title: Comparison of visual results in initial and re-treatment laser in situ keratomileusis procedures for myopia and astigmatism.
abstract: OBJECTIVE
  To report the results of initial and re-treatment laser in situ keratomileusis procedures for myopia and astigmatism.
  
  
  METHODS
  A total of 1161 consecutive inital and retreatment laser in situ keratomileusis procedures in 697 patients performed between September 19, 1996, and June 20, 1998, were retrospectively analyzed. Baseline and postoperative best spectacle-corrected visual acuity, uncorrected visual acuity, spherical and cylindrical refractions, computerized video keratography, and biomicroscopy were measured or performed on each eye.
  
  
  RESULTS
  Of 1,071 eyes, 900 (84%) underwent a single-laser in situ keratomileusis procedure, and 171 of 1,071 eyes (16%) underwent one or two re-treatment procedures. The preoperative mean +/- SD spherical equivalent was -5.09 +/- 3.15 diopters (range, -0.75 to -14.38 diopters) and the cylinder was 0.97 +/- 1.09 diopters (range, 0.00 to 3.25 diopters) in the group that underwent a single laser in situ keratomileusis treatment. The preoperative mean +/- SD spherical equivalent was -6.26 +/- 3.04 diopters (range, -1.75 to -12.88 diopters) and the cylinder was 1.53 +/- 1.11 diopters (range, 0.00 to 3.50 diopters) in the group that underwent re-treatment. Before re-treatment, 110 eyes (64.3%) in the group that underwent re-treatment achieved 20/40 or better uncorrected visual acuity and 23 eyes (13.5%) achieved 20/25 or better. Three months after re-treatment, 155 eyes (90.6%) achieved 20/40 or better, and 80 eyes (46.8%) achieved 20/25 or better. In the single-procedure group, uncorrected visual acuity at 3 months revealed 20/40 vision or better in 856 eyes (95.1%) and 20/25 vision or better in 572 eyes (63.6%). In this study group, 23.6% of eyes with a preoperative spherical equivalent greater than -6.0 diopters underwent re-treatment compared with 11.8% of eyes with a preoperative spherical equivalent of -6.0 diopters or less.
  
  
  CONCLUSIONS
  Laser in situ keratomileusis appears to be an effective procedure for mild, moderate, and severe myopia. In eyes with residual refractive error, re-treatment laser in situ keratomileusis procedures can result in good visual outcomes.
authors.affiliation: Cornea Service, John A. Moran Eye Center, University of Utah Health Sciences Center, Department of Ophthalmology, Salt Lake City, Utah USA.
authors.forename: N P
authors.initials: NP
authors.lastname: Patel
authors.forename: T E
authors.initials: TE
authors.lastname: Clinch
authors.forename: J R
authors.initials: JR
authors.lastname: Weis
authors.forename: C
authors.initials: C
authors.lastname: Ahn
authors.forename: M K
authors.initials: MK
authors.lastname: Lundergan
authors.forename: K
authors.initials: K
authors.lastname: Heidenreich
mesh_terms: D001251:Astigmatism / Q000601:surgery*; D003315:Cornea / Q000601:surgery*; D019781:Corneal Topography; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D009216:Myopia / Q000601:surgery*; D012086:Reoperation; D012189:Retrospective Studies; D013524:Surgical Flaps; D013997:Time Factors; D014792:Visual Acuity