Electrodiagnosis of red-green colour deficiency.

The electroretinographic rapid off-response and the early receptor potential were studied in congenital red-green colour deficiency. The sensitivity of the rapid off-response was low in protans and high in deutans at long wavelengths, and high in protans and low in deutans at short or medium wavelengths, as compared with normal subjects. The ratio of the sensitivity at 480 nm to the sensitivity at 620 nm (S480/S620) was higher in all cases of protans and lower in all cases of deutans so far tested than in normal subjects. The amplitude of the rapid off-response to white stimulus light did not differ among normals, protans and deutans. The S480/S620 was abnormal in some protan-carriers, deutan-carriers and Farbenamblyopie. The mean amplitude of the early receptor potential (R2) was small in protans at long wavelengths, and small in deutans at short or medium wavelengths. A significant correlation was found between the amplitude ratio of the R2 and the sensitivity ratio of the rapid off-response at short and long wavelengths.