QUANTIFYING CORNEAL TORICITY FROM VIDEOKERATOGRAPHY WITH FOURIER-ANALYSIS

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. R epeatability of Fourier-derived toricity values between sessions was e xamined, 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 dete cting longitudinal toricity change in normal corneas.