Retinal dysfunctions in schizophrenia.

The purpose of this study was to investigate the earliest stages of visual information processing using electroretinography (ERG) in patients with schizophrenia and bipolar disorder and to compare these values with those of healthy control volunteers. In the acute stage of the illness, patients with schizophrenia exhibited decreased a-wave amplitude (a measure of photoreceptor function) as compared with healthy controls. In patients with bipolar disorder, ERG measures were intact. At the baseline assessment, there was a significant negative relationship between a-wave amplitude and positive symptoms. After an 8-week follow-up period, clinical symptoms showed significant improvement and the amplitude of the a-wave significantly increased in patients with schizophrenia. At the follow-up assessment, there was no significant difference between patients with schizophrenia and controls. These results indicate that retinal dysfunctions are specific for schizophrenia, as compared with bipolar disorder, and are confined to the acute stage of the illness.