Evaluation of the Insertion Depth of the iStent Inject W and Its Association with Surgical Outcomes Using Automated...

Background/Objectives: The iStent is a trabecular micro-bypass device used in glaucoma management. Its depth has been evaluated using anterior segment optical coherence tomography; however, no reports have assessed it using gonioscopy. We evaluated the depth of the iStent inject W using the GS-1 automated gonioscope (GS-1) and determined its association with outcomes. Methods: Patients who underwent iStent inject W implantation were followed for 1 year. Angle photographs were obtained using a GS-1. The depth was graded from the GS-1 images as Grades 1 (anterior edge of the flange protruding into the anterior chamber) and 2 (anterior edge embedded within the trabecular meshwork). Based on the two implants' depths, the eyes were categorized into Grades 1 + 1, 2 + 2, and 1 + 2. The percentages of intraocular pressure (IOP) reduction at 12 months were compared among the groups using the Kruskal-Wallis test. Results: Data from 31 patients (41 eyes and 82 stents) were analyzed. The depth distribution for Grades 1 and 2 was 51 (62.2%) and 31 (37.8%) stents, respectively. In the Grade 1 + 1, 2 + 2, and 1 + 2 groups, the number of eyes was 18, 8, and 15, respectively. IOP reductions at 12 months were 12.81 ± 20.27%, 22.85 ± 15.30%, and 16.04 ± 20.41% for the Grade 1 + 1, 2 + 2, and 1 + 2 groups, respectively, with no significant differences (p = 0.493). Conclusions: The impact of insertion depth on outcomes appears to be minimal in eyes where the iStent inject W was visualized using the GS-1. Further studies with larger cohorts should clarify the effects of insertion depth and its interplay with position.