Eyeworld

JULY 2021 | EYEWORLD | 101 R References 1. Hamilton D, et al. Comparison of early visual outcomes after low-energy SMILE, high-energy SMILE, and LASIK for myopia and myopic astigmatism in the United States. J Cataract Refract Surg. 2021;47:18–26. 2. Pradhan KR, et al. Small incision lenticule extraction (SMILE) for hyperopia: 12-month refractive and visual outcomes. J Refract Surg. 2019;35:442–450. Relevant disclosures Doane: Carl Zeiss Meditec Hamilton: Carl Zeiss Meditec, Johnson & Johnson Vision Reinstein: Carl Zeiss Meditec Contact Doane: jdoane@discovervision.com Hamilton: rex@rexhamiltonmd.com Reinstein: dzr@londonvisionclinic.com treatment proceeds. A –9 D LASIK correction, for example, would result in the tissue being exposed for longer than a –1 D correction. In SMILE, however, the time the laser is firing to create the lenticule is the same regardless of the correction amount. "The variability in terms of the depth of a femto laser cut primarily comes from the vari- ability in the disposable interface with the eye. … With SMILE, because you're doing two cuts with the same interface, any kind of variability subtracts out; that's something that hasn't been talked about much that is also contributing to the higher predictability of the procedure. I'm at a point now where if I have a patient with SMILE who is off and needs an enhancement, which is less than 1% of the time, it's probably a function of the preoperative refraction," Dr. Hamilton said. One barrier to SMILE adoption from a surgeon standpoint is the need to purchase additional technology. The procedure currently approved in the U.S. uses the VisuMax laser platform (ReLEx SMILE, Carl Zeiss Meditec). Other companies are working on laser platforms that could perform SMILE procedures, though they're not yet approved in the U.S. Once more devices to perform SMILE or lenticule extraction reach the U.S. market, Dr. Doane said the technique will achieve further validation in the refractive surgery field and even wider acceptance as a whole. Dr. Reinstein noted that one should expect a settling period with new devices. "It took the VisuMax close to 5 years to reach clinical equivalency to LASIK from building and releasing the device itself," Dr. Reinstein said. "Our textbook contains a road map for new companies to work from, which will shorten this time, but femto cutting is a delicate balance of parameters, and each laser is different." There are several parameter adjustments with the current SMILE procedure that are likely to come to the U.S. with FDA approval as well, Dr. Doane said. These include the ability to treat lower and higher amounts of astigma- tism; the ability to treat lower myopic sphere (currently to treat astigmatism, at least –1 D of sphere needs to be corrected); and the ability to treat up to 2 D more sphere than the current 10 D. Dr. Reinstein said SMILE approval for hy- peropia is in the near future, with the 12-month outcomes from his investigator-initiated trial conducted with Kishore Pradhan, MD, in Nepal published in 2019. 2 Comparison of bubble pattern for high-energy optimized treatments; A) Bubble pattern with high energy, manifesting a significant opaque bubble layer in the visual axis and fluffy irregularity at the side cut; B) Bubble pattern with optimized energy without an opaque bubble layer or black spots and a sharp lenticular border, suggestive of an easier dissection Source: D. Rex Hamilton, MD A B

• Blank Page
• Blank Page (1)