Eyeworld

66 | EYEWORLD | SEPTEMBER 2023 G UCOMA COMPLICATED CASES by Liz Hillman Editorial Co-Director About the physicians Manjool Shah, MD Associate Professor of Ophthalmology NYU Langone Health New York, New York Arsham Sheybani, MD Associate Professor of Ophthalmology and Visual Sciences Washington University School of Medicine in St. Louis St. Louis, Missouri T he reason for MIGS, according to Manjool Shah, MD, is to address the gap that existed with the conventional paradigm in glaucoma management— the paradigm that had patients either on "safe" options, like drops or SLT, or facing higher-risk surgeries, like trabeculectomy and tube shunts, with little in between. "The promise of MIGS is to fill that gap, specifically when it comes to safety," he said. While MIGS do, for the most part, fulfill that promise, there can be complications during and after MIGS procedures that the surgeon needs to be prepared to identify and address. Arsham Sheybani, MD, said that if you're performing MIGS procedures, you should be able to address the common complications that occur without needing to refer the patient to another surgeon for management, at least not immediately. Dr. Shah agreed that management of many common MIGS complications are with- in the wheelhouse of those performing MIGS. "If you can place the stent, if you can do the canaloplasty or the goniotomy, you've already performed the most nuanced surgical technique that day," Dr. Shah said. "The hardest part of dealing with complications is recognition and choosing the appropriate intervention to manage it, and the management is completely in the skillset of those who perform the initial procedures." Complications with stenting MIGS Dr. Shah said the most common complication with stenting MIGS, which in the U.S. include iStent (Glaukos) and Hydrus (Alcon), is malpo- sitioning. "The key to success and safety with any angle surgery is visualization," he said. "A good en face gonioscopic view will allow you to catch a misplaced stent easily." If you notice that the stent is in the wrong place, generally you can reposition it, Dr. Shah said, but he noted that the current iStent Inject only has a few clicks available with the cur- rent generation injector. This issue has been addressed with the newest generation iStent Infinite, which is rolling out across the U.S. Dr. Shah said reloading an iStent into the injector is a skill. "You might need to rethread it in the anterior chamber, then redeploy it, assuming you have more clicks at your disposal. If you run out of your four clicks, you can reposition an iStent manually using some microforceps, directly placing it where you need to or move it from point A to point B." Dr. Shah shared that over deployed iStents (usually caused by over dimpling of the cannu- la) can be repositioned with microforceps. To avoid under deployed stents, Dr. Shah advised applying a bit more force than you think you need, especially with the second stent. With the Hydrus, the injector system allows you to remove and replace the stent as needed. Dr. Shah also noted the importance of a 15-de- gree upward angle of the cannula for proper Hydrus entry, as well as the importance of creating a separate paracentesis incision about 3–4 clock hours away from the area of planned stent insertion to allow the Hydrus to optimally match the curvature of the canal. Bleeding (hyphema) is also a possibility with stenting procedures, as is damage that can occur due to contact with the iris root and/ or ciliary body. There are two distinct bleeding patterns that surgeons need to be aware of with MIGS. One is a slow, focal, and normal amount of blood reflux. "A little blood reflux is a confirmatory sign that you're in the right place, doing the right thing," Dr. Shah said. This is in contrast to traumatic hyphema, which can occur due to inadequate visualization, abnor- mal anatomy, or patient movement that causes you to inadvertently touch or interact with the iris root or ciliary body. Dr. Shah said that this bleeding is more diffuse and at a higher veloci- ty. He said cohesive viscoelastic should be used to tamponade this type of bleed, preventing more blood from entering the anterior chamber. The surgeon should also take the time to figure out what caused such hyphema and address it, if possible. "Typically you're going to have to move half a millimeter to a millimeter more anterior," he said. Dr. Sheybani said if a stent is placed in the wrong tissue plane, it doesn't generally cause major intraoperative complications, again, unless it creates a cyclodialysis cleft. He clar- Common complications associated with MIGS

• Blank Page