title: Topography-guided transepithelial photorefractive keratectomy for irregular astigmatism using a 213 nm solid-state laser.
abstract: OBJECTIVE
  To explore the use of the Pulsar Z1 solid-state 213 nm photorefractive laser platform in topography-guided transepithelial photorefractive keratectomy (PRK) for irregular astigmatism.
  
  
  METHODS
  Moorfields Eye Hospital, London, United Kingdom.
  
  
  METHODS
  Prospective clinical case series.
  
  
  METHODS
  Patients with irregular astigmatism after previous refractive surgery or corneal transplantation were treated with topography-guided transepithelial PRK. Preoperatively and 1-year postoperatively, corrected distance visual acuity (CDVA) and secondary outcome measures (including manifest refraction, contrast sensitivity, haze score, index of surface variation, root-mean-square higher-order aberrations, and subjective visual change) were compared between groups. Adjunctive mitomycin-C was not used.
  
  
  RESULTS
  Seven patients had previous refractive surgery, and 7 had previous corneal transplantation. All but 2 patients with a marked haze response had subjective gains in vision and improved CDVA. Gains in CDVA for patients with irregular astigmatism after previous refractive surgery (median 2 lines gain; range 0 to 2 lines gained) were higher than for patients with irregular astigmatism after keratoplasty (median 0 lines; range 5 lines lost to 4 lines gained). Trends in secondary outcome measures were similar, with greater variation in post-keratoplasty patients. Haze scores were higher in post-keratoplasty patients.
  
  
  CONCLUSIONS
  213 nm topography-guided transepithelial PRK was easy to perform and well tolerated by patients with irregular astigmatism. Most patients gained CDVA; however, increased haze responses were observed in post-keratoplasty cases.
authors.affiliation: From Moorfields Eye Hospital, London, United Kingdom. Electronic address: bruce.allan@ucl.ac.uk.
authors.forename: Bruce D
authors.initials: BD
authors.lastname: Allan
authors.affiliation: From Moorfields Eye Hospital, London, United Kingdom.
authors.forename: Hala
authors.initials: H
authors.lastname: Hassan
mesh_terms: D000328:Adult; D000368:Aged; D001251:Astigmatism / Q000209:etiology / Q000503:physiopathology / Q000601:surgery*; D015350:Contrast Sensitivity / Q000502:physiology; D019781:Corneal Topography; D057108:Corneal Wavefront Aberration / Q000503:physiopathology; D004847:Epithelial Cells; D006801:Humans; D053844:Lasers, Solid-State / Q000627:therapeutic use*; D008875:Middle Aged; D018903:Photorefractive Keratectomy / Q000379:methods*; D011183:Postoperative Complications / Q000601:surgery; D011446:Prospective Studies; D012029:Refraction, Ocular / Q000502:physiology; D014792:Visual Acuity / Q000502:physiology; D055815:Young Adult