The review is a summary of structural and functional changes in the human retina observed in patients with schizophrenia. The main focus is on the potential of these changes to serve as schizophrenia-specific biomarkers accessible to clinicians. We identified three features of the retina that can be detected non-invasively in humans and which appear to show charateristic changes in schizophrenia: (1) retinal microvasculature displaying abnormally wide venules; (2) electroretinograms indicating altered function of photoreceptors or other cells in the retinal component of the visual pathway; (3) optical coherence tomography pointing to structural differences between the retinae of patients with schizophrenia and those of healthy volunteers. We propose that the most feasible approach to evaluating the data would be to study the genetic and epigenetic background of the schizophrenia-associated retinal abnormalities and establish their significance and specificity as potential biomarkers for the disease. The studies should include longitudinal observations focusing on the possible involvement of medication and comorbid conditions in the mechanism of the disease; a comparison of schizophrenia with other mental disorders; and investigating retinal abnormalities in animal models of psychoses. Biomarkers identified in the process could represent an important addition to the arsenal of non-invasive techniques available to both clinicians and researchers. These novel biomarkers could facilitate research of the biological basis of psychosis and help to address the diagnostic, predicitive, preventative, prophylactic and therapeutic aspects of schizophrenia.

Department of Ophthalmology Charles University Faculty of Medicine in Hradec Kralove and University Hospital Hradec Kralove Czech Republic

Department of Psychiatry Charles University Faculty of Medicine in Hradec Kralove and University Hospital Hradec Kralove Czech Republic

Institute of Animal Physiology and Genetics Academy of Sciences of the Czech Republic Brno Czech Republic

Laboratory of Neurobiology and Molecular Psychiatry Department of Biochemistry Faculty of Sciences Masaryk University Brno Czech Republic

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Early-stage visual perception impairment in schizophrenia, bottom-up and back again