title: Photorefractive keratectomy with a transition zone for myopia from -7 to -14 diopters.
abstract: OBJECTIVE
  To study transition zone excimer laser photorefractive keratectomy (PRK) in moderate and high myopia defined as a spherical equivalent of -7.00 diopters (D) or more. The follow-up period was 18 months.
  
  
  METHODS
  Forty eyes of 40 patients with myopia of 7.00 to -13.50 D (mean +/- SD, -921 +/- 1.98) underwent transition zone (5.0 to 7.0 mm transition zone) PRK using the Aesculap Meditec Mel 60 excimer laser. The mean attempted correction was 8.3 +/- 1.64 D (range: -6.50 to -12.00 D).
  
  
  RESULTS
  At 18 months, 83% achieved an unaided visual acuity of 20/50 or better and HOW 12% 20/25 or better. Eighty-eight percent were within +/-2 D of emmetropia. the mean spherical equivalent was -1.1 D (+3.00 to -9.00 D).
  
  
  CONCLUSIONS
  Transition zone PRK is useful in moderate to high myopia. Regression, as well as overcorrection are issues for further investigation.
authors.affiliation: Vardinoyannion Eye Institute of Crete, Greece.
authors.forename: D S
authors.initials: DS
authors.lastname: Siganos
authors.forename: I G
authors.initials: IG
authors.lastname: Pallikaris
authors.forename: V N
authors.initials: VN
authors.lastname: Margaritis
mesh_terms: D000328:Adult; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D054018:Lasers, Excimer; D008297:Male; D009216:Myopia / Q000145:classification / Q000601:surgery*; D018903:Photorefractive Keratectomy; D012029:Refraction, Ocular; D014792:Visual Acuity / Q000502:physiology