白努力模型應用於分析眼內壓

Abstract

吹氣量測所測得前房眼壓究竟等不等於玻璃體眼壓一直是眼科醫師的疑問。眼壓量測目前為量測前房眼壓。對於玻璃體後之眼壓並無法直接量測，僅能透過假設相等的方式令前房眼壓相等於後房眼壓。但正常人與青光眼患者之房水通道黏滯性並不相同，閉隅型青光眼(ACG)患者的後房房水並不易流至前房。相對的，吹氣量測時，房水將不易往後房流通，而會更多的堆積在前房。造成前房眼壓被高估。我們將使用白努力定律為核心建構我們的眼壓連通管模型，以級數解之形式得到解析解，並評估前後房與玻璃體在吹氣量測時眼內壓的升降幅度與升降速度。為考慮變型造成阻尼與級數解之適用性，最後使用彈簧阻尼系統模擬周圍組織抵抗腔室變形之力，評估系統受吹氣壓力時，各腔室壓力上升的延時性。結果顯示，虹膜通道的完全堵塞與完全暢通會影響後房腔室水頭高為正常人上升幅度0.2至2倍，在吹氣量測實驗下，極短時間內量測到的前房眼壓會存在高估玻璃體眼壓的情形。

Whether the intraocular pressure(IOP) in the anterior chamber measured by insufflation equal to the vitreous is a question for ophthalmologists. The IOP measurement is currently measuring the IOP of the anterior chamber, since we cannot directly measure the IOP of the vitreous. However, the friction of the aqueous channel of normal participants and glaucoma patients is not the same, and the aqueous humor in the posterior chamber of patients with angle-close glaucoma (ACG) is not easy to flow to the anterior chamber. On the other hand, during the air blow measurement, the aqueous humor is not easily flow to the posterior chamber, but it accumulates more in the anterior chamber. That lets the IOP in the anterior chamber to be overestimated. In this paper, we used Bernoulli's principle to construct the IOP model, and obtained analytical solutions in the form of a series solution. These solutions evaluated the rise and fall of the IOP in the anterior and posterior chambers and the vitreous during insufflation measurement. Considering damping dued by deformation and the applicability of the series solution, the spring damping system was finally added to simulate the force of the surrounding tissue to resist the deformation of the chamber, and the delay of the pressure rise of each chamber at system startup. The results show that whether blockage complete or not the iris channel affects the posterior chamber rise by 0.2 to 2 times than normal people, and the measurement of the anterior chamber intraocular pressure overestimates the vitreous intraocular pressure.