The recorded signal is shaped mainly by light-evoked activity in retinal ON-bipolar cells and Müller glia. These cells generate currents that contribute to the positive field potential detected at the cornea after stimulation. Consequently, a reduced measurement can indicate impaired function in inner-retinal pathways rather than simply reflecting a change in the photoreceptor response.
B-wave amplitude changes with both the strength of the light stimulus and the retina’s adaptation state. These variables alter the light-evoked response before it reaches the recording electrode, so measurements made under different conditions may not be directly comparable. Standardizing stimulus and adaptation conditions is therefore essential when assessing changes over time or between individuals.
Recording conditions can affect the size of the field potential obtained at the cornea, independently of the underlying retinal disorder. A small value should therefore be interpreted in relation to the protocol used, including stimulus and adaptation conditions. Consistent recording conditions improve the reliability of comparisons and help distinguish biological change from measurement-related variation.
Evaluation begins by exposing the retina to a defined light stimulus and recording the resulting ERG at the cornea. The positive response is then quantified as an amplitude, with the measurement interpreted under the relevant adaptation and recording conditions. Using a standardized ERG protocol allows the result to be compared across examinations, participants, or experimental groups.
Standardized comparisons make it possible to identify consistently reduced responses and to follow their behavior across repeated examinations. This supports assessment of inner-retinal dysfunction while limiting the influence of differing stimulus or recording conditions. In clinical and research settings, such comparisons can contribute to diagnosis, disease monitoring, and evaluation of retinal therapies.
Reduced amplitude may accompany retinal dystrophies, ischemia, or toxic injury, reflecting compromised inner-retinal function in those settings. The measurement is not used in isolation from the ERG protocol and clinical context. Instead, clinicians and researchers use standardized results to help characterize retinal disease, monitor progression or response, and assess effects of treatment.