Eyeworld

EW GLAUCOMA 144 April 2017 by Stefanie Petrou Binder, MD, EyeWorld Contributing Writer Unique device The XEN stent bypasses Schlemm's canal and the trabecular meshwork, which affords the XEN the potential to help a wide spectrum of glauco- ma patients, from mild to moderate to advanced/refractory cases, by exploiting the "untapped" potential of the subconjunctival space. While other stents rely on the eye's own drainage system, making them more suitable for mild to moderate cases in which aqueous drainage is still somewhat intact, the XEN connects the anterior chamber directly with the subconjunctival space. "I'm excited about the tech- nology. I think it's a big advance in glaucoma surgery that will pro- vide an effective alternative to our traditional approaches, and that will be safer and a little less compli- cated for surgeons than traditional surgeries. This is a procedure that all ophthalmologists will be able to learn. Eye doctors are trained in glaucoma surgery during residency and some continue to do it whether or not they are glaucoma specialists. Implanting the XEN is a decided- ly shorter procedure and far less cumbersome than what we are used to. There is much less tissue ma- nipulation, and it should be widely adopted by many ophthalmologists, not just specialists," said Dr. Lewis, who was a medical monitor for all of the U.S. XEN trials leading up to its recent FDA approval, and was also involved in training. According to Dr. Lewis, the XEN fits many different roles in glauco- ma surgery. It can be used to relieve pressure at all stages of glaucoma. "Because of the labeling, the XEN is not indicated only for patients who need cataract surgery, which is the case with all the other MIGS devices. In addition, it does not necessarily require an open angle. This broad- ens the label use and its appeal," he said. He said that the learning curve was reasonable and somewhat de- pendent on a surgeon's experience with MIGS and bleb procedures. De- spite videos that make surgery seem clean and simple, he said it may take about 10 cases for most doctors to understand the subtleties of the procedure. "Like everything else, surgery looks easy when you watch it done by an experienced surgeon. This is an elegant procedure but not without its complications. There are nuances to it that you have to learn, and you have to know what to do if Plan A does not go well," Dr. Lewis Changing the game with the XEN implant T he MIGS revolution has been terrific for mild to moderate glaucoma, but has left two gaps in therapy: patients not undergoing cataract surgery and patients who need more aggressive pressure-lowering. The XEN implant (Allergan, Dublin, Ireland) addresses these issues with breakthrough technology in an elegant new procedure. The XEN procedure remakes the trabeculectomy by distilling its essential elements and performing the operation from the inside out. The result is a streamlined, full-thickness drainage operation that preserves the more profound pressure-lowering of a trabeculectomy but with greatly reduced risk. XEN eliminates the conjunctival incision and dissection, the scleral dissection and flap closure, and the iridectomy. Each of these steps has its own risks and complications that are wiped away by the internal approach of XEN. The idea of doing a glaucoma drainage procedure from inside the eye has been an appealing option ever since the early days of phaco and vitrectomy instrumentation. We de- veloped a trephine to perform an internal sclerectomy in the 1980s. 1,2 The missing ingredient was a device to keep the hole open as well as to control drainage. The XEN implant has solved this problem by incorporating the features of a trabeculectomy flap but without requiring the complex freehand scleral dissection and closure. The XEN removes the uncertainty of scleral flap sutures that always seemed either too tight or too loose. XEN will find a welcome place among the expanding options for glaucoma surgery. The procedure can be used at all stages of glaucoma, it does not need to be performed at the time of cataract surgery, and it doesn't need a completely open anterior chamber angle. The XEN procedure may initially be performed as a less risky form of trabeculectomy but its safety and efficiency may allow it to be used earlier than we would be comfortable doing a trabeculec- tomy or tube-shunt. One key question is whether the XEN procedure can thread the needle of achieving the lower pressure-lowering of a bleb-creating procedure without the risks. XEN joins the iStent (Glaukos, San Clemente, California) and CyPass (Alcon, Fort Worth, Texas) as the third device approved by the FDA in the last 5 years. This is unprecedented in glaucoma surgical history and is particularly amazing since each device has a different mechanism of action. The XEN procedure promises to be a safer, less complicated, and more successful drainage operation that could quickly replace trabeculectomies—to the great benefit of both glaucoma surgeons and our patients. 1. Brown RH, et al. Internal sclerectomy for glaucoma filtering surgery with an automated trephine. Arch Ophthalmol. 1987;105:133. 2. Brown RH, et al. Internal sclerectomy with an automated trephine for advanced glaucoma. Ophthalmology. 1988;95:682. Reay H. Brown, MD, Glaucoma editor With Allergan's U.S. launch of the XEN gel implant underway, specialists are tapping into this exciting new technology M icroinvasive glaucoma surgery (MIGS) is the subject of tremendous interest in the glauco- ma world, providing neat, pressure-lowering solutions without the complications and risks associated with traditional glaucoma surgery. A recent U.S. Food and Drug Administration (FDA)-approved option is the minimally invasive AqueSys XEN45 Gel Stent (Allergan, Dublin, Ireland), which was shown to effectively lower IOP and reduce topical medication in both U.S. and international studies. Along with the XEN injector, the XEN implant offers a unique solution to reducing pressures in even the toughest glau- coma patients, in whom previous surgical treatments have failed or medical therapy has reached its lim- it. Richard Lewis, MD, Sacramento, California, and Davinder Grover, MD, attending surgeon and clini- cian, Glaucoma Associates of Texas, Dallas, spoke to EyeWorld about different aspects of the XEN, which became accessible to U.S. doctors in early 2017. Gonioscopic photograph demonstrating the XEN45 implant in the superior nasal angle. Source (all): Davinder Grover, MD Glaucoma editor's corner of the world

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