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PUBLICATION EXCLUSIVE: Refractive surgeons look to SMILE into the new year
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Premium surgeons are embarking upon the new year with new refractive surgery procedures recently approved by the FDA, such as the Raindrop corneal inlay from ReVision Optics. Even more exciting is the FDA approval of the VisuMax small incision lenticule extraction procedure from Carl Zeiss Meditec for reduction or elimination of myopia from –1 D to –8 D, with 0.5 D cylinder or less and manifest refraction spherical equivalent of –8.25 D in the eye to be treated in patients who are 22 years of age or older with documentation of stable manifest refraction over the past year.
With more than 51 million LASIK procedures performed worldwide, SMILE brings a new era of sophistication to myopia correction in the U.S. in what we can call microincisional refractive surgery (MIRS), no different from MICS and MIGS in cataract and glaucoma surgery, respectively. SMILE has already been established in global markets such as Europe, China, Australia, Canada and India.
Pivotal FDA study results
The U.S. FDA trial was composed of 336 eyes in a prospective, multicenter, open-label, single-arm study at five investigational sites with unilateral treatment and a minimum of 12 months of follow-up. Central corneal thickness had to be at least 500 µm. Endpoint data showed excellent uncorrected visual acuity results, such that 88% were 20/20 or better and 65% were 20/16 or better at 12 months. Refractive stability postoperatively was excellent as well, as 93.9% were within 0.5 D of target and 99.6% were within 1 D at the 12-month data point. At 12 months, 74% of patients ended up with better UCVA postoperatively than best corrected visual acuity preoperatively. Only five eyes of the 336 eyes treated had intraoperative adverse events: one cap perforation, two difficult lenticule removals with tissue damage and two cases of retained tissue with lenticule removal. Overall, primary efficacy endpoints and safety data were obtained to grant FDA approval in September 2016.
Commercial U.S. launch
As Zeiss launches SMILE in the U.S. market, there are a few differences in the approval parameters here compared with internationally. The optical zone can be 6 mm or 6.5 mm in the U.S. but can go to 7 mm internationally, and the cap is always 1 mm larger than the intended optical zone treatment. Treatment depth is locked at 120 µm in the U.S. but is adjustable internationally. Some surgeons have stated that SMILE can be more difficult in lower myopia because of a thinner lenticule, but Dan Reinstein has published that by increasing lenticule thickness by using a larger optical zone and a minimum lenticule thickness of 20 µm to 25 µm instead of the standard 10 µm, this issue can be easily avoided.
- Click here to read the full publication exclusive, The Premium Channel, published in Ocular Surgery News U.S. Edition, February 10, 2017.