[Indications for electrophysiologic studies of the eye]

The phenomena of light-evoked electrical activity of the retinal pigment epithelium, retina, and visual cortex can be used for specific diagnostic testing. The EOG, with standing potential and light peak, reflects the functional state of the pigment epithelium; the ERG reflects the function of the photoreceptors (a-wave) and inner nuclear layer (b-wave), and the visual evoked response (VER) provides information on signal conduction along the entire visual pathway. The indications for electroretinography are discussed in detail, resulting in a broad spectrum including degenerative, metabolic, inflammatory and toxic changes of the retina. In addition, a condensed table of diagnoses that can hardly be established without ERG is proposed. The value of ERG recordings is extended by the possibility to document rate of progression and relative involvement of the rod- and/or the cone system of the retina. VER procedures are mainly directed towards demyelinating diseases of the CNS. We attempt to interpret results of electrophysiologic testing synoptically with subjective complaints and clinical observations.