T132. RETINAL GANGLION CELLS DYSFUNCTIONS IN SCHIZOPHRENIA PATIENTS

BACKGROUND: Structural and functional retinal anomalies are documented in neurologic, substance use and psychiatric disorders. In schizophrenia, flash electroretinogram (fERG) measures have revealed photoreceptors, bipolar cells and retinal ganglion cells (RGC) dysfunctions. To date, no study has explored RGC using a pattern electroretinogram (pERG) protocol as recommended by the International Society for Clinical Electrophysiology of Vision (ISCEV) standards for RGC measurements. We aim to study retinal functional responses of the photoreceptors and RGC in schizophrenia patients in comparison with healthy controls. METHODS: fERG conducted in scotopic (dark-adapted 0.01 and dark-adapted 3.0 ERG) and photopic conditions (light-adapted 3.0 ERG) and pERG were recorded in schizophrenia patients (n=29) and healthy controls (n=29). PERG provides the measurements of 2 waves: the P50 wave which arises in RGC with a contribution of bipolar cells and relates to the spatial distribution and density of the RGC bodies and the N95 wave which represents ganglion cell activity. RESULTS: fERG results showed a decrease in the b-wave amplitude (t(51)=-3.4, p<.05, d=0.63) (dark-adapted 0.01 ERG), a-wave amplitude (t(48)=4.7, p<.001, d =1.33) (dark-adapted 3.0 ERG), b-wave amplitude (t(48)=-2.8, p<.005, d=0.78) (dark-adapted 3.0 ERG), a-wave amplitude (t(52)=2.8, p<.001, d=0.29) (light-adapted 3.0 ERG) in schizophrenia patients compared to controls. We found as well a significant decrease of the a-wave implicit time (t(52)=-2.5, p<.05, d =1.19) (light-adapted 3.0 ERG) in schizophrenia patients compared to controls. pERG results showed a significant increase of the P50 (t(55)=2.1, p<.05, d=0.55) and a significant increase of the N95 implicit time in schizophrenia patients compared with controls (t(55)=4.2; p<.001, d=0.66). DISCUSSION: Our results replicate previous findings regarding photoreceptors and bipolar cells dysfunction in schizophrenia patients. pERG results demonstrate a delay in transmission of action potentials by the ganglion cells along the visual pathway via the optic nerve and the lateral geniculate nucleus to the visual cortex in schizophrenia patients which could support alterations in cerebral visual processing in schizophrenia.