EyeWorld is the official news magazine of the American Society of Cataract & Refractive Surgery.
Issue link: https://digital.eyeworld.org/i/511377
EW FEATURE 50 Secondary glaucoma challenges May 2015 by Maxine Lipner EyeWorld Senior Contributing Writer trabecular meshwork is the primary pathology. "That's what we're removing from the system," Dr. Grover said. He finds that patients with pse - doexfoliation glaucoma and those with juvenile open angle glaucoma or some type of developmental glaucoma, as well as traumatic and steroid- induced glaucoma, do well with GATT. In such cases, the suc- cess rate is about 70–80%, he noted, adding that even for those in whom Performing GATT Davinder Grover, MD, Glaucoma Associates of Texas, who performed the first G TT procedure together with Dr. Fellman, elaborated on how it is done. "First we make 2 small in- cisions in the cornea through which we do all of our manipulation," he said. "Through 1 of the incisions the suture, or the catheter, goes in and through the other we use our microsurgical instrument to pass the suture or catheter around the drain." Once the suture is introduced into the eye, the strategy is to look at the nasal quadrant of the drainage system and cut down on the trabec- ular meshwork. "That gives us direct access to Schlemm's canal," he said, adding that they then cannulate the canal with the suture or with the cathe- ter, passing it around 360 degrees until the distal end can be retrieved. Traction is placed on the proximal and the distal end of the catheter, allowing for the creating of an ab interno 360-degree trab, he said. Dr. Fellman said that this is dif- ferent from the ab externo 360-de- gree trabeculotomy that was done in the past. When this was performed, the conjunctiva was opened and incisions were made in the sclera. "That violated the territory for trabeculectomy," Dr. Fellman said. "That's why GATT is so special—it's done ab interno, everything is done internally, and we never violate the conjunctiva or the sclera." The beauty of the procedure is it took an approach that used to be done externally and internalized it to make it a microinvasive tech- nique, he said. At the same time it does not violate tissues that may need to be worked on later. In addi- tion, the GATT procedure makes it possible to open all of the patient's drains in one sitting. Dr. Grover finds that those who tend to do best with GATT are those glaucoma patients for whom the Shedding light on GATT Monthly Pulse Keeping a Pulse on Ophthalmology T he topic of this Monthly Pulse survey was "Secondary glaucoma challenges." We asked, "How many cases have you seen of secondary pigmentary glaucoma from the IOL optic or haptic rubbing against the iris or ciliary body?" The majority of respondents said 1–5. When asked about their current level of experience or interest with gonioscopy-assisted transluminal trabeculotomy, responses were almost evenly split between "I have heard of it and am interested in learning more and trying it" and "I am not inter- ested." We presented this scenario: A 70-year-old patient with pseudoexfoliation glaucoma has pressures in the mid-20s despite previous SLT and maximal medical therapy. You are worried about a possible new visual field defect but you are not certain. The vision is 20/25 and 20/40 if you glare test. The majority of respondents would perform cataract surgery in this situation. Finally, we asked if additional predictors of IOP reduction after cataract surgery based on biometrics such as anterior chamber depth would be useful, and the majority of respondents answered, "Mildly useful." Revitalizing the natural drainage system H elping to rejuvenate glaucoma patients' own drainage system is the aim with the canal-based surgery known as GATT (gonioscopy-assisted translumi- nal trabeculotomy), according to Ronald L. Fellman, MD, Glaucoma Associates of Texas, Dallas. This con- junctival-sparing, low-complication procedure is a stark departure from trabeculectomy, which involves creation of an artificial drain. "Now we're trying to enhance the patients' own natural drainage system instead of making an artifi- cial one," Dr. Fellman said. "That's one thing we're really excited about in canal-based surgery because if we could increase flow into the patient s natural drainage system, that's much more physiologic than creating an artificial passagewa ." AT A GLANCE • GATT can be used as a first-line surgical approach. • With GATT everything is done internally, without violating the conjunctiva. • The procedure is lifestyle friendly and avoids the risks of infection or hardware erosion that can accompany traditional techniques. This series of intraoperative photographs demonstrates the key portions of the gonioscopy-assisted transluminal trabeculotomy (GATT) surgery: A: Initially a goniotomy is created with a microvitreoretinal blade.