First Author: S.Patel USA
Co Author(s): J. McLaren W. Bourne
Purpose:
LASIK flaps created with a femtosecond laser (bladeless) have a planar configuration compared to flaps created with a mechanical microkeratome, and this might confer an advantage in optical and visual outcomes after LASIK. In this study, we determined optical properties and visual outcomes at 5 years in eyes randomized to LASIK with the flap created by a femtosecond laser and LASIK with the flap created by a mechanical microkeratome.
Setting:
Prospective, randomized paired-eye study of patients attending the refractive surgery service at Mayo Clinic, Rochester, Minnesota from 2004-2010.
Methods:
Twenty-one patients received LASIK for myopia or myopic astigmatism. One eye of each patient was randomized to flap creation with a 15 kHz femtosecond laser (IntraLase) and the other eye to flap creation with a mechanical microkeratome (Hansatome). Eyes were examined before and at 1 and 5 years after LASIK. Wavefront errors from the anterior corneal surface were derived from corneal topograms and were expressed as Zernike polynomials through the sixth order across 4 mm- and 6 mm-diameter optical zones. Intraocular forward light scatter was measured with a straylight meter by using the compensation comparison method. Best-corrected visual acuity (BCVA) was measured by using the electronic-ETDRS protocol. Differences between LASIK treatments, and before and after LASIK, were assessed by using paired tests and significances were adjusted for multiple comparisons.
Results:
Across a 4 mm optical zone, total high-order aberrations (HOAs) before bladeless LASIK (0.14 ± 0.07 µm, mean ± standard deviation) did not differ from that before LASIK with the microkeratome (0.13 ± 0.04 µm; p=0.50). Total HOAs were increased at 1 year after LASIK (femtosecond laser, 0.19 ± 0.07 µm, p=0.04; microkeratome, 0.19 ± 0.08 µm, p<0.01) and remained unchanged at 5 years (femtosecond laser, 0.18 ± 0.05 µm, p=0.62; microkeratome, 0.19 ± 0.05 µm, p=0.85). Across a 6 mm optical zone, total HOAs before bladeless LASIK (0.46 ± 0.18 µm) did not differ from that before LASIK with the microkeratome (0.47 ± 0.22 µm; p=0.57). Total HOAs were increased at 1 year after LASIK (femtosecond laser, 0.72 ± 0.20 µm, p<0.001; microkeratome, 0.67 ± 0.18 µm, p<0.01) and remained unchanged at 5 years (femtosecond laser, 0.75 ± 0.22 µm, p=0.26; microkeratome, 0.70 ± 0.19 µm, p=0.43). Total HOAs did not differ between treatments at any time (p?0.11). At 5 years, there were no differences between treatments for forward scatter (femtosecond laser, 1.14 ± 0.14 log(S); microkeratome, 1.17 ± 0.12 log(S); p=0.41) or BCVA (femtosecond laser, -0.08 ± 0.06 logMAR; microkeratome, -0.04 ± 0.08 logMAR, p=0.15).
Conclusions:
At 5 years after LASIK, anterior corneal HOAs, intraocular forward scatter, and BCVA, are similar with both methods of flap creation. Corneal aberrations remain stable between 1 and 5 years after LASIK. The planar configuration of femtosecond laser flaps does not confer any optical or visual advantage compared to microkeratome flaps. FINANCIAL DISCLOSURE?: No
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