UK EXPERIENCE OF GONIOSCOPY-ASSISTED TRANSLUMINAL TRABECULOTOMY (GATT): REAL WORLD INTERMEDIATE RESULTS

To report 5-year clinical outcomes of gonioscopy-assisted transluminal trabeculotomy (GATT) in a heterogeneous glaucoma cohort.

Single-center, multi-surgeon, retrospective case series from Birmingham Midland Eye Centre, including all patients undergoing GATT with a minimum of 3 years follow-up.

Primary outcome was surgical success based on World Glaucoma Association criteria. Secondary measures included intraocular pressure (IOP), medication usage, visual field indices, retinal nerve fiber layer (RNFL) changes, reoperation, and complications. A total of 111 eyes from 95 patients were analyzed.  

The cohort had a mean age of 64.4 years, with 52.6% Caucasian and 14.7% Afro-Caribbean. Primary glaucoma was most common (68 eyes, 61.6%), predominantly open-angle (43.2%), while secondary glaucoma comprised 38.7%, primarily uveitic (18.0%). Furthermore, 60 eyes (54.05%) underwent GATT alone, and 51 eyes (45.95%) had GATT with cataract surgery. Median follow-up was 5.05 years (range: 3.03–6.87 years).

Mean IOP decreased significantly from 30.22 mmHg (SD 10.52) on 3.76 medications to 17.45 mmHg (SD 7.68) on 2.22 medications at the final follow-up. Qualified and complete success rates were 57.7% and 20.7%, respectively, with an overall failure rate of 42.3% and reoperation required in 25.2%. Visual acuity (VA) remained stable, while visual field indices, including mean deviation (MD) and visual field index (VFI), showed improvement, suggesting that effective IOP control positively impacted functional vision outcomes. However, RNFL thickness declined from 69.4 μm to 61.6 μm (p < 0.0001), reflecting glaucoma’s natural progression despite successful IOP reduction. Mean time to failure was 1.55 years (SD 1.46), with 21.37% of failures occurring within the first postoperative year. Among the 75 phakic eyes, 8 (10.67%) required cataract extraction, with an average time to surgery of 2.64 years (SD 1.75).

GATT-alone cases had a higher failure rate, with a shorter mean survival time of 4.09 years (SD 0.37) versus 4.93 years (SD 0.36) for GATT combined with cataract extraction, though this difference was not statistically significant (p=0.2326).

This is the largest and longest study of GATT outcomes, supporting GATT as an effective option for diverse glaucoma types. Outcomes were not significantly affected by combining GATT with cataract surgery. Overall, GATT offers an effective, minimally invasive alternative to traditional surgeries.