Exploring the Pressure Characteristics of the PRESERFLO MicroShunt in In Vitro Studies and Effects of Sclera on Device Performance

Abstract

This study aims to investigate the pressure characteristics of the PRESERFLO MicroShunt, a microinvasive glaucoma device, using an in vitro setup. Additionally, the study explores the impact of the scleral tissue surrounding the device on its pressure and lumen area. Ten PRESERFLO MicroShunts were subjected to an in vitro experimental setup. A constant flow of physiological saline was maintained at 2 μL/min using an infusion syringe pump. The PRESERFLO was connected to a pressure transducer via a 23 G needle. Pressure characteristics were measured under three different conditions: without sclera [sclera (-)], passing through sclera at a 90° angle (sclera 90°), and passing through sclera at a 30° angle (sclera 30°). The lumen area of the device was measured using microscopic observation. We observed peak and trough pressures in this experimental setting; the peak pressure (6.76 mmHg) was significantly higher than the trough pressure of 4.74 mmHg (p = 0.0020) in the sclera (-) condition. Compared to sclera (-), the peak pressures were significantly higher in the sclera 90° (7.81 mmHg, p = 0.0020) and the sclera 30° (7.96 mmHg, p = 0.0039) conditions. Additionally, compared to sclera (-), the trough pressure was significantly higher in the sclera 90° (6.25 mmHg, p = 0.0039) and the sclera 30° (5.76 mmHg, p = 0.037) conditions. The lumen area was significantly smaller in the sclera 90° condition (3515 μm2) than the sclera (-) condition (3927 μm2, p = 0.0078). The study found that when the distal end of PRESERFLO MicroShunt was free and in air, it exhibited both peak and trough pressures. The presence of scleral tissue surrounding the PRESERFLO MicroShunt affects its lumen area and pressure characteristics. Understanding these effects can provide valuable insights into the device’s performance.