Dvoriashyna M, Repetto R, Romano M R, Tweedy J H
Department of Civil, Chemical and Environmental Engineering, University of Genoa, Genoa, Italy.
Department of Biomedical Sciences, Humanitas University, Rozzano (Milano), Italy.
Math Med Biol. 2018 Dec 5;35(4):447-467. doi: 10.1093/imammb/dqx012.
The anterior chamber (AC) and posterior chamber (PC) of the eye are connected through the pupil and are filled with aqueous humour. The aqueous flows from the posterior to the AC at an approximately constant rate, and the intraocular pressure is governed by this rate and the resistance to aqueous outflow. In some patients the iris and lens come into contact, leading to pressure build-up in the PC, peripheral axial shallowing of the AC and, possibly, to angle-closure glaucoma. This can lead to blindness, which may be prevented by surgically creating an iridotomy, that is a hole through the iris to facilitate the flow from the posterior to the AC. The problem of optimal size and location of an iridotomy is still poorly understood. In this article, we study aqueous flow in the PC and investigate how it is modified in the presence of an iridotomy. Our approach is based on the lubrication theory, which allows us to solve the problem semi-analytically. We treat the iridotomy as a point sink and assume that the flux through it is proportional to the pressure. We find that the ideal size and location of an iridotomy are influenced by various geometrical and fluid mechanical factors, the most relevant of which are the size of the hole and the length and height of the iris-lens channel. For certain iridotomy diameters, we find that the jet velocity through the iridotomy might be large enough to cause possible corneal damage.
眼睛的前房（AC）和后房（PC）通过瞳孔相连，并充满房水。房水以大致恒定的速率从后房流向AC，眼内压由该速率和房水流出阻力决定。在一些患者中，虹膜和晶状体接触，导致后房压力升高、AC周边轴向变浅，并可能导致闭角型青光眼。这可能导致失明，通过手术制造虹膜切开术可以预防失明，虹膜切开术即穿过虹膜的一个孔，以促进房水从后房流向AC。虹膜切开术的最佳大小和位置问题仍未得到很好的理解。在本文中，我们研究后房中的房水流动，并研究在存在虹膜切开术的情况下它是如何改变的。我们的方法基于润滑理论，这使我们能够半解析地解决该问题。我们将虹膜切开术视为一个点汇，并假设通过它的通量与压力成正比。我们发现虹膜切开术的理想大小和位置受各种几何和流体力学因素影响，其中最相关的是孔的大小以及虹膜 - 晶状体通道的长度和高度。对于某些虹膜切开术直径，我们发现通过虹膜切开术的射流速度可能足够大，从而可能导致角膜损伤。
