The integrated optokinetic nystagmus inter-saccadic interval scales statistical different in a group of vertigo patients depended on the stimulation velocity, but not for healthy subjects

Optokinetic nystagmus is rhythmic eye movements, back and forth, with a slow and fast phase, when the eyes are presented for full-field visual stimulus. OKN was recorded in 10 healthy subjects and 10 patients suffering from vertigo, for four conditions: stripes moving 30 o/s left and right and 60 o/s left and right.
The aim of the present study was to analyze if the optokinetic stimulation intensity, stripes moving with angular velocity of 30 and 60 o/s, below and above the normal threshold for smooth pursuit function, influences the scaling properties of the integrated optokinetic nystagmus inter-saccadic intervals in a group of patients suffering from vertigo and a group of healthy subjects.
Calculating the scaling, the spread over time, for the integrated optokinetic nystagmus inter-saccadic intervals, the time intervals between the onsets of consecutive fast components, shows lower Hurst exponent for velocity stimulation of 30o/s compared to 60o/s for both patients and health subjects, but only reach statistical significance for the group of patients. This result is a novel finding.