title: Comparison of visual outcomes after variable spot scanning ablation versus wavefront-optimized myopic LASIK.
abstract: OBJECTIVE
  To compare the refractive and visual outcomes of variable spot scanning ablation versus the wavefront-optimized ablation for myopia and myopic astigmatism.
  
  
  METHODS
  Fifty patients with myopia who underwent LASIK (100 eyes) were divided into two equal groups. Myopic correction performed using the variable spot scanning (VSS) ablation with the VISX STAR S4/IR platform (Abbott Medical Optics, Inc., Santa Ana, CA) (VSS group) and wavefront-optimized (WFO) ablation profile with the WaveLight Allegretto Wave Eye-Q platform (Alcon Laboratories, Inc., Fort Worth, TX) (WFO group). Manifest refraction, uncorrected distance visual acuity, and corrected distance visual acuity were obtained preoperatively and 1 day and 1 and 3 months postoperatively. Wavefront measurement and contrast sensitivity testing were done preoperatively and 3 months postoperatively.
  
  
  RESULTS
  Postoperative mean refractive spherical equivalent was -0.14 ± 0.2 diopters for the VSS group and -0.15 ± 0.28 diopters for the WFO group. Forty-eight eyes of the VSS group and 47 eyes of the WFO group were within ±0.5 diopters. Postoperative mean corrected distance visual acuity was 1.05 ± 0.13 for the VSS group and 1.06 ± 0.12 for the WFO group. The postoperative uncorrected distance visual acuity was 1.01 ± 0.16 for the VSS group and 1.01 ± 0.11 for the WFO group. The safety index was 1.12 for the VSS group and 1.06 for the WFO group, whereas the efficacy index was 1.07 for the VSS group and 1.01 for the WFO group. The mean induced positive spherical aberration was 0.041 ± 0.046 µm for the VSS group and 0.195 ± 0.171 µm for the WFO group (P < .001). Mesopic contrast sensitivity testing showed no statistically significant differences between groups at all tested spatial frequencies.
  
  
  CONCLUSIONS
  Both VSS and WFO treatments showed similar refractive and visual outcomes. Both induced significant positive spherical aberration, significantly more with WFO.
authors.forename: Mounir A
authors.initials: MA
authors.lastname: Khalifa
authors.forename: Ehab F
authors.initials: EF
authors.lastname: Mossallam
authors.forename: Tamer H
authors.initials: TH
authors.lastname: Massoud
authors.forename: Mohamed Shafik
authors.initials: MS
authors.lastname: Shaheen
mesh_terms: D000293:Adolescent; D000328:Adult; D015350:Contrast Sensitivity; D057108:Corneal Wavefront Aberration; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D008297:Male; D009216:Myopia / Q000175:diagnosis / Q000601:surgery*; D011446:Prospective Studies; D016896:Treatment Outcome; D014787:Vision Tests; D014792:Visual Acuity; D055815:Young Adult