Eyeworld

EW FEATURE 46 MIGS roundup • July 2017 AT A GLANCE • MIGS lowers IOP with less tissue disruption than traditional glaucoma surgeries. • Currently approved MIGS work in three different areas of the eye: the canal, the suprachoroidal space, and the subconjunctival space. • The ideal MIGS patient is someone who needs a modest amount of IOP lowering. • The key to success with MIGS is getting comfortable with gonioscopy in the operating room. • Three types of ophthalmologists should consider incorporating MIGS into their practices: comprehensive ophthalmologists, high-volume cataract surgeons, and glaucoma specialists. by Michelle Stephenson EyeWorld Contributing Writer and the openings along the length of the tube allow aqueous to flow out. "Instead of targeting the tra- becular meshwork, CyPass goes into the suprachoroidal space, which can offer an alternative pathway for aqueous to flow," Dr. Greenwood said. "It may be a viable alternative for patients with elevated episcleral venous pressure." Subconjunctival procedure XEN45 Gel Stent (Allergan, Dublin, Ireland) is a stent made of a soft, collagen-derived gelatin. It is 6 mm long and is approximately the width of a human hair. The stent is injected through a small self-sealing corneal incision using a preload- ed IOL-like injector. After being implanted in the eye, it creates a gentle outflow of aqueous from the anterior chamber into the subcon- junctival space. "XEN is a much safer interven- tion for people who might otherwise need a traditional tube surgery," Dr. Greenwood said. "The data on both the CyPass and the XEN are early but good, so we are learning more as surgeons gain more experience with these devices." Why MIGS? According to Dr. Berdahl, the ideal patient for a MIGS procedure is someone who needs a modest amount of IOP lowering. "Some procedures, like XEN, can get the pressure a little bit lower, but that comes with a trade for a little more risk and a little more postoperative care as opposed to an iStent, which can provide nice IOP lowering with a nice safety profile, but likely not down into the very low double digits. In general, it is a balance between efficacy and risk. The more IOP lowering you are looking for, the more risk is associated with it. A more modest IOP response comes with a lower amount of risk," he explained. Dr. Lewis agreed. "MIGS are much safer than traditional glauco- ma surgeries and achieve reasonable pressure reduction with minimal risk. We are becoming comfortable with how and when to use them. I think all of them will ultimately Another MIGS procedure is the TRAB 360. "It is a trabeculo- tome, which allows you to make a 180-degree incision in the trabecular meshwork. The surgeon makes one pass clockwise and one pass counter- clockwise. This allows 360 degrees of cutting of the trabecular meshwork. Again, you don't need any addi- tional equipment except the device itself," Dr. Greenwood noted. ABiC is a new MIGS procedure that can comprehensively restore the natural outflow pathways in glaucoma patients. It is performed via a self-sealing, clear corneal inci- sion, which preserves the clinically proven benefits of 360-degree visco- dilation of Schlemm's canal provid- ed by traditional canaloplasty but has the speed and ease of a MIGS procedure. It has been shown to be effective alone or in combination with cataract surgery. GATT is a MIGS procedure that effectively manages open-angle glaucoma. It is performed via micro- incisions in the cornea. A 1.0-mm incision is made in the periphery of the cornea through which the sur- gery is completed. After entering the eye, the surgical procedure involves cutting through the trabecular meshwork, cannulating Schlemm's canal 360 degrees, and then unroof- ing Schlemm's canal. One major advantage of the procedure is that it accesses the entire natural drainage system and opens it 360 degrees, rather than targeting only a small portion of the drainage system. Opening the whole drainage system provides adequate pressure lowering. Another advantage is that it does not involve opening conjunctival tissues to access Schlemm's canal. Suprachoroidal procedure The CyPass Micro-Stent (Alcon, Fort Worth, Texas) is a supraciliary device designed to create a controlled out- flow pathway to the suprachoroidal space. The device is a 6.35-mm long tube made of a polyimide material with an outer diameter of 0.51 mm. It can be placed through a 1.5-mm corneal incision and is inserted on a small guidewire with a special tip that separates the iris from the scler- al spur. The CyPass Micro-Stent is inserted into the cleft that's created, find that these procedures are useful in pseudophakic and phakic eyes. However, this is currently off-label, so there are concerns about reim- bursement." Canal-based procedures According to Dr. Lewis, the canal- based procedures require an open angle. They include iStent (Glaukos, San Clemente, California), ABiC (ab interno canaloplasty, Ellex, Minne- apolis), TRAB 360 (Sight Sciences, Menlo Park, California), goniosco- py-assisted transluminal trabeculot- omy (GATT), and the Kahook Dual Blade (New World Medical, Rancho Cucamonga, California). iStent is a trabecular micro-by- pass implant. It was the first FDA-ap- proved device for the treatment of mild to moderate open-angle glauco- ma and the first MIGS implant to improve the eye's natural fluid out- flow by creating a permanent open- ing in the trabecular meshwork to lower IOP. It can be safely implanted in the eye during cataract surgery, and it spares important eye tissue that is often damaged by tradition- al surgeries. It can be implanted through a 1.5-mm corneal incision. Instead of inserting a device into the eye, the Kahook Dual Blade has a pointed tip and two blades that excise the trabecular meshwork and remove it, which allows for aqueous flow from the anterior chamber into Schlemm's canal, without having to go through the trabecular meshwork, which is thought to be the site of greatest resistance. "This procedure can be performed in any patient, regard- less of whether they have a cataract or have previously had cataract surgery," said Michael Greenwood, MD, Fargo, North Dakota. "It can also treat all severities of glaucoma, while the iStent is only approved for mild and moderate glaucoma." According to Dr. Greenwood, the Trabectome (NeoMedix, Tus- tin, California) is very similar to the Kahook Dual Blade, but it uses electrocautery to ablate the trabec- ular meshwork. "You do need extra equipment to do the Trabectome, whereas the Kahook Dual Blade does not require any additional equip- ment," he added. Microinvasive glaucoma surgery (MIGS) lowers IOP with less tissue disruption than traditional glaucoma surgeries and has been found to effectively treat mild to moderate glaucoma "T here are a lot of approved MIGS procedures all of a sudden, and these procedures fill a tremendous gap as we are trying to move toward safer procedures and earlier intervention," said John Berdahl, MD, Sioux Falls, South Dakota. "The gap that used to exist between eye drops and a trabeculec- tomy or a tube shunt was enormous. This allows us to intervene earlier in the disease in a safer way." The currently approved proce- dures work in three different areas of the eye: the canal, the suprachoroi- dal space, and the subconjunctival space. "The FDA labeling indications for the canal and suprachoroidal space procedures is in addition to cataract surgery for mild to moder- ate glaucoma," said Richard Lewis, MD, Sacramento. "Over time, I think that will change, and I think we will Tips and techniques for optimizing approved MIGS

• Blank Page
• Blank Page (1)