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標題: | 眼角膜振動之模態分析 Modal Analysis of Corneal Vibration |
作者: | Hsin-Ju Lai 賴歆儒 |
指導教授: | 顏家鈺(Jia-Yush Yen) |
關鍵字: | 角膜生物力學,模態分析,二維波動,圓錐角膜,早期診斷, corneal biomechanics,modal analysis,two-dimensional wave,keratoconus,early diagnosis, |
出版年 : | 2018 |
學位: | 碩士 |
摘要: | 角膜為位於眼睛前方透明的薄膜,表面光滑、質地堅韌並有彈性,覆蓋虹膜、瞳孔及前房,提供眼睛大部分的屈光力。本研究目標為探索執行眼壓量測時,眼角膜在受到氣壓後產生之不規律振動所代表的意義,角膜的振動會依角膜的幾何形狀而改變,而幾何形狀隱含了病理特徵。首先,我們架設了豬角膜吹氣實驗,在高速攝影下,觀測和分析角膜的運動,發展出一套演算法,能利用影像處理的技術來獲取二維角膜運動,並用勒壤得多項式解構出振動的特徵函數及模態係數,分別比較了不同眼壓大小、吹氣角度及受損角膜和正常角膜在模態係數歷時上的差異,找出其對應特徵,接下來,我們使用由臺大醫院及林宏洲診所提供之非接觸式Corvis®ST眼壓計,套用同樣的模態分析演算法,結果發現角膜模態係數會隨左右眼、角膜厚度、眼壓高低及患有圓錐角膜與否而有所變化。依據所定五個判斷圓錐角膜準則計算其靈敏度、特異性及準確度,並繪製ROC曲線,可分別達到靈敏度0.98、特異性1及準確度0.92,此演算法未來將有助於早期圓錐角膜的診斷及屈光手術前的評估。 Cornea is a transparent material locating in front of the eye with smooth, tough and elastic surface. It covers the iris, pupil and anterior chamber and accounts for most of the eye's refractive power. The aim of this study is to analyze cornea’s irregular vibration during air-puff time in the measurement of intraocular pressure. The differences in corneal vibration result from the geometric differences in cornea which would indicate to corneal pathologies. Firstly, we developed an air-puff experiment with porcine cornea to observe and analyze the movement of cornea under a high-speed camera. We developed an algorithm to acquire two-dimensional corneal deformation with the technique of image processing. Besides, we use Legendre polynomials to decompose Legendre orthogonal modes (vibrational eigenfunctions) and their modal parameters. By testing different intraocular pressure, different air-puff angle and artificial-injured cornea, changes in modal parameters can be identified. Next, we use non-contact Corvis® ST tonometer provided by National Taiwan University Hospital and Dr. Lin’s Eye Clinic and implement the same modal analysis. The result shows that the modal parameters of left and right eyes, cornea with various thickness, with different intraocular pressure are different in value. Furthermore, cornea with keratoconus also shows differences comparing with normal cornea. By establishing five diagnostic indexes and their ROC curves, the sensitivity in diagnosing keratoconus is 0.98, the specificity is 1 and the accuracy can be up to 0.92 respectively. This algorithm can play a role in early diagnosis of keratoconus and preoperative evaluation in the near future. |
URI: | http://tdr.lib.ntu.edu.tw/jspui/handle/123456789/69599 |
DOI: | 10.6342/NTU201800955 |
全文授權: | 有償授權 |
顯示於系所單位: | 機械工程學系 |
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