title: Long-term results of excimer laser procedure to correct astigmatic refractive errors.
abstract: BACKGROUND
  The aim of this study was to evaluate long-term efficacy, safety, stability, and predictability of photorefractive keratectomy (PRK) as treatment of astigmatism.
  
  
  METHODS
  Ninety-four eyes of 52 patients, treated with PRK for compound myopic astigmatism, compound hyperopic astigmatism, and mixed astigmatism were studied during a 36-month period. Main outcome measures were uncorrected and best-corrected visual acuity (UCVA, BCVA), refraction, and corneal transparency. Astigmatism correction was analyzed by a power vector method.
  
  
  RESULTS
  In myopic astigmatism group (42 eyes), postoperative UCVA was 20/40 or better in 100% of eyes, 20/25 or better in 38 eyes out of 42 (90.5%), and 20/20 or better in 25/42 eyes (59.5%). No eye lost lines of the BCVA, 40/42 (95.2%) eyes had refraction within ± 1D and 37/42 (88.1%) within ± 0.50 D. In the hyperopic astigmatism group (28 eyes), the UCVA was 20/40 or better in 100% of eyes, 20/25 or better in 26/28 eyes (92.8%), and 20/20 or better in 24/28 eyes (85.7%); 1/28 eyes (3.6%) lost 1 line of the BCVA, 23/28 eyes (82.1%) were within ± 1D, and 21/28 (75%) were within ± 0.50D. In the mixed astigmatism group (24 eyes), the UCVA was 20/40 or better in 100% of eyes, 20/25 or better in 22/24 eyes (91.7%) and 20/20 in 15/24 (62.5%) eyes. No eye lost lines of BCVA, 23/24 eyes (95.8%) were within 1.0 D, and 20/24 eyes (83.3%) were within 0.50 D of defocus refraction. Power vector analysis showed a significant reduction of blurring strength in all examined groups.
  
  
  CONCLUSIONS
  PRK is a safe and effective procedure for correction of all types of astigmatism, with good stability and efficacy at 3-year follow-up.
authors.affiliation: Ophthalmology Unit, Department of Surgical Specialties, University Hospital of Messina, Messina, Italy.
authors.forename: Anna M
authors.initials: AM
authors.lastname: Roszkowska
authors.forename: Letteria
authors.initials: L
authors.lastname: De Grazia
authors.forename: Alessandro
authors.initials: A
authors.lastname: Meduri
authors.forename: Edward
authors.initials: E
authors.lastname: Wylegala
authors.forename: Pasquale
authors.initials: P
authors.lastname: Aragona
mesh_terms: D001251:Astigmatism / Q000601:surgery*; D005500:Follow-Up Studies; D006801:Humans; D054018:Lasers, Excimer / Q000627:therapeutic use*; D018903:Photorefractive Keratectomy / Q000379:methods* / Q000639:trends; D012189:Retrospective Studies; D016896:Treatment Outcome; D014792:Visual Acuity / Q000502:physiology