title: Vector analysis of cross cylinder LASIK with the NIDEK EC-5000 excimer laser for high astigmatism.
abstract: OBJECTIVE
  To evaluate visual outcomes of LASIK in eyes with high astigmatic refractive errors with low spherical component.
  
  
  METHODS
  We prospectively evaluated cross cylinder LASIK in patients with high astigmatic eyes with low spherical component over a 2-year period. All laser surgeries were performed with the NIDEK EC-5000 excimer laser. We used power vectors (M [spherical equivalent] and J(0), and J(45) [cylinder]) to analyze the astigmatic results. Main outcome measures were uncorrected visual acuity (UCVA), best spectacle-corrected visual acuity (BSCVA), manifest refraction, and complications.
  
  
  RESULTS
  Thirty-four eyes of 22 patients were included. Patients were followed for 21.8+/-3.7 months. At the last examination, UCVA of 20/40 or better was observed in 33 (97.1%) eyes. Best spectacle-corrected visual acuity after LASIK improved significantly in comparison to BSCVA before surgery (P<.005). Mean preoperative cylinder was -4.73+/-0.89 diopters (D) (range: -4.00 to -7.00 D), which decreased to -0.29+/-0.47 D (range: 0.00 to -1.50 D) at last follow-up (P<.001). Reduction in the magnitude of power vectors was 92.4% for M, 103.2% for J(0), and 76.4% for J(45). No cases of post-operative astigmatic regression or corneal haze were observed.
  
  
  CONCLUSIONS
  Cross cylinder LASIK with the NIDEK EC-5000 excimer laser is a successful procedure for correcting high astigmatism and improving vision.
authors.affiliation: Basir Eye Center, Tehran, Iran.
authors.forename: Abbas
authors.initials: A
authors.lastname: Abolhassani
authors.forename: Ahmad
authors.initials: A
authors.lastname: Shojaei
authors.forename: Ali Reza
authors.initials: AR
authors.lastname: Baradaran-Rafiee
authors.forename: Medi
authors.initials: M
authors.lastname: Eslani
authors.forename: Behzad
authors.initials: B
authors.lastname: Elahi
authors.forename: Farsad
authors.initials: F
authors.lastname: Noorizadeh
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000503:physiopathology / Q000601:surgery*; D005500:Follow-Up Studies; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer / Q000627:therapeutic use*; D017060:Patient Satisfaction; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D012086:Reoperation; D014792:Visual Acuity / Q000502:physiology*