title: Comparison of two techniques of marking the horizontal axis during excimer laser keratorefractive surgery for myopic astigmatism.
abstract: OBJECTIVE
  To compare two methods of limbal marking used during laser refractive surgery for myopic astigmatism.
  
  
  METHODS
  Retrospective chart review.
  
  
  METHODS
  Forty-two eyes of 42 patients who underwent photorefractive keratectomy (PRK) or laser-assisted in-situ keratomileusis (LASIK) for myopic astigmatism were marked preoperatively to identify the horizontal axis. In 18 eyes, marks were placed at the slit lamp (SL) with the slit beam set at 180 degrees as a reference. In 24 eyes, marks were placed in the laser room (LR) immediately before reclining under the laser. All treatments were performed with the Alcon LADARVision excimer laser system. Vector analysis of postoperative cylinder and reduction in cylinder and uncorrected and best-corrected visual acuity were evaluated for both groups.
  
  
  RESULTS
  The mean postoperative magnitude of error was -0.19 +/- 0.44 diopters for the LR group and -0.09 +/- 0.42 diopters for the SL group (P = .439, NS). Both groups had a mean angle of error indicating an overall counterclockwise rotation of axis with an angle of error of 6.3 +/- 8.7 degrees for the LR group and 8.0 +/- 10.2 degrees for the SL group (P = .562, NS).
  
  
  CONCLUSIONS
  We found no significant difference in outcomes with an overall trend toward undercorrection of cylinder in both groups, leaving room for improvement after refractive surgery for myopic astigmatism.
authors.affiliation: Ophthalmology Service, Walter Reed Army Medical Center, Washington, DC 20037, USA.
authors.forename: Jenna M
authors.initials: JM
authors.lastname: Burka
authors.forename: Kraig S
authors.initials: KS
authors.lastname: Bower
authors.forename: David L
authors.initials: DL
authors.lastname: Cute
authors.forename: Richard D
authors.initials: RD
authors.lastname: Stutzman
authors.forename: Prem S
authors.initials: PS
authors.lastname: Subramanian
authors.forename: Jeff C
authors.initials: JC
authors.lastname: Rabin
mesh_terms: D001251:Astigmatism / Q000601:surgery*; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D054018:Lasers, Excimer; D016850:Limbus Corneae / Q000033:anatomy & histology*; D009216:Myopia / Q000601:surgery*; D018903:Photorefractive Keratectomy / Q000379:methods*; D011183:Postoperative Complications; D012189:Retrospective Studies; D014792:Visual Acuity