Prospective, Randomized, Controlled Pivotal Trial of an Ab Interno Implanted Trabecular Micro-Bypass in Primary Open-Angle Glaucoma and Cataract: Two-Year Results

Abstract

Evaluate the safety and effectiveness of an ab interno implanted (iStent inject) Trabecular Micro-Bypass System (Glaukos Corporation, San Clemente, CA) in combination with cataract surgery in subjects with mild to moderate primary open-angle glaucoma (POAG). Prospective, randomized, single-masked, concurrently controlled, multicenter clinical trial. Eyes with mild to moderate POAG and preoperative intraocular pressure (IOP) ≤24 mmHg on 1 to 3 medications, unmedicated diurnal IOP (DIOP) 21 to 36 mmHg, and cataract requiring surgery. After uncomplicated cataract surgery, eyes were randomized 3:1 intraoperatively to ab interno implantation of iStent inject (Model G2-M-IS; treatment group, n= 387) or no stent implantation (control group, n= 118). Subjects were followed through 2 years postoperatively. Annual washout of ocular hypotensive medication was performed. Effectiveness end points were ≥20% reduction from baseline in month 24 unmedicated DIOP and change in unmedicated month 24 DIOP from baseline. Safety measures included best spectacle-corrected visual acuity (BSCVA), slit-lamp and fundus examinations, gonioscopy, pachymetry, specular microscopy, visual fields, complications, and adverse events. The groups were well balanced preoperatively, including medicated IOP (17.5 mmHg in both groups) and unmedicated DIOP (24.8±3.3 mmHg vs. 24.5±3.1 mmHg in the treatment and control groups, respectively, P= 0.33). At 24 months, 75.8% of treatment eyes versus 61.9% of control eyes experienced ≥20% reduction from baseline in unmedicated DIOP (P= 0.005), and mean reduction in unmedicated DIOP from baseline was greater in treatment eyes (7.0±4.0 mmHg) than in control eyes (5.4±3.7 mmHg; P < 0.001). Of the responders, 84% of treatment eyes and 67% of control eyes were not receiving ocular hypotensive medication at 23 months. Furthermore, 63.2% of treatment eyes versus 50.0% of control eyes had month 24 medication-free DIOP ≤18 mmHg (difference 13.2%; 95% confidence interval, 2.9-23.4). The overall safety profile of the treatment group was favorable and similar to that in the control group throughout the 2-year follow-up. Clinically and statistically greater reductions in IOP without medication were achieved after iStent inject implantation with cataract surgery versus cataract surgery alone, with excellent safety through 2 years.