title: Spectral-domain optical coherence tomography epithelial and flap thickness mapping in femtosecond laser-assisted in situ keratomileusis.
abstract: OBJECTIVE
  To evaluate the change of epithelial and flap thickness after femtosecond laser-assisted in situ keratomileusis (LASIK) using spectral-domain optical coherence tomography (SD OCT) in correlation with the spherical equivalent refraction treated and clinical outcomes.
  
  
  METHODS
  Prospective, randomized, contralateral-eye study.
  
  
  METHODS
  Forty myopic eyes underwent LASIK using an excimer laser with refraction ranging from -1.00 to -7.25 diopters (mean -3.25±1.9). Flap creation was randomized between eyes, using the IntraLASE FS60 laser (IL) in 1 eye and WaveLight FS200 laser (FS) in the contralateral eye. SD OCT was used to evaluate the epithelial and flap thickness profiles and corneal power preoperatively and at 1 week and 1, 3, and 9 months postoperatively. Manifest and wavefront refractions were performed at each postoperative visit.
  
  
  RESULTS
  Statistically significant epithelial thickening was observed in both IL and FS groups as early as 1 month postoperatively (P=.033 and P=.042), but this stabilized between 3 (P=.042 and P=.035) and 9 months (P=.043 and P=.041). Femtosecond-LASIK flaps were thicker in the IL group in comparison to the FS group at 3 and 9 months postoperatively (P=.003 and P=.005, respectively). There was a statistically significant correlation between the magnitude of preoperative myopic refraction and the central epithelial thickness at 1, 3, and 9 months (Pearson correlation coefficients 0.485, 0.587 and 0.576) (P=.0021, P=.0010, and P=.0011), respectively. SD OCT corneal power maps showed steepening at 3 and 9 months along with mild myopic shift.
  
  
  CONCLUSIONS
  Progressive epithelial and flap thickening with increased corneal power were observed after femtosecond laser-assisted in situ keratomileusis for myopia with consequent stabilization between 3 to 9 months postoperatively. The magnitude of epithelial and flap thickness remodeling correlated to the preoperative myopic refractive error.
authors.affiliation: Cleveland Clinic Foundation - Cole Eye Institute, Cleveland, Ohio. Electronic address: karolinnemaia@gmail.com.
authors.forename: Karolinne Maia
authors.initials: KM
authors.lastname: Rocha
authors.affiliation: Cleveland Clinic Foundation - Cole Eye Institute, Cleveland, Ohio.
authors.forename: Ronald R
authors.initials: RR
authors.lastname: Krueger
mesh_terms: D000328:Adult; D003315:Cornea / Q000473:pathology* / Q000601:surgery; D005260:Female; D005500:Follow-Up Studies; D006801:Humans; D020731:Keratomileusis, Laser In Situ / Q000379:methods*; D008297:Male; D009216:Myopia / Q000473:pathology / Q000503:physiopathology / Q000601:surgery*; D011446:Prospective Studies; D012029:Refraction, Ocular; D015203:Reproducibility of Results; D013524:Surgical Flaps / Q000473:pathology*; D041623:Tomography, Optical Coherence / Q000379:methods*; D016896:Treatment Outcome; D014792:Visual Acuity; D055815:Young Adult