Progressive supranuclear palsy: the relationship between ocular motor dysfunction and psychological test performance.

The performance of patients with progressive supranuclear palsy on visual search and scanning tasks was related to the pattern of ocular deficits observed in these patients during horizontal refixation. Comparisons were made to age-matched normals and patients with Parkinson disease or cerebellar damage. The poor performance of the progressive supranuclear palsy group on visual search and scanning could not be attributed to the restricted range of vertical gaze or the large number of hypometric saccades during horizontal refixation. Instead, we believe that their impaired scanning resulted from the presence of square-wave jerks during attempted fixation.