Smooth pursuit impairment in schizophrenia--what does it mean?

The significance and nature of smooth pursuit impairments in schizophrenia are considered. Studies of potential artifacts show that the phenomenon is not due to medications, age, inattention, or poor motivation. Abnormal pursuit eye movements in schizophrenics consist of intrusive saccades which are present during any visually guided slow eye movements, and in some patients are related to nonvoluntary attention. These results rule out a generalized motor or oculumotor dysfunction, as well as a specific pursuit system dysfunction. The findings are consistent with a cortical dysfunction which results in saccadic disinhibition. Questions are raised for future research.