title: Photorefractive keratectomy in mild to moderate keratoconus: outcomes in over 40-year-old patients.
abstract: BACKGROUND
  Keratoconus is a contraindication for photorefractive keratectomy (PRK). In the recent decade, some efforts have been made to perform PRK in patients with keratoconus whose corneas are stable naturally or by doing corneal collagen crosslinking. These studies have suggested residual central corneal thickness (CCT) ≥450 μm.
  
  
  OBJECTIVE
  The aim was to evaluate the long-term outcomes of PRK in patients with mild to moderate keratoconus in patients older than 40 with residual CCT ≥ 400 μm.
  
  
  METHODS
  This prospective study was conducted in our Cornea Research Center, Mashhad, Iran.
  
  
  METHODS
  Patients over 40 years old, with a grade I/II keratoconus without progression in the last 2 years were recruited. Patients with a predicted postoperative CCT < 400 μm were excluded. PRK with tissue saving protocol was performed with Tecnolas 217 Z. Mitomycin-C was applied after ablation. The final endpoints were refraction parameters the last follow-up visit (mean: 35 months). Paired t-test and Chi-square were used for analysis.
  
  
  RESULTS
  A total of 38 eyes of 21 patients were studied; 20 eyes (52.6%) with a grade I and 18 eyes (47.4%) with grade II keratoconus. The mean uncorrected visual acuity, best corrected visual acuity (BCVA), spherical equivalent, cylindrical power and keratometric readings were significantly improved at the final endpoint compared to preoperation measurements (P < 0.001). Two eyes (5%) lost two lines of BCVA at the final visit. No case of ectasia occurred during the follow-up course.
  
  
  CONCLUSIONS
  PRK did not induce keratoconus progression in patients older than 40 with a grade I/II keratoconus. Residual CCT ≥ 450 μm seems to be sufficient to prevent the ectasia.
authors.forename: Hamid
authors.initials: H
authors.lastname: Khakshoor
authors.forename: Fatemeh
authors.initials: F
authors.lastname: Razavi
authors.forename: Alireza
authors.initials: A
authors.lastname: Eslampour
authors.affiliation: Department of Ophthalmology, Eye Research Center, Faculty of Medicine, Khatam-Al-Anbia Eye Hospital, Mashhad University of Medical Sciences, Mashhad, Khorasan Razavi, Iran.
authors.forename: Arash
authors.initials: A
authors.lastname: Omdtabrizi
mesh_terms: D000328:Adult; D003315:Cornea / Q000473:pathology* / Q000601:surgery; D019781:Corneal Topography; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D007640:Keratoconus / Q000473:pathology / Q000601:surgery*; D054018:Lasers, Excimer / Q000627:therapeutic use; D008297:Male; D008875:Middle Aged; D018903:Photorefractive Keratectomy / Q000379:methods*; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology*; D013997:Time Factors; D016896:Treatment Outcome; D014792:Visual Acuity
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