Electrophysiological examinations of vision play a very important role in the diagnosis of diseases of the retina, optic nerve, and visual pathways.

There are six exams that are practiced in this field, the Electro-oculogram (EOG), the standard Electro-retinogram (ERG), the Multifocal Electro-retinogram (MFERG), the Pattern Electro-retinogram (PERG), Visual Evoked Potential in Pattern (P-VEP) and in Flash (VED flash) and Potential Visual Acuity Measurement (PVEAV).

This set of combined tests help determine, at a given time, at what level between the retina and the brain (occipital cortex) is the damage or pathology of the visual system.

Electro-oculogram. EOG is an exam or diagnostic means that allows us to identify a mass response of the entire retina. It especially records the corneal-retinal resting potential with the cornea being positive. This potential seems to depend on the metabolic activity of the retinal pigment epithelium. For its registration, the patient must follow from one side to the other, two fixation lights, separated by 30 degrees of arc.