title: Quantifying corneal toricity from videokeratography with Fourier analysis.
abstract: BACKGROUND
  Fourier analysis can be used to quantify corneal toricity from videokeratography data. This study measures the repeatability of Fourier-derived toricity values in normal adult corneas.
  
  
  METHODS
  The Topographic Modeling System (TMS) was used to model the corneas of 29 subjects on two occasions, and Fourier analysis applied to the data. Repeatability of Fourier-derived toricity values between sessions was examined, and 95% limits of agreement were established.
  
  
  RESULTS
  The 95% limits of agreement between sessions for the Fourier method were -0.02 +/- 0.16 diopters (D) and -0.5 +/- 5.7 degrees for toricity amount and axis, respectively.
  
  
  CONCLUSIONS
  The Fourier method yields highly repeatable toricity values and thus provides a sensitive means of detecting longitudinal toricity change in normal corneas.
authors.affiliation: School of Optometry, University of California, Berkeley 94720-2020, USA.
authors.forename: N E
authors.initials: NE
authors.lastname: Friedman
authors.forename: K
authors.initials: K
authors.lastname: Zadnik
authors.forename: D O
authors.initials: DO
authors.lastname: Mutti
authors.forename: R E
authors.initials: RE
authors.lastname: Fusaro
mesh_terms: D000328:Adult; D003315:Cornea / Q000033:anatomy & histology*; D005583:Fourier Analysis; D006801:Humans; D009885:Ophthalmology / Q000379:methods*; D012016:Reference Values; D015203:Reproducibility of Results; D013690:Television