16 EyeWorld Asia-Pacific | December 2024 SMILE vs. LASIK LASIK is a revolutionary procedure that is safe, effective, and the most successful and widely-studied elective procedure in the world.1-5 In its relatively short history, LASIK has changed the lives of millions of people worldwide by precisely correcting their refractive errors. Despite its rich clinical history and high patient satisfaction rates,6,7 LASIK has several key limitations, particularly relating to corneal biomechanics,8,9 the risk for post-LASIK ectasia,10 side effects such as dry eye, and the potential need for an enhancement. Newer procedures such as SMILE aim to address some of LASIK’s shortcomings and inject surgical volume into the slow market growth seen recently with LASIK. The Evolution Of Refractive Surgery With any surgical specialty—and particularly corneal refractive surgery—two of the driving forces pushing the field forward are safety and efficacy. Procedures such as radial keratotomy (RK) and PRK propelled the field forward in its early days, followed by LASIK and eventually SMILE. Each procedure advanced the precision and outcomes of corneal refractive surgery, with LASIK particularly making a massive impact when it gained FDA approval in 1996. Three years after FDA approval, about 27% of LASIK patients achieved 20/20 vision at 1-month postoperative.11 By 2000, 1-month postoperative outcomes improved to 60% with second-generation hardware (Table 1).12 Although groundbreaking for the era, especially compared to RK, these outcomes seem almost primitive by today’s standards. Refinements to both technique and technologies continued to drive improvements in postoperative outcomes. With fourth-generation hardware and the maturation of femtosecond LASIK techniques, outcomes have improved by William F. Wiley, MD SMILE: Continuing the Evolution of Corneal Refractive Surgery dramatically. By 2018, 94% of LASIK patients were achieving 20/20 uncorrected distance visual acuity at 1-month postoperative,13 moving the needle significantly in terms of efficacy and bringing us closer to modern LASIK results. As good as LASIK has been, shortcomings in some safety aspects, including the potential of flap dislocation,8,9 the potential risk for post-LASIK ectasia,10 side effects such as dry eye, and the potential need for an enhancement, however, may be contributing to a slowing corneal refractive surgery market. The What-Ifs Of Refractive Surgery Postoperative outcomes with SMILE have improved at a faster rate than LASIK. Six years after FDA approval, most of our patients were already achieving 20/20 uncorrected visual acuity at 1 and 6 months (95% and 98%, respectively; Figure 1). FEATURE Pathways to Precision and Perfection – SMILE vs. LASIK Table 1. One-Month Results of LASIK With First- and Second-Generation Excimer Lasers First-Generation Laser* UCVA 20/20 20/25 20/40 POSTOP MONTH 1 27% 54% 87% 3 31% 53% 93% 6 24% 44% 100% Second-Generation Laser** UCVA 20/20 20/25 20/40 POSTOP MONTH 1 60% 79% 90% * N=93 to 41, single surgeon ** N=480, multicenter, multi surgeon The procedure addresses some of the limitations of LASIK.
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