New applications and analyses of ERGs

Abstract

The electroretinogram (ERG) represents the summed electrical response of retinal neurons to light stimuli and allows direct non‐invasive assessment of human retinal function. Over recent decades there have been numerous developments in our understanding of the cellular basis of different ERG components as well as in techniques of recording and analysing the waveforms elicited by both standard and novel stimulus protocols. Portable devices are now available with automated stimulus adjustment according to pupil diameter, thus permitting non‐mydriatic recordings to be obtained rapidly in the outpatient clinic. Non‐standard stimulus protocols have been devised, for example to selectively isolate rod or cone‐driven contributions to dark‐adapted responses, or to track changes in rod and cone system sensitivity during retinal light and dark adaptation. New methods of analysis have been developed, including fitting of mathematical models to ERGs, application of machine‐learning techniques and interrogation of genetic associations with ERG parameters, the latter potentially shedding light on the effects of common genetic variants in the population. Many of these developments will be discussed, together with insights yielded into retinal physiology and pathophysiology (in both rare and common eye disease), concluding with a discussion of anticipated future investigations and applications in the field.