Gonioscopy-Assisted Transluminal Trabeculotomy (Gatt) Versus Hemi-Gatt: A Retrospective Case-Control Study

To compare the six months surgical outcomes for GATT and Hemi-GATT with and without simultaneous phacoemulsification.

This is a retrospective case-control study, performed on all patients with Open-Angle Glaucoma, who underwent a GATT or a Hemi-GATT procedure at Kaplan medical center from January 2021 with at least 6 months of follow-up postoperatively.

Patients were divided into four groups: GATT 360, GATT 180 (Hemi-GATT), GATT combined with phacoemulsification cataract (CE+GATT 360) and Hemi GATT combined with phacoemulsification cataract (CE+GATT 180). The primary outcome measures were IOP and number of glaucoma medications (NGM) at 1 month, 3 month and 6 months. Intra or postoperative complications were recorded within the first six months of follow up.

The study included 44 eyes of 39 patients. Patients' baseline characteristics were not significantly different between the four groups. Average IOP was reduced from 17.07±5.7 to 12.8±3.3 mmHg in GATT after 6 months (Δ =-4.04 mmHg, P=0.03), and from 17.9±4.7 to 13.4±4.09 mmHg in Hemi-GATT after 6 months (Δ=-4 mmHg, P=0.01). Average NGM was also reduced by 2.8 medications after GATT, and by 2.1 medications after Hemi-GATT. Comparison between GATT and Hemi-GATT demonstrated no significant change in both IOP and NGM following the procedures (p=0.98, p=0.16 respectively). In addition, no significant difference was found in the complication rate after GATT and Hemi-GATT.

Our results highlight that GATT with or without concomitant cataract surgery successfully reduces IOP and medication overload. Moreover, Hemi-GATT might be an equally effective and safe procedure as GATT, yet to be further elucidated in future prospective studies.