Velocities of vertical saccades with different eye movement recording methods

Voluntary vertical saccades were recorded in five normal human subjects with electro-oculography (EOG), an infrared, limbus tracking system (IR), and a magnetic scleral search coil method. The peak velocity-amplitude relationships of up and down saccades were measured during refixations across the center of the orbit and within the upper and lower fields of the orbit. The search coil was the most accurate method and did not reveal significant differences between the group mean velocities of up and down saccades in the different fields of the orbit. However, subjects can have idiosyncratic differences in velocities between up and down saccades. EOG overestimated the velocities of up saccades. IR underestimated the velocities of up saccades. The search coil was used to record vertical saccades in adduction and abduction. Horizontal eccentric gaze did not significantly affect the velocities of vertical saccades.