title: Comparison of postoperative higher-order aberrations and contrast sensitivity: tissue-saving versus conventional photorefractive keratectomy for low to moderate myopia.
abstract: OBJECTIVE
  To assess the efficacy, predictability, safety, contrast sensitivity, higher-order aberrations (HOAs), and patient satisfaction after tissue-saving photorefractive keratectomy (PRK) and conventional PRK.
  
  
  METHODS
  Department of Ophthalmology, Farabi Eye Hospital, Tehran Medical University, Tehran, Iran.
  
  
  METHODS
  Comparative case series.
  
  
  METHODS
  This prospective study evaluated eyes with low to moderate myopia that had PRK with a Technolas 217z excimer laser. Patients were randomly assigned to have surgery using a conventional algorithm (PlanoScan) or a tissue-saving algorithm (Zyoptix). Contrast sensitivity, HOAs, and patient satisfaction were analyzed preoperatively and 1, 3, and 6 months postoperatively.
  
  
  RESULTS
  The conventional group comprised 42 eyes (21 patients) and the tissue-saving group, 62 eyes (31 patients). At 6 months, all eyes in both groups were within ±0.50 diopter of the attempted correction and had an uncorrected distance visual acuity of 20/25 or better. However, the tissue-saving group had a statistically significantly greater increase in the mean root mean square of total HOAs and more induced spherical aberration than the conventional group (P<.05). There was no significant difference between the 2 groups in mesopic or photopic contrast sensitivity. The level of satisfaction after surgery was the same in the 2 groups.
  
  
  CONCLUSIONS
  Although the conventional and tissue-saving algorithms for PRK were both safe and effective in treating low to moderate myopia, tissue-saving PRK induced a greater increase in HOAs than conventional PRK; this may be because of the smaller blend zone of the tissue-saving algorithm. Contrast sensitivity and patient satisfaction were comparable between the 2 methods.
authors.affiliation: Ophthalmology Department, Farabi Eye Hospital, Tehran Medical University, Tehran, Iran.
authors.forename: Hassan
authors.initials: H
authors.lastname: Hashemi
authors.forename: Rahman
authors.initials: R
authors.lastname: Nazari
authors.forename: Javad
authors.initials: J
authors.lastname: Amoozadeh
authors.forename: Amir Houshang
authors.initials: AH
authors.lastname: Beheshtnejad
authors.forename: Mahmoud
authors.initials: M
authors.lastname: Jabbarvand
authors.forename: Mehrdad
authors.initials: M
authors.lastname: Mohammadpour
authors.forename: Hesam
authors.initials: H
authors.lastname: Hashemian
mesh_terms: D000328:Adult; D000465:Algorithms; D015350:Contrast Sensitivity / Q000502:physiology*; D057108:Corneal Wavefront Aberration / Q000209:etiology*; D005260:Female; D006801:Humans; D054018:Lasers, Excimer / Q000627:therapeutic use*; D008297:Male; D009216:Myopia / Q000601:surgery*; D017060:Patient Satisfaction; D018903:Photorefractive Keratectomy / Q000379:methods*; D011183:Postoperative Complications; D011446:Prospective Studies; D011795:Surveys and Questionnaires; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult