MODIFIED GATT WITH EXCISIONAL TRABECULAR PEELING: EVALUATION OF EFFICACY AND SAFETY

To evaluate the efficacy and safety of a modified Gonioscopy-Assisted Transluminal Trabeculotomy (GATT) incorporating an excisional trabecular peeling step in the nasal quadrant to prevent re-adhesion or fibrosis of residual trabecular tissue (TT) and improve Schlemm’s canal (SC) patency and intraocular pressure (IOP) control.

A retrospective study conducted at a tertiary glaucoma referral center including patients with open-angle glaucoma who underwent GATT between 2022 and 2025.

58 eyes that underwent successful 360° GATT using a Prolene suture were analyzed. After completing GATT, in eyes where the trabecular cleft and posterior wall of SC were visible in the nasal quadrant, an excisional peeling step was performed with 23G micro-forceps to remove residual TT (Group 1: GATT + Peeling, n = 23). Eyes that underwent standard GATT without additional manipulation formed Group 2 (n = 35). Postoperative assessments included IOP, medication count, and gonioscopic evaluation of SC posterior wall visibility, blood reflux, and peripheral anterior synechiae (PAS). Parameters were recorded in clock hours across nasal, temporal, superior, and inferior quadrants. Follow-up visits were at 1, 3, 6, and 12 months.

Both groups showed significant IOP reduction from baseline (p < 0.001). At 6 and 12 months, mean IOP was lower in Group 1 (14.6 ± 3.2 and 15.7 ± 3.1 mmHg) than in Group 2 (16.4 ± 3.6 and 17.1 ± 3.5 mmHg; p = 0.03 and 0.04). At 12 months, mean SC posterior wall visibility was 8.1 ± 2.1 vs 5.7 ± 2.4 clock hours (p = 0.01). Blood reflux averaged 3.2 ± 1.5 vs 2.1 ± 1.3 clock hours (p = 0.04), while PAS extended 3.2 ± 2.4 vs 3.7 ± 2.1 (p = 0.27). In the nasal quadrant, where peeling was performed, SC visibility and reflux were greater (p < 0.05). Both groups showed a marked reduction in medications (baseline 3.3 ± 0.7 vs 3.2 ± 0.8; 12-month 0.5 ± 0.8 vs 0.9 ± 1.0). Hyphema was the most frequent postoperative finding, occurring at similar rates in both groups (microhyphema in all eyes, macrohyphema in 74% vs 70%; p = 0.42), resolving spontaneously within 7–10 days without sequelae. No cyclodialysis, lens injury, or vision-threatening complications were observed.

GATT provides a 360° circumferential opening of SC, enhancing aqueous outflow via multiple collector channels. However, because TT is torn but not excised in standard GATT, residual tissue may undergo fibrosis or re-adhesion, reducing long-term efficacy. Adding an excisional peeling step in the nasal quadrant under direct gonioscopic view removes residual TT, preserves canal patency, and stabilizes IOP reduction without added complications. This modification combines the circumferential advantage of GATT with the tissue-clearing benefit of excisional goniotomy, offering a cost-effective, device-free alternative to Kahook Dual Blade. By addressing fibrosis-prone tissue within the same session, it may ensure better anatomic continuity and more durable long-term pressure control.