Trabecular Meshwork Thickness Measured by Swept-Source AS-OCT as a Predictor of Surgical Outcomes After Trabecular Micro-Bypass Stent Implantation

Background: Although minimally invasive glaucoma surgery (MIGS), including trabecular micro-bypass stent implantation, is safe, its surgical outcomes remain variable, with limited reliable success predictors. We evaluated whether preoperative trabecular meshwork (TM) thickness is associated with surgical outcomes after iStent inject® W implantation. Methods: Patients with open-angle glaucoma (n = 28) who underwent iStent inject® W implantation were included. Preoperative AS-SS-OCT was used to measure TM thickness and conventional angle parameters, including angle opening distance, angle recess area, trabecular–iris space area, and trabecular–iris angle. Surgical success was IOP ≤ 15 mmHg with ≥25% reduction or final IOP ≤ 12 mmHg under specified conditions. Logistic regression analyses were performed to identify factors associated with surgical outcomes. Results: At 12 months, 22 eyes (78.6%) achieved surgical success. Mean TM thickness was significantly greater in the unsuccessful than in the successful group (250.62 ± 32.05 μm vs. 180.75 ± 30.61 μm, p = 0.001), with similar findings for nasal and temporal TM thickness. Conventional angle parameters were not associated with surgical outcomes. In univariable analysis, both mean and nasal TM thickness were significantly associated with an increased risk of failure (per 10 μm increase; mean TM: OR = 2.77, 95% CI = 1.12–6.86, p = 0.027; nasal TM: OR = 1.64, 95% CI = 1.04–2.58, p = 0.034). Conclusions: Increased preoperative mean and nasal TM thickness was significantly associated with surgical failure following iStent inject® W implantation. TM’s microstructural properties are more relevant than angular configuration in determining MIGS outcomes. Preoperative assessment of TM thickness using AS-SS-OCT may serve as a useful imaging biomarker for optimizing patient selection.