title: Clinical outcomes of optimized prolate ablation and custom aspheric treatment in laser-assisted subepithelial keratectomy.
abstract: OBJECTIVE
  To compare visual acuity, refractive, wavefront, and visual quality outcomes between optimized prolate ablation (OPA) and optical path difference custom aspheric treatment (OPDCAT) algorithms for myopia correction.
  
  
  METHODS
  Private practice, Busan, South Korea.
  
  
  METHODS
  Prospective randomized masked clinical trial.
  
  
  METHODS
  One eye of each patient was randomly selected to have laser-assisted subepithelial keratectomy with the OPA algorithm and the contralateral eye with the OPDCAT algorithm. Visual acuity, manifest refraction, ocular and corneal higher-order aberrations (HOAs), corneal asphericity (Q value), and modulation transfer function (MTF) in the 2 groups were compared 1, 3, and 6 months postoperatively.
  
  
  RESULTS
  The study enrolled 39 patients. The mean manifest refraction spherical equivalent at 6 months was 0.19 diopter (D) ± 0.37 (SD) in the aspheric ablation group and 0.00 ± 0.33 D in the prolate ablation group. Predictability (± 0.50 D from intended refraction) at 6 months was 82% and 100%, respectively. Twenty-six eyes (93%) in the aspheric ablation group and 27 (96%) in the prolate ablation group had an uncorrected distance visual acuity of 20/20 or better. One eye in the aspheric ablation group and no eye in the prolate ablation group lost 1 line of corrected distance visual acuity. The prolate ablation group had fewer induced corneal and ocular spherical aberrations than the aspheric ablation group. Corneal asphericity was unchanged postoperatively in the prolate ablation group. The MTF under the correction of lower-order aberrations was higher in the prolate ablation group than in the aspheric ablation group.
  
  
  CONCLUSIONS
  The prolate ablation algorithm gave more predictable visual outcomes, induced fewer corneal HOAs, and conserved more preoperative corneal asphericity than the aspheric algorithm.
  
  
  BACKGROUND
  No author has a financial or proprietary interest in any material or method mentioned.
authors.affiliation: Institute of Vision Research, Department of Ophthalmology, Yonsei University College of Medicine, Seoul, South Korea.
authors.forename: Eui Chun
authors.initials: EC
authors.lastname: Kang
authors.forename: Bong Joon
authors.initials: BJ
authors.lastname: Choi
authors.forename: Eung Kweon
authors.initials: EK
authors.lastname: Kim
authors.forename: Tae-Im
authors.initials: TI
authors.lastname: Kim
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000503:physiopathology / Q000601:surgery*; D057108:Corneal Wavefront Aberration; D005260:Female; D006801:Humans; D049008:Keratectomy, Subepithelial, Laser-Assisted / Q000379:methods*; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult