ISCEV extended protocol for the stimulus–response series for light-adapted full-field ERG

The International Society for Clinical Electrophysiology of Vision (ISCEV) standard for full-field electroretinography (ERG) describes a minimum protocol for clinical testing but encourages additional ERG testing when appropriate. This ISCEV extended protocol describes methods to record and evaluate a light-adapted (LA) ERG stimulus–response series with increasing flash strengths. The LA ERG stimulus–response series (also referred to as the luminance–response or intensity–response series in the published literature) can characterise generalised cone system function more comprehensively than the ISCEV standard LA ERGs alone. The amplitude of LA ERG a-waves, arising from cones and cone off-bipolar cells, typically shows a saturating function. The LA ERG b-wave amplitudes, which arise primarily from activity of retinal bipolar cells, show an amplitude peak followed by a nonzero plateau (the “photopic hill” phenomenon). This ISCEV extended protocol specifies a stimulus–response series suitable to evaluate generalised dysfunction affecting the LA retina, to aid in distinguishing between the on- and off-responses of the cone system and to monitor ERG changes in these characteristics. The LA ERG stimulus–response series for a- and b-waves is recorded to a sequence of nine flash stimuli ranging from 0.03 to 300 cd s m⁻², superimposed on a standard background of 30 cd m⁻². A shorter protocol is also presented to measure the mid-range of the function (the “photopic hill”) using 5 flash stimuli.