Eyeworld

EW REFRACTIVE 62 November 2017 by Michelle Stephenson EyeWorld Contributing Writer FDA approval for myopic astigmatism expected soon L ast year, the U.S. Food and Drug Administration (FDA) approved the VisuMax femtosecond laser (Carl Zeiss Meditec, Jena, Germany) for small incision lenticule extraction (SMILE) to reduce or eliminate myopia in patients who are 22 years of age or older. This procedure is gaining popularity and has advan- tages over LASIK, according to some surgeons. With SMILE, the VisuMax removes a small amount of corneal tissue, permanently reshaping the cornea. The laser cuts a disc-shaped piece of tissue that is removed by the surgeon through a small incision in the cornea. The removal of tissue causes the cornea to change shape, which corrects myopia. Candidates for SMILE According to Gregory Parkhurst, MD, San Antonio, the FDA indi- cations are limited to myopia, but that is expected to change in the near future. "We are limited to spherical myopia, so patients who have hyperopia or astigmatism are not currently good candidates for SMILE," he said. "We expect that in the relatively near future, we will have at least myopic astigmatism approved. In the meantime, we are treating patients who are –1 to –10 myopes with up to 0.5 D of astigma- tism. These patients also need to be good corneal laser vision correction candidates from an anatomy per- spective, so just like we do screening corneal topography for our LASIK and PRK patients, the same preop testing is required for SMILE patients to look at the health and thickness of the cornea and screen for corneal pathology. For example, if someone has keratoconus, we are not going to recommend any corneal laser vision correction procedure including SMILE." Additionally, SMILE patients must have adequate corneal thick- ness. "Although, because the SMILE procedure is working sub-Bow- man's, the requirements in terms of preoperative pachymetry as well as predicted residual bed are a little different than LASIK and PRK," Dr. Parkhurst said. "For example, if someone is a little on the thin side SMILE still limited to treating myopia E ver since the entry of LASIK onto the refractive surgery scene, we have not seen a corneal refractive surgery procedure bring such energy and attention. According to Carl Zeiss Meditec, the number of SMILE procedures performed in the world just passed 1 million. There are good reasons for this. SMILE combines the features we respect about PRK and LASIK. Computer modeling has shown that SMILE has potentially higher biomechanical stability, like PRK, while the vision return is more like LASIK. Since it does not involve a flap and there is much less of a side cut, there is less incidence of dry eye during the healing process. For patients who are good candidates and who do not want the slower vision return of PRK and do not want the flap of LASIK, this procedure can be a great option. For our patients who are good candidates, we educate them and offer all three options. It is an honor to get the perspectives of three great refractive surgeons, Gregory Parkhurst, MD, Dan Reinstein, MD, and Sonia Yoo, MD. They have a tremendous amount of experience with all three of these well-respected corneal refractive procedures. Vance Thompson, MD, Refractive editor Dr. Parkhurst performs a SMILE procedure. Source: Gregory Parkhurst, MD Refractive editor's corner of the world Comparison of wavefront- guided LASIK to SMILE Edward Manche, MD, discusses preliminary results of his contralateral comparison of SMILE to wavefront-guided LASIK.

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