EyeWorld India September 2019 Issue

EWAP SEPTEMBER 2019 27 SECONDARY FEATURE techniques as sometimes, if the ab externo technique does not provide the ideal positioning for the XEN, I occasionally convert to an ab interno approach. Rarely, when using the ab externo approach, the XEN can be implanted too posteriorly and close to the iris. I then retrieve the device via an ab interno approach and reimplant via an ab interno approach.” He therefore recommends that surgeons still learn the traditional ab interno approach wÀÃÌ LivÀi º«>Þ} >ÀÕ`» with ab externo techniques. Dr. Do and Dr. Panarelli avoid this problem by having an open peritomy and direct visualization of the external tip of the XEN 45, allowing them to make micro-adjustments, pulling the stent out and pushing it into the anterior chamber to ensure that the stent is properly positioned in the intrascleral and sub-Tenon’s space. Ensuring ideal positioning of the distal end of the microstent beneath the Tenon’s layer and conjunctiva has resulted in surgical outcomes being more predictable, they said. Moreover, the blebs are more diffuse and posteriorly directed, and this improved bleb morphology makes them comfortable injecting higher concentrations of MMC. Their needling rate is less than 5%, and they have not had any erosions with their approach. Expanding toolbox Even as XEN use evolves, surgeons are already expectantly awaiting the FDA approval PreserFlo: The device formerly known as the InnFocus Microshunt I mplanted via an ab externo technique similar to the way Dr. Do and Dr. Panarelli are currently implanting the XEN 45, they expect the PreserFlo will help surgeons “bridge the large gap between our trabecular bypass/ ablative procedures and traditional glaucoma surgeries,” they said. “In a sense, it functions similarly to a trabeculectomy in that it creates a subconjunctival bleb, but the procedure is considerably less invasive and requires much less postoperative intervention.” Dr. Kim posits how his practice might look with these new devices in his surgical toolbox. “I think for those patients for whom I am seeking profound IOP lowering that Schlemm’s canal-based MIGS cannot deliver, and who have healthy and unscarred conjunctiva, open angles, no history of uveitis/ y>>Ì] >` ÃÌÀÞ v 6 ] Ü iÞ ÕÃi 8 iÝ >L iÝÌiÀ ÌÀ>ÃVÕVÌÛ> 8 «>Ì>Ì® >Ã Ìi wÀÃÌ i surgical treatment,” he said. “If this fails and bleb needling for it fails, I will turn to the InnFocus Microshunt (if and when it gets FDA approved and becomes commercially available) placed in an adjacent superior quadrant. If this fails, I would then likely turn to glaucoma drainage implants such as a Baerveldt >ÕV> «>Ì Q Ã E Ã 6ÃR° 8 iÝ>Ã the advantage of being extremely vast, not requiring incisions, and offering immediate visual recovery. The InnFocus has the advantage of having a larger diameter lumen less likely to get clogged by pigment and debris but would have the disadvantage of requiring extensive conjunctival dissection and closure. I think the InnFocus would replace my current open XEN with tenonectomy technique, so I would probably use it in place of XEN-ex in cases at higher risk for failure (young, deeply «}iÌi`] y>i` VÕVÌÛ>] iÌV®°» The devices differ in terms of material and size. “The InnFocus Microshunt is 8.5 mm in length with a luminal diameter of 70 micrometers and is composed of SIBS (styrene- block-isobutylene-block-styrene) material,” Dr. Do and Dr. Panarelli said. “By contrast, the XEN gel stent is 6 mm in length with a 45-micrometer lumen and is made of porcine gelatin. These subtle differences may lead to slight differences in outcomes with each device, but a comparison among the two new microstents has not been performed yet.” EWAP of another microsurgical glaucoma drainage device: the PreserFlo (formerly the InnFocus Microshunt, Santen Pharmaceutical). While we can postulate, Dr. Grover said that we don’t know yet how exactly ÌiÃi `iÛViÃ Ü wÌ Ì}iÌiÀ in the expanding glaucoma surgical toolbox. He was a primary investigator for the FDA trial on the InnFocus and speaks Ì Ìi ivwViVÞ v ÌÃ ÃÕÀ}iÀÞ as well. Moreover, what he does know is that the XEN has been a game changer; if and when the PreserFlo is approved, he thinks the device will be a game changer as well. “We’ll have to play it by ear and determine which surgery is better for which patient, but I think the big theme is they both will be tremendous additions to our surgical armamentarium,” he said, adding, “The data coming out of Canada and the Dominican Republic with regard to PreserFlo are extremely encouraging and make most U.S. glaucoma doctors excited to get their hands on the PreserFlo.” EWAP 'FKVQTUo PQVG 6JG XKGYU GZRTGUUGF KP this article attributed to Dr. Kim are JKU QYP CPF FQ PQV TGƃGEV VJG QHƂEKCN policy of the Department of Army/Navy/ Air Force, Department of Defense, or 7 5 )QXGTPOGPV 6JG KFGPVKƂECVKQP QH URGEKƂE RTQFWEVU QT UEKGPVKƂE instrumentation is considered an integral RCTV QH VJG UEKGPVKƂE GPFGCXQT CPF FQGU not constitute endorsement or implied endorsement on the part of Dr. Kim, DoD, or any component agency. 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