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. 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.