Recording of Horizontal Saccadic Eye Movements: Methodological Comparison Between Electro-Oculography and Infrared Reflection Oculography

Abstract

Simultaneous recordings with monocular direct current electro-oculography (EOG) and infrared reflection oculography (IROG) from the same eye were performed to investigate methodological differences. In six healthy volunteers 20 and 30 degree midline crossing horizontal saccades were recorded using different low bandpass filtering and two different temporal EOG electrode placements. Important dissimilarities with regard to peak velocity and saccade duration were found between the two recording techniques. The most striking difference was encountered in the abducting (temporal) saccades, where EOG measured significantly slower velocities and, in most instances, longer durations of the saccades. As a consequence, EOG usually measured faster adducting and IROG faster abducting saccades. This discrepancy was further demonstrated in two additional control groups of healthy individuals with the two methods used separately. The authors conclude that the IROG more faithfully reflects rapid eye movements within the linear range of this method (± 15 deg) and is therefore more appropriate for investigation of subtle disorders of saccades. Furthermore, IROG seemed more accurate for assessing saccade durations, because there are no muscular artefacts with this method.