Eyeworld

45 EW FEATURE June 2017 • Rebirth of laser vision correction front. However, the data from the SMILE trial for astigmatism has been submitted to the FDA for approval and "that data is excellent," Dr. Slade said, noting that he expects approval will come within the next year and a half. Potential benefits to the SMILE procedure include biomechan- ical stability in the cornea, less inflammation, and fewer dry eye symptoms, though these have yet to be fully established, according to Moshirfar et al. 2 SMILE has been shown to result in less corneal denervation, fewer higher-order aberrations, and faster corneal nerve healing compared to LASIK, the study authors wrote. What's more, as a flapless proce- dure, it could be an option for those whose lifestyle or hobbies would carry the risk of flap trauma, Dr. Wiley said. "Some of the things that are more borderline—mild dryness or a slightly thinner cornea, a slightly higher prescription coupled with lifestyle—factor in to one procedure being a little better suited for a pa- tient than another," Dr. Wiley said. "At this point, it's more of an art than a science, understanding the relative advantages versus disadvan- tages of these new procedures." SMILE, Dr. Wiley pointed out, can take longer compared to LASIK in some cases to get the "wow effect." "In someone who has a small prescription, thick cornea, and doesn't have lifestyle concerns, LASIK might get them to 'wow' quicker and be more straightfor- ward," he said. There might also be patients who are worried about a flap in their cornea but who are reluctant to have PRK, due to discomfort and delayed visual recovery, Dr. Manche said. These patients, who Dr. Slade described as those psychologically worried about LASIK, might find SMILE a palatable alternative. Not replacing but expanding the market Dr. Thompson sees newer laser vision correction technologies as "additives to the menu." With all of the options available, includ- ing traditional LASIK and PRK, Dr. Thompson said the patient consult their corneas that were not being addressed. "Being able to do these abla- tions and deliver more energy to the elevations and less energy to the depressions has been something that we've been surprised at how many abnormal corneas can benefit from this in both PRK and LASIK," he said. Dr. Wiley treats all of his LASIK patients with topography-guided technology, provided he is able to obtain a good topography scan. However, he sees some physicians reserve the technology only for pa- tients with more irregular corneas. "Some people say, 'Why use it if it's a virgin eye with no problems?' Yes, chances are it may not make a big difference in those eyes where the topography effect is so small that you might only be treating 1 to 2 microns of irregularity; howev- er, there has been no demonstrat- ed downside to treating even the slightest topographic irregularities. … To me, it self-limits the eyes that are more regular," Dr. Wiley said. On the other hand, he added that research has shown that some wave- front-guided technologies are not necessarily better for all cases. iDesign wavefront technology Edward Manche, MD, director of cornea and refractive surgery, Byers Eye Institute, and professor of ophthalmology, Stanford Univer- sity School of Medicine, Stanford, California, has used the iDesign aberrometer—which incorporates aberrometry, wavefront refraction, topography, keratometry, and pup- illometry—for more than 5 years, participating in the FDA clinical trials that led to its approval. "I have had outstanding results with the iDesign wavefront-guid- ed treatments," Dr. Manche said. "A higher percentage of patients achieve visual acuities of 20/20 and 20/16 compared to the older WaveScan wavefront-guided treat- ments. The technology can also be used in an off-label fashion to treat highly aberrated eyes that were pre- viously untreatable." Similarly, Dr. Thompson men- tioned how this technology could benefit those with higher-order ab- errations, as well as those with low light image quality issues. Dr. Manche went on to say that the current iDesign wavefront-guid- ed technology has five times the resolution compared to the previous generation WaveScan system. "I have not found any disadvantages to the new system and use it nearly exclusively for all of my wavefront- guided treatments," he said. Dr. Wiley said that his practice has looked at iDesign but hasn't brought on the technology yet. "It's nice to see that the VISX platform [Johnson & Johnson Vision] is im- proving their technology," he said. A 2016 study published in the Journal of Refractive Surgery compared visual outcomes of wavefront-guided ablation using the iDesign aberrom- eter and STAR S4 IR excimer laser system (Johnson & Johnson Vision) and topography-guided ablations with the EC-5000 CXII excimer laser system (Nidek). 1 Overall, the study authors concluded that both systems yielded "excellent results in predict- ability and visual function." The wavefront-guided system showed some possible advantages in quality of vision, and selecting the appropri- ate system based on each patient's eye conditions may be important, according to the study authors. SMILE As Dr. Slade put it, physicians are just starting to figure out who might be good SMILE candidates. In the U.S., SMILE is currently only ap- proved to correct sphere, not astig- matism, limiting indications on that continued on page 46 Dr. Wiley performs topography-guided LASIK with the Nidek Quest excimer laser following a femtosecond laser-created flap. Source (all): William Wiley, MD

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