EyeWorld India September 2017 Issue

Tips and techniques for optimizing approved MIGS by Michelle Stephenson EyeWorld Contributing Writer AT A GLANCE r .*(4 MPXFST *01 XJUI MFTT UJTTVF EJTSVQUJPO UIBO USBEJUJPOBM HMBVDPNB TVSHFSJFT r $VSSFOUMZ BQQSPWFE .*(4 XPSL JO UISFF EJGGFSFOU BSFBT PG UIF FZF UIF DBOBM UIF TVQSBDIPSPJEBM TQBDF BOE UIF TVCDPOKVODUJWBM TQBDF r 5IF JEFBM .*(4 QBUJFOU JT TPNFPOF XIP OFFET B NPEFTU BNPVOU PG *01 MPXFSJOH r 5IF LFZ UP TVDDFTT XJUI .*(4 JT HFUUJOH DPNGPSUBCMF XJUI HPOJPTDPQZ JO UIF PQFSBUJOH SPPN r 5ISFF UZQFT PG PQIUIBMNPMPHJTUT TIPVME DPOTJEFS JODPSQPSBUJOH .*(4 JOUP UIFJS QSBDUJDFT DPNQSFIFOTJWF PQIUIBMNPMPHJTUT IJHI WPMVNF DBUBSBDU TVSHFPOT BOE HMBVDPNB TQFDJBMJTUT 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 trabeculectomy or a tube shunt was enormous. This allows us to intervene earlier in the disease in a safer way.” The currently U.S. Food and Drug Administration (FDA) approved procedures work in three different areas of the eye: the canal, the suprachoroidal 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 mod- erate glaucoma,” said Richard Lewis, MD , Sacramento. “Over time, I think that will change, and I think we will find that these pro- cedures are useful in pseudophakic and phakic eyes. However, this is currently off-label, so there are con- cerns about reimbursement.” Canal-based procedures According to Dr. Lewis, the canal-based procedures require an open angle. They include iStent (Glaukos, San Clemente, Califor- nia), ABiC (ab interno canaloplasty, Ellex, Minneapolis), TRAB 360 (Sight Sciences, Menlo Park, Cali- fornia), gonioscopy-assisted translu- minal trabeculotomy (GATT), and the Kahook Dual Blade (New World Medical, Rancho Cucamonga, California). iStent is a trabecular micro- bypass implant. It was the first FDA-approved device for the treatment of mild to moderate open-angle glaucoma and the first MIGS implant to improve the eye’s natural fluid outflow by creating a permanent opening in the trabecu- lar meshwork to lower IOP. It can be safely implanted in the eye dur- ing cataract surgery, and it spares important eye tissue that is often damaged by traditional 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 al- lows for aqueous flow from the an- terior chamber into Schlemm’s ca- nal, 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 sur- gery,” 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, Tustin, California) is very similar to the Kahook Dual Blade, but it uses elec- trocautery to ablate the trabecular meshwork. “You do need extra equipment to do the Trabectome, whereas the Kahook Dual Blade does not require any additional equipment,” he added. Another MIGS procedure is the TRAB 360. “It is a trabecul- otome, which allows you to make a 180-degree incision in the trabecu- lar meshwork. The surgeon makes one pass clockwise and one pass counterclockwise. This allows 360 degrees of cutting of the trabecular meshwork. Again, you don’t need any additional 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 incision, which preserves the clini- cally proven benefits of 360-degree viscodilation of Schlemm’s canal provided by traditional canaloplas- ty but has the speed and ease of a MIGS procedure. It has been shown to be effective alone or in combina- tion with cataract surgery. GATT is a MIGS procedure that effectively manages open- angle glaucoma. It is performed via microincisions in the cornea. A 1.0-mm incision is made in the periphery of the cornea through which the surgery is completed. After entering the eye, the surgical procedure involves cutting through the trabecular meshwork, cannulat- ing Schlemm’s canal 360 degrees, and then unroofing 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 pres- sure lowering. Another advantage is that it does not involve open- ing 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 con- trolled outflow 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 scleral spur. The CyPass Micro-Stent is in- serted into the cleft that’s created, 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 September 2017 22 EWAP SECONDARY FEATURE