title: Effect of myopic laser in situ keratomileusis on epithelial and stromal thickness: a confocal microscopy study.
abstract: OBJECTIVE
  To determine changes in central epithelial and stromal thickness in human corneas in vivo after laser in situ keratomileusis (LASIK).
  
  
  METHODS
  Prospective, nonrandomized, comparative trial.
  
  
  METHODS
  Eighteen eyes of 12 patients received LASIK (performed using the VISX Star laser [VISX, Santa Ana, CA]) with a planned 180- micro m flap (created using an automated Hansatome microkeratome [Bausch & Lomb, Irvine, CA]) to correct refractive errors between -2.0 diopters (D) and -11.0 D.
  
  
  METHODS
  Corneas were examined by using confocal microscopy in vivo before LASIK and at 1 week and 1, 3, 6, and 12 months after LASIK. Epithelial thickness was the distance between images of the surface epithelium and subbasal nerve plexus or, when nerves were not visible, the subbasal peak (if present in the light intensity profile). Total flap thickness was the distance between images of the surface epithelium and interface debris (or peak), and total stromal thickness was the distance between images of the most anterior keratocytes and endothelium.
  
  
  METHODS
  Corneal epithelial and stromal thickness.
  
  
  RESULTS
  Epithelial thickness before LASIK was 46 +/- 5 micro m (mean +/- standard deviation) and increased 22% by 1 month after LASIK (56 +/- 5 micro m; P = 0.01). Thereafter, epithelial thickness did not change, but remained thicker at 12 months after LASIK (54 +/- 8 micro m) than before LASIK (P = 0.02). Total flap thickness at 1 month after LASIK was 160 +/-28 micro m and did not change thereafter. Changes in total stromal thickness between 1 and 12 months after LASIK were not significant.
  
  
  CONCLUSIONS
  The central corneal epithelium was thicker in the first year after LASIK than before LASIK. There was no change in central stromal thickness between 1 month and 12 months after LASIK.
authors.affiliation: Department of Ophthalmology, Mayo Clinic, Rochester, Minnesota, USA. erie.jay@mayo.edu
authors.forename: Jay C
authors.initials: JC
authors.lastname: Erie
authors.forename: Sanjay V
authors.initials: SV
authors.lastname: Patel
authors.forename: Jay W
authors.initials: JW
authors.lastname: McLaren
authors.forename: Manuel
authors.initials: M
authors.lastname: Ramirez
authors.forename: David O
authors.initials: DO
authors.lastname: Hodge
authors.forename: Leo J
authors.initials: LJ
authors.lastname: Maguire
authors.forename: William M
authors.initials: WM
authors.lastname: Bourne
mesh_terms: D000328:Adult; D003319:Corneal Stroma / Q000473:pathology*; D004847:Epithelial Cells / Q000473:pathology; D019573:Epithelium, Corneal / Q000473:pathology*; D006801:Humans; D006984:Hypertrophy; D020731:Keratomileusis, Laser In Situ; D018613:Microscopy, Confocal; D008875:Middle Aged; D009216:Myopia / Q000601:surgery*; D011184:Postoperative Period; D011446:Prospective Studies; D013524:Surgical Flaps; D013997:Time Factors; D014945:Wound Healing