Eyeworld

EW SECONDARY FEATURE 92 March 2016 by Ellen Stodola EyeWorld Staff Writer converting the procedure to a LASIK with an extra side cut with SMILE must be used. Dr. Kanellopoulos still finds SMILE a bit more challenging than a LASIK procedure. As far as cyclorotation adjustment and dy- namic visual axis centration, LASIK technologies are currently better. With the femtosecond laser, both procedures would require a similar surgical skill for the creation, for the femtosecond laser portion, with docking, reassuring the patient, designing the ablation, and deliver- ing the femtosecond laser flap creation in LASIK and lenticule carving in SMILE. "The second part of the procedure, though, is far more surgically challenging in SMILE compared to LASIK," Dr. Kanellopoulos said. This is why it is not recommended yet for myopes under 3 D. Targeting new patients? LASIK carries with it the baggage from public perception of technolo- gy used 2 decades ago, Dr. Dell said. "Certainly some patients treated to PRK, has had a higher adaptation due to its facility and quick recovery and very minimal postoperative pain for the patients in contrast to PRK, but no one can deny that at 1 month's time, it is quite difficult to note the significant differences [of the procedures]." SMILE appears to be a procedure that resembles LASIK in regard to the very little postop- erative pain involved and the quick recovery, Dr. Kanellopoulos said. Having had a little less than a year of experience with the SMILE procedure, Dr. Kanellopoulos' learn- ing curve has taught him that SMILE is a bit more of a "surgeon-depen- dent" procedure in regard to the surgical manipulation needed to remove the "carved" lenticule from inside the cornea without causing significant injury to the SMILE opening and/or the potential pocket that is created. "Our initial data are excellent for low and moderate myopia, but we did encounter some under corrections in higher myopes in the range of –8 to –10," he said. Although an easy enhancement for LASIK, to retreat SMILE cases, PRK or of the cuts, as opposed to a signifi- cantly longer ablation time with LASIK for high myopia," Dr. Dell said. In its first iteration, SMILE would be most analogous to wave- front-optimized LASIK, and it would lack the ability to achieve truly wavefront-guided treatments, 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 challeng- es. "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 bar- riers to adoption as well, including the inability to treat hyperopia or mixed astigmatism and challeng- es associated with enhancements. "SMILE enhancements would seem to be best performed with surface excimer ablation," Dr. Dell added. One obvious barrier for SMILE is that LASIK has come to be a very popular, very safe, and very stable procedure, Dr. Kanellopoulos said. "SMILE promises to offer the same, therefore, there will be a very small incentive to convert from a suc- cessful LASIK practice into a SMILE practice," he said. "We, nevertheless, are currently experiencing the large wave of SMILE adopters along with the larger number of reports from clinicians who are the next genera- tion of adopters who will establish potential advantages that SMILE has compared to LASIK." Dr. Kanellopoulos said that patients seem motivated to have laser vision correction so they do not have to wear contact lenses and glasses. Hesitation comes from fear of a procedure on their eyes and the cost. "Once they have made that de- cision, I see very little differentiation between them having SMILE, LASIK, or PRK," he said. "LASIK, compared 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 oph- thalmology, New York University Medical School, New York, medical director, LaserVision Clinical and Research Institute, Athens, Greece, and current president of the Interna- tional Society of Refractive Surgery (ISRS), and Steven Dell, MD, medi- cal director, Dell Laser Consultants, Austin, Texas, discussed how SMILE compares to other procedures, po- tential barriers, and how they see it playing out in the future. How SMILE compares to wavefront-guided or wavefront-optimized With initial clinical experience, Dr. Kanellopoulos said that it appears SMILE compares favorably with both wavefront-guided and wave- front-optimized LASIK for myopes –3 to –10 D. When observing post- SMILE cornea pachymetry changes, he said that tissue removal from 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 advantag- es over LASIK, Dr. Dell said. "Bio- mechanically, 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 neurotroph- ia 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 Update on small incision lenticule extraction (SMILE) 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 finally a 2- to 3-mm small incision is created super-temporally (4). The lenticule interfaces are separated using a flap separator and the lenticule is extracted manually, all via the small incision. Source: Dan Reinstein, MD

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