In retinal assessments, what does the C wave of the ERG indicate?

The C wave of the electroretinogram (ERG) primarily reflects the activity of the retinal pigment epithelium (RPE) cells. The RPE plays a crucial role in supporting photoreceptors by facilitating the recycling of visual pigments, maintaining the blood-retinal barrier, and providing nutrients. The C wave is generated following the photoreceptor and bipolar cell responses, but it specifically represents the bioelectrical changes associated with the hyperpolarization of the outer segments of photoreceptors and the subsequent activity of the RPE after light exposure.

This wave occurs after the initial A and B waves, which are associated with the activity of photoreceptors and the inner retinal layers, respectively. Therefore, understanding that the C wave is a marker of RPE functionality is important in retinal assessments and helps in diagnosing conditions that may impair RPE function.