Eyeworld

99 EW GLAUCOMA February 2018 by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer "For instance, someone who is well controlled on different medica- tions and is going to have cataract surgery would benefit from the least traumatic of the current MIGS technologies, the iStent, in terms of collateral damage to the canal. If someone is pseudophakic or phakic, that would change my approach. I'd be more likely to use tissue cutting technologies, mainly GATT, which I find works extremely well in phakic young patients. We have had incon- sistent results when putting devices into the canal in phakic patients, whether iStents or more newly developed ones. We get a better response by removing trabecular tis- sue in younger phakic patients, es- pecially myopes or uveitic patients. In pseudophakic patients, inserting iStents is an off-label procedure, so the treatment of choice might be the KDB or the Trabectome in that patient group." Three pathologies respond particularly well to tissue removal techniques, such as Trabectome. These include pseudoexfoliation, due to pigment buildup in the TM; Axenfeld-Rieger syndrome; and patients with controlled uveitic glaucoma, who seem to have an element of steroid response. For each technique addresses a relatively unique scenario and is less likely to be applicable in patients across the board. Ab interno Schlemm's canal surgeries can be broken down into four groups. The first involves the removal of the TM and inner wall of Schlemm's canal by an internal ap- proach (ab interno trabeculectomy), which can be done using Trabec- tome (NeoMedix, Tustin, California) and Kahook Dual Blade (KDB, New World Medical, Rancho Cucamonga, California). Next, microstents can be used to bypass the TM, such as the iStent (Glaukos, San Clemente, Cal- ifornia) and the Hydrus Microstent (Ivantis, Irvine, California). A third approach involves the dissection of the TM and Schlemm's canal via an ab interno trabeculotomy proce- dure, such as gonioscopy-assisted transluminal trabeculotomy (GATT) or a 360-degree sutured trabeculo- tomy approach (TRAB 360, Sight Sciences, Menlo Park, California). Finally, Schlemm's canal can be di- lated using ab interno canaloplasties like ABiC (Ellex, Adelaide, Australia) and Visco360 (Sight Sciences). "I think that different tech- niques are necessary to treat glaucoma and that certain ones can be advantageous for different patients," Dr. Harasymowycz said. In the absence of comparative data, glaucoma surgeons rely on their own experiences to guide them through the maze of new and old glaucoma treatment options P rimary open angle glau- coma (POAG) is the most common form of glauco- ma, in which pathologic changes to the trabecular meshwork (TM) and Schlemm's ca- nal (conventional outflow pathway) encumber aqueous outflow, causing an increase in IOP. One approach to treatment in patients with mild to moderate POAG aims to lower IOP by reinforcing the conventional outflow pathway, thereby facilitating physiologic aqueous outflow. Within this framework, ab interno ap- proaches to the TM and Schlemm's canal have recently stolen the spot- light due to their excellent safety and efficacy profiles. However, in the absence of prospective, random- ized trials comparing different ab interno procedures, choosing the right technique can prove confus- ing. EyeWorld spoke to two special- ists who shared their preferences in the use of ab interno, microinvasive glaucoma surgery (MIGS) to help clarify the issue. Do all MIGS have a place in glaucoma surgery? MIGS has flushed the arena of glaucoma treatment with so much optimism, in providing simple solutions to IOP dilemmas that eye doctors never thought possible, that it has left us wondering: Do we dare ask for more? While it's tempting to hope that one MIGS device or procedure could be the answer to all of our glaucoma problems, the complexity of the disease rules out any one winner. According to Paul Harasymowycz, MD, chief of glaucoma, University of Montreal, Canada, who spoke with EyeWorld on his personal MIGS criteria, it pays to become comfortable with different MIGS techniques because Deciding on the right MIGS I n this "Glaucoma editor's corner of the world," two dynamic glaucoma specialists, Paul Harasymowycz, MD, and Douglas Rhee, MD, tackle the elusive topic of how to find the right MIGS procedure. Because the two physicians do such a good job of taking the reader down the "complicated matrix" of MIGS decision making, I took a moment to consider all of the different aspects of the decision. In discussing which procedure might fall in what place, our experts had to consider the glaucoma diagnosis or angle status, the age of the patient, the severity of the glauco- ma, the presence or absence of the native crystalline lens (as well as any cataract), potential exacerbating factors such as uve- itis or steroid response, how well controlled the pressure is on current medications, the baseline and target pressure, reimburse- ment challenges, any history of previous angle surgeries, the physician's experience with each approach, resources available at each surgeon's facility, the safety of each procedure as well as its efficacy, the avail- ability of any long-term efficacy data, and the quality (retrospective or prospective) of the data for the procedure. So they had just a few things to consider when choosing the right procedure! I think the complexity of the decision making process gives us some insight into how difficult it might be to ultimately reach a unanimous consensus on these proce- dures. However, the discussion that follows demonstrates that the art of glaucoma surgical decision making is alive and well in the MIGS era. Nathan Radcliffe, MD, Glaucoma editor Two well-positioned trabecular bypass stents Source: Paul Harasymowycz, MD continued on page 100 Glaucoma editor's corner of the world

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