To evaluate the nature of photopic negative response (PhNR) in normal subjects.

The electroretinogram (ERG) waves were recorded in 52 eyes of 26 normal subjects with UTAS E-3000® (LKC Technologies Inc., Gaithersberg, MD, USA). Photopic cone response was obtained for analysis from a white flash with white background illumination (group 1) and a red flash with blue background illumination (group 2), after stimulations ranging from 0.007674 cd.s/m² (-25dB) to 7.736 cd.s/m² (5dB) with a 5dB interval.

PhNRs were observed in all 52 eyes in group 1 stimulated with the white flash at 0.9933 cd.s/m² (-4dB). PhNRs were also observed in all 52 eyes in group 2 at 2.4297 cd.s/m² (0dB) after stimulation with the red flash. There was correlation between the amplitudes of PhNR and intensity of stimuli ( p <0.001). Implicit times of PhNR were correlated with age in both groups, but amplitudes decreased with age in group 1.

The amplitudes of PhNR were correlated with intensity of stimuli and age had an influence on PhNR. Standardization of examination conditions is necessary when recording PhNR.