Effectiveness and Safety of iStent Infinite Trabecular Micro-Bypass for Uncontrolled Glaucoma

Abstract

Précis: The iStent Infinite Trabecular Micro-Bypass System implanted in patients with open angle glaucoma (OAG) (uncontrolled by prior surgical or medical therapy) was effective in reducing mean diurnal intraocular pressure with a favorable safety profile. Purpose: The purpose of this study is to evaluate safety and effectiveness of the iStent infinite Trabecular Micro-Bypass System in patients with OAG uncontrolled by prior surgical or medical therapy. Design: Prospective, multicenter, single-arm, open-label clinical trial. Methods: Implantation of iStent infinite (3 iStent inject W stents) was performed as a stand-alone surgical procedure in eyes with OAG uncontrolled by prior incisional or cilioablative surgeries or maximum tolerated medical therapy (MTMT). Prospectively declared effectiveness endpoints were proportion of eyes achieving ≥20% mean diurnal intraocular pressure (MDIOP) reduction from baseline at month 12 on the same or fewer intraocular pressure (IOP)-lowering medication classes (responder endpoint) and mean change in MDIOP from baseline at month 12. Safety parameters included visual acuity, slit-lamp and fundus examinations, gonioscopy, perimetry, surgical complications, and adverse events. Results: Seventy-two eyes of 72 patients (mean age 71.9 y) with preoperative mean medicated MDIOP of 23.4±2.8 mm Hg on a mean of 3.1±0.9 IOP-lowering medication classes were enrolled: 61 eyes with failed prior surgery/ies (Failed-Surgery subgroup) and 11 eyes uncontrolled on MTMT (MTMT subgroup). A total of 76.1% of all enrolled patients met the responder endpoint (73.4% Failed-Surgery, 90.9% MTMT), with mean reduction (SE) in MDIOP at month 12 of 5.9(0.6) mm Hg [5.5(0.7) mm Hg Failed-Surgery subgroup, 8.1(0.9) mm Hg MTMT subgroup]. For patients on the same or fewer medication(s) as baseline, 53.0% achieved ≥30% MDIOP reduction without surgical interventions/other events. Safety was favorable, with no explants, infection, or device-related interventions or hypotony. Conclusions: iStent infinite stand-alone surgery achieved clinically significant IOP reduction and favorable safety in patients with OAG uncontrolled by prior therapy.

Spotlight on Schlemm’s Canal MicroStent Injection in Patients with Glaucoma

“… 29 The iStent infinite contains three preloaded iStent inject W devices designed to be placed two clock hours apart, over the four nasal clock hours of the TM to promote bypass of aqueous humor to Schlemm’s canal and reduce IOP. 30 The only present trial of the iStent infinite evaluates 12-month outcomes of standalone implantation in 72 eyes with uncontrolled glaucoma despite prior surgical interventions or maximum tolerated medical therapy. 30 Clinically significant results were achieved, with 76.1% of all enrolled eyes achieving ≥20% MDIOP reduction from baseline on the same or fewer antiglaucoma medications.…”

Complications of Glaucoma Surgery

“…All device-related adverse events in these studies were nonserious. In multiple prospective studies evaluating the various iStent iterations, BCVA loss has been between 1.3% and 8,64,67,71 In the prospective, multicenter HORIZON RCT comparing cataract surgery with or without Hydrus insertion, adverse events from Hydrus surgery within 5 years included PAS (14.6%), postoperative inflammation >1month (5.9%), stent obstruction (8.4%), and stent malposition (1.4%) (Table 3). 68 The rate of > 30% ECL at 5 years was 20.8% in the Hydrus group versus 10.6% in the control group.…”

“…All device-related adverse events in these studies were nonserious. In multiple prospective studies evaluating the various iStent iterations, BCVA loss has been between 1.3% and 15.4% 8,64,67,71 …”

“… 67 There was no difference in those with >30% ECL at 2 years (10.4% in the iStent group vs. 9.5% in the control group). In a nonrandomized prospective study evaluating the insertion of 3 iStent infinites as a standalone procedure, adverse events included dry eye (9.7%), perioperative inflammation (6.9%) hyphema (4.2%), stent obstruction (2.8%), stent migration (2.8%), IOP spike (2.8%), and hyperemia (2.8%) 71 . With the exception of stent obstruction or migration, adverse events were usually transient.…”

“…hyperemia (2.8%). 71 With the exception of stent obstruction or migration, adverse events were usually transient. All device-related adverse events in these studies were nonserious.…”