Polymeric Micro Check Valve for Glaucoma Treatment Considering Rate of Aqueous Humor Formation

摘要

This paper describes a novel glaucoma drainage device (GDD) to regulate intraocular pressure (IOP) considering the rate of aqueous humor formation. The device functionally consists of a polymeric cannula (silicone tube) and a micro check valve (PDMS: polydimethylsiloxane). The check valve has three layers: a top layer (cover), which has rounded edges to reduce fibrosis, an intermediate layer (thin movable valve membrane), and a bottom layer (base plate). A feedforward channel is employed in the top layer to prevent reverse flow by compensating the pressure of the outlet channel. The thickness of thin the PDMS membrane was determined considering the cracking pressure and the rate of aqueous humor formation. The cracking pressure in-vitro test was conducted at 15 mmHg, which lies within the normal intraocular pressure range (10 ～ 20 mmHg). The experimental mean value and standard deviation of the flow rate at the cracking pressure was 2.18 ± 0.69 μL/min, which is confirmed to cover the rate of aqueous humor formation in the normal human eye (1.5 ～ 3.4 μL/min). Flow in a reverse direction was not observed.