Quantitative effects of typical and atypical neuroleptics on smooth pursuit eye tracking in schizophrenia.

Smooth pursuit eye movement (SPEM) gain, total saccades, and subtypes of saccades were quantified from the visual pursuit tracking of 26 fluphenazine-treated patients with schizophrenia and 42 normal controls. Tracking was repeated in 16 patients who underwent a placebo-controlled, double-blind crossover comparison of fluphenazine and clozapine. Fluphenazine-treated patients showed significant reduction in SPEM gain and significant increases in both total, intrusive, and anticipatory saccades and in saccadic amplitude, when compared to controls. Clozapine significantly reduced SPEM gain and significantly increased total and catch-up saccades, when compared to placebo or fluphenazine. High amplitude of intrusive saccades in drug-free patients predicted poor response to clozapine, suggesting that intact frontal cortical function may enable optimal clozapine response.