Laser-Responsive Shape Memory Device to Program the Stepwise Control of Intraocular Pressure in Glaucoma

Abstract

There is an unmet need in the glaucoma clinic to control changes in the intraocular pressure (IOP), i.e., patient-specific hypotony and tissue fibrosis-mediated ocular hypertension, owing to the fixed tube diameter of the glaucoma drainage device. As a potential solution, the tube diameter can be adjusted, depending on the IOP, by shape memory polymer (SMP) and clinical laser systems, which can control the energy level, focus, and frequency by minimizing untargeted influences. To develop a translatable device, a laser-responsive SMP with two additional elements: i) a tube with an intimal gel coating to release 5-fluorouracil as an anti-fibrotic drug and ii) a safety lock ring to block late hypotony in special cases is employed. When the SMP tube is inserted into a silicone tube and wrapped externally by the ring, intimal gel degradation and argon laser-triggered diameter increase enable a three-step IOP control. Sustained drug release of the intimal gel suppresses tissue fibrosis, and the ring prevents late hypotony by externally squeezing the silicone tube. The advanced design and functions are validated using computational in vitro and rabbit glaucoma models by determining clinic-friendly argon laser parameters.