title: LASIK versus photorefractive keratectomy for high myopic (> 3 diopter) astigmatism.
abstract: OBJECTIVE
  To compare the efficacy, safety, predictability, and vector analysis indices of LASIK and photorefractive keratectomy (PRK) for correction of high cylinder of greater than 3 diopters (D) in myopic eyes.
  
  
  METHODS
  The efficacy, safety, and predictability of LASIK or PRK performed in 114 consecutive randomly selected myopic eyes with an astigmatism of greater than 3 D were retrospectively analyzed at the 2- to 6-month follow-up visits. Vector analysis of the cylindrical correction was compared between the treatment groups.
  
  
  RESULTS
  A total of 57 eyes receiving PRK and 57 eyes receiving LASIK of 114 refractive surgery candidates were enrolled in the study. No statistically significant difference in efficacy [efficacy index = 0.76 (±0.32) for PRK vs 0.74 (±0.19) for LASIK (P = .82)], safety [safety index = 1.10 (±0.26) for PRK vs 1.01 (±0.17) for LASIK (P = .121)], or predictability [achieved astigmatism < 1 D in 39% of PRK- and 54% of LASIK-treated eyes, and < 2 D in 88% of PRK- and 89% of LASIK-treated eyes (P = .218)] was demonstrated. Using Alpins vector analysis, the surgically induced astigmatism and difference vector were not significantly different between the surgery methods, whereas the correction index showed a slight and significant advantage of LASIK over PRK (1.25 for PRK and 1.06 for LASIK, P < .001).
  
  
  CONCLUSIONS
  LASIK and PRK are comparably safe, effective, and predictable procedures for excimer laser correction of high astigmatism of greater than 3 D in myopic eyes. Predictability of the correction of the cylindrical component is lower than that of the spherical equivalent.
authors.forename: Toam
authors.initials: T
authors.lastname: Katz
authors.forename: Lars
authors.initials: L
authors.lastname: Wagenfeld
authors.forename: Peter
authors.initials: P
authors.lastname: Galambos
authors.forename: Benedikt Große
authors.initials: BG
authors.lastname: Darrelmann
authors.forename: Gisbert
authors.initials: G
authors.lastname: Richard
authors.forename: Stephan Johannes
authors.initials: SJ
authors.lastname: Linke
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000503:physiopathology / Q000601:surgery*; D016022:Case-Control Studies; D003319:Corneal Stroma / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects / Q000379:methods*; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D047728:Myopia, Degenerative / Q000503:physiopathology / Q000601:surgery*; D018903:Photorefractive Keratectomy / Q000009:adverse effects / Q000379:methods*; D012189:Retrospective Studies; D013524:Surgical Flaps; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult