Normal values of retinal response densities in multifocal electroretinogram

Multifocal electroretinograms (ERG) were recorded from 21 normal eyes to investigate the spatial distribution and inter-individual variation of local cone responses. To compensate for the effect of refractive lenses, test distances were adjusted to obtain a constant magnification on the retina. Significant nasal-temporal asymmetry was observed near the fovea with higher response densities in the temporal retina along the horizontal meridian. No significant supero-inferior asymmetry was observed along the vertical meridian. The average coefficient variation (standard deviation/average) of retinal response density for all areas was 0.35. In the clinical application of the multifocal ERG these results must be taken into consideration.