Analysis of smooth pursuit by the fast Fourier transform.

Eye movement during smooth pursuit examination was converted to digital values and analyzed by the fast Fourier transform (FFT). It was found that the power spectra differences between the eye and target movements at 0.3 Hz were significantly lower in the pathological pursuit patterns (saccadic and ataxic pursuit patterns). In addition, sums of the power spectra difference above 0.3 Hz were significantly greater in pathological pursuit patterns.