Characterization of an Active Microvalve for Glaucoma Using Fluid-Structure Interaction

Abstract

Glaucoma Drainage Device (GDD) have the potential to eliminate hypotony but still suffer from poor flow control and fibrosis. The ideal shunt should change its hydraulic resistance to achieve the desired intraocular pressure. In this work the characterization of a preliminary design of a new GDD is presented. This is activated by means of a diaphragm, which is actuated by conducting polymers.
The valve can be manufactured employing Micro Electro Mechanical System (MEMS) technology by soft lithography. The characterization process is performed by numerical simulation using the Finite Element Method, considering the coupling between the fluid and the structure (diaphragm), obtaining the hydraulic resistance for several positions of the diaphragm. In order to analyze the hydraulic system of the microvalve implanted in a human eye an equivalent circuit model was used. The parameters of the equivalent circuit model were obtained from numerical simulation. The designed GDD has a greater range of variation of the hydraulic resistance if compared with the Ahmed valve. The proposed preliminary design allows to control intraocular pressure (IOP) by varying the hydraulic resistance in a greater range than existing passive valves and the numerical simulation facilitates the characterization and the improvement of the design before its construction, reducing time and costs.