眼內流場之模擬

Ocular Hydrodynamic Simulator: A digital model

蔡振行(Chen-Hsin Tsai)

指導教授 ： 黃曼菁

共同指導教授 ： 李宗翰

臺北醫學大學/醫學院/臨床醫學研究所/碩士(2012年)

https://doi.org/10.6831/TMU.2012.00094

摘要

人類眼球是一個相對封閉的球狀器官，主要負責視覺與日夜週期的調整。視覺的功能仰賴眼球內緩慢而穩定的流場維持著眼球固定形狀，提供一致的屈光特性，因而眼睛房水的生成與代謝必須被精密的調控，當眼壓過高則會壓迫視神經，造成視力受損稱為青光眼。臨床上對於青光眼的治療目前僅止於降低眼壓，然而對於眼內的流場狀況並無從得到資訊，流場相對於眼內構造形成的影響也無法測量。
本研究是利用電腦軟體 Pro/Engineer 和 ANSYS 模擬眼球模型，以有限元素分析方法探討眼內流場，進而比較青光眼疾病臨床數據與模擬的可行性。
本研究成功模擬眼內慢速流場的變化，模型中可模擬出的眼壓值與臨床大致相仿，青光眼眼內壓力最大值出現於睫狀體附近，累積而往後傳遞到視神經，造成視神經受損。此外由於流動的力場對於眼內各點產生的壓力不一致，眼球後方的實際壓力值低於臨床測得的眼壓值，顯示視神經實際上對於壓力的耐受閥值可能低於我們過去的認知。

關鍵字

有限原素分析, 青光眼, 房水

並列摘要

Human eye is a relative close system severing for vision and diurnal cycle. The stable hydrodynamic system of eye maintains a constant shape of eyeball, which is essential for refractive purpose. Glaucoma is one of the leading causes of blindness in developing country, which is strongly related to high intra-ocular pressure. However, the hydrodynamic changes, even intra-ocular pressure of the eye is not easy to measure directly.
We uses Pro/Engineer and ANSYS software to build a digital model of ocular hydrodynamics in this study. The data would then compare with the real conditions of disease and verify the feasibility of simulation of the eyeball model.
The calculated intraocular pressure of normal and glaucoma models shows similar reading with clinical data. The highest intra-ocular pressure presents near the ciliary body in glaucoma model and passes backward to optic disc, causing optic injury. Due to the low flow rate, complexity of surface texture and aging changes of human tissue (ex, liquefaction of vitreous, cataract formation, accommodation changes of lens, etc), the intra-ocular fluid flow is difficult to represent by digital model. The different pressure gradient inside the eyeball shows that the pressure is lower in the posterior pole than anterior chamber. This may imply that the threshold pressure of optic injury may lower than we thought before.

並列關鍵字

finite element method, glaucoma, aqueous humor

參考文獻

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