title: Rotational malposition during laser in situ keratomileusis.
abstract: OBJECTIVE
  To investigate the degree of rotational malposition in eyes undergoing laser in situ keratomileusis.
  
  
  METHODS
  Prospective observational study.
  
  
  METHODS
  We measured the rotational position of 240 eyes of 169 patients who underwent treatment for myopic or hyperopic astigmatism with the Alcon Summit Autonomous (Orlando, Florida) LADARVision excimer laser. Immediately preoperatively, each eye was marked while the patient was seated upright. Rotational position was measured on the supine patient immediately before beginning the laser exposure.
  
  
  RESULTS
  For all 240 eyes, mean +/- standard deviation (SD) torsional misalignment was 4.1 +/- 3.7 degrees (right eye 3.8 +/- 3.7 degrees, left eye 4.2 +/- 3.6 degrees). A total of 20 eyes (8%) had a deviation of greater than 10 degrees.
  
  
  CONCLUSIONS
  A 4 degree and 10 degree misalignment would theoretically result in a 14% and 35% undercorrection of astigmatism, respectively. Preoperative marking of the upright patient and subsequent rotational alignment of the supine patient before laser treatment may reduce the error in correction of astigmatism during excimer laser vision correction surgery.
authors.affiliation: New England Eye Center, Tufts University School of Medicine, Boston, Massachusetts, USA.
authors.forename: Anil U
authors.initials: AU
authors.lastname: Swami
authors.forename: Roger F
authors.initials: RF
authors.lastname: Steinert
authors.forename: Winifred E
authors.initials: WE
authors.lastname: Osborne
authors.forename: April A
authors.initials: AA
authors.lastname: White
mesh_terms: D001251:Astigmatism / Q000601:surgery; D003319:Corneal Stroma; D005133:Eye Movements; D006801:Humans; D006956:Hyperopia / Q000601:surgery; D007431:Intraoperative Complications; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects*; D009216:Myopia / Q000601:surgery; D011446:Prospective Studies; D012399:Rotation; D016683:Supine Position; D013524:Surgical Flaps; D014102:Torsion Abnormality