Eyeworld

EW CATARACT 26 July 2018 Device focus by Michelle Stephenson EyeWorld Contributing Writer fined as an eye pressure reduction of 20% or more from baseline, so that should also be considered success in the real world setting. Typically, patients are able to get off at least one medication," she explained. According to Dan Bettis, MD, University of Iowa, Iowa City, ideal patients for MIGS are those with mild to moderate open angle glaucoma. They should be relatively well controlled on medication. "We know from Medicare data that this includes 15–20% of patients under- going cataract surgery in the United States," he said. "This represents an opportunity for the cataract surgeon to offer additional value to his or her patients by helping them better manage their glaucoma. Given the improved safety profile and more rapid visual recovery, MIGS can also be considered in patients for whom traditional glaucoma surgery is deemed relatively high risk. Though early studies show MIGS may be less effective in lowering IOP than tradi- tional glaucoma surgeries, MIGS fills an important gap in the treatment of patients who would benefit from lower IOP but do not warrant the risk of traditional surgery." Dr. Okeke agreed that the angle should be open. "Ideally, that angle should be nice and open, with no other pathology. Patients should have good nerve reserve, meaning that their optic nerve cup-to-disc anisms of action, and it is FDA approved to be performed only in conjunction with cataract surgery. The CyPass Micro-Stent (Alcon, Fort Worth, Texas) is a microstent that allows the surgeon to have access from the anterior chamber to the su- praciliary space to allow for flow to that area. "The Glaukos iStent Supra is coming down the pipeline. It is not yet available, but it also accesses the supraciliary space," Dr. Okeke said. "The term supraciliary space versus suprachoroidal space are seen as one and the same." Shunting to the subconjunctival space This is done with the XEN Gel Stent (Allergan, Dublin, Ireland), which allows fluid to flow from the anteri- or chamber through to the subcon- junctival space. "Soon to come down the pipeline is the Hydrus Microstent by Ivantis [Irvine, California]," Dr. Okeke added. Candidates for MIGS procedures Dr. Okeke said it is important to set realistic patient expectations to achieve a good outcome. "When thinking about who is a good candi- date, success should be achieving a 20–30% pressure reduction or a pres- sure that is in the mid-teens. Success in many of the MIGS studies was de- Bypass of the trabecular meshwork The iStent (Glaukos, San Clemente, California) bypasses the trabecular meshwork, and this is FDA approved to be performed in conjunction with cataract surgery. "By bypassing the trabecular meshwork tissue, one is able to create a conduit that directly allows fluid to enter Schlemm's ca- nal," Dr. Okeke explained. "A single iStent is currently available. We're hoping to soon have access to the iStent Inject, which is a more intui- tive design and offers placement of two stents at one time." Dilation of Schlemm's canal Canaloplasty lowers pressure by dilating Schlemm's canal to restore natural outflow. "Two devices have this mechanism of action: Visco360 by Sight Science and ab interno canaloplasty (ABiC), which uses the illuminated iTrack catheter by Ellex [Adelaide, Australia]," Dr. Okeke said. "Both devices allow for a cathe- ter to be inserted into Schlemm's canal, which allows for the place- ment of viscoelastic that can dilate Schlemm's canal and open up any areas of adhesions and stretch open the distal collector channels." Shunting to the suprachoroidal space This is one of the newer mech- M any new MIGS tech- nologies have come to the market during the past decade. According to Constance Okeke, MD, Virginia Eye Consultants, Nor- folk, Virginia, "One of the best ways to categorize the various technolo- gies is by mechanism of action." Removal of trabecular meshwork Several MIGS procedures involve the removal of trabecular meshwork, which is the area thought to be of highest outflow resistance. These include the Trabectome (NeoMedix, Tustin, California), TRAB 360 (Sight Sciences, Menlo Park, California), the Kahook Dual Blade (New World Medical, Rancho Cucamonga, California), and gonioscopy-assisted transluminal trabeculotomy (GATT). "All of these devices or procedures remove either a portion of or up to 360 degrees of trabecular mesh- work tissue," Dr. Okeke said. "The TRAB 360, the Kahook Dual Blade, and GATT are procedures that can be done with a disposable device, whereas the Trabectome comes with a whole electrical system for removal with fluidics. These trabec- ular meshwork removal procedures can be done in combination with cataract surgery or stand alone." MIGS for cataract surgeons Ab interno canaloplasty (ABiC) using the iTrack catheter Source: Ellex iStent Trabecular Micro-Bypass Stent Source: Glaukos

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