Femtosecond Laser versus Mechanical Microkeratome for LASIK : A Randomized Controlled Study

PurposeTo compare corneal haze (backscattered light) and visual outcomes between fellow eyes randomized to LASIK with the flap created by a femtosecond laser (bladeless) or with the flap created by a mechanical microkeratome.DesignRandomized, controlled, paired-eye study.ParticipantsTwenty-one patients (42 eyes) received LASIK for myopia or myopic astigmatism.MethodsOne eye of each patient was randomized to flap creation with a femtosecond laser (IntraLase FS, IntraLase Corp., Irvine, CA) with intended thickness of 120 μm, and the fellow eye to flap creation with a mechanical microkeratome (Hansatome, Bausch & Lomb, Rochester, NY) with intended thickness of 180 μm. Patients were examined before and at 1, 3, and 6 months after LASIK.Main Outcome MeasuresCorneal backscatter, high-contrast visual acuity, manifest refractive error, contrast sensitivity, and intraocular forward light scatter were measured at each examination. Flap thickness was measured by confocal microscopy at 1 month, and patients were asked if they preferred the vision in either eye at 3 months.ResultsCorneal backscatter was 6% higher after bladeless LASIK than after LASIK with the mechanical microkeratome at 1 month (P = 0.007), but not at 3 or 6 months. High-contrast visual acuity, contrast sensitivity, and forward light scatter did not differ between treatments at any examination. Flap thicknesses at 1 month were 143±16 μm (bladeless, mean ± standard deviation) and 138±22 μm (mechanical microkeratome), with no statistical difference in variances. At 3 months, 5 patients preferred the bladeless eye, 7 patients preferred the microkeratome eye, and 9 patients had no preference.ConclusionsThe method of flap creation did not affect visual outcomes during the first 6 months after LASIK. Although corneal backscatter was greater early after bladeless LASIK than LASIK with the mechanical microkeratome, patients did not perceive a difference in vision.