title: Five years results of photorefractive keratectomy for myopia.
abstract: OBJECTIVE
  To evaluate the long-term stability, complications, and causative factors in eyes that had photorefractive keratectomy (PRK) for myopia.
  
  
  METHODS
  Kangnam St. Mary's Hospital, Seoul, Korea.
  
  
  METHODS
  This study evaluated the results of PRK in 201 myopic eyes with a consecutive 5 year follow-up. Preoperative myopia ranged from 2.25 to 12.50 diopters (D), with astigmatism of less than 1.50 D. The Excimer laser was set to a maximum correction of -6.50 D at a 5.0 mm diameter ablation zone. Patients with more than 7.00 D of myopia had double-pass PRK with two different ablation zone sizes (5.0 and 4.5 mm). The data were statistically analyzed using polynomial regression for evaluating long-term stability and myopic regression and Cox's proportional hazard model for evaluating causative factors.
  
  
  RESULTS
  An uncorrected visual acuity better than 20/25 was achieved in 62.4% of eyes. The main complication after PRK was myopic regression. Mean refractive error 5 years after PRK was -2.43 +/- 1.90 D. It was -1.49 +/- 0.60 D in moderately myopic eyes (less than 6.50 D) and -3.55 +/- 2.31 D in highly myopic eyes (over 7.00 D). According to our evaluation, the possible causative factors for myopic regression were pre-PRK refraction (P < .0001) and post-PRK corneal haze (P = .01); their relative risks were 3.33 and 1.93, respectively. Multivariate analysis eliminated the corneal haze factor.
  
  
  CONCLUSIONS
  Myopic regression occurred as long as 5 years after PRK, with the most important factor for myopic regression being pre-PRK refraction.
authors.affiliation: Department of Ophthalmology, Catholic University Medical College, Seoul, Korea.
authors.forename: J H
authors.initials: JH
authors.lastname: Kim
authors.forename: M S
authors.initials: MS
authors.lastname: Kim
authors.forename: T W
authors.initials: TW
authors.lastname: Hahn
authors.forename: Y C
authors.initials: YC
authors.lastname: Lee
authors.forename: W J
authors.initials: WJ
authors.lastname: Sah
authors.forename: C K
authors.initials: CK
authors.lastname: Park
mesh_terms: D000328:Adult; D003315:Cornea / Q000503:physiopathology / Q000601:surgery*; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D054018:Lasers, Excimer; D008297:Male; D009216:Myopia / Q000503:physiopathology / Q000601:surgery*; D018903:Photorefractive Keratectomy / Q000009:adverse effects / Q000379:methods; D011183:Postoperative Complications; D011379:Prognosis; D012008:Recurrence; D012029:Refraction, Ocular / Q000502:physiology; D012189:Retrospective Studies; D014792:Visual Acuity / Q000502:physiology