on either side of the eyes. The potential arises due to the differences
in ionic activity at the apical end of the retinal pigment epithelium
(RPE) cells, where they abut the photoreceptors, and their basal
When the eyes moves a large difference in potential between
electrodes placed on the skin each side of the eyes can be recorded.
The standing potential measures around 6 milli-volts with positivity at
To acquire an Arden index a patient needs to acquire an Arden index
a patient needs to co-operate sufficiently to co-operate sufficiently to
make reproducible, eye movements towards reproducible, eye
movements towards 2 LEDs every 2 minutes during 2 LEDs every 2
minutes during a period of 10-15 minutes of dark period of 10-15
minutes of dark adaptation followed by 10-15 minutes light adaptation.
adaptation followed by 10-15 minutes light adaptation.
In normal subjects the dark trough and light rise each occur
approximately 8 minutes in either lighting condition.
Children around 5yrs and upwards should be able to complete the
investigation. The EOG is most often used to investigate
maculopathies in the paediatric clinic. For example in Best’s disease
the EOG is often markedly subnormal early on while ERG normal.