Glaucoma Associates of Texas are pioneers of an internationally recognized, minimally-invasive surgery for open-angle glaucoma called GATT. Their procedure is a variation of traditional trabeculectomy, which has been safely and effectively used for decades. Learn what GATT is, how it works, and what you can expect if you choose to pursue it.*

GATT explained

GATT stands for Gonioscopy-Assisted Transluminal Trabeculectomy.

• Gonioscopy is an eye test for whether the drainage angle (space between the iris and cornea where fluid drains) is sufficient and functioning properly.
• Transluminal means through the tubular cavity (lumen) of the eye’s drainage structure (made up of the trabecular meshwork and Schlemm’s canal).
• Trabeculectomy is a surgical procedure for widening Schlemm’s canal.

Since GATT targets natural outflow pathways, there’s no need to make an opening in the eye wall, as there is with trabeculectomy surgery.

How GATT is performed

The surgery takes little time and carries few risks.

• A roughly 1-millimeter incision is made in the periphery of the cornea (the clear covering over the iris and pupil).
• Through this tiny incision, the surgeon inserts a microsurgical blade and cuts through the tissue of the trabecular meshwork to reveal Schlemm’s canal with a microsurgical blade.
• A lighted microcatheter is fed through the circular canal to clear an opening for fluid outflow.

Major advantages

GATT has two major advantages over conventional surgery.

• It is able to access and clear the entire drainage pathway, all 360 degrees of Schlemm’s canal, for the best chance at lowering eye pressure.
• The conjunctiva covering the white part of the eye (sclera) doesn’t need to be opened to access Schlemm’s canal, allowing for less scar tissue and much better odds of success if further surgery is required.

Who it’s for and what to expect

GATT is intended for adults and children with open-angle glaucoma, and can also benefit some kinds of closed-angle glaucoma. It is an outpatient procedure that generally takes under an hour to complete, and may be combined with other surgeries. Local anesthesia, with light sedation, is provided prior to the surgery.

If you decide to pursue GATT, you’ll meet with the scheduling nurse to discuss preparations. After surgery, you’ll be given an eye patch with a plastic shield to wear during sleep. You’ll have a follow-up eye exam the next day, and your doctor will give you eye drops to prevent infection and inflammation.

Patients are closely monitored for several weeks after surgery, though healing can take up to three months. Your vision and eye pressure can vary during this time. A new eyeglass prescription will be needed about six to eight weeks after surgery.

*Glaucoma Associates of Texas. (n.d.). GATT Procedure. https://www.glaucomaassociates.com/gonioscopy-assisted-transluminal-trabeculotomy

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