A Multi-Lumen Glaucoma Stent With Titratable Pressure-Lowering Effect: A Proof of Concept Study

PURPOSE: To explore the feasibility of a glaucoma stent with a titratable pressure-lowering effect. METHODS: This was an in vitro study. We created a resin stent with a micro-precision three-dimensional printer. It represented a cylinder with one primary and two secondary lumina. The inner opening of each secondary lumen was sealed with a membrane. We used a surgical eye model to simulate implantation of the stent and a laser procedure analogous to argon laser trabeculoplasty (ALT) to ablate each membrane. To study the fluid dynamics, we used a high-precision syringe pump and measured the steady-state pressure for one, two, and three lumina in parallel at flow rates of 2.5, 5.0, and 10.0 µL/min. RESULTS: The stent could be implanted into the eye model and visualized in the anterior chamber angle. Coloring the membrane facilitated laser membranotomy, and a 0.1-second laser pulse with 250-mW power was enough to ablate one membrane. The steady-state pressure for one lumen increased linearly with increasing flow rate, in accordance with the Hagen–Poiseuille equation. Two and three lumina in parallel decreased the pressure by factors of 2.1 and 3.2, respectively, in accordance with the electronic–hydraulic analogy and Ohm's law applied to parallel resistors. CONCLUSIONS: The study presents proof of concept for a glaucoma stent with multiple lumina, which can be separately opened with an ALT-like procedure to induce a predictable, stepwise increase in pressure-lowering effect. TRANSLATIONAL RELEVANCE: The glaucoma stent in this experimental study can be reproduced in a biocompatible material and further studied in vivo.