Optokinetic nystagmus: a comparative study of two stimulators.

The neural mechanisms for optokinetic nystagmus (OKN) may be clinically relevant to the two methods used to detect these abnormalities. If one subscribes to the cortical (macular) theory, visual fixation is always involved and results by conventional drum rotation or by pursuit of a moving light source ought to be the same. Conversely, if OKN can be the result of peripheral vision and subcortical pathways, results with the drum (which does not require macular vision) and moving light (which does) ought to be different. Both the drum and moving light methods were compared on a sample of 514 patients. Both methods compared equally in eliciting abnormal responses in patients with an established diagnosis and in correlation with calibration, gaze, and false positive responses. The drum was superior in the remainder of comparisons.