Compare The Three-Month Clinical Outcome Of 5 Different Keratorefractive Lenticule Extraction(Klex) And Laser Assisted In Situ Keratomileusis(Lasik)

To compare the clinical outcomes of 5 different keratorefractive lenticule extraction(KLEx) techniques: SMILE (Zeiss Visumax 500), SMILE Pro (Zeiss Visumax 800), CLEAR (Zeimer Z8), SmartSight(Schwind ATOS) and SILK(Johnson & Johnson Elita) and LASIK in terms of postoperative uncorrected distance visual acuity (UDVA) and residual refractive error, Effective Optical Zone (EOZ), Central Stromal Thickness Reduction(CCSR), Contrast Sensitivity and Higher-order Aberrations (HOAs, including spherical, trefoil, coma, and total HOAs).

prospective matched cohort study

Data were prospectively collected from Taipei Nobel Eye Clinic (2024/8/1-2025/6/31). Analysis included 55 SMILE (110 eyes), 78 SMILE Pro (156 eyes), 4 CLEAR (8 eyes), 31 SmartSight (62 eyes) and 13 SILK( 26 eyes) and 8 LASIK(16 eyes) patients, focusing on preoperative and postoperative BCVA, UDVA, EOZ, CCSR, Contrast Sensitivity and HOAs(including spherical, trefoil, coma, and total HOAs). LASIK was done by Custom-Q LASIK by EX500(Alcon) with flap made by Visumax 500 (Zeiss). The preoperative baseline characteristics of age, sex, degree of sphere, degree of cylinder, programmed optical zone (POZ) were matched between the 5 KLEx and LASIK.

Patients' average age ranged from 29–33 years. Preoperative spherical errors were -4.74 to -5.98D and cylindrical errors -0.88 to -1.53D. Three month post-op, UDVA was similar across all groups (SMILE: 0.004; SMILE Pro: 0.006; CLEAR: 0.056; SmartSight: 0.011; SILK: -0.008, LASIK: 0.003 logMAR), with residual errors near 0D. All groups had smaller EOZ compared to POZ, with LASIK showing the largest reduction (1.30±0.14mm) and SILK the least (0.55±0.35mm), and other KLEx had similar reduction around 1 mm (SMILE: 1.05±0.40; SMILE Pro: 0.99±0.34; CLEAR: 0.93±0.19; SmartSight: 1.00±0.31mm). All KLEx overestimated CCSR by 12–26μm, while LASIK underestimated by 0.5μm. Contrast sensitivity and increases in HOAs were comparable among all procedures.

Three months after operation, the UDVA, Residual Spherical and cylinder Error, Contrast Sensitivity, and HOAs are all good and similar in all 5 KLEx and LASIK. However, all 5 KLEx & LASIK have smaller EOZ compared with POZ, with that LASIK decrease the most and SILK decrease the least. All 5 KLEx overestimate CCSR at the comparable level, while LASIK underestimate CCSR.