Electroretinography records electrical responses generated by the retina when it is stimulated with light. In full-field electroretinography, diffuse flashes stimulate a broad retinal area, and an electrode at or near the eye records a potential difference relative to a recording reference. The trace is a summed response of retinal tissue, rather than a recording of one photoreceptor or a direct report of perceived brightness.[ref]
ISCEV Standard for full-field clinical electroretinography (2022 update) by Anthony G. Robson and others. Sections on full-field stimulation, recording electrodes and standard responses.
Dark-adapted and light-adapted recordings help distinguish response systems under controlled conditions. Standardization matters because flash strength, adaptation and electrode configuration change the trace. A simple experimental comparison uses the same flash and recording arrangement before and after an intervention: differences then become evidence about which retinal processes contribute, subject to the intervention's selectivity.[ref]
ISCEV Standard for full-field clinical electroretinography (2022 update) by Anthony G. Robson and others. Dark-adapted and light-adapted standard-response protocols.
The positive b-wave illustrates how component interpretation is tested. Richard A. Stockton and Malcolm M. Slaughter measured retinal field responses together with extracellular potassium changes in amphibian preparations. A drug that suppressed ON retinal bipolar cell responses also removed the b-wave; treatments suppressing OFF-pathway responses removed the light-offset d-wave while preserving the b-wave. This supported a central role for ON retinal bipolar cell activity in generating the b-wave, rather than treating all deflections as direct rod voltages.[ref]
An independent example is the RPE65 knockout: disrupted visual cycle chemistry caused loss of normal rod responses on electroretinography, connecting pigment regeneration to a measurable tissue-level signal.[ref]
Rpe65 is necessary for production of 11-cis-vitamin A in the retinal visual cycle by T. M. Redmond and others. Rod electroretinographic phenotype and retained cone function.
The electroretinogram b-wave is a prominent positive-going component of many light-evoked electroretinography traces, associated strongly with the activity of ON retinal bipolar cells. It is an extracellular tissue-level signal, rather than the intracellular membrane potential of one photoreceptor or one bipolar cell. Its appearance and amplitude depend on the stimulus and recording conditions.[ref]
B-wave of the electroretinogram. A reflection of ON bipolar cell activity by Richard A. Stockton and Malcolm M. Slaughter. Abstract: intraretinal fields, pharmacological isolation and ON bipolar contribution.
The assignment was tested by perturbing retinal pathways. In amphibian preparations, APB suppressed ON bipolar responses and removed the b-wave; treatments suppressing OFF-related responses removed the light-offset d-wave while preserving the b-wave. Recording potassium changes along with field responses helped link the electrical component to a specific functional pathway.[ref]
B-wave of the electroretinogram. A reflection of ON bipolar cell activity by Richard A. Stockton and Malcolm M. Slaughter. Selective pharmacological comparisons and extracellular potassium measurements.
A later molecular perturbation supplied independent evidence. Mice lacking TRPM1 retained a normal rod a-wave but lacked the b-wave, while direct bipolar-cell recordings supported disruption of postsynaptic ON signaling. A signal from the early photoreceptor stage can therefore persist when the later response is lost.[ref]
For an illustrative trace, a preceding trough at and a positive peak at are separated by . That trough-to-peak difference differs from the peak's displacement above a zero baseline. Always state the amplitude convention; these invented values are not diagnostic limits or data from either study.
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