title: Vector Analysis of 1-Year Astigmatic Outcomes From a Randomized Fellow Eye Comparison of Photorefractive Keratectomy Using 2 Excimer Laser Platforms.
abstract: OBJECTIVE
  To compare the astigmatic outcomes of photorefractive keratectomy (PRK) with a wavefront-guided (WFG) and a wavefront-optimized (WFO) excimer laser performed on two different platforms.
  
  
  METHODS
  Setting: institutional.
  
  
  METHODS
  Prospective, randomized, fellow eye comparison clinical trial.
  
  
  METHODS
  A total of 142 eyes of 71 patients with myopia of 12 diopters (D) or less and astigmatism of 3D or less were enrolled at the Byers Eye Institute at Stanford between April 2009 and March 2011.
  
  
  METHODS
  One eye of each patient underwent WFG-PRK with the VISX CustomVue Star S4 IR (Abbott Medical Optics, Abbott Park, IL) and the contralateral eye underwent WFO-PRK with the Wavelight Allegretto Eye-Q 400-Hz laser platform (Alcon, Inc., Hüenberg, Switzerland). Alpins vector analysis of astigmatism was performed using manifest refraction measured preoperatively and 12 months postoperatively and vertexed to the corneal plane. Eyes were stratified for subgroup analysis based on preoperative manifest astigmatism.
  
  
  RESULTS
  WFG-PRK and WFO-PRK were similar regarding surgically induced astigmatism, difference vector, magnitude of error, correction index, flattening index, and index of success. The angle of error was 60% less in the WFG group compared with the WFO group (4.9±1.1° vs. 11.8±2.4°, P=0.01).
  
  
  CONCLUSIONS
  WFG-PRK with the VISX CustomVue Star S4 IR and WFO-PRK with the Alcon WaveLight Allegretto Eye-Q 400-Hz excimer laser platform produce similar astigmatic results in myopic patients; however, the WFG mode may produce slightly more predictable astigmatic corrections.
authors.affiliation: Byers Eye Institute, Stanford University School of Medicine, Palo Alto, CA.
authors.forename: Brian C
authors.initials: BC
authors.lastname: Toy
authors.forename: Edward E
authors.initials: EE
authors.lastname: Manche
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000209:etiology*; D057108:Corneal Wavefront Aberration; D005260:Female; D006801:Humans; D054018:Lasers, Excimer / Q000009:adverse effects / Q000627:therapeutic use*; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D018903:Photorefractive Keratectomy / Q000009:adverse effects / Q000379:methods*; D011183:Postoperative Complications / Q000209:etiology*; D011446:Prospective Studies; D055815:Young Adult