The Electro-oculogram (EOG)

This test examines the function of the retinal pigment epithelial cells (RPE). When this layer is healthy a standing potential is established between the front and the back of the eye that responds to change in background illumination. The standing potential can be measured by measuring the voltage induced across a pair of electrodes put around the eye as the eye looks from side to side. The test is most useful for a hereditary retinal degeneration called Best’s disease.