Oculomotor abnormalities and their clinical correlates in schizophrenia

Smooth pursuit eye movements (SPEMs) have been consistently found to be abnormal in the majority of schizophrenic patients. The traditional SPEM measurement technique, however, fails to inform us about the underlying oculomotor deficit in these patients, since it remains a non-specific and a global oculomotor measure. A number of diverse clinical features such as tardive dyskinesia (TD) or negative symptoms correlate with the SPEM abnormality. Other eye movement abnormalities such as fixation difficulties, increased "volitional" saccadic latency and saccadic distractibility in anti-saccade paradigm have also been noted in schizophrenic patients. Still, it remains unclear how these different eye movement measures relate with each other and with the traditional SPEM measure, the presence of which is so widely described in schizophrenia. The advantage of some newer oculomotor paradigms is their functional specificity and the degree to which their biology is known. To further address these issues and to search for clinical correlates of various eye movement abnormalities found in schizophrenia, we have developed a battery of oculomotor measures to be administered to a large number of clinically well described schizophrenic patients and normal controls. The results from a preliminary analysis of a relatively small number of subjects are presented here, thus limiting the scope of possible conclusions. But, these results do indicate that this technique of studying multiple paradigms for oculomotor control in schizophrenia may prove to be fruitful.