 Electroretinography

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]

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]

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]