Altered central vision and amacrine cells dysfunction as marker of hypodopaminergic activity in treated patients with schizophrenia

Background: Retinal dysfunction is widely documented in schizophrenia using flash (fERG) and pattern electroretinograms (PERG), but the role of dopamine transmission has seldom been explored. Methods: We explored the role of dopamine transmission by evaluating the spatial location of retinal anomalies using multifocal ERG (mfERG) in photopic condition and the oscillatory potentials (OPs) extracted from fERG measured in scotopic condition in 29 patients with schizophrenia and 29 healthy controls. Results: With the mfERG, our main results revealed reduced amplitudes in the center of the retina: P1 (p < .005) and N2 amplitudes (p < .01) in the <2 region, N1 (p < .0005) and P1 amplitudes (p < .001) in the 2-5 degrees region and P1 amplitude (p < .05) in the 5-10 region. For OPs, our results showed a decrease in the O1 (p < .005), O2 (p < .005), O3 (p < .05) and overall O1, O2, O3 index amplitudes (p < .005) in patients with schizophrenia. Conclusions: Both the central location of retinal dysfunctions of the mfERG and OPs results could reflect a hypodopaminergic effect in patients with schizophrenia. In future studies, OPs should be considered as a measure to evaluate the hypodopaminergy in patients.