Analysis Of Surgical Outcomes And Risk Factors For Failure After Gonioscopy-Assisted Transluminal Trabeculotomy

Minimally invasive glaucoma surgery (MIGS) has gained attraction among treating physicians, owing to its decreased complication rate and higher postoperative patient rehabilitation. Gonioscopy-assisted transluminal trabeculotomy (GATT) surgery, is a conjunctival sparing MIGS procedure involving an ab interno trabeculotomy approach to circumnavigate Schlemm’s canal using either an illuminated microcatheter or a blunt-tip suture. There are several factors influencing success after GATT, however, efforts for elaborating predictors of GATT success have not been conclusive. In the present study we aimed to specify clinical outcomes and predictors of surgical failure by analyzing a relatively large cohort of patients who underwent GATT.

Karadeniz Technical University, Faculty of Medicine, Department of Ophthalmology

Prospective, observational clinical study including GATT cases with primary open-angle glaucoma (POAG, 24 eyes), pseudoexfolation glaucoma (PEXG, 121 eyes), pigmentary glaucoma (PG, 8 eyes), juvenile open-angle glaucoma (JOAG, 8 eyes) and primary angle-closure glaucoma (PACG, 24 eyes), between February 2021 and January 2025. Qualified (with topical therapy) and complete (w/o topical therapy) surgical success rates were determined using Kaplan-Meier analysis with IOP levels under 18, 15 and 12 mmHg. Cox regression analysis was done to determine the influence of several clinical factors on surgical success, including age, sex, lens status, cataract surgery, glaucoma type and severity, GATT extent, hyphema grade, clot formation and IOP spike.

Totally 185 patients (67, 36.7% female) with a median age 69 years were analysed. 25 (13.5%), 47 (25.4%) and 113 (61.1%) eyes had mild, moderate and advanced glaucoma, respectively. 122 (65.9%) received additional phacoemulsification surgery. Cumulative surgical success rates for IOP levels, <18 mmHg, <15 mmHg and <12 mmHg were, 86.4%, 84.7% and 54.7% at last visit, respectively. Univariate and multivariate models revealed age (≤60 years), IOP spike, moderate and advanced glaucoma levels and non-PEXG as predictors of failure for complete success. Complete success rates were significantly higher in PEXG eyes compared to non-PEXG eyes for all success criteria (p=0.0092 for IOP <18 and IOP <15 mmHg, p=0.0055 for IOP <12 mmHg). 

This study highlighted reasonable overall success rates of GATT even with more strict success criteria. Our findings stress the presence of potential factors for surgical failure, including younger age, IOP spike, moderate-advanced glaucoma and non-PEXG, which might have importance especially in patients who have non-adherence to anti-glaucoma medication usage. We firstly determine that PEXG could be a potential factor to be associated with higher surgical success even under lower target IOP levels compared to several other forms of glaucoma. This finding also arises the utility of GATT surgery in PEXG eyes indicating this MIGS technique as an optimal procedure in this patient group.