Table 1.

Main points

The photopic negative response (PhNR) of the cone-driven ERG is a slow negative wave that follows the b-wave and originates from the innermost layers of the retina

The PhNR is an objective measure of retinal ganglion cells (RGCs) functional status and sensitive to glaucomatous alterations

A monochromatic red stimulus on blue background (R/B) results more effective in isolating the PhNR

The PhNR test does not require refractive correction, meticulous fixation monitoring or ocular media transparency

A reduced PhNR may play a potential role in early glaucoma detection, risk stratification and disease progression monitoring, especially when visual field testing and/or OCT measurement are inconclusive, not reliable, or difficult to perform