title: Evidence for superior efficacy and safety of LASIK over photorefractive keratectomy for correction of myopia.
abstract: OBJECTIVE
  To examine possible differences in efficacy and safety between LASIK and photorefractive keratectomy (PRK) for correction of myopia.
  
  
  METHODS
  Meta-analysis/systematic review.
  
  
  METHODS
  Patient data from previously reported prospective randomized controlled trials (PRCTs) and a systematic review of prospective case series in the Food and Drug Administration (FDA) clinical trials database.
  
  
  METHODS
  A comprehensive literature search was performed using the Cochrane Collaboration methodology to identify PRCTs comparing LASIK and PRK for correction of myopia. A meta-analysis was performed on the results of PRCTs. In parallel, a systematic review of prospective data from FDA case series of LASIK and PRK for correction of myopia was undertaken.
  
  
  METHODS
  Key efficacy outcomes (uncorrected visual acuity [UCVA] > or = 20/20, +/-0.50 diopters [D] of the target mean refractive spherical equivalent) and safety outcomes (loss of > or =2 lines of best spectacle-corrected visual acuity [BSCVA], final BSCVA > or = 20/40, and final BSCVA < 20/25 where preoperative BSCVA was > or =20/20).
  
  
  RESULTS
  Seven PRCTs were identified comparing PRK (683 eyes) and LASIK (403 eyes) for correction of myopia. More LASIK patients achieved UCVA > or = 20/20 at 6 months (odds ratio, random effects model [95% confidence interval], 1.72 [1.14-2.58]; P = 0.009) and 12 months (1.78 [1.15-2.75], P = 0.01). Loss of > or =2 lines of BSCVA at 6 months was less frequent with LASIK (2.69 [1.01-7.18], P = 0.05). Data from 14 LASIK (7810 eyes) and 10 PRK (4414 eyes) FDA laser approval case series showed that more LASIK patients achieved UCVA of 20/20 or better at 12 months (1.15 [1.03-1.29], P = 0.01), significantly more LASIK patients were within +/-0.50 D of target refraction at 6 months (1.38 [1.26-1.50], P<0.00001) and 12 months (1.21 [1.08-1.36], P = 0.0009) after treatment, and loss of > or =2 lines of BSCVA at 6 months was less frequent with LASIK (2.91 [2.22-3.83], P<0.00001).
  
  
  CONCLUSIONS
  LASIK appears to have efficacy and safety superior to those of PRK. However, the data examined are from studies conducted > or =5 years ago. It is therefore unclear how our findings relate to present-day methods and outcomes. Further trials comparing contemporary equipment and techniques are needed to reevaluate the relative merits of these procedures.
authors.affiliation: Moorfields Eye Hospital, London, United Kingdom. a.shortt@ucl.ac.uk
authors.forename: Alex J
authors.initials: AJ
authors.lastname: Shortt
authors.forename: Catey
authors.initials: C
authors.lastname: Bunce
authors.forename: Bruce D S
authors.initials: BD
authors.lastname: Allan
mesh_terms: D002986:Clinical Trials as Topic; D005139:Eyeglasses; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects / Q000592:standards*; D054018:Lasers, Excimer; D009216:Myopia / Q000503:physiopathology / Q000601:surgery* / Q000628:therapy; D018903:Photorefractive Keratectomy / Q000009:adverse effects / Q000592:standards*; D012449:Safety; D016896:Treatment Outcome; D014792:Visual Acuity