title: Conventional versus custom ablation in photorefractive keratectomy: randomized clinical trial.
abstract: OBJECTIVE
  To compare visual outcomes and changes in total higher-order aberrations (HOAs) between conventional photorefractive keratectomy (PRK) and custom PRK SETTING: Department of Ophthalmology, Labbafinejad Medical Center, Ophthalmic Research Center, Shahid Beheshti University of Medical Sciences and Negah Eye Center, Tehran, Iran.
  
  
  METHODS
  This clinical trial comprised eyes having bilateral myopic PRK with the Technolas 217z excimer machine. One eye had conventional ablation (conventional group) and the other eye, wavefront-guided custom treatment (custom group). Changes in postoperative visual acuity, cycloplegic refraction, contrast sensitivity function, and root mean square higher-order aberrations (RMS HOAs) were compared between the 2 groups.
  
  
  RESULTS
  The mean age of the 28 patients (56 eyes) was 26.7 years. The mean preoperative cycloplegic spherical equivalent refractive error was -4.92 diopters (D) +/- 1.6 (SD) and the mean refractive astigmatism, 0.91 +/- 1.0 D. There was no statistically significant difference between the 2 groups in preoperative cycloplegic refractive error, HOAs, or contrast sensitivity function. The mean follow-up was 8.1 +/- 3.3 months. The increase in RMS HOAs from preoperatively to postoperatively was statistically significantly higher in the custom group in the 6.0 mm zone (P = .03) but not in the 4.0 mm zone (P = .26). The decrease in low mesopic contrast sensitivity function was statistically significant in both groups.
  
  
  CONCLUSIONS
  The RMS HOAs significantly increased after PRK with both methods. The results suggest that custom ablation is more sensitive to optical zone (OZ) size and may yield more aberrations with an OZ smaller than 6.0 mm.
authors.affiliation: Ophthalmic Research Center, Labbafinejad Medical Center, Tehran, Iran. karimianf@yahoo.com
authors.forename: Farid
authors.initials: F
authors.lastname: Karimian
authors.forename: Sepehr
authors.initials: S
authors.lastname: Feizi
authors.forename: Mohammad Reza
authors.initials: MR
authors.lastname: Jafarinasab
mesh_terms: D000293:Adolescent; D000328:Adult; D001251:Astigmatism / Q000503:physiopathology; D015350:Contrast Sensitivity / Q000502:physiology; D057108:Corneal Wavefront Aberration / Q000503:physiopathology*; D004311:Double-Blind Method; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D009216:Myopia / Q000601:surgery*; D018903:Photorefractive Keratectomy / Q000379:methods*; D012029:Refraction, Ocular / Q000502:physiology*; D014792:Visual Acuity / Q000502:physiology*; D055815:Young Adult