EyeWorld Asia-Pacific June 2016 Issue

EWAP SECONDARY FEATURE 25 June 2016 by Ellen Stodola EyeWorld Staff Writer Update on small incision lenticule extraction (SMILE) T he ReLEx small incision lenticule extraction (SMILE) technique (Carl Zeiss Meditec, Jena, Germany) is a new procedure in refractive surgery. But will it replace LASIK? What barriers are there to overcome before the majority of surgeons begin to adopt it in their practices? A. John Kanellopoulos, MD , clinical professor of ophthalmology, New York University Medical School, New York, medical director, LaserVision Clinical and Research Institute, Athens, Greece, and current president of the International Society of Refractive Surgery (ISRS), and Steven Dell, MD , medical director, Dell Laser Consultants, Austin, Texas, discussed how SMILE compares to other procedures, potential barriers, and how they see it playing out in the future. How SMILE compares to wavefront-guided or wave- front-optimized With initial clinical experience, Dr. Kanellopoulos said that it appears SMILE compares favorably with both wavefront- guided and wavefront-optimized LASIK for myopes –3 to –10 D. When observing post-SMILE cornea pachymetry changes, he said that tissue removal from he said. It may be possible to perform wavefront-guided or topography-guided treatments in the future with SMILE. “While SMILE offers great promise, it is competing with LASIK, which has advanced to the point of achieving truly remarkable levels of safety and accuracy,” Dr. Dell said. Greatest barriers in adopting SMILE Dr. Dell said that centration with SMILE could present some challenges. “We have learned over the years how vital treatment centration and registration is in achieving excellent outcomes,” he said. “Excimer laser surgery has developed very robust pupil tracking technology to address this.” Should SMILE become available in the U.S., there may be other barriers to adoption as well, including the inability to treat hyperopia or mixed astigmatism and challenges associated with enhancements. “SMILE enhancements would seem SMILE appears to be more “en bloc.” There appears to be “more tissue removed in the mid- periphery. This along with the absence of flap ‘shrinking’ creates effectively larger optical zones postoperatively, with significantly better asphericity, in contrast to wavefront-optimized and wavefront-guided LASIK, where the mid-periphery of the cornea appears to have less removed tissue than the central cornea,” he said. SMILE offers great potential and presents some theoretical advantages over LASIK, Dr. Dell said. “Biomechanically, it makes sense that a SMILE pocket would be stronger than a flap, all other things being equal,” he said. “Epithelial ingrowth issues would also be greatly reduced with SMILE.” Dr. Dell said dry eye issues resulting from neurotrophia would likely favor SMILE over LASIK. “For higher degrees of myopia, the accuracy of SMILE might be better than LASIK because SMILE achieves these higher corrections simply through a change in the radii of the cuts, as opposed to a significantly longer ablation time with LASIK for high myopia,” Dr. Dell said. In its first iteration, SMILE would be most analogous to wavefront-optimized LASIK, and it would lack the ability to achieve truly wavefront-guided treatments, Incision geometry of the ReLEx SMILE procedure. The lenticule cut is performed on the underside of the lenticule (1), followed by the lenticule side cuts (2). The cap interface is created on the upper side of the lenticule (3), and nally a 2- to 3-mm small incision is created super-temporally (4). The lenticule interfaces are separated using a ap separator and the lenticule is extracted manually, all via the small incision. Source: Dan Reinstein, MD continued on page 26