The International Society for Clinical Electrophysiology of Vision (ISCEV) Standard for full-field electroretinography (ERG) describes a minimum procedure, but encourages more extensive testing. This ISCEV extended protocol describes an extension to the ERG Standard, namely the photopic negative response (PhNR) of the light-adapted flash ERG, as a well-established technique that is broadly accepted by experts in the field. The PhNR is a slow negative-going wave after the b-wave that provides information about the function of retinal ganglion cells and their axons. The PhNR can be reduced in disorders that affect the innermost retina, including glaucoma and other forms of optic neuropathy. This document, based on existing literature, provides a protocol for recording and analyzing the PhNR in response to a brief flash. The protocol includes full-field stimulation, a frequency bandwidth of the recording in which the lower limit does not exceed 0.3 Hz, and a spectrally narrowband stimulus, specifically, a red flash on a rod saturating blue background. Suggested flash strengths cover a range up to and including the minimum required to elicit a maximum amplitude PhNR. This extended protocol for recording the PhNR provides a simple test of generalized retinal ganglion cell function that could be added to standard ERG testing.

In eyes with suspect glaucoma, important decrease in PhNR amplitude is associated with small changes in peripapillary retinal and macular NFL thicknesses. These findings suggest that PhNR may be a useful and sensitive test in eyes with diagnostic dilemma, although further follow-up of such eyes is required for definitive confirmation.

The International Society for Clinical Electrophysiology of Vision (ISCEV) standard for full-field electroretinography (ERG) describes a minimum procedure, but encourages more extensive testing. This ISCEV extended protocol describes an extension to the ERG standard, namely the photopic On–Off ERG, and outlines common clinical applications. A light stimulus duration of 150–200 ms is used in the presence of a rod-suppressing background to elicit cone-driven On- and Off-system ERG components. The On-response occurs after the stimulus onset and has a negative a-wave and positive b-wave. The Off d-wave is a positive component evoked by stimulus offset. Common diagnoses that may benefit from additional photopic On–Off ERG testing include retinal dystrophies and retinal disorders that cause dysfunction at a level that is post-phototransduction or post-receptoral. On–Off ERGs assess the relative involvement of On- and Off-systems and may be of use in the diagnosis of disorders such as complete and incomplete congenital stationary night blindness (complete and incomplete CSNB), melanoma-associated retinopathy, and some forms of autoimmune retinopathy. The photopic On–Off ERGs may also be useful in X-linked retinoschisis, Batten disease, Duchenne muscular dystrophy, spinocerebellar degeneration, quinine toxicity, and other retinal disorders.

The aim was to investigate the effects of monochromatic and broadband stimuli on the amplitude of the photopic negative response (PhNR) and to compare the sensitivities of these stimuli for the detection of ganglion cell damage in glaucoma patients. Forty-one healthy subjects were studied, along with 16 patients with open-angle glaucoma. Photopic electroretinograms (ERGs) were elicited with monochromatic red, amber, green, and broadband white stimuli of progressively brighter intensities in a blue background. Pattern ERGs were also recorded using a 0.8 degrees checkerboard pattern on a 21.6 degrees x 27.8 degrees screen. In the photopic ERGs of the control subjects, the PhNR amplitude was significantly higher (P < 0.01) to red than to monochromatic amber, green, and broadband white stimuli of the same intensity. In glaucoma patients, the percentage of amplitude reduction was greater for the PhNR to red (68%, P < 0.001) than to the broadband stimulus (38%, P = 0.001). The PhNR to red monochromatic stimulus appeared to be a more sensitive parameter, with a larger area enclosed by the receiver-operating characteristic curve (0.97) than for the PhNR to broadband stimulus (0.76). Also, the PhNR to red stimulus showed a more significant correlation with the pattern ERG and the visual field defects (P < 0.05) than the PhNR elicited with broadband stimulus. These findings suggest that ganglion cell activity can be more efficiently evaluated with the PhNR elicited with a red than with a broadband stimulus. The PhNR thus appears to be a promising test for the diagnostics of the ganglion cell dysfunction.

The aim of this study was to explore the effect of stimulus duration, stimulus intensity, stimulus wavelength and background luminance on the amplitude and waveform of the ON- (b-wave) and OFF- (d-wave) response of the photopic ERG. The following parameters were used in this study: stimulus duration from 5 to 200 ms, the flash intensities from 0.4 to 2.1 log cd s/m2, the background luminance from 20 to 50 cd/m2 and stimulus wavelengths 460, 508 and 667 nm. Prolonging the stimulus duration from 75 to 200 ms did not influence the amplitudes of a-, b- and d-waves significantly. Higher stimulus intensities (1.9 log cd s/m2) broadened the b-wave and increased variability of its implicit time. With a brighter background (50 cd/m2) the b-wave did not broaden and its optimal amplitude was preserved. Stimuli of longer wavelengths (667 nm) significantly reduced the d-wave amplitude. Our results suggest that high intensities and longer wavelengths (red) may not be suitable stimulus parameters in the routine clinical ON- and OFF-response recording.