Minimally Invasive Glaucoma Surgery Procedure in the Human Eye. A Fluid Structure Interaction Study

Aqueous humor is a clear fluid pressurized at an intraocular pressure (IOP) within a range of 8–20 mmHg in healthy conditions that fills and shapes the anterior and posterior chambers of the eye. It is typically drained through the trabecular meshwork, but reduced permeability of this structure can lead to impaired drainage, elevated IOP, and the development of glaucoma. Minimally invasive glaucoma surgeries (MIGS) offer a treatment option by implanting micro stents to create alternative pathways for aqueous humor drainage. Despite their potential, limited research has explored the biomechanical changes in ocular tissues and the hydrodynamic interactions following MIGS implantation. This paper aims to study the aqueous humor flow after the surgery by means of computational simulations. For the first time, the implantation process has been simulated to assess residual stresses on ocular structures post-implantation. Then, this study introduces a Fluid–Structure Interaction (FSI) simulation to model the aqueous humor dynamics after MIGS implantation. The results demonstrate the necessity of FSI simulations, as they reveal the interplay between the eye's biomechanical properties and the aqueous humor dynamics. The advantage of using an FSI simulation is its ability to capture the aqueous humor dynamics, providing a more realistic representation compared to the Computational Fluid Dynamic (CFD) simulations found in the literature. Using only CFD, the outflow velocity of the aqueous humor through the stent is approximately 1e−4 m/s, whereas with an FSI approach, the velocity reaches up to 0.8 m/s as the deformation of the ocular tissues has a substantial impact on the flow dynamics and cannot be neglected. This novel methodology can be potentially used for visualizing and quantifying the aqueous humor flow as a function of implant design, position and dimensions in order to design next-generation MIGS devices and optimize implantation strategies, offering significant advancements in glaucoma treatment.