Ex Vivo implantation study of minimally invasive glaucoma drainage device

We present in this paper the first ex vivo implantation results of our minimally invasive glaucoma drainage device (GDD.) The GDD is designed to treat glaucoma patients by draining out their extraneous aqueous humor out of the anterior chamber utilizing a MEMS micro-fluidic normally closed (NC) check valve. The NC check valve is encapsulated in protective tubing made from parylene C, which has been proved to be biocompatible in implantation. A new packaging and a bench-top testing procedure is established to characterize the integrated GDD prior to its implantation into enucleated porcine eyes. Pre-implanted characterization curve demonstrates a cracking pressure of 10-20 mmHg of the NC check valve, which agrees with our theoretical design. Ex vivo implantation results show that cracking pressure is measured as 24 mmHg by unloading the eye pressure. The little offset of the cracking pressure comes from the differences between the in vitro and ex vivo testing environments. The hysteresis behavior of the NC check valve is also examined during implantation and is presented here.