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A hemispheric approach to gonioscopy-assisted transluminal trabeculotomy (GATT)

Poster Details

First Author: D.Wang CANADA

Co Author(s):    A. Arora   S. Nazarali   S. Cote   M. Schlenker   B. Ford   P. Gooi     

Abstract Details


To report surgical outcomes of a novel hemispheric approach to gonioscopy assisted transluminal trabeculotomy (GATT). GATT is an ab interno minimally invasive glaucoma surgery (MIGS) originally described as a 360-degrees trabeculotomy performed with 5-0 prolene. We elected to perform a hemispheric rendition such that only 180-degrees of Schlemm’s canal is treated rather than the full 360-degrees.


Cloudbreak Eye Care (5340 1 St SW, T2H 0C8), Calgary, Alberta


We performed a retrospective chart review of all GATT and hemispheric GATT procedures performed by one ophthalmologist at a single surgical site. The primary outcome assessed was the number of patients achieving surgical success, defined as IOP lower than 21 mmHg or reduced at least 20% by 6 months, AND not requiring further glaucoma surgery. Secondary outcomes assessed were post-operative IOP and number of medications at 1, 3, and 6 months. The study adhered to the Declaration of Helsinki and was approved by Health Research Ethics Board.


132 patients (57 GATT and 77 hemi-GATT) were included. Baseline demographics (age, gender, previous surgeries, mean visual field deviation, logMAR BCVA) were similar in both groups. For GATT, the mean IOP decreased from 22.8±9.3mmHg to 13.2±4.9mmHg at 6 months, and mean number of glaucoma medications decreased from 2.1±1.5 to 1.4±1.2 at 6 months. For hemi-GATT, the mean IOP decreased from 31±10.3mmHg to 14.4±4.4mmHg at 6 months, and mean number of medications decreased from 3.6±1.2 to 1.7±1.4 at 6 months. There was no significant difference in outcomes between techniques.


Surgical outcomes and post-operative IOP reduction and number of glaucoma medications for hemi-GATT and GATT did not significantly differ between groups. The hemi-GATT procedure is a novel technique that can be used to preserve 180-degrees of Schlemm’s canal, allowing for future GATT or angle surgery to be performed.

Financial Disclosure:

receives consulting fees, retainer, or contract payments from a company producing, developing or supplying the product or procedure presented

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