title: Gaussian optics for photorefractive keratectomy. Increased predictability for larger diopter corrections.
abstract: OBJECTIVE
  To evaluate clinically a formula based on spherical Gaussian optics for enhanced predictability of excimer photorefractive keratectomy (PRK) in both high and low degrees of myopia.
  
  
  METHODS
  Patients (24 eyes) were evaluated preoperatively with refractive measurements and corneal topography. After excimer PRK (3-24 months), postoperative remaining spectacle correction and corneal topography were measured. The attempted laser correction, calculated using algebraic equations, was compared with the achieved laser correction.
  
  
  RESULTS
  The absolute laser correction error (mean +/- standard deviation), defined as the difference between the achieved and attempted laser corrections, was 0.37 +/- 0.31 diopter (D) for the 24 eyes. No significant difference was found in the error for attempted corrections greater than 6 D versus those less than 6 D.
  
  
  CONCLUSIONS
  The use of a spherical Gaussian optics formulation results in accurate laser correction values for a wide range of myopia, even for large diopter corrections.
authors.affiliation: Department of Ophthalmology, Institut Arthur Vernes, Paris, France.
authors.forename: J P
authors.initials: JP
authors.lastname: Colliac
authors.forename: J P
authors.initials: JP
authors.lastname: Pérez
mesh_terms: D000328:Adult; D003315:Cornea / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D005139:Eyeglasses; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D054018:Lasers, Excimer; D008297:Male; D008433:Mathematics; D008875:Middle Aged; D009216:Myopia / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D018903:Photorefractive Keratectomy; D015203:Reproducibility of Results; D014792:Visual Acuity