15 EyeWorld Asia-Pacific | December 2024 There is, however, more to refractive surgery than uncorrected visual acuity. SMILE achieves the precision of LASIK but also addresses some of its most significant what-ifs. It therefore is becoming the pinnacle of corneal refractive surgery. No. 1: What if a patient has an increased risk of dry eye? The severing of corneal nerves during LASIK flap formation often leads to dry eye symptoms.14 This side-effect can be particularly problematic for patients with a predisposition to dry eyes and those who work in environments where dry eye could be exacerbated. SMILE, on the other hand, avoids the creation of a flap and transects fewer corneal nerves.15 This translates to a lower risk of dry eye. No. 2: What if there are flap-related trauma or biomechanical concerns? Without having a flap, SMILE eliminates the short- and long-term concern of traumatic flap dislocation. Furthermore, there may be biomechanical advantages to eliminating the flap. SMILE preserves more of the anterior corneal structure and maintains greater corneal strength compared to LASIK.16 The added biomechanical stability may be theoretically beneficial in terms of reducing the risk of post–refractive surgery ectasia. No. 3: What if the expected target is not achieved? SMILE is performed in a closed system. The treatment produces a stable outcome over a wide range of refractive errors with a low regression rate.17 As a result, there is a lower enhancement rate compared to LASIK. No. 4: What if a patient needs an enhancement years after surgery? One underappreciated aspect of SMILE is its flexibility for enhancements. LASIK is a fantastic procedure for many patients, but if an enhancement is required years after surgery, it may become complicated. Lifting the original flap carries a risk of epithelial ingrowth,18 whereas performing PRK over the LASIK flap can be unpredictable because of the altered healing process associated with epithelial hyperplasia.19 FEATURE Pathways to Precision and Perfection – SMILE vs. LASIK Figure 1. SMILE results with first- and second-generation software at 1 and 6 months. 160 EYES (PLANO TARGET) 6 MONTHS POSTOP 100 80 60 40 20 0 1 1 0 20/12.5 20/32 20/20 20/50 20/80 20/16 20/40 20/25 20/63 20/100 CUMULATIVE SNELLEN VA (20/X OR BETTER) CUMULATIVE % OF EYES 55 98 97 99 100 99 100 100100 100100 100100 100100 100100 213 EYES (PLANO TARGET) 3 MONTHS POSTOP POSTOP UDVA PREOP CDVA 100 80 60 40 20 0 0 0 3 20/12.5 20/32 20/20 20/50 20/80 20/16 20/40 20/25 20/63 20/100 CUMULATIVE SNELLEN VA (20/X OR BETTER) CUMULATIVE % OF EYES 37 95 97 99 100 100100 100100 100100 100100 100100 100100 *WILEY, HURA, BAFNA, DECOURCY ASCRS 2022
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