Impact of regional retinal responses on cortical visually evoked responses: Multifocal ERGs and VEPs in the retinitis pigmentosa model

Objective: To determine the impact of the regional retinal responses on cortical visually evoked responses, by evaluating the relationship between multifocal ERG (mfERG) and multifocal VEP (mfVEP), in the retinitis pigmentosa (RP) model. Methods: MfERGs and mfVEPs were recorded from 20 typical RP patients. Response amplitude density (RAD, nV/deg²) and implicit time (ms) of the mfERG 1st order binary kernel (N1-P1) and mfVEP 2nd order binary kernel (P1) components were measured. Ring analysis, matched for mfERG and mfVEP stimuli, was performed between fovea and mid-periphery (0-2.5, 2.5-5, 5-10, 10-15 and 15-20 deg). Results: At central and pericentral retinal regions (four eccentricities between 0 and 15 deg), mfERG N1 RADs were positively correlated (r ≥ 0.68, p <0.01) with corresponding mfVEP P1 RADs. Similarly, mfERG P1 implicit times were positively correlated (r ≥ 0.65, p <0.01) with corresponding mfVEP N1 implicit times. Conclusions: There are quantitative correlations between mfERG and mfVEP components in RP. Significance: The data suggest that regional responses of the photoreceptors and off-bipolar cells, the main generators of mfERG N1, have a major impact on the corresponding cortical activity.