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C. B. Nau, S. V. Patel, J. W. McLaren, L. J. Maguire, W. M. Bourne; Central Epithelial and Flap Thickness After LASIK: Femtosecond Laser vs. Mechanical Microkeratome. Invest. Ophthalmol. Vis. Sci. 2007;48(13):5329.
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© ARVO (1962-2015); The Authors (2016-present)
To determine if epithelial and flap thicknesses differ after LASIK with the flap created by using a femtosecond laser versus the flap created by using a mechanical microkeratome.
Twenty-one patients received bilateral LASIK in a paired-eye study. One eye of each patient was randomized to flap creation by using a femtosecond laser (IntraLase FS, IntraLase Corp., Irvine, CA) with intended thickness of 120 µm, and the fellow eye to flap creation with a microkeratome (Hansatome, Bausch & Lomb, Rochester, NY) with intended thickness of 180 µm. Preoperative spheroequivalent refractive error was -3.7 ± 1.7 D (mean ± SD) and -3.8 ± 1.8 D for femtosecond laser and microkeratome eyes respectively. Corneas were examined by using confocal microscopy before and at 1, 3, 6, and 12 months after surgery by scanning the focal plane through the cornea at constant speed. Epithelial and flap thicknesses were determined from the number of video frames between images of the epithelial surface and subbasal nerve plexus (or the corresponding intensity peak if nerves were not visible) and between images of the epithelial surface and interface particles, respectively.
Epithelial thickness did not differ between treatments at any time; mean minimum detectable difference (MDD) was 9.3 µm (α=0.05/5, ß=0.20). Postoperative epithelial thickness did not differ from preoperative at any time (MDD= 7.3 µm; α=0.05/4, ß=0.20). Measured flap thickness differed from intended flap thickness for both treatments (P≤ 0.001).
The method of flap creation does not influence epithelial thickness after LASIK. Femtosecond laser flaps were thicker than intended whereas microkeratome flaps were thinner than intended. Epithelial and flap thicknesses remain stable during the first year after LASIK, regardless of the method of flap creation.
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