title: Proper positioning of the plume evacuator in the VISX Star3 excimer laser minimizes central island formation in patients undergoing laser in situ keratomileusis.
abstract: OBJECTIVE
  To identify risk factors in a series of patients who developed steep central islands after laser in situ keratomileusis (LASIK).
  
  
  METHODS
  We analyzed and compared the refractive and topographic outcome of a study group composed of 83 eyes of 44 patients who underwent LASIK using the VISX Star3 excimer laser with a refraction-matched control group of 83 eyes treated later. The vacuum aspirator of the excimer laser was abnormally positioned during the surgeries performed in the study group.
  
  
  RESULTS
  Mean preoperative spherical equivalent refraction in the study group was -6.75 +/- 2.50 D. Four eyes with a mean preoperative spherical equivalent refraction of -9.27 +/- 2.29 D developed steep central islands. Thirty-three (38%) of 83 eyes treated needed retreatment for residual myopia or myopic astigmatism. In the control group, mean preoperative spherical equivalent refraction was -6.76 +/- 2.50 D. Ninety-three percent of eyes were within +/- 1.00 D of target refraction. Five (6.02%) of 83 eyes required retreatment and no eyes developed central islands.
  
  
  CONCLUSIONS
  The abnormally positioned vacuum aspirator coupled with the higher preoperative refractive correction were the likely causative factors for central island formation and the increased incidence of undercorrection in these patients.
authors.affiliation: Pepose Vision Institute, Chesterfield, MO 63017, USA.
authors.forename: Irwin Y
authors.initials: IY
authors.lastname: Cua
authors.forename: Jay S
authors.initials: JS
authors.lastname: Pepose
mesh_terms: D001251:Astigmatism / Q000601:surgery*; D003315:Cornea / Q000601:surgery*; D003316:Corneal Diseases / Q000209:etiology / Q000517:prevention & control*; D019781:Corneal Topography; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000009:adverse effects / Q000379:methods*; D009216:Myopia / Q000601:surgery*; D011183:Postoperative Complications / Q000517:prevention & control*; D012086:Reoperation; D012189:Retrospective Studies; D012307:Risk Factors