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Di Wu, Yan Wang; Differences in the corneal biomechanical effects between Small Incision Lenticule Extraction, Femtosecond Laser LASIK and LASEK. Invest. Ophthalmol. Vis. Sci. 2014;55(13):1532.
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© ARVO (1962-2015); The Authors (2016-present)
To investigate the biomechanical properties of the cornea after small incision lenticule extraction (SMILE) surgery and compare corneal biomechanical effects between SMILE, LASIK and surface ablation.
This prospective study comprised myopic SMILE eyes (n=37), Femto-LASIK eyes (n=34) and LASEK eyes (n=35). Corneal hysteresis (CH), corneal resistance factor (CRF), and 37 other biomechanical waveform parameters were quantitatively assessed with the use of an Ocular Response Analyzer preoperatively and at postoperative 1, 3, and 6 months.
CH and CRF decreased significantly after surgery in all 3 groups (P<0.0001). In the SMILE group, the 3-month and 6-month postoperative CH values showed a significant increase compared with 1-month values (P<0.003), while this recovery tendency of CH was not observed in the Femto-LASIK group and LASEK group. The percentage change in CRF and CH were significantly greater in the Femto-LASIK group than in the SMILE group and LASEK group (P=0.022 and P=0.001, CRF; P=0.143 and P=0.009, CH). Additionally, the correlation between residual stromal thickness index and the percentage change in CRF and CH were statistically significant in the ReLEx smile group (r=0.590, P<0.0001, CRF; r=0.483, P=0.002), whereas no significant correlation was shown in the Femto-LASIK group and LASEK group. The smallest percentage change in biomechanical waveform parameters was in the LASEK group.
Flap creation combined with stromal ablation had greater effect on the cornea’s viscoelastic properties than flapless procedures. The smallest change in biomechanical waveform parameters was in the surface ablation group (LASEK). SMILE caused a significantly more predictable change in corneal biomechanics, which correlated strongly with RST index, than the change with Femto-LASIK and LASEK.
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