Simulation of the Outflow Pathway in the Human Eye

The eye structure and function highly depend on the stability of the intraocular pressure (IOP). Glaucoma is an ophthalmic disease that can potentially lead to irreversible blindness. Glaucoma results from optic nerve damages due to persistent elevated IOP. Aqueous humor production, drainage and resistance to egress are the key elements that determine the IOP. After travelling from the posterior to the anterior chamber, the aqueous humor passes through the trabecular meshwork to collect into Schlemm's canal, where collector channels eventually drain into the venous system. The highest resistance to egress is located at the outer portion of the trabecular meshwork and inner wall of Schlemm's canal. In this work we intended to simulate the basic geometry and physiological parameters that determine the aqueous humor dynamics and the IOP values. A 3-D modeling of the human eye was made based on histology. Great attention was given to details in the geometry of the trabeculum, Schlemm's canal and the collector channels. Using Matlab program, the pressure distribution in the eye was computed. Flow was computed using Poisseuille's law. The 3-D modeling was meshed by ICEM Ansys before being implemented using Fluent 6.3. 2-D and 3-D meshes were obtained. The results were showing the pressure distribution from the posterior and anterior chambers, the trabeculum, Schlemm's canal and the collector channels. Most of the resistance to aqueous egress occurred at the level of the trabeculum and Schlemm's canal where the pressure drop was the greatest. Refinements in the mesh density would greatly enhance the quality of the modeling. In conclusion this simulation of the outflow pathway in the human eye provided interesting data about the pressure drop and the localization of the main resistance to aqueous egress.