Presented by: Siempis Thomas MD
Edited by: Penelope Burle de Politis MD
The GATT technique was first described in 2014 by Grover’s group, in Dallas, Texas (USA), and has since been applied in various centers worldwide with excellent outcomes in both primary and secondary glaucomas. Clinical studies have shown that the GATT technique is effective not only in primary open-angle and closed-angle glaucoma, but also in pseudoexfoliative, pigmentary, uveitic, and juvenile glaucoma.
The major advantage of this technique is its conjunctiva-sparing intraocular approach. This translates into a shorter and less traumatic operation, while not affecting the effectiveness of a future bleb-based antiglaucoma surgery – i.e., traditional trabeculectomy – which may eventually be needed. This therefore allows for a gradual therapeutic strategy. The GATT technique can be combined with cataract surgery or performed as an independent procedure, which is particularly attractive as an option for secondary glaucomas, especially in younger individuals, in whom a more invasive glaucoma operation may not be the ideal first-line modality.
In this video, recorded at the Ophthalmica Eye Institute in Thessaloniki, Greece, Dr. Thomas Siempis (MD, FRCOphth, FEBO), consultant in glaucoma, cataract and advanced anterior segment surgery (GAASS), and specialist in interventional glaucoma and microinvasive glaucoma surgery (MIGS), performs the GATT technique as a “stand-alone” intervention in the left eye of an 83-year-old pseudophakic patient with uncontrolled moderate pseudoexfoliative glaucoma and allergy to multiple antiglaucoma drops. The preoperative intraocular pressure (IOP) was 32 mm Hg on oral acetazolamide 250mg BID. The patient had already undergone a combined cataract-goniotomy procedure with Sinskey hook in the contralateral eye, with very good results; hence, the decision to proceed with the same minimally invasive technique. The patient’s recovery was uneventful, and the postoperative IOP remains stable between 12 and 13 mm Hg at 1 month after surgery without any topical or systemic medication.
The surgical steps and timing in the video are as follows: subtenon anesthesia (00:02); cauterization of the tip of a 5-0 Prolene™ suture segment into a mushroom-shaped head (00:16); main temporal 1-mm incision using an MVR blade and injection of viscoelastic (00:22); special GATT superonasal side port directed toward the nasal angle, with additional viscoelastic injection into the angle (00:30); insertion of the suture into the anterior chamber (00:45) and apposition of a surgical goniolens onto the cornea (00:52); creation of a 2 mm nasal goniotomy (00:58); inferiorly-directed insertion of the suture tip into Schlemm’s canal, and progression of the suture within the canal with 12 “advancements” for an inferior 180-degree trabeculotomy* (01:10); grasping of the suture with microforceps at the level of the nasal goniotomy, followed by gradual withdrawal, thereby opening the inner wall of the canal (01:34); verification with the goniolens of an expected microhemorrhage at the angle, indicating that the initial 180-degree trabeculotomy was effectively performed (01:57); clearer visualisation of the goniotomy inferonasally (02:03); inferonasal side port and superiorly-directed reinsertion of the suture (02:20); suture progression with 12 “advancements”, checking at times that it is inside the canal (02:48); gradual withdrawal of the suture for a superior 180-degree trabeculotomy (02:56), thus completing the total 360 degrees; flushing of viscoelastic with BSS (03:09); air injection into the anterior chamber to check for residual viscoelastic (03:24); sealing of the incisions, antibiotic injection into the anterior chamber, IOP check (03:30); end of the procedure (03:59).
*12 for a 180-degree trabeculotomy, 24 for a 360-degree trabeculotomy. Because there is often resistance to progression of the suture when it reaches 180 degrees (opposite the nasal goniotomy) – as seen in this case at 01:29 and 01:31 – the lower 180-degree trabeculotomy is carried out first and the remaining superior trabeculotomy is done as a second step.
“Less is more only when more is too much.” – Frank Lloyd Wright
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