Intensity of stimulation and rod and cone response in clinical electroretinography.

We exposed adult Rhesus monkeys who were fully dark adapted to paired flashes of white light which increased in intensity by increments of 0.1 log. units. As intensity increased, the amplitudes of both the cone and rod systems increased while the implicit times decreased so that the responses overlapped. High intensities produce a complex waveform which prevents separation of the rod and cone components or timing of the peaks. On the other hand, low intensities separate the early and late receptor potentials (L.R.P.) of cones and rods well and make it easy to time normal and pathological variations.