Computational problems in the analysis of eye movement signals in the determination of vestibulo-ocular reflex

The vestibule-ocular reflex preserves clear vision when the head is moving fast. Measurement of the vestibule-ocular reflex during the head autorotation test is usually calibrated using a dynamic technique in which the initial part of the eye movement signal and the corresponding part of the stimulating head movement signal are matched. Dynamic techniques can, however, be prone to generate excessively small or large calibration coefficients if a calibration segment of such a signal is corrupted by saccades or artifacts of large amplitudes. We have implemented an effective improvement for computation of difficult signals, not infrequent in clinical data, by limiting influence of distorting parts in the eye movement signal. We also discuss pitfalls of parameter accuracy concerning gain and phase parameters of the vestibule-ocular reflex that are used to differentiate abnormal results from the normal. Furthermore, we call the ubiquituous Fast Fourier Transform method into question with regard to these signals. (C) 1997 Academic Press.