title: Evaluation of three different approaches to perform excimer laser photorefractive keratectomy for myopia.
abstract: OBJECTIVE
  The aim of this study was to evaluate the results of myopic excimer laser photorefractive keratectomy (PRK) performed using three different ablation approaches.
  
  
  METHODS
  Using the Apex excimer laser (Summit Technology, Inc., Waltham MA), we have treated 75 eyes. Twenty-five of them were treated by a single ablation zone (SA, 6.5 mm diameter) to correct myopia of -4.50 +/- 2.10 D (mean +/- SD); 25 eyes underwent PRK for the correction of myopia of -4.98 +/- 2.17 D using a multipass multizone technique (MP, 3 zones); and 25 eyes were corrected for myopia of -5.03 +/- 1.98 D using new software which enables the creation of three ablation zones in a single-pass fashion (MZ).
  
  
  RESULTS
  Mean refractive error (+/-SD) at the first post-operative month was +1.34 +/- 1.00 D for SA, +1.78 +/- 1.49 D for MP, and +0.90 +/- 0.75 D for MZ. Eyes treated by MZ had significantly better uncorrected visual acuity than those treated by SA (P=0.04). Corneal topography revealed a central island in 14 eyes (56%) of those treated by SA and 2 eyes (8%) of those treated by MZ, but in no eyes treated by MP. Six months after treatment, mean refractive error was +0.28 +/- 0.75 D for SA, +0.36 +/- 0.92 D for MP, and - 0.07 +/- 0.77 D for MZ.
  
  
  CONCLUSIONS
  MZ ablation induced less hyperopic shift at 1 month, thus leading to a faster visual recovery and better uncorrected visual acuity. MP and MZ ablations proved effective in preventing central island formation, thus inducing less visual disturbances than SA ablations. These results suggest that MZ ablation may be preferable to the other techniques in performing myopic PRK.
authors.affiliation: Department of Ophthalmology and Visual Sciences, Scientific Institute San Raffaele Hospital, University of Milan, Italy.
authors.forename: F
authors.initials: F
authors.lastname: Carones
authors.forename: R
authors.initials: R
authors.lastname: Brancato
authors.forename: A
authors.initials: A
authors.lastname: Morico
authors.forename: E
authors.initials: E
authors.lastname: Venturi
authors.forename: P G
authors.initials: PG
authors.lastname: Gobbi
mesh_terms: D000328:Adult; D000894:Anti-Inflammatory Agents, Non-Steroidal / Q000627:therapeutic use; D003315:Cornea / Q000473:pathology; D003318:Corneal Opacity / Q000209:etiology; D003519:Cyclopentolate / Q000627:therapeutic use; D004008:Diclofenac / Q000627:therapeutic use; D004311:Double-Blind Method; D005069:Evaluation Studies as Topic; D005260:Female; D005839:Gentamicins / Q000627:therapeutic use; D006801:Humans; D006956:Hyperopia / Q000209:etiology; D054018:Lasers, Excimer; D008297:Male; D008875:Middle Aged; D009184:Mydriatics / Q000627:therapeutic use; D009216:Myopia / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D009428:Netilmicin / Q000627:therapeutic use; D018903:Photorefractive Keratectomy / Q000295:instrumentation / Q000379:methods*; D012029:Refraction, Ocular; D012984:Software; D016896:Treatment Outcome; D014792:Visual Acuity
chemical_list: D000894:Anti-Inflammatory Agents, Non-Steroidal; D005839:Gentamicins; D009184:Mydriatics; D004008:Diclofenac; D009428:Netilmicin; D003519:Cyclopentolate