A method for computer analysis of the skipping eye tracking test was developed as a functional test of saccadic eye movement. The saccadic visual stimuli were applied by seven small lamps horizontally placed at the same interval with eight degrees of visual amplitude and turned on in a stepwise jump manner with the period of 0.04, 0.06 and 0.1Hz. Recording eye movement was made with DC or AC (time constant with 3.0sec) and was stored on magnetic tape (TEAC R-410).
In normal subjects, DC-ENG recordings of eye movements following the stepwise skipping visual stimuli showed regularly stepwise saccadic patterns corresponding with the visual stimuli. However, pathological patterns of the stepwise saccadic eye movements showed irregular and/or delayed patterns. These pathological patterns have been interpreted by visual intuitive reading from the ENG recordings in the conventional way. Therefore, to evaluate the patterns of saccadic eye movements quantitatively, we measured the amplitude, duration, and velocity of saccadic eye movements, and the period during fixation at the luminous lamp. The normal limits of these measurements calculated from six normal subjects were statistically evaluated by means of a small general purpose digital computer (PDP 11/40). Thus, it can be seen from our measurements that the normal variations of saccadic eye movements obtained from our skipping eye tracking tests have a tendency to decrease with the shorter period of the stepwise skipping target movements. After these normal observations, we would like to recommend that the skipping eye tracking test with a period of 0.1Hz is most appropriate for clinical observations.
Moreover, from our normal observations, we reconfirmed certain predictive control of saccadic eye movements in our saccadic eye movement tests, which was applied in the same amplitude, stepwise manner, with the same interval of saccadic jump.
