title: Photorefractive keratectomy for low myopia at 6 mm treatment diameter. A comparison of two excimer lasers.
abstract: OBJECTIVE
  The aim of the retrospective study was to evaluate the algorithms and the surgical performance of two excimer lasers; the VISX 20/20 and the Summit Omnimed.
  
  
  METHODS
  Twenty patients were treated with the VISX-laser and 20 with the Summit-laser. The indications were myopia between -1 to -6 diopters which also allowed correction of astigmatism up to -2 in the VISX patients group. The treatment diameter was 6 mm and the follow-up time was 12 months. The parameters studied were visual acuity uncorrected and corrected, contrast sensitivity in light, dark and glare, endothelial cell count, corneal topography, and subjective estimation of dark vision problems.
  
  
  RESULTS
  Both groups showed the same median refraction, -0.3 diopters. All the Summit patients had uncorrected visual acuity of 0.7 or better. In the VISX group 17 patients saw > or = 0.7 uncorrected and all patients saw 0.5 or better s.c. The remaining result parameters showed no statistical differences between the two groups.
  
  
  CONCLUSIONS
  The study does not lend conclusive support for any difference between the results obtained by the two lasers.
authors.affiliation: St. Erik's Eye Hospital, Karolinska Institute, Stockholm, Sweden.
authors.forename: H L
authors.initials: HL
authors.lastname: Hamberg-Nyström
authors.forename: P P
authors.initials: PP
authors.lastname: Fagerholm
authors.forename: B T
authors.initials: BT
authors.lastname: Tengroth
mesh_terms: D000328:Adult; D001251:Astigmatism / Q000150:complications / Q000503:physiopathology; D006801:Humans; D007834:Lasers; D054018:Lasers, Excimer; D009216:Myopia / Q000150:complications / Q000503:physiopathology* / Q000601:surgery*; D018903:Photorefractive Keratectomy / Q000295:instrumentation* / Q000379:methods*; D011184:Postoperative Period; D012029:Refraction, Ocular / Q000502:physiology; D012189:Retrospective Studies; D014792:Visual Acuity / Q000502:physiology