title: Correction of postkeratoplasty astigmatism by femtosecond laser compared with mechanized astigmatic keratotomy.
abstract: OBJECTIVE
  To compare the effectiveness of arcuate keratotomy (AK) performed with a femtosecond laser (FSL) or Hanna keratome (Moria, Anthony, France) for correction of postkeratoplasty astigmatism.
  
  
  METHODS
  Prospective, randomized study.
  
  
  METHODS
  This clinical study included 20 eyes. Two groups of 10 eyes underwent AK using an FLS or keratome. Refractive and keratometric astigmatism were evaluated before surgery and 6 months after surgery. The astigmatic changes in the 2 groups were measured through arithmetic and vector analysis (Alpins method).
  
  
  RESULTS
  Six months after surgery, the mean uncorrected and corrected visual acuities did not change significantly. The mean preoperative refractive cylinder was 8.6 +/- 3.0 diopters (D) and 6.7 +/- 2.1 D, decreasing to 3.9 +/- 2.4 D and 4.7 +/- 2.4 D after laser AK and mechanized AK, respectively. The mean arithmetic change was significantly higher after laser AK, with a decrease of -55.4 +/- 20.7% (P = .011). Vector analysis showed a systematic undercorrection of astigmatism in both groups with a refractive correction index of 0.82 and 0.90 after laser AK and mechanized AK, respectively. Although no statistically significant differences were detected, a wider spread of angle of error and an almost significant difference of mean absolute angle of error (P = .052) suggest a larger misalignment of treatment during mechanized AK. All cases were uncomplicated after laser AK, 1 microperforation occurred and 1 case with off-center incisions occurred after mechanized AK.
  
  
  CONCLUSIONS
  AK performed with the femtosecond laser was effective in reducing postkeratoplasty astigmatism and has some advantages over conventional techniques. However, efficacy could be improved by a more accurate nomogram and alignment of treatment.
authors.affiliation: Department of Ophthalmology, Hopital de la Timone, Marseille, France. louis.hoffart@ap-hm.fr
authors.forename: Louis
authors.initials: L
authors.lastname: Hoffart
authors.forename: Helene
authors.initials: H
authors.lastname: Proust
authors.forename: Frederic
authors.initials: F
authors.lastname: Matonti
authors.forename: John
authors.initials: J
authors.lastname: Conrath
authors.forename: Bernard
authors.initials: B
authors.lastname: Ridings
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001251:Astigmatism / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D003316:Corneal Diseases / Q000601:surgery; D005260:Female; D006801:Humans; D015948:Keratoplasty, Penetrating; D053685:Laser Therapy / Q000379:methods*; D008297:Male; D008875:Middle Aged; D011183:Postoperative Complications; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D054140:Refractive Surgical Procedures; D014792:Visual Acuity / Q000502:physiology