The iStent inject for POAG: Safety and Efficacy Results
Ophthalmology, June 2019
Microinvasive glaucoma surgery (MIGS) may offer sustained reduction of intraocular pressure (IOP) while avoiding the drawbacks of ocular hypotensive drugs and filtering surgery. The first FDA-approved MIGS device, the iStent (Glaukos), has been used successfully in patients with open-angle glaucoma undergoing concomitant cataract surgery. A newer device, the iStent inject Trabecular Micro-Bypass System (also by Glaukos), creates two patent bypasses through the trabecular meshwork. Samuelson et al. looked at the safety and effectiveness of combining this approach with cataract surgery in patients with mild or moderate primary open-angle glaucoma (POAG). Relative to cataract surgery alone, the system achieved greater IOP reductions, and the two-year safety profile was good.
This multicenter study included 505 eyes with mild or moderate POAG that also required cataract surgery. Preoperative IOP was ≤24 mm Hg (with one to three medications), and unmedicated diurnal IOP ranged from 21 mm Hg to 36 mm Hg. After uncomplicated cataract surgery, eyes were randomized intraoperatively to receive either the iStent inject (treatment group, n = 387) or no stent (control group, n = 118). Follow-up lasted two years and included annual washout of ocular hypotensive medication. The effectiveness endpoints were ≥20% reduction from baseline to month 24 in unmedicated diurnal IOP and change in unmedicated diurnal IOP from baseline to month 24. Safety measures included gonioscopy, pachymetry, and slit-lamp and fundus examinations; visual field and acuity tests; and documentation of adverse events.
The preoperative mean medicated IOP was 17.5 mm Hg in both groups; mean unmedicated diurnal IOP was 24.8 ± 3.3 mm Hg in the treatment group and 24.5 ± 3.1 mm Hg in controls. By 24 months, 75.8% of treated eyes and 61.9% of control eyes had a reduction from baseline in unmedicated diurnal IOP of at least 20% (p = .005). The mean reduction was greater in the treatment group (7.0 vs. 5.4 mm Hg; p < .001).
Among responders, 84% of treated eyes and 67% of control eyes were not receiving ocular hypotensive agents at 23 months. By month 24, medication-free diurnal IOP ≤18 mm Hg was achieved in 63.2% of treated eyes and 50.0% of control eyes. The safety profiles were favorable and similar.
The original article can be found here.