title: Stromal thickness in the normal cornea: three-dimensional display with artemis very high-frequency digital ultrasound.
abstract: OBJECTIVE
  To characterize the stromal thickness profile in a population of normal eyes.
  
  
  METHODS
  Stromal thickness profile was measured in vivo by Artemis very high-frequency digital ultrasound scanning (ArcScan, Morrison, Colo) across the central 10-mm corneal diameter on 110 normal eyes. Maps of the average, standard deviation, minimum, maximum, and range of stromal thickness were plotted. The average location of the thinnest stroma was found. The cross-sectional hemi-meridional stromal thickness profile was calculated using annular averaging. The absolute stromal thickness progression relative to the thinnest point was calculated using annular averaging as well as for 8 hemi-meridians individually.
  
  
  RESULTS
  The mean stromal thickness at the corneal vertex and at the thinnest point were 465.4+/-36.9 mum and 461.8+/-37.3 mum, respectively. The thinnest stroma was displaced on average 0.17+/-0.31 mm inferiorly and 0.33+/-0.40 mm temporally from the corneal vertex. The average absolute stromal thickness progression from the thinnest point could be described by the quadratic equation: stromal thickness = 6.411 x radius(2) + 2.444 x radius (R(2) = 0.999). Absolute stromal thickness progression was independent of stromal thickness at the thinnest point. The increase in hemi-meridional absolute stromal thickness progression was greatest superiorly and lowest temporally.
  
  
  CONCLUSIONS
  Three-dimensional thickness mapping of the corneal stroma and stromal thickness progression in a population of normal eyes represent a normative data set, which may help in early diagnosis of corneal abnormalities such as keratoconus and pellucid marginal degeneration. Absolute stromal thickness progression was found to be independent of stromal thickness.
authors.affiliation: London Vision Clinic, London, United Kingdom. dzr@londonvisionclinic.com
authors.forename: Dan Z
authors.initials: DZ
authors.lastname: Reinstein
authors.forename: Timothy J
authors.initials: TJ
authors.lastname: Archer
authors.forename: Marine
authors.initials: M
authors.lastname: Gobbe
authors.forename: Ronald H
authors.initials: RH
authors.lastname: Silverman
authors.forename: D Jackson
authors.initials: DJ
authors.lastname: Coleman
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001837:Body Weights and Measures; D003319:Corneal Stroma / Q000000981:diagnostic imaging*; D019781:Corneal Topography; D005260:Female; D006801:Humans; D021621:Imaging, Three-Dimensional / Q000295:instrumentation; D008297:Male; D008875:Middle Aged; D012029:Refraction, Ocular / Q000502:physiology; D012189:Retrospective Studies; D014463:Ultrasonography