title: Efficacy of an aspheric treatment algorithm in decreasing induced spherical aberration after laser in situ keratomileusis.
abstract: OBJECTIVE
  To determine the effectiveness of an aspheric laser in situ keratomileusis (LASIK) algorithm for myopia with and without astigmatism in minimizing postoperative induction of spherical aberration.
  
  
  METHODS
  Four sites in Asia.
  
  
  METHODS
  Patients with -1.00 to -10.00 diopters (D) of spherical myopia with -4.00 D or less of astigmatism were recruited. Patients randomly had bilateral Zyoptix aspheric algorithm (aspheric group) or bilateral conventional Zyoptix Tissue Saving algorithm (control group). A Technolas 217z100 excimer system was used for LASIK ablation. Visual effectiveness, safety, higher-order aberrations, and corneal asphericity (Q value) were evaluated postoperatively.
  
  
  RESULTS
  The aspheric group comprised 86 eyes and the control group, 84 eyes. At 3 months, the high-contrast uncorrected distance visual acuity was 20/20 or better in 78% of eyes in the aspheric group and 83% of eyes in the control group. The control treatment induced 0.22 microm of spherical aberration, which was significantly higher than the 0.04 microm induced with the aspheric treatment (6.0 mm pupil) (P<.0001). The aspheric treatment induced significantly less vertical coma and trefoil (P = .02). Eyes in the aspheric group had significantly lower Q values (P<.0001). There was no statistically significant difference in the manifest refraction spherical equivalent between the 2 groups (P >.05). Although high- and low-contrast corrected distance visual acuity (CDVA) was similar between the groups, the aspheric group gained more lines of low-contrast CDVA.
  
  
  CONCLUSIONS
  The aspheric algorithm was more effective than the conventional algorithm in reducing induced spherical aberration and maintaining corneal asphericity after myopic LASIK.
authors.affiliation: Asian Eye Institute, Makati City, Philippines. rtang@asianeyeinstitute.com
authors.forename: Robert Edward T
authors.initials: RE
authors.lastname: Ang
authors.forename: Wing Kwong
authors.initials: WK
authors.lastname: Chan
authors.forename: Tze-Lin
authors.initials: TL
authors.lastname: Wee
authors.forename: Hung Ming
authors.initials: HM
authors.lastname: Lee
authors.forename: Pattaramon
authors.initials: P
authors.lastname: Bunnapradist
authors.forename: Ian
authors.initials: I
authors.lastname: Cox
mesh_terms: D000328:Adult; D000465:Algorithms; 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; D008875:Middle Aged; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D012029:Refraction, Ocular / Q000502:physiology*; D011795:Surveys and Questionnaires; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult