Photopic Negative Response (PhNR) in Normal Subjects

ABSTRACT

PURPOSE: To evaluate the nature of photopic negative response (PhNR) in normal subjects. METHODS: The electroretinogram (ERG) waves were recorded in 52 eyes of 26 normal subjects with UTAS E-3000(R) (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. RESULTS: 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. CONCLUSIONS: 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.