title: Corneal irregular astigmatism after laser in situ keratomileusis for myopia.
abstract: OBJECTIVE
  To quantitatively evaluate the changes in corneal irregular astigmatism after laser in situ keratomileusis (LASIK) in relation to the amount of laser ablation.
  
  
  METHODS
  In 189 eyes of 116 patients undergoing LASIK for myopia, corneal topography was obtained before and 1 month after surgery. Using Fourier harmonic analysis of the topography data, corneal irregular astigmatism (asymmetry and higher order irregularity) was calculated.
  
  
  RESULTS
  By surgery, asymmetry component significantly increased (p < 0.0001, Wilcoxon signed rank test), while higher order irregularity did not (p = 0.767). The increases in the asymmetry component significantly correlated with ablation depth (Spearman rank correlation coefficient r(s) = 0.440, p < 0.0001). No significant correlation was found between changes in higher order irregularity and ablation depth (r(s) = 0.137, p = 0.074).
  
  
  CONCLUSIONS
  LASIK significantly increases the asymmetry component of the cornea which is dependent on the amount of laser ablation.
authors.affiliation: St Mary's Eye Hospital, Pusan, Korea.
authors.forename: T M
authors.initials: TM
authors.lastname: Baek
authors.forename: K H
authors.initials: KH
authors.lastname: Lee
authors.forename: A
authors.initials: A
authors.lastname: Tomidokoro
authors.forename: T
authors.initials: T
authors.lastname: Oshika
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000209:etiology*; D019781:Corneal Topography; D004307:Dose-Response Relationship, Radiation; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects* / Q000379:methods; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D018709:Statistics, Nonparametric