以靜力與動力學分析計算眼角膜力學性質

Abstract

眼疾病患中有著大部分的患者是角膜受損，現今大部分的角膜檢查技術多以定性的觀測少有定量的數值，特別是生物力學參數的應用。角膜生物力學(biomechanical)的改變不僅會產生角膜病變，同時也會影響眼壓的量測結果。由於眼球的力學參數量測必需以非侵入的方式執行，而且必須在極小時間和接觸力的情形之下，這條件增加眼角膜觀測的難度。藉由眼壓機所輸出的角膜變形資料是目前最先進的方式，本研究提供三種方式探討角膜的基本臨床力學參數─楊氏模數。首先以薄殼理論所建立的數學模型並結合最佳化數值方法來計算眼角膜的靜力環境下的平面內楊氏模數。再以質量阻尼彈簧系統分析眼角膜動態環境下的平面外楊氏模數。最後結合球體振動模態、波動理論與最佳化數值法來計算眼角膜在動力模型下的楊氏模數與阻尼係數，同時以眼睛解剖學來說明所推估眼球振動模態關係。本技術提供臨床的楊氏模數值，相較於目前文獻中的檢體楊氏模數值更有臨床醫學上的價值，未來此技術可輔助現有眼壓設備提供眼科醫學建立量化資料庫。

Cornea is a very small structure in the eye, but it holds the key to clear vision. Once a cornea is damaged, it will leads to all kinds of eye diseases. Most of the techniques for cornea examination nowadays are based on qualitative analysis. Only very few of them are based on quantitatively analysis, especially the application of the biomechanical parameters. The biomechanical change of the cornea is not only the cause of retinopathy, but also effect the measurement of the intraocular pressure. Since getting the biomechanical parameters with the non-invasive modalities is necessary, it became more difficult to get the right measurements. In this study, there are three different approaches to calculate the Yong’s modulus. First, based on the theory of thin shell and combined with numerical optimization techniques. Second, using the Lumped mass-damping-spring system. And the last is the combination of the shell modal analysis and the wave propagation theories. By calculating the Young’s modulus with the techniques in this study, they can provide much more invaluable and accurate data in clinical medicine of ophthalmology.