Fig. 6. Human electroretinographic recordings under dark-adapted scotopic conditions and light-adapted photopic conditions from a 43-cd/m2 background light. The scotopic flash is dim and elicits only a small a-wave, with a larger b-wave following it. The waveforms are similar for the short, 10-microsecond and for the long, 200-millisecond stimuli in the scotopic condition; only a small inflection occurs at the termination of the long stimulus. For the 10-microsecond flash, photopic condition, the a-wave and b-wave are found. With the 150-millisecond stimulus, however, both the b-wave at stimulus appearance and the d-wave at stimulus termination are present. The number at the ends of each trace gives trace duration in milliseconds.