Eye-movements deficits in schizophrenia: A metanalysis of evidence

INTRODUCTION: Although eye-movement disorders are one of the most replicated deficits in the psychiatric literature, the strong heterogeneity of results is still an unexplained issue that could be effectively addressed with a quantitative review of evidence. OBJECTIVES: For this reason, a large-scale metanalytic study comprising more than 200 studies was conducted to analyse the presence of eye-movement deficits in schizophrenia patients, as compared to healthy controls. METHODS: To this aim, saccadic eye movements were grouped based on the type of task required (e.g., standard, predictive) and the quantification method used (e.g., number, duration, amplitude). For each sub-group separate meta-analysis were computed. Cohen’s d was used as measure of effect size. Risk of bias within and between studies and heterogeneity were also analysed. RESULTS: indicated low Cohen’s d with the exception of the number of correct antisaccades – where schizophrenia patients reportedless correct anti-saccadesthan healthy controls - and antisaccades error rate – where schizophrenia patients reported a higher number of errors than healthy controls. CONCLUSIONS: Antisaccades emerged as better suited to differentiate between patients and healthy controls, thus making them the most promising candidate as a possible biomarker for schizophrenia.