title: Evaluation of corneal epithelial and stromal thickness in keratoconus using spectral-domain optical coherence tomography.
abstract: OBJECTIVE
  We sought to assess the corneal thickness of the epithelium and stroma in keratoconic and normal eyes by spectral-domain optical coherence tomography (SD-OCT).
  
  
  METHODS
  Fifty-seven keratoconic and 20 normal eyes were studied. The eyes were examined by SD-OCT, and the keratoconic eyes were subdivided into 2 groups: those showing only smooth corneal thinning and corneal protrusion on the image (KC1 group) and those showing abnormalities in the Bowman layer or in the stroma, or in both (KC2 group). The thicknesses at the corneal vertex and at the superior, inferior, nasal, and temporal cornea 1.5 mm from the corneal vertex in the KC1 group were compared with those in the normal group. The OCT findings in the KC2 group were described.
  
  
  RESULTS
  The epithelial thickness at the corneal vertex and at the inferior and temporal cornea, and the stromal thickness at all points were significantly thinner in the KC1 group than in the normal group (p < 0.05). The epithelial and stromal thicknesses at the corneal vertex were significantly correlated in the KC1 group and the normal group (r (2)  = 0.427, p < 0.0001).The epithelial thickness in the KC2 group was not uniform owing to Bowman layer scarring, stromal scars, and secondary corneal amyloidosis.
  
  
  CONCLUSIONS
  Although epithelial thinning is associated with stromal thinning, when the cornea remains clear, the epithelial thickness may vary because of the irregularity of the stroma beneath the epithelium in patients with keratoconus.
authors.affiliation: Department of Ophthalmology, Osaka University Graduate School of Medicine, Room E7, 2-2 Yamadaoka, Suita, Osaka, 565-0871, Japan, nmaeda@ophthal.med.osaka-u.ac.jp.
authors.forename: Naoyuki
authors.initials: N
authors.lastname: Maeda
authors.forename: Tomoya
authors.initials: T
authors.lastname: Nakagawa
authors.forename: Ritsuko
authors.initials: R
authors.lastname: Higashiura
authors.forename: Mutsumi
authors.initials: M
authors.lastname: Fuchihata
authors.forename: Shizuka
authors.initials: S
authors.lastname: Koh
authors.forename: Kohji
authors.initials: K
authors.lastname: Nishida
mesh_terms: D000328:Adult; D003319:Corneal Stroma / Q000473:pathology*; D003430:Cross-Sectional Studies; D019573:Epithelium, Corneal / Q000473:pathology*; D005260:Female; D006801:Humans; D007640:Keratoconus / Q000473:pathology*; D008297:Male; D008875:Middle Aged; D041623:Tomography, Optical Coherence; D055815:Young Adult