May 2015




GATT-lite on tap

by Maxine Lipner EyeWorld Senior Contributing Writer


The TRAB360

The unit has a sharp tip that can be used to penetrate through the inner wall of Schlemms canal.

Source: Savak Teymoorian, MD

Exploring ab interno trabeculotomy with the TRAB360

A unique approach to ab interno trabeculotomy using a device known as the TRAB360 (Sight Sciences, Menlo Park, Calif.), which might be thought of as a sort of GATT-lite (gonioscopy-assisted transluminal trabeculotomy), is making inroads in glaucoma treatment. A rigid nylon probe is encased with a metal guide that comes to a point, and on the handle of the device is a roller, according to Steven Sarkisian, MD, clinical professor, University of Oklahoma College of Medicine, and glaucoma fellowship director, Dean McGee Eye Institute, Oklahoma City. When youre in the eye, the metal tip makes a microscopic entry point into the canal, Dr. Sarkisian said. As you use the roller the probe cannulates Schlemms canal; once the canal is cannulated, you pull the probe forward and it unroofs the canal. It does this 180 degrees at a time, he said. This gives practitioners the option of doing just 180 degrees of trabeculectomy or the full 360 degrees.

GATT alternative

Savak Teymoorian, MD, Harvard Eye Associates, Laguna Hills, Calif., views such titratability as an advantage over traditional GATT. He said that with GATT, the illuminated catheter must be threaded all the way around 360 degrees and sometimes this can get caught on scar tissue, making it impossible to go the full distance. If you cant go all the way around on those procedures, you cant complete the procedure, Dr. Teymoorian said. In this case, however, if you run into some kind of obstruction, its OK because as soon as you pull out, youre at least going to unroof that many clock hours of Schlemms canal. Then you can always flip it around and go to the other side. Dr. Sarkisian said there are other advantages over traditional GATT as well. While it remains to be seen exactly what the cost for the TRAB360 device will be, he estimates that it will be less than that of the iTRACK microcatheter (Ellex Medical, Adelaide, Australia). In addition, he views ab interno trabeculectomy with the TRAB360, which can be done through a single incision, as a more efficient procedure than GATT. The problem with GATT is you have to make 2 or 3 incisions in the cornea, Dr. Sarkisian said. In addition, he said that GATT uses existing ab externo technology to perform an ab interno procedure, whereas the TRAB360 was designed purely for an ab interno procedure. In his view, the only disadvantage of the ab interno approach with the TRAB360 is the same as with any trabeculotomy, and that is postop hyphema. Its the same issue that people who do the Trabectome [NeoMedix, Tustin, Calif.] procedures see, Dr. Sarkisian said. Almost always that hyphema is transient and resolves on its own. However, it can be troubling for the patient to have several days of blurred vision because of hyphema. In contrast, the iStent (Glaukos, Laguna Hills, Calif.) has such a small wound that the hyphema is often gone on day 2, if it occurs at all, he said.

Patient considerations

Dr. Teymoorian finds that prime candidates for the procedure are those who need to minimize glaucoma drops. The goal is to minimize the need to do trabeculectomy or tube shunt surgery, he said. Compliance is one of the major issues with any glaucoma drops, whether related to cost or to patients remembering to use them. So any intervention that can minimize the need for medications is useful, he said.

Dr. Sarkisian agreed that compliance issues can factor into use of the TRAB360. I have done it in advanced glaucoma cases where patients were controlled on medications; however, they were not compliant with their medications for a variety of reasons, he said. With average pressures in the mid-teens, he finds that this procedure lends itself most to the mild-to-moderate glaucoma patient. Patients do not necessarily need to have a cataract to benefit from the procedure, he said. Ive done it combined with phaco or as a standalone procedure, he said. One of the advantages that this might have over the iStent is that the iStent is an off-label procedure when its a standalone procedure. However, with the TRAB360, nothing is left in the eye, making this in many ways just a sophisticated cutting instrument, Dr. Sarkisian said. Dr. Teymoorian pointed out that in cases where glaucoma patients do have cataracts, this can be readily done at the same time. If youre already doing a cataract surgery, its the natural next step in taking care of the patient, he said, adding that this is in line with MIGS procedures.

Dr. Teymoorian views this procedure as an important new option for glaucoma and anterior segment specialists. The fact that the conjunctiva is preserved with the approach is no small thing, he said. He sees trabeculectomy with the TRAB360 as a lower-risk procedure to take better care of glaucoma patients.

The way I think about taking care of glaucoma patients is that you have to have a long-term view of whats going onits not a sprint, its more of a marathon, Dr. Teymoorian said. Every small step we do at the beginning has a significant influence on how things end up.

Editors note: Dr. Sarkisian has financial interests with Sight Sciences. Dr. Teymoorian has financial interests with Glaukos.

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