The early receptor potential in the human eye. III. ERP in dichromats.

The human early receptor potential (ERP) was studied in 42 dichromats, 13 cases of protanopia and 29 cases of deuteranopia, and the results were compared with those in 28 normal subjects. The amplitudes of the R2 wave of the ERP in the protanopia as well as the deuteranopia cases were significantly smaller than that of the normal subjects. The sensitivity of the R2 wave of the ERP in the dichromats was higher than that of the normal subjects. Possibilities are discussed that dichromats have fewer cones or that they have lower pigment density in individual cones than normal subjects.