One-year clinical outcomes of iStent infinite® versus iStent inject® in open-angle glaucoma

To compare the clinical outcomes of the iStent inject® and the iStent infinite® in a homogeneous population of patients with mild-to-moderate primary open-angle glaucoma (POAG), assessing the additive effect of a third trabecular micro-bypass stent.

Retrospective comparative study between eyes submitted to iStent inject® (group 1) or iStent infinite® (group 2). IOP, number of medications, visual function, type of surgery (combined or standalone), success rates, and safety were evaluated over 12 months.

The study included 163 eyes with a mean patient age of 68.2 years. Groups 1 (n=103) and 2 (n=60) were statistically comparable preoperatively. Mean IOP decreased by 16.0% in the overall population, from 15.6±3.2mmHg to 13.1±1.9mmHg at 12 months (P<0.001). At month 12, IOP was 13.7mmHg in group 1 versus 12.3mmHg in group 2 (P<0.001). Both groups showed significant reductions from baseline, but the iStent infinite® achieved a greater IOP reduction at all mid- and long-term time points. Medication burden decreased by 85.7%, from 2.1±0.7 to 0.3±0.7 medications (P<0.001). Group 1 reduced medications by a mean of 1.61, while group 2 reduced by 1.92 medications (P=0.032). At 12 months, 79.1% of all eyes required no medication. Absolute success rates (IOP<18mmHg without medication) were 83.5% for iStent inject® and 96.7% for iStent infinite® (P=0.008). By stricter criteria, the iStent infinite® consistently outperformed the iStent inject®: IOP<15mmHg: 59.2% vs. 78.3% (P=0.009); IOP<12mmHg: 6.8% vs. 36.7% (P<0.001).

In a homogeneous population with similar baseline characteristics, the addition of a third trabecular stent resulted in greater IOP reduction, larger medication decrease, and higher success rates compared with two stents. These findings support the physiological advantage of increasing the number of trabecular bypass points to enhance access to functional collector channels.