title: Femtosecond laser versus mechanical keratome LASIK for myopia.
abstract: OBJECTIVE
  To assess efficacy, safety, predictability, stability, and changes in corneal higher-order aberrations (CHOAs) and contrast sensitivity (CS) after a femtosecond laser for LASIK and standard LASIK for myopia.
  
  
  METHODS
  Prospective, randomized, comparative clinical study.
  
  
  METHODS
  Two hundred eyes of 100 consecutive patients who underwent LASIK treatment using the VISX S2 laser system. A femtosecond laser for flap creation was used in 100 eyes (50 patients; spherical equivalent [SE], -2.85+/-1.79 diopters [D]), and a mechanical microkeratome was used in 100 eyes (50 patients; SE, -2.90+/-1.63 D).
  
  
  METHODS
  Uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, CS by means of the Functional Acuity Contrast Test, and CHOAs by means of custom software linked to topography were evaluated preoperatively and 6 months after treatment.
  
  
  METHODS
  Efficacy, safety, predictability, stability, CHOAs, and CS were evaluated before and after surgery at 6 months' follow-up.
  
  
  RESULTS
  At 6 months postoperatively, UCVA was 1.0 or better in 100% of the eyes. Efficacy indexes were 1.07 for the femtosecond laser for LASIK patients and 1.00 for LASIK patients. No eye lost > or =1 lines of BCVA; for the femtosecond laser for LASIK group, 24 eyes gained 1 line, and 18 eyes gained > or =2 lines; for the LASIK group, 18 eyes gained 1 line. The femtosecond laser for LASIK group showed a percentage of eyes (98%) within the 0.5-D range in SE higher than that of the LASIK group (92%). For a 3.5-mm pupil, CHOAs' root-mean-square (RMS) increased for both the femtosecond laser for LASIK (2.21-fold) and LASIK (2.81-fold) groups. For a 6-mm pupil, CHOA RMSs were increased significantly after femtosecond laser for LASIK (4.18-fold) and LASIK (5.07-fold) surgeries (P<0.01). Contrast sensitivity improved only in the femtosecond laser for LASIK group at the highest spatial frequency (18 cycles/degree; P<0.01) after surgery.
  
  
  CONCLUSIONS
  A femtosecond laser for LASIK surgery is an effective and, in this series, safe procedure for treatment of myopia. The improvements in UCVA and CS after the femtosecond laser for LASIK are related to the differences in postoperative CHOAs found with femtosecond and microkeratome flap creation.
authors.affiliation: Optics Department, Faculty of Physics, University of Valencia, Valencia, Spain. roberto.montes@uv.es
authors.forename: Robert
authors.initials: R
authors.lastname: Montés-Micó
authors.forename: Antonio
authors.initials: A
authors.lastname: Rodríguez-Galietero
authors.forename: Jorge L
authors.initials: JL
authors.lastname: Alió
mesh_terms: D000328:Adult; D015350:Contrast Sensitivity / Q000502:physiology; D003315:Cornea / Q000503:physiopathology / Q000601:surgery*; D019781:Corneal Topography; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects / Q000295:instrumentation / Q000379:methods*; D007834:Lasers; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D013524:Surgical Flaps; D014065:Tonometry, Ocular; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology