Distribution of quick-phase intervals in optokinetic nystagmus

The distribution of the intervals between quick phases in optokinetic nystagmus shows the same general characteristics as saccadic latency to visual targets and as congenital nystagmus. In each case, for intervals of 150 ms and above, the distribution of reciprocal latency is normal; at shorter intervals, there may be a second component equivalent to 'express' saccades.