Saccadic intrusions into smooth pursuit in patients with schizophrenia or affective disorder and normal controls.

Two types of saccadic intrusions into smooth pursuit eye tracking, anticipatory saccades (AS), and square wave jerks (SWJ), were measured in 23 patients with schizophrenia, 16 patients with affective disorder, and 21 normal controls. Constant velocity (5 degrees and 20 degrees/sec) predictable targets were employed. High resolution infrared oculography was employed to record eye movements. Although most subjects had at least one SWJ, there were no significant group differences, and the highest individual rates of SWJ were seen in the normal control group. On the other hand, AS were never seen in normals, but were present in 25%-44% of patients with either schizophrenia or affective disorder. Both patient groups had significantly more AS than controls, but the two patient groups were not significantly different.