Outcomes of Gonioscopy-Assisted Transluminal Trabeculotomy (GATT) in Advanced Glaucoma: A Retrospective Analysis

Background and Objectives: The search for less invasive and more effective methods in the surgical treatment of glaucoma continues. For advanced glaucoma, all surgical options carry a high risk of complications and vision loss. The aim of this study was to evaluate the outcomes of gonioscopy-assisted transluminal trabeculotomy (GATT) surgery in advanced glaucoma. Materials and Methods: In this retrospective study, advanced open-angle glaucoma (OAG) patients were followed up on the 1st day, 1st week, and 1st month, then monthly for 6 months and then every 3 months after GATT surgery. Outcomes at 6 and 24 months were analyzed to evaluate early and long-term surgical success. Surgical success was defined as a ≥20% intraocular pressure (IOP) reduction from baseline, final IOP ≤21 mmHg, and no need for additional glaucoma surgery. Pre- and postoperative measurements included IOP, retinal nerve fiber layer (RNFL) thickness by optical coherence tomography (OCT), peripapillary vessel density (VD) via optical coherence tomography angiography, and visual field (VF) tests. Results: Among 44 advanced glaucoma patients (61.4% pseudoexfoliative glaucoma), surgical success was 81.8% at 6 months and 76.5% at 24 months. Mean IOP decreased from 26.9 ± 10.4 mmHg preoperatively to 13.8 ± 8.3 mmHg at 3 months (40.36% reduction, p < 0.001) and 13.9 ± 4.0 mmHg at final follow-up (42.12% reduction, p < 0.001). Disease progression was absent in 66% of patients. BCVA initially declined (0.61 ± 0.36 to 0.41 ± 0.33 logMAR at 3 months, p = 0.011) but returned to baseline (0.59 ± 0.35 logMAR at final follow-up, p = 1.00). Glaucoma medications decreased by 66.2%, and peripapillary VD remained stable (p > 0.05). The most common complication was mild hyphema (34.1%), which resolved without intervention; only one patient (2.3%) experienced vision-threatening complications (wipe-out phenomenon in degenerative myopia). Conclusions: GATT is a safe and effective alternative to trabeculectomy for advanced glaucoma, achieving significant IOP reduction with stable VD and low rates of serious complications. This study provides novel insights by offering long-term (24-month) follow-up data, evaluating peripapillary VD stability, and specifically assessing GATT outcomes in an advanced glaucoma cohort. However, caution is advised in patients with additional ocular pathologies.