Development of a controllable glaucoma drainage implant with anti-fibrotic properties - Glaukom-AF - TP LUH

Glaucoma is the most common irreversible cause of blindness worldwide. An estimated 57 million people worldwide are affected by this disease. Currently, lowering intraocular pressure (IOP) is the only therapeutic approach. Filtering surgery can be used to create a connection between the space under the conjunctiva and the interior of the eye in order to lower IOP. However, these operations have a high profile of side effects, necessitating revision surgery, which means further trauma for the affected patients. Potential complications includescarring processes (fibrosis), which can cause the artificial connection to close again, or the prevention of fluid absorption due to fibrosis under the conjunctiva. In addition, despite the operation, there is a possibility of continued increased IOP, whereby subsequent correction is considered difficult to impossible.

In this joint project between Hannover Medical School, Hannover University of Applied Sciences and Arts, the Institute for Forming Technology and Machines (IFUM), and the Institute for Quantum Optics of the Leibniz University Hannover, a novel, controllable implant is being researched that aims to solve the known problems of scarring and IOP adjustment. The implant is designed so that the valve opens automatically when the IOP rises, allowing the chamber fluid to drain, while it closes passively again when the IOP falls. To limit the initial opening, one or more struts are integrated to ensure a controlled opening mechanism. If fibrotic tissue prevents autonomous opening, an external actuator enables targeted, medically initiated opening of the valve.

As part of the project, IFUM is supporting the development of the implant through numerical finite element simulations. To this end, comprehensive experimental material characterization is carried out. The results form the basis for the parameterization of a (hyper)elastic material model and are then used to create a numerical simulation model of the implant. Fluid-structure simulations are performed by coupling the simulation model with a numerical eye model. Different IOD and opening states of the implant are investigated with regard to the resulting stress distribution and the flow of the chamber fluid. The aim is to identify potential failure mechanisms at an early stage and to assess the service life. These findings are incorporated into an iterative improvement of the implant design. Various geometric variants of the implant are numerically investigated. The result will be an implant design that combines reliable function, low invasive forces, and a compact design.