title: Epithelial, stromal, and total corneal thickness in keratoconus: three-dimensional display with artemis very-high frequency digital ultrasound.
abstract: OBJECTIVE
  To characterize the epithelial, stromal, and total corneal thickness profile in a population of eyes with keratoconus.
  
  
  METHODS
  Epithelial, stromal, and total corneal thickness profiles were measured in vivo by Artemis very high-frequency (VHF) digital ultrasound scanning (ArcScan) across the central 6- to 10-mm diameter of the cornea on 54 keratoconic eyes. Maps of the average, standard deviation, minimum, maximum, and range of epithelial, stromal, and total corneal thickness were plotted. The average location of the thinnest epithelium, stroma, and total cornea were found. The cross-sectional semi-meridional stromal and total corneal thickness profiles were calculated using annular averaging. The absolute stromal and total corneal thickness progressions relative to the thinnest point were calculated using annular averaging as well as for 8 semi-meridians individually.
  
  
  RESULTS
  The mean corneal vertex epithelial, stromal, and total corneal thicknesses were 45.7+/-5.9 microm, 426.4+/-38.5 microm, and 472.2+/-41.4 microm, respectively. The average epithelial thickness profile showed an epithelial doughnut pattern characterized by localized central thinning surrounded by an annulus of thick epithelium. The thinnest epithelium, stroma, and total cornea were displaced on average by 0.48+/-0.66 mm temporally and 0.32+/-0.67 mm inferiorly, 0.31+/-0.45 mm temporally and 0.54+/-0.37 mm inferiorly, and 0.31+/-0.43 mm temporally and 0.50+/-0.35 mm inferiorly, respectively, with reference to the corneal vertex. The increase in semi-meridional absolute stromal and total corneal thickness progressions was greatest inferiorly and lowest temporally.
  
  
  CONCLUSIONS
  Three-dimensional thickness mapping of the epithelial, stromal, and total corneal thickness profiles characterized thickness changes associated with keratoconus and may help in early diagnosis of keratoconus.
authors.affiliation: London Vision Clinic, London, United Kingdom. dzr@londonvisionclinic.com
authors.forename: Dan Z
authors.initials: DZ
authors.lastname: Reinstein
authors.forename: Marine
authors.initials: M
authors.lastname: Gobbe
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Archer
authors.forename: Ronald H
authors.initials: RH
authors.lastname: Silverman
authors.forename: D Jackson
authors.initials: DJ
authors.lastname: Coleman
mesh_terms: D000293:Adolescent; D000328:Adult; D000886:Anthropometry; D003315:Cornea / Q000000981:diagnostic imaging; D003319:Corneal Stroma / Q000000981:diagnostic imaging*; D019781:Corneal Topography; D019573:Epithelium, Corneal / Q000000981:diagnostic imaging*; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional; D007640:Keratoconus / Q000000981:diagnostic imaging*; D008297:Male; D012189:Retrospective Studies; D014463:Ultrasonography; D055815:Young Adult