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

TL;DR

This study evaluates how deep the iStent inject W is placed in the eye using automated gonioscopy and finds no significant link between insertion depth and surgical outcomes.

Contribution

The study is the first to assess iStent inject W insertion depth using automated gonioscopy and its association with outcomes.

Findings

51 out of 82 stents were graded as Grade 1, and 31 as Grade 2 based on insertion depth.

No significant differences in IOP reduction were found among the three depth groups at 12 months.

The study suggests insertion depth has minimal impact on surgical outcomes.

Abstract

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.

Figures