Intraocular Pressure, Aqueous Humor Dynamics, And Fibrosis Using A Novel Glaucoma Drainage Pathway

Abstract

The purpose of this study was to compare fibrosis, aqueous humor dynamics, and intraocular pressure (IOP) of two suprachoroidal shunts that are part of a new class of glaucoma drainage devices. After in vitro testing, 20 rabbits were implanted with either a gold shunt (GS, GMSplus+, Solx) or polypropylene shunt (PS, Aquashunt, OPKO). Ten eyes received mitomycin C (MMC) and triamcinolone. Peak and trough IOP were monitored with a pneumatonometer and tono-pen through 15 weeks. Aqueous humor dynamics were evaluated fluorophotometrically and tonographically. Fibrosis was quantified using ImageJ. In vitro growth was similar. In vivo, both shunts were devoid of foreign body reaction but exhibited fibrosis, and GS showed vascularization. There was no significant difference in aqueous or uveoscleral flow. Preoperative morning IOP was 23.7 ± 2 mm Hg and evening IOP was 26.5 ± 2 mm Hg (p=0.000). Morning IOP was decreased through 15 weeks and evening IOP through 8 weeks in all groups. The morning IOP decrease was most profound at 15 weeks in PS (41%) compared to GS (18%). Antifibrotics initially enhanced but eventually diminished shunt performance. At 15 weeks, thickness of scleral fibrosis was greater in GS (246 ± 47 μ) and PS (188 ± 47 μ, p=0.285) compared with GS+MMC (109 ± 26 μ, p=0.023 to GS) and PS+MMC (48 ± 30 μ, p=0.028 to PS). In a rabbit model, suprachoroidal polypropylene and gold shunts allow access to a new drainage pathway with different IOP profiles that can be modified with antifibrotics