Gonioscopy assisted transluminal trabeculotomy (GATT): A hemispheric approach
Author Disclosure Block: A. Arora: None. S. Nazarali: None. S. Cote: None. A. Duimering: None. M. Schlenker: None. B. Ford: None. P. Gooi: Other financial or material interest; Name of Commercial Company(s); Consultant for Glaukos (iStent), Consultant for Allergan (XEN).
Abstract Body:
Purpose: To report surgical outcomes of a novel hemispheric approach to gonioscopy assisted transluminal trabeculotomy (GATT).
Study Design: Retrospective Cohort Study
Methods: GATT is a recent minimally invasive glaucoma surgery (MIGS) technique, originally described with a 360-degrees trabeculotomy to successfully reduce intraocular pressure (IOP). We elected to perform a hemispheric rendition such that only 180-degrees of Schlemm’s canal is treated rather than the full 360-degrees. The study adhered to the Declaration of Helsinki and Health Research Ethics Board was processed. The primary outcome of interest was the number of patients achieving IOP lower than 21 mmHg or reduced by least 20% by 6 months, not requiring further surgery. IOP lowering and medications were secondary outcomes studied at 1,3, and 6 months.
Results: 132 patients were included in this study, including 57 receiving GATT and 77 receiving hemi-GATT. Of these patients, diagnoses included primary open angle (53), primary closed angle (15), pseudoexfoliation (12), pigmentary (7), uveitic (22), mixed mechanism (6), trauma/angle recession (6), neovascular (3), steroid induced (3), post-penetrating keratoplasty (1), hemolytic (1), and Posner Syndrome (1) glaucoma. The mean age for patients studied was 62 years (15-88) with 56 males and 76 females. 50 patients had underwent previous glaucoma surgery. At the time of surgery, 60 patients had a cataract extraction concurrently and 6 had intraocular lens exchanges. The mean visual field deviation was -14.93 dB with a mean baseline logMAR best corrected visual acuity of 0.43. For GATT, the mean IOP decreased from 22.8±9.3mmHg to 13.0±4.4mmHg (p<0.001) at 1 month, 13.0±9.3mmHg (p<0.001) at 3 months, and 13.2±4.9mmHg (p<0.001) at 6 months post-operatively. The mean number of glaucoma medications decreased from 2.1±1.5 to 1.4±1.2 at 6 months post-operatively. For hemi-GATT, the mean IOP decreased from 31±10.3mmHg to 15.7±6.8mmHg (p<0.0001) at 1 month, 14.9±4.6mmHg (p<0.001) at 3 months, and 14.4±4.4mmHg (p<0.001) at 6 months post-operatively. The mean number of medications decreased from 3.6±1.2 to 1.7±1.4 at 6 months post-operatively. The most prominent complications were hyphema (9%) and presence of cells (21%). The success rate for GATT was 74% and 70% for hemi-GATT. There were no significant differences in outcomes between techniques.
Conclusions: Within the present cohort, IOP and number of glaucoma medications were reduced significantly at 6 months from baseline in both GATT and hemi-GATT and did not significantly differ between groups. The hemi-GATT procedure is a novel technique that preserves 180-degrees of Schlemm’s canal, allowing for future GATT or angle surgery to be performed.
