Electro-Oculogram (EOG) Tests
The Electro-Oculogram (EOG) provides a measure of retinal function that depends upon the integrity of the retinal pigment epithelial layer. When this layer is healthy, a standing potential is established between the front and the back of the eye that responds to changes in background illumination. The standing potential in the eye is estimated by measuring the voltage induced across a pair of electrodes as the eye looks from side to side. This potential declines during dark adaptation to a minimum value and rises during light adaptation to a maximum value before returning to a steady equilibrium value. The ratio of the maximum amplitude under light adapted conditions divided by the minimum amplitude under dark adapted conditions is called the Arden ratio. The Arden ratio is the standard diagnostic measure of the EOG.
Fast-Oscillation (FO) EOG
In FO, a minimum of six light/dark cycles are used. Each light or dark period lasts between 60 and 80 seconds and the rest period associated with standard EOG is eliminated to avoid missing peaks.
An effort is being made to standardize FO protocols for corollary purposes. Initial testing suggests that FO is an equally reliable measure to standard EOG.
- Best’s Disease
- Inherited Retinal Disorders
- Stationary Night Blindness
- Pigment Epithelial Dystrophies
- UTAS Visual Diagnostic System