Eyeworld

EW REFRACTIVE 64 June 2017 " By the end of 2017, about 1 million SMILE procedures will have been performed. The rate of growth is just incredible. " —John Doane, MD by Michelle Stephenson EyeWorld Contributing Writer it has not been studied, there are probably going to be fewer dry eye problems than with LASIK because fewer nerves are cut." Dr. Dishler added that en- hancements with LASIK are more straightforward than enhancements with SMILE. "With LASIK, we can do an enhancement by relifting the flap. With SMILE, there is no flap to relift, so if a patient needs an enhancement, he or she would need to undergo a PRK-like surface treatment. Fortunately, it seems like the number of people who will need retreatment is low, so it probably won't present much of an issue," Dr. Dishler said. Additionally, LASIK can treat hyperopia and SMILE cannot. "LASIK can also treat patients who have smaller degrees of myopia of 1 D or less, which is currently not yet available for SMILE," Dr. Vukich said. "LASIK can treat higher levels of myopia. SMILE is approved to –10, and LASIK is approved over –10 for many platforms. I think the two procedures will co-exist. For the foreseeable future, physicians who specialize in providing refractive services to their patients will likely have both modalities available." Candidates for surgery According to Dr. Doane, if a person is a LASIK candidate, he or she will be a SMILE candidate. "Right now in my clinic, about 35% of nearsighted people who walk through the door get SMILE. Sixty-five percent of pa- tients have astigmatism to a degree that they are better off with LASIK at this point," he said. Dr. Dishler said that SMILE is particularly well suited for people I n September 2016, the U.S. Food and Drug Administration approved the VisuMax femto- second laser (Carl Zeiss Med- itec, 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 has some advantages over LASIK, according to some physicians, and has been gain- ing popularity internationally. With SMILE, the VisuMax femtosecond laser removes a small amount of corneal tissue, perma- nently reshaping the cornea. The laser cuts a disc-shaped piece of tissue—analogous to the Munnerlyn shape as predicted with excimer laser treatment—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. "I think SMILE will absolutely continue to gain popularity. We are seeing that worldwide," said John Doane, MD, Leawood, Kansas. "By the end of 2017, about 1 million SMILE procedures will have been performed. The rate of growth is just incredible. A certain percentage of surgeons are embracing it, and it seems to be accepted by patients readily. As we expand the treatment range to include higher levels of my- opia and astigmatism, we will open the door for more patients to have the opportunity to undergo SMILE." In the device's clinical trial, the procedure resulted in stable vision correction at 6 months. Of the 328 patients evaluated at the 6-month postop visit, all but one had uncor- rected visual acuity of 20/40 or bet- ter, and 88% had uncorrected visual acuity of 20/20 or better. SMILE expected to gain popularity as myopia treatment in the U.S. Postoperative complications included debris at the site of tissue removal, dry eye, moderate to severe glare, and moderate to severe halos. SMILE vs. LASIK Both procedures are corneal surgery performed with a laser; however, there are some important differ- ences. "SMILE is the same as LASIK in that it is a laser-based procedure that recontours the cornea to bring balance back to the visual system," said John Vukich, MD, Madison, Wisconsin. "It is different because it is a different type of laser and uses a different wavelength. It doesn't ablate tissue. It very accurately cuts the lenticule to bring balance to the visual system. Conceptually they are similar, but fundamentally they work in different ways." According to Dr. Doane, the predictability of SMILE is just as good as it is for LASIK. "The one thing that is wonderful about SMILE is that it is dose-independent, mean- ing that a –10 correction is just as predictable as a –1. We don't usually see that with laser vision correction. Predictability tends to fall off at higher corrections because excimer laser surgery is performed in open air, so there is dehydration of the corneal tissue for larger correction/ treatment times. With SMILE, we have a contact lens connected to the eye, and we are doing a treatment within the cornea, so it is essentially doing surgery in a vacuum. We don't have to worry about environmental factors such as barometric pressure, humidity, and temperature to any degree like we do with excimer laser treatments," Dr. Doane said. SMILE is currently approved to correct 1 to 10 D of myopia, but it is not yet approved for astigmatism correction. "Patients with astigma- tism will need to have LASIK or wait for the upcoming approval that we hope will happen in the next year of SMILE for astigmatism," said Jon Dishler, MD, Greenwood Village, Colorado. "The strong points for SMILE are that it's minimally invasive, it's a small incision, the recovery is quick, and there are fewer concerns about complications because there is no flap. Although continued on page 66 PiXL offers patients a noninva- sive vision correction option in a simple, safe, and effective procedure that does not involve tissue removal. Patients with a mild prescription can eliminate the high costs of glass- es, contacts, or refractive surgery entirely. Complications may include post-surgical dryness, an increased risk of infection while the eye heals, or temporary cloudiness of vision. "Epi-on PiXL in room air re- duces myopia about 0.25 D, which is not very much. In high oxygen, however, the effect averages 1.25 D. The method is safe from an endo- thelial perspective but requires fine tuning, both to increase the treat- ment effect and to reduce the vari- ability of outcomes, which is evident sometimes even between two eyes of the same patient. PiXL is a promis- ing new method for the treatment of low grade myopia. The long-term durability of the effect remains to be evaluated," he said. EW References 1. Murphy C, et al. Refractive error and visual outcome after cataract extraction. J Cataract Refract Surg. 2002;28:62– 66. 2. Acar BT, et al. Can the effect of transepi- thelial corneal cross-linking be improved by increasing the duration of topical riboflavin application? An in vivo confocal microscopy study. Eye Contact Lens. 2014;40:207–12. Editors' note: Dr. Behndig has no finan- cial interests related to his comments. Contact information Behndig: anders.behndig@umu.se High continued from page 63 Device focus

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