During cataract surgery the clouded lens is broken up by phacoemulsification. The iris can become highly mobile and could be entrained by the phacoemulsification probe, under a condition known as intraoperative floppy iris syndrome (IFIS). In this study we explore the mechanism of IFIS during phacoemulsification-based cataract surgery using fluid-structure interaction (FSI) simulations. As the first study of its kind, we developed a simplified two-dimensional simulation framework and utilized it to elucidate the dynamics of the iris and surrounding aqueous humor during phaco-emulsification. Three types of iris dynamics were observed when the phaco probe was operated in the torsional vibration mode and placed at various locations in the anterior chamber, which we termed as the repulsion (where the iris is repelled by the probe), attraction (where the iris is drawn toward the probe) and adhesion mode (where the iris is adhered to the probe at some point along its length), respectively. The anterior chamber is partitioned into different zones which exhibit each of these three modes. Furthermore, the effects of iris stiffness and length as well as the power and frequency of the probe operation were investigated. It was found that IFIS could be mitigated by increasing the iris stiffness, shortening the iris length (i.e., pupil dilation), decreasing the power of the emulsification probe, and maintaining the probe operation frequency in a range around the frequency of the iris’ fundamental bending mode. This study provides new physical insights into the dynamics of fluid-iris interaction during phaco-emulsification, which may guide clinicians to optimize their surgical protocol.

在白内障手术期间，混浊的晶状体通过超声乳化术破碎。在称为术中虹膜软盘综合征 (IFIS) 的情况下，虹膜可以变得高度移动并可能被超声乳化探头夹带。在这项研究中，我们使用流固耦合 (FSI) 模拟探索了 IFIS 在基于超声乳化白内障手术期间的机制。作为同类研究中的第一项，我们开发了一个简化的二维模拟框架，并利用它来阐明超声乳化过程中虹膜和周围房水的动力学。当超声探头在扭转振动模式下操作并放置在前房的不同位置时，观察到三种类型的虹膜动力学，我们称之为排斥（虹膜被探头排斥），吸引（虹膜被拉向探头）和粘附模式（虹膜沿其长度的某个点粘附在探头上），分别。前房被分成不同的区域，这些区域表现出这三种模式中的每一种。此外，研究了虹膜刚度和长度以及探头操作的功率和频率的影响。研究发现，通过增加虹膜刚度、缩短虹膜长度（即瞳孔扩张）、降低乳化探头的功率以及将探头工作频率保持在虹膜基本频率附近的范围内，可以减轻 IFIS。弯曲模式。这项研究为超声乳化过程中流体-虹膜相互作用的动力学提供了新的物理见解，