title: Comparison of the effects of cylindrical correction with and without iris recognition technology in wavefront laser-assisted in situ keratomileusis.
abstract: BACKGROUND
  To analyse the magnitude of cylindrical corrections over which cyclotorsion compensation with iris recognition (IR) technology is beneficial during wavefront laser-assisted in situ keratomileusis.
  
  
  METHODS
  A retrospectively comparative case series.
  
  
  METHODS
  Fifty-four eyes that underwent wavefront laser-assisted in situ keratomileusis without IR (non-IR group) and 53 eyes that underwent wavefront laser-assisted in situ keratomileusis with IR (IR group) were recruited.
  
  
  METHODS
  Subgroup analysis based on baseline astigmatism were: a low degree of astigmatism (≥1.00 D to <2.00 D), a moderate degree of astigmatism (≥2.00 D to <3.00 D) and a high degree of astigmatism (≥3.00 D).
  
  
  METHODS
  Vector and non-vector analyses were used for comparison.
  
  
  RESULTS
  The mean cylinder was -1.89 ± 0.76 D in the non-IR group and -2.00 ± 0.77 D in the IR group. Postoperatively, 38 eyes (74.50%) in the IR group and 31 eyes (57.50%) in the non-IR group were within ± 0.50 D of the target induced astigmatism vector (P = 0.063). The difference vector was 0.49 ± 0.28 in the IR group and 0.63 ± 0.40 in the non-IR group (P = 0.031). In the analysis of subgroups, the magnitude of error was significantly lower in the moderate IR subgroup than that of the moderate non-IR subgroup (P = 0.034). Furthermore, the moderate IR subgroup had a lower mean difference vector (P = 0.0078) and a greater surgically induced astigmatism (P = 0.036) than those of the moderate non-IR group.
  
  
  CONCLUSIONS
  Wavefront laser-assisted in situ keratomileusis for the treatment of astigmatism using IR technology was effective and accurate for the treatment of myopic astigmatism.
authors.affiliation: Department of Ophthalmology, Taipei Medical University Hospital, No. 7 Chung-Shan South Road, Taipei, Taiwan.
authors.forename: Tsung-Jen
authors.initials: TJ
authors.lastname: Wang
authors.forename: Yu-Huang
authors.initials: YH
authors.lastname: Lin
authors.forename: David C-K
authors.initials: DC
authors.lastname: Chang
authors.forename: Hsiu-Chu
authors.initials: HC
authors.lastname: Chou
authors.forename: I-Jong
authors.initials: IJ
authors.lastname: Wang
mesh_terms: D057128:Aberrometry; D000328:Adult; D001251:Astigmatism / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D006801:Humans; D007498:Iris / Q000033:anatomy & histology*; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D012029:Refraction, Ocular / Q000502:physiology; D012189:Retrospective Studies; D014792:Visual Acuity / Q000502:physiology