The effect of digital lowpass filters on the maximum velocity of saccadic eye movements.

The present paper is a study of how the inaccuracy of coefficients of digital lowpass filters may distort the maximum angular velocities of saccadic eye movements. Maximum velocity is one of the most important parameters of saccades. There are several diseases which decrease the maximum velocities of saccades. It was investigated how a fourth order Butterworth lowpass filter can affect maximum velocities. The lowpass filter has been tested by simulation as well as real eye movement data recorded electro-oculographically and photoelectrically. The coefficients of digital lowpass filters should be computed and applied with sufficient accuracy to prevent filters from altering the maximum velocities a phenomenon which might lead to erroneous diagnosis.