Quantitative analysis of oblique ocular movements.

In the present study, oblique saccadic eye movements in the orthogonal and oblique directions were investigated in 10 normal subjects, and a computer program was used to accomplish quantitative assessment of oblique eye movements. Eye movements were recorded with direct-current electronystagmography (DC-ENG) and a 12-bit analog to digital converter was used to collect analog data of horizontal and vertical eye position, and stimulus signals at a sampling rate of 200 Hz. The oblique eye movement was displayed two-dimentionally on a high-resolution color graphic terminal for the evaluation of the trace of eye movements, and the peak velocity and the amplitude of the horizontal, vertical and oblique saccades were calculated. It was frequently found that the tracing line in the oblique saccadic eye movement was not completely straight, but loosely curved. The velocity of the vertical component of the oblique saccade was much lower than that of the horizontal component. This suggests that oblique saccades might be made by synchronized but independent vertical and horizontal pulse generators, and the system developed this time might be very useful for investigation of oblique eye movements in both the clinical and physiological field.