title: Factors affecting the forward shift of posterior corneal surface after laser in situ keratomileusis.
abstract: OBJECTIVE
  To evaluate the anteroposterior movement of the corneal back surface after laser in situ keratomileusis (LASIK).
  
  
  METHODS
  Retrospective noncomparative case series.
  
  
  METHODS
  One hundred ninety-six eyes of 120 subjects with myopic refractive errors of -2.0 to -12.5 diopters.
  
  
  METHODS
  LASIK was performed. Corneal topography of the posterior corneal surface was obtained with the scanning slit topography system before and 1 month after surgery.
  
  
  METHODS
  The amount of forward shift of the posterior corneal surface was determined. Multiple regression analysis was used to assess the factors that affect the forward shift of the posterior corneal surface.
  
  
  RESULTS
  After surgery, the posterior corneal surface displayed mean forward shift of 40.9 +/- 24.8 micrometer. Explanatory variables relevant to the forward shift of corneal posterior surface were, in the order of magnitude of influence, the amount of laser ablation (partial regression coefficient B = 0.561, P < 0.0001), preoperative corneal thickness (B = -0.176, P = 0.00096), and preoperative intraocular pressure (B = 1.676, P = 0.0053). Preoperative refraction and achieved myopic correction showed collinearity with the amount of laser ablation.
  
  
  CONCLUSIONS
  LASIK induces a forward shift of the cornea. Eyes with thinner corneas, higher intraocular pressure, and higher myopia requiring greater laser ablation are more predisposed to the anterior shift of the cornea.
authors.affiliation: St. Mary's Eye Hospital, Pusan, South Korea.
authors.forename: T
authors.initials: T
authors.lastname: Baek
authors.forename: K
authors.initials: K
authors.lastname: Lee
authors.forename: F
authors.initials: F
authors.lastname: Kagaya
authors.forename: A
authors.initials: A
authors.lastname: Tomidokoro
authors.forename: S
authors.initials: S
authors.lastname: Amano
authors.forename: T
authors.initials: T
authors.lastname: Oshika
mesh_terms: D000328:Adult; D003315:Cornea / Q000473:pathology*; D019781:Corneal Topography; D004108:Dilatation, Pathologic / Q000209:etiology / Q000473:pathology; D005260:Female; D006801:Humans; D007429:Intraocular Pressure; D020731:Keratomileusis, Laser In Situ; D008297:Male; D009216:Myopia / Q000601:surgery*; D012044:Regression Analysis; D012189:Retrospective Studies; D014792:Visual Acuity