title: Noncontact measurements of central corneal epithelial and flap thickness after laser in situ keratomileusis.
abstract: OBJECTIVE
  To investigate the changes in the epithelium and flap after laser in situ keratomileusis (LASIK), when measured with optical coherence tomography (OCT).
  
  
  METHODS
  Twenty-eight eyes of 14 patients (age: 39.9 +/- 8.6 years) underwent LASIK. The central thickness of corneal epithelium and flap were measured with a real-time 1310 nm OCT 1 day, 1 week, and 1 month after surgery. A custom software program was used to process multiple images of each eye on each visit.
  
  
  RESULTS
  After surgery, the corneal epithelium changed significantly (ANOVA: F((3, 81)) = 12.3, P = 0.000) with not statistically significant thinning at one day (mean +/- SD: 57.8 +/- 5.9 micro m, P = 0.26, compared with baseline: 59.9 +/- 5.9 micro m) and statistically significant thickening at 1 week (60.8 +/- 5.8 micro m, P = 0.04, compared with 1 day) and 1 month (64.6 +/- 6.1 micro m, P = 0.008 compared with all others). There were statistically significant changes in the corneal flap thickness (ANOVA: F((2, 54)) = 4.59, P = 0.01) with thickening in the intervals between 1 day (143.3 +/- 20.6 micro m) and 1 week (149.7 +/- 24.6 micro m, P = 0.12), and between 1 week and 1 month (152.7 +/- 19.3 micro m, P = 0.01). There was a strong correlation (r = 0.898) between the difference of corneal thickness before and after surgery and predicted laser ablation depth.
  
  
  CONCLUSIONS
  OCT is a useful noncontact tool for thickness measurements of the epithelium, flap, and total cornea. After LASIK, the epithelium and flap showed thickening during the study period.
authors.affiliation: School of Optometry, University of Waterloo, Waterloo, Ontario, Canada. jianhua_wang@urmc.rochester.edu
authors.forename: Jianhua
authors.initials: J
authors.lastname: Wang
authors.forename: Joseph
authors.initials: J
authors.lastname: Thomas
authors.forename: Ian
authors.initials: I
authors.lastname: Cox
authors.forename: Andrew
authors.initials: A
authors.lastname: Rollins
mesh_terms: D000328:Adult; D003319:Corneal Stroma / Q000473:pathology*; D003941:Diagnostic Techniques, Ophthalmological; D019573:Epithelium, Corneal / Q000473:pathology*; D005260:Female; D006801:Humans; D020731:Keratomileusis, Laser In Situ; D008297:Male; D011184:Postoperative Period; D013524:Surgical Flaps / Q000473:pathology*; D041623:Tomography, Optical Coherence / Q000379:methods*