内压（IOP）升高为特征。青光眼的早期发现很重要，因为在许多情况下，该疾病可以在早期得到成功治疗。监测眼压是检测青光眼的最常见方法。在这项研究中，通过一系列有限元和实验模态分析，研究了眼内压（IOP）与眼睛振动特性之间的相关性。尸体猪眼因其大小和结构特性与人眼相似而用于本研究。使用三维壳模型进行了有限元分析，以检查IOP和眼睛振动特性之间的相关性。然后使用锤子和加速度计进行实验模态分析，以通过执行频谱分析来获取振动参数。使用压力计系统控制并逐渐改变眼睛的IOP。有限元模型与实验结果之间的比较显示出良好的相关性：IOP的增加也增加了固有频率。因此，振动特性可用于估计IOP的变化。还通过一系列回归分析研究了眼睛的不同物理参数与眼压之间的相关性。；在眼压与自然频率相关的前提下，设计并测试了非接触式眼压计。设计分析确定了基于振动的眼压计中的三个关键系统：眼睛的激励，输入信号的测量和输出信号的测量。该方法用于开发用于眼压测量的非接触式EMA技术。通过使用由电磁阀控制的准直空气脉冲激发悬臂梁，探索了这种非接触式EMA技术的概念证明。从光束表面反射的无线电波通过麦克风阵列进行测量。实验测试证明了所提出的方法在准确和平移地测量结构动力学方面的有效性。还对尸体猪眼在不同眼压下进行了评估，该方法在动力学和眼压之间显示出良好的相关性。这项研究为开发基于振动的便携式眼压计提供了基础，患者可以自我监测眼压以防止视力丧失。

著录项

  • 作者

    Farshidi, Reza.;

  • 作者单位

    University of Calgary (Canada).;

  • 授予单位 University of Calgary (Canada).;
  • 学科 Engineering Mechanical.
  • 学位 M.Sc.
  • 年度 2010
  • 页码 204 p.
  • 总页数 204
  • 原文格式 PDF
  • 正文语种 eng
  • 中图分类
  • 关键词

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