Ocular motor responses to unpredictable and predictable smooth pursuit stimuli among patients with obsessive-compulsive disorder.

This study was conducted to evaluate the smooth pursuit system functioning of patients with obsessive-compulsive disorder (OCD). For Study 1, 12 subjects with OCD and 12 nonpsychiatric subjects were administered 9-deg-per-sec ramp stimuli to elicit smooth pursuit eye movements. Consistent with a previous report, patients with OCD did not significantly differ from nonpsychiatric subjects on pursuit gain, or frequency of corrective and intrusive saccades. Patients with OCD, however, had smaller catch-up saccades during smooth pursuit than nonpsychiatric subjects. For Study 2, 12 subjects with OCD and 12 nonpsychiatric subjects were administered 2 different triangle wave stimuli with target velocities of 12 (0.2 Hz) deg per sec and 24 (0.4 Hz) deg per sec. Subjects with OCD and nonpsychiatric subjects did not significantly differ on any variable in the slow target velocity condition. When following 24-deg-per-sec targets, however, patients with OCD had significantly lower pursuit gain than the nonpsychiatric subjects. Results from Study 1 and 2 are consistent with the hypothesis that patients with OCD have a modest smooth pursuit deficit that is elicited only while following faster velocity targets.