Spectral characteristics of electroretinography in congenital red-green color blindness.

There are few conclusive electroretinography (ERG) studies comparing the spectral characteristics in deutans and normals in contrast to protans and normals. The difficulties of research on deutans were thought to be due to problems in detecting the very slight differences in the spectral characteristics between deutans and normal subjects. To record monochromatic ERG responses accurately in deutans, our time-locked scanning method was improved as follows: We used 12 interference filters for stimulus lights with narrow half widths (4-6 nm) and wavelengths of peak transmission arranged at intervals of 10 nm between 520 nm and 600 nm. Each stimulus light was strictly adjusted to an equal energy and checked simultaneously with ERG recordings. Contact lens electrodes were reformed for comfortable fitting to subjects' corneas. The time interval between each stimulation was set at 300 msec and one scanning of all stimulations took only 3.9 sec. ERG bp-waves were recorded in congenital color blindness by scanning monochromatic light stimuli, and spectral responses obtained could be evaluated as a spectral pattern. Different spectral patterns of responses from those of normal subjects and shift of the peak in the spectral response curves were obtained for congenital color blind subjects. The maximal responses were recorded at around 540 nm in protans and at 570-580 nm in deutans under white adaptation. Differences in the response curves were not found between dichromats and anomalous trichromats. Moreover, selective chromatic adaptation disclosed the separate responses of green cone and red cone systems. In normal subjects the peak of the spectral response curves was shifted to around 540 nm by red adaptation and to around 580 nm by blue adaptation. The spectral patterns changed so that they looked like the patterns under white adaptation of protans and deutans, respectively. But in protans and deutans the same spectral response patterns and almost the same wavelengths of the peak in the spectral response curves as those obtained under white adaptation were recorded under chromatic adaptation. This method provides the possibility of differentiating between red and green color blind subjects and normal subjects by the ERG. Defects or marked abnormality in the red cone system in protans and the green cone system in deutans can also be detected. Monochromatic ERGs of deutans were recorded under more intense red adaptation.(ABSTRACT TRUNCATED AT 400 WORDS)