title: Photorefractive keratectomy (PRK) versus laser-assisted in-situ keratomileusis (LASIK) for myopia.
abstract: BACKGROUND
  Myopia (also known as short-sightedness or near-sightedness) is an ocular condition in which the refractive power of the eye is greater than is required, resulting in light from distant objects being focused in front of the retina instead of directly on it. The two most commonly used surgical techniques to permanently correct myopia are photorefractive keratectomy (PRK) and laser-assisted in-situ keratomileusis (LASIK).
  
  
  OBJECTIVE
  The aim of this review was to compare the effectiveness and safety of PRK and LASIK for correction of myopia.
  
  
  METHODS
  We searched the Cochrane Central Register of Controlled Trials (CENTRAL) in The Cochrane Library (2005, Issue 3), MEDLINE (1966 to September 2005), EMBASE (1980 to September 2005) and LILACs (1982 to 3 November 2005). We also searched the reference lists of the studies and the Science Citation Index.
  
  
  METHODS
  We included randomised controlled trials comparing PRK and LASIK for correction of any degree of myopia. We also included data on adverse events from prospective multicentre consecutive case series in the Food and Drugs Administration (FDA) trials database (http//www.fda.gov/cdrh/LASIK/lasers.htm).
  
  
  METHODS
  Two authors independently assessed trial quality and extracted data. Data were summarised using odds ratio and mean difference. Odds ratios were combined using a random-effects model after testing for heterogeneity.
  
  
  RESULTS
  This review included six randomised controlled trials involving a total of 417 eyes, of which 201 were treated with PRK and 216 with LASIK. We found that although LASIK gives a faster visual recovery than PRK, the effectiveness of these two procedures is comparable. We found some evidence that LASIK may be less likely than PRK to result in loss of best spectacle-corrected visual acuity.
  
  
  CONCLUSIONS
  LASIK gives a faster visual recovery than PRK but the effectiveness of these two procedures is comparable. Further trials using contemporary techniques are required to determine whether LASIK and PRK are equally safe.
authors.affiliation: Moorfields Eye Hospital, 162 City Road, London, UK, EC1V 2PD. a.shortt@ucl.ac.uk
authors.forename: A J
authors.initials: AJ
authors.lastname: Shortt
authors.forename: B D S
authors.initials: BD
authors.lastname: Allan
mesh_terms: D006801:Humans; D020731:Keratomileusis, Laser In Situ; D054018:Lasers, Excimer; D009216:Myopia / Q000601:surgery*; D018903:Photorefractive Keratectomy; D016032:Randomized Controlled Trials as Topic