title: Bitoric laser in situ keratomileusis for the correction of simple myopic and mixed astigmatism.
abstract: OBJECTIVE
  To evaluate the safety and efficacy of bitoric laser in situ keratomileusis (LASIK) for the correction of simple myopic and mixed astigmatism.
  
  
  METHODS
  Retrospective, single-center, and noncomparative case series.
  
  
  METHODS
  Eighty-six eyes of 56 patients were analyzed for this study. Six-month and 1-year follow-up data were available on 86 eyes and 72 eyes, respectively. Eyes were divided in two groups according to the type of astigmatism: myopic astigmatism with low sphere (< -2 diopters) and mixed astigmatism. The range of astigmatism was 1.25 to 7.5 diopters.
  
  
  METHODS
  LASIK was performed using the Automated Corneal Shaper (ACS) microkeratome (Bausch & Lomb, Claremont, CA) to create a cornea flap using the 130- or 160-micron thickness plate. A bitoric mid-stromal ablation was performed using the Nidek EC-5000 excimer laser (Nidek Company, Gamagori, Japan).
  
  
  METHODS
  Uncorrected visual acuity, manifest refraction, and best spectacle-corrected visual acuity were the parameters measured preoperatively and at months 1, 3, 6, and 12.
  
  
  RESULTS
  At the last visit, an uncorrected visual acuity of 20/20 or better was achieved in 77% and 68% of the myopic and mixed astigmatism groups, respectively. Ninety-two percent of all eyes had a mean spherical equivalent within +/- 0.50 diopter of emmetropia. A mean decrease in the vectorial magnitude of the astigmatism of 94% and 91% was achieved for those eyes with myopic and mixed astigmatism, respectively. There was no loss of best spectacle-corrected visual acuity. In two eyes, the axis of the positive cylinder was misaligned.
  
  
  CONCLUSIONS
  Bitoric LASIK is an effective procedure to correct myopic and mixed astigmatism. Eighty-five percent of the eyes achieved an uncorrected visual acuity of 20/25 or better and had a final cylinder of 0.5 diopter or less. It is a safe operation, because no eyes lost any lines of best spectacle-corrected visual acuity. Longer follow-up may be needed to assess these results.
authors.affiliation: Codet Instituto de Oftalmología, Tijuana, Mexico. codet@infosel.net.mx
authors.forename: A S
authors.initials: AS
authors.lastname: Chayet
authors.forename: M
authors.initials: M
authors.lastname: Montes
authors.forename: L
authors.initials: L
authors.lastname: Gómez
authors.forename: X
authors.initials: X
authors.lastname: Rodríguez
authors.forename: N
authors.initials: N
authors.lastname: Robledo
authors.forename: S
authors.initials: S
authors.lastname: MacRae
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000601:surgery*; D003315:Cornea / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D008297:Male; D009216:Myopia / Q000601:surgery*; D011183:Postoperative Complications; D012189:Retrospective Studies; D012449:Safety; D016896:Treatment Outcome; D014792:Visual Acuity