title: A multicenter trial of photorefractive keratectomy for residual myopia after previous ocular surgery. Summit Therapeutic Refractive Study Group.
abstract: OBJECTIVE
  The Summit Therapeutic Refractive Clinical Trial is a nine-center prospective, nonrandomized, self-controlled trial to assess the efficacy, stability, and safety of using a standardized technique of excimer laser photorefractive keratectomy (PRK) to correct residual myopia in eyes with previous refractive surgery or cataract surgery.
  
  
  METHODS
  Eligible eyes with a mean residual myopia of -3.7 +/- 1.8 diopters (D) (range, -0.63 to -11.00 D) underwent PRK with a 193-nm excimer laser for myopic corrections between -1.50 and -7.50 D. Standardized settings were used for the ablation zone, ablation rate, repetition rate, and fluence. One hundred seven of the first 114 treated eyes were examined 1 year after PRK, with 98% of eyes having had refractive keratotomy and 2% having had cataract surgery.
  
  
  RESULTS
  One year postoperatively, the mean manifest spherical equivalent refraction was -0.6 +/- 1.4 D (range, -6.50 to 2.50 D); 63% of eyes were within +/-1.00 D of the attempted correction; and uncorrected visual acuity was 20/40 or better in 74% of eyes. Twenty-nine percent of eyes lost two or more Snellen lines of best-corrected visual acuity, and central corneal haze was moderate or severe in 8% of eyes.
  
  
  CONCLUSIONS
  Excimer laser PRK is effective in reducing residual myopia after previous refractive and cataract surgery. However, it is less accurate than PRK in eyes that did not undergo surgery and is more likely to cause a loss of best-corrected visual acuity 1 year after treatment.
authors.affiliation: Department of Ophthalmology, University of California, School of Medicine, Los Angeles 90024-7003, USA.
authors.forename: R K
authors.initials: RK
authors.lastname: Maloney
authors.forename: W K
authors.initials: WK
authors.lastname: Chan
authors.forename: R
authors.initials: R
authors.lastname: Steinert
authors.forename: P
authors.initials: P
authors.lastname: Hersh
authors.forename: M
authors.initials: M
authors.lastname: O'Connell
mesh_terms: D000328:Adult; D000368:Aged; D001251:Astigmatism / Q000601:surgery; D002387:Cataract Extraction / Q000009:adverse effects*; D015350:Contrast Sensitivity / Q000502:physiology; D003315:Cornea / Q000601:surgery*; D003318:Corneal Opacity / Q000209:etiology / Q000503:physiopathology; D005260:Female; D006801:Humans; D007646:Keratotomy, Radial / Q000009:adverse effects*; D054018:Lasers, Excimer; D008297:Male; D008875:Middle Aged; D009216:Myopia / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D018903:Photorefractive Keratectomy / Q000009:adverse effects; D011183:Postoperative Complications; D011446:Prospective Studies; D012029:Refraction, Ocular; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology