title: Photorefractive keratectomy versus laser in situ keratomileusis: a control-matched study.
abstract: OBJECTIVE
  Photorefractive keratectomy (PRK) and laser in situ keratomileusis (LASIK) outcomes were compared at 1, 3, 6, and 12 months after surgery.
  
  
  METHODS
  Retrospective, nonrandomized, comparative study.
  
  
  METHODS
  One hundred seven LASIK-treated eyes (58 patients) and 107 PRK-treated eyes (91 patients) having myopia between -1 and -9.50 diopters (D). All LASIK-treated eyes were analyzed retrospectively and matched with PRK-treated eyes having sphere within +/-0.25 D, +/-1 D of cylinder, and +/-7 years of age.
  
  
  METHODS
  For PRK and LASIK, the refractive surgery was performed with the slit-scanning excimer laser Nidek EC-5000, (Nidek Co. Tokyo, Japan)
  
  
  METHODS
  Manifest refraction, best-spectacle and uncorrected Snellen visual acuity, haze, halos, and keratometry were evaluated before surgery and up to 12 months after surgery.
  
  
  RESULTS
  Seventy percent of eyes were evaluated at the 12-month postoperative exam. Of these eyes, 83% of LASIK cases and 86% of PRK cases had uncorrected visual acuities of 20/20 or better. Refractions within +/-0.5 D represented 78% of the LASIK eyes and 83% of the PRK eyes at that follow-up. Patients who underwent LASIK reported halos twice as often as patients who underwent PRK using a subjective scale. The odds ratio of high halos for LASIK versus PRK was 3.50 (95% confidence interval, 1.89-6.46; P<0.0001). At 1 month after surgery, 64% of the LASIK eyes were within +/-0.50 D compared with 77% of the PRK eyes. No eye lost 2 Snellen lines of best corrected visual acuity at 6 or 12 months after surgery. Ten PRK eyes (9.3%) and three LASIK eyes (2.8%) were retreated.
  
  
  CONCLUSIONS
  PRK and LASIK achieved equal refractive outcomes at all postoperative follow-ups, but LASIK patients were twice as likely to experience halos.
authors.affiliation: Michel Pop Clinics, Montreal, Quebec, Canada.
authors.forename: M
authors.initials: M
authors.lastname: Pop
authors.forename: Y
authors.initials: Y
authors.lastname: Payette
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000503:physiopathology; D016022:Case-Control Studies; D003315:Cornea / Q000601:surgery*; D019466:Glare; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects / Q000379:methods*; D054018:Lasers, Excimer; D009216:Myopia / Q000601:surgery*; D018903:Photorefractive Keratectomy / Q000009:adverse effects / Q000379:methods*; D011680:Pupil / Q000502:physiology; D012029:Refraction, Ocular; D012189:Retrospective Studies; D016896:Treatment Outcome; D014786:Vision Disorders / Q000209:etiology; D014792:Visual Acuity / Q000502:physiology