Study of blue and red flash in dark-adapted electroretinogram.

PURPOSE To investigate the characteristics of the waveform generated by blue and red light stimulations in a dark-adapted electroretinogram (ERG) and those of cone responses in the dark-adapted condition. METHODS The study subjects were 52 persons (88 eyes) with no previous medical history. The author recorded b-waves (rod response) with red light stimulation and the x-waves (dark-adapted cone response) that appeared before the b-waves. The author also recorded b-waves with blue light stimulation, which had the same amplitude as the b-waves from the red light stimulation. The differences with respect to age and gender were studied. Waveforms of the dark-adapted cone ERGs were recorded by using a digital subtraction technique. RESULTS The x-wave always appeared before the b-wave with 0 dB (2.4 cd.s/m2) red stimulation. With blue stimulation, a b-wave equivalent to the b-wave stimulated with the red light of 0 dB intensity appeared at an average of -14.57 dB. The implicit time for the b-wave was delayed significantly for the male group. There were no significant differences between different age groups. The dark-adapted cone ERG demonstrated the waveform of a negative response followed by a series of oscillatory potentials (OPs) and a positive response. CONCLUSIONS The cone responses were followed by the rod responses with red light stimulation of 0 dB in the dark-adapted ERG. The waveforms of the cone ERGs were obtained in dark adaptation with red and blue light stimulation.