Impaired saccadic eye movements on stationary targets in patients with schizophrenia spectrum disorder

Abstract

This study examined tracking eye movements on predetermined stationary targets in patients with schizophrenia spectrum disorder. The targets were 8 black points or 8 arabic-numbered points placed on the circumference of a circle. Self-paced eye movements during clockwise tracking of these points by 23 patients and 23 normal controls were recorded using an infrared eye-mark recorder. Eye movements were analyzed at two settings: firstly, when "fixation point" was defined as a point at which a gaze was held for at least 200-ms; and secondly, when held for at least 100-ms. The results indicated that at the 200-ms setting schizophrenic patients track with significantly fewer correct scores and more deviant scores than controls under black-point conditions. At the 100-ms setting, however, the correct scores of patients were not significantly different from those of controls, although patients displayed more aberrant paths than controls. The superfluous fixations in the patients improved significantly under numbered-point conditions, but patients still achieved lower correct scores than controls. Four of the 23 patients exhibited centering (aberrant path directed toward the center point), suggesting immature control of eye movements under black-point conditions, but not numbered-point conditions. These results suggest that some schizophrenic patients viewed the targets too quickly, and that they have impaired directed attention, which can be improved by cues, and may have impaired preprogramming of eye movements, which is not improved by external cues.

Exploratory eye movements in schizophrenia

“…Therefore, the present result may provide additional evidence for impaired neurocognitive function in schizophrenia. Consistent with this, Matsui et al (1995Matsui et al ( , 1997. reported that patients with schizophrenia showed more deviant scan paths than normal controls, and that some patients accurately tracked target points at the100-ms setting but not at the 200-ms setting.…”

“…In most previous studies on exploratory eye movement, a fixation point has been defined as a point at which a gaze is held for longer than 200 ms. However, Matsui et al (1995Matsui et al ( , 1997. found that some schizophrenic patients viewed the targets in a shorter period during saccadic tracking task.…”