Eyeworld

6 Evolving technology and outcomes in cataract and refractive surgery Figure 1. Predictability between SMILE and WFG-LASIK is not so different, but with a slight trend toward more myopic residual SE in SMILE. Source: David Piñero, PhD Figure 2. There is no better efficacy with SMILE compared to WFG-LASIK. Source: David Piñero, PhD Published data As we know, WFG-LASIK can correct myopia, hyperopia, and mixed astigmatism; to date, the only scientific evidence for SMILE as a safe and effective technique is for the correction of myopia. In terms of astigmatism, there are some papers illustrat- ing that there is a trend toward undercorrection by vector analysis. 1 In terms of hypero- pia, the only scientific evidence reported to date that can be related to SMILE is with its flap-creating cousin, the fem- tosecond lenticule extraction (FLEx) procedure. FLEx has been reported in one study to correct hyperopia (mean pre- operative spherical equivalent of the sample: +2.80±1.30 D), but with only 35% of eyes with a spherical equivalent within ±0.50 D postoperatively. 2 Predictability between SMILE and WFG-LASIK is not so different (Figure 1). Howev- er, there is a minimal but sig- nificant trend to more myopic residual spherical error (SE) with SMILE (–0.01 to –0.33 D) compared with WFG-LASIK (–0.02 to –0.17 D), and while the published percentages of eyes within ±1.00 D of target are similar between SMILE and WFG-LASIK, the published percentages of eyes within ±0.50 D range more widely with SMILE (67.60% to 100%) than with WFG-LASIK (80% to 100%). 3 It should be said that the trend toward myopic resid- ual SE was seen in the first ar- ticles evaluating the outcomes L ASIK remains the most common surgical refractive procedure, and wavefront-guid- ed LASIK (WFG-LASIK) has become the gold standard of LASIK. WFG-LASIK aims to avoid inducing higher order ab- errations postoperatively while reducing preoperative ocular aberrations, thus preserving visual quality to achieve patient satisfaction. The procedure is based on the patient's entire individual optical system. Some years ago, small incision lenticule extraction (SMILE) technology was devel- oped for correcting refractive errors based on the use of the femtosecond laser technology. This femtosecond laser-based technique corrects refractive errors without creating a flap— potentially reducing complica- tions associated with LASIK. As such, it has the potential to be a replacement for the older procedure. But does it offer real bene- fit over WFG-LASIK? David Piñero, PhD Future of corneal refractive surgery: Meta-analysis of custom LVC vs. SMILE David Piñero, PhD, University of Alicante, Alicante, Spain Figure 3. Visual recovery with SMILE is delayed in the initial postop period. Source: David Piñero, PhD

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