Use of Electrophysiology in the Diagnosis of Optic Nerve Disorders

Visual electrodiagnostic tests are non invasive, easily applicable that enable objective evaluation of the functions of the visual pathways. The most preferred among these test are; electroretinography (ERG), pattern electroretinography (PERG), electrooculography (EOG) and visual evoked potential (VEP). ERG is used to evaluate retinal functions especially rod and cone responses. PERG is used to evaluate functions of macular and retinal ganglion cells. EOG is used to evaluate retinal pigment epithelium functions. VEP is preferred method for evaluating the visual pathways up to the optic nerve and occipital cortex as a whole. Photopic negative response (PhNR) is originates from the electrical activity of amacrine and glial cells and also mostly retinal ganglion cells. In this study, VEP, PERG and PhNR tests which are the most preferred in the diagnosis of optic nerve disorders, will be mainly mentioned.