title: Vector analysis of astigmatism before and after LASIK: a comparison of two different platforms for treatment of high astigmatism.
abstract: OBJECTIVE
  To compare the outcomes of astigmatic laser in-situ keratomileusis (LASIK) procedures between two different platforms using J0 and J45 vector analysis.
  
  
  METHODS
  Patients were divided into four groups, depending on the type of astigmatism and laser platform on which they were treated. Astigmatism was between 2 and 7 diopters (D). One hundred and thirty-five patients with myopic astigmatism (246 eyes) and 102 patients with mixed astigmatism (172 eyes) underwent unremarkable LASIK correction on Wavelight Allegretto Eye-Q 400Hz and Schwind Amaris 750S laser platform. The preoperative and postoperative sphere, negative cylinder [C] and axis (ø) of manifest refractions were subjected to vector analysis by calculations of the standard J0 (cos [4π(ø-90)/360]xC/2) and J45 (sin[4π(ø-90)/360]xC/2).
  
  
  RESULTS
  Reporting the key results, we found J0 significantly reduced after LASIK in both groups (p < 0.001) but not J45. There was no significant association between individual pairs of pre and postoperative J0 & J45 values. There was no significant difference between the outcomes of the two platforms.
  
  
  CONCLUSIONS
  Wavelight Allegretto 400Hz and Schwind Amaris 750S showed excellent results for treating patients with astigmatism, regardless whether it is mixed or myopic astigmatism. The J45 did not reduce significantly possibly because of the low number of eyes with oblique astigmatism. There was no genuine difference post-operatively between groups treated on two different laser platforms according to the vector analyses.
authors.affiliation: Specialty Eye Hospital "Svjetlost", Heinzelova 39, 10000, Zagreb, Croatia. alma.biscevic@svjetlost.hr.
authors.forename: Alma
authors.initials: A
authors.lastname: Biscevic
authors.affiliation: Specialty Eye Hospital "Svjetlost", Heinzelova 39, 10000, Zagreb, Croatia. maja.bohac@svjetlost.hr.
authors.forename: Maja
authors.initials: M
authors.lastname: Bohac
authors.affiliation: Specialty Eye Hospital "Svjetlost", Heinzelova 39, 10000, Zagreb, Croatia. mateja.koncarevic@svjetlost.hr.
authors.forename: Mateja
authors.initials: M
authors.lastname: Koncarevic
authors.affiliation: Specialty Eye Hospital "Svjetlost", Heinzelova 39, 10000, Zagreb, Croatia. marija.anticic@svjetlost.hr.
authors.forename: Marija
authors.initials: M
authors.lastname: Anticic
authors.affiliation: Specialty Eye Hospital "Svjetlost", Heinzelova 39, 10000, Zagreb, Croatia. iva.dekaris@svjetlost.hr.
authors.forename: Iva
authors.initials: I
authors.lastname: Dekaris
authors.affiliation: Specialty Eye Hospital "Svjetlost", Heinzelova 39, 10000, Zagreb, Croatia. spatel9@nhs.net.|NHS National Services Scotland, Edinburgh, UK. spatel9@nhs.net.
authors.forename: Sudi
authors.initials: S
authors.lastname: Patel
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000503:physiopathology / Q000601:surgery*; D003315:Cornea / Q000503:physiopathology*; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D011184:Postoperative Period; D057234:Preoperative Period; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology
keywords: Astigmatism; Excimer laser; LASIK; Vector analysis