Comparison Of The Clinical Outcome Of 5 Different Klex Techniques (Smile (Zeiss Visumax 500), Smile Pro (Zeiss Visumax 800), Clear (Zeimer Z8), Smartsight(Schwind Atos), Silk(Johnson & Johnson Elita)) And Lasik (Alcon Ex500)

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 cohort study

Data were prospectively collected from Taipei Nobel Eye Clinic (2024/8/1-2025/1/31). Analysis included 72 SMILE (144 eyes), 82 SMILE Pro (164 eyes), 8 CLEAR (16 eyes), 26 SmartSight (52 eyes) and 7 SILK(14 eyes) and 5 LASIK(10 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.

Average ages across 5 KLEx and LASIK group ranged from 29-33 years. In each group, preoperative average spherical refractive errors ranged between -4.63 to -6.15D, while average cylinder refractive errors ranged from -0.68 to -1.30D. Average POZ from 6.41 to 6.54mm. One month post-operation, UDVA was similar across all groups (0.016 to 0.055 logMAR), with residual spherical and refractive errors near 0D. All groups had smaller EOZ compared to POZ, with LASIK showing the largest reduction (1.35mm) and SILK the least (0.59mm). KLEx techniques overestimated CCSR by 12–26μm, while LASIK underestimated by 8μm. Contrast sensitivity and increases in HOAs were comparable among all procedures.

At one month post-op, all five KLEx techniques and LASIK showed comparable results in UDVA, residual errors, contrast sensitivity, and HOAs. However, EOZ reduction was greatest in LASIK and least in SILK, with KLEx overestimating and LASIK underestimating CCSR.