Author’s Disclosure Block: Hala Helmi: none; Ali Salimi: none; Hady El-Saheb: receives consulting fees from Alcon, Allerganonebbvie, Bausch Health, Glaukos, Ivantis, and Labtician Thea, and receives honoraria from Alcon, Allerganonebbvie, and Bausch Health; Paul Harasymowycz: Alcon, Allerganonebbvie, Glaukos, Ivantis, J & J Vision, Santen, and Bausch Health.

Abstract Body
Purpose:While short-term outcomes of gonioscopy-assisted transluminal trabeculotomy (GATT) have been well-studied, long-term outcomes remain less understood. This study evaluates the long-term efficacy and safety of GATT, with or without cataract surgery, in eyes with primary or secondary open angle glaucoma, and assesses disease stability using optical coherence tomography (OCT) over five years.Setting:Retrospective cohort study.
Methods: We included glaucomatous eyes that underwent GATT, either alone or with concomitant cataract surgery. Five-year efficacy outcomes were assessed, including mean intraocular pressure (IOP), medication use, and surgical success rates. Safety outcomes included best-corrected visual acuity (BCVA), cup-to-disc ratio (CDR), retinal nerve fiber layer (RNFL) thickness, ganglion cell-inner plexiform layer (GC-IPL) thickness, and any adverse events. Results: A total of 101 eyes were included, with 24 lost to follow-up. At five years postoperatively, IOP decreased by 38.6% (from 23.3 mmHg to 14.3 mmHg, P<0.001). Notably, 91.67% achieved IOP ≤18 mmHg (vs. 31.68% preoperatively), and 64.58% achieved IOP ≤15 mmHg (vs. 18.81% preoperatively). Mean number of medications used decreased from 3.13 to 2.21 (P<0.001), and surgical success was recorded at 60% at five years. Among the 37 eyes that failed, the mean time to failure was 48 months. Safety outcomes remained stable over five years, with any BCVA reductions attributed to non-glaucomatous causes. The most common adverse events were hyphema (64.35%), which resolved spontaneously, and IOP spikes within 8 weeks (44.55%) which was managed with medications and/or anterior chamber paracentesis. Conclusions: This five-year study represents the longest follow-up data on the efficacy and safety of GATT for glaucoma. Our findings support the procedure's long-term effectiveness and stability in functional and structural disease markers.