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

Abstract

Prcis: 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.

FIGURE 1

A, iStent infinite Stent (iStent inject W model). B, iStent infinite Stent dimensions. C, iStent infinite injector distal end. D, iStent infinite injector design.

FIGURE 2

Responder effectiveness endpoint: proportion of responders at month 12. Data from intent-to-treat population in all groups. Multiple imputation was used for 1 patient with missing data at month 12. Responders: patients with ≥20% reduction in mean diurnal intraocular pressure at month 12 versus baseline on the same or fewer ocular hypotensive medication classes as baseline were responders; Nonresponders: patients with (1) hypotony (intraocular pressure <6 mm Hg) associated with clinically significant findings, (2) loss of light perception, (3) intraocular pressure -related SSIs, (4) cyclodialysis cleft, and/or (5) no stents visible were treated as nonresponders. Vertical lines represent 95% CI. MTMT indicates maximum tolerated medical therapy.

FIGURE 3

IOP change from baseline effectiveness endpoint: 12-month diurnal IOP change from baseline. Data from intent-to-treat population in all groups. Multiple imputation was used for 1 patient with missing data at month 12. Vertical lines represent 95% CI. The following imputation methods were used for the 12-month mean diurnal intraocular pressure: (1) For patients with hypotony associated with clinically significant findings, cyclodialysis cleft, and/or no stents visible, the worst postoperative IOP on the same or greater number of OHT medication classes as baseline was used. If a patient was on fewer OHT medication classes than baseline, then the baseline IOP was used. (2) For patients with loss of light perception, the observed 12-month MDIOP was used. (3) For patients with IOP-related secondary surgical interventions, the worst postoperative IOP before secondary surgical intervention on the same or greater number of OHT medication classes as baseline was used. If a patient was on fewer OHT medication classes than baseline, then the baseline IOP was used. (4) For patients on more OHT medication classes than at baseline, the worst postoperative IOP on the same or greater number of OHT medication classes as baseline was used. IOP indicates intraocular pressure; MTMT, maximum tolerated medical therapy; OHT, ocular hypotensive.

FIGURE 4

A, Distribution of 12-month diurnal intraocular pressure (IOP) percent change categories. Data from intent-to-treat population in all groups. B, Distribution of diurnal IOP categories at month 12. Data from intent-to-treat population in all groups. MDIOP was ≥6 mm Hg for all IOP categories. N=number of patients with month 12 diurnal IOP; %=100 × (n ÷ N); not reported = number of available patients without month 12 diurnal IOP and with no IOP-related secondary surgical interventions or other events. Other events include hypotony (IOP <6 mm Hg) associated with clinically significant findings, loss of light perception, cyclodialysis cleft, and/or no stents visible. MDIOP indicates mean diurnal intraocular pressure; MTMT, maximum tolerated medical therapy.