Electroretinography

Electroretinography measures the electrical responses of various cell of the retina, namely the Photoreceptors (Rods and Cones. A standard flash of light is emitted on to the retina and the resulting electrical pulse is measured using electrodes on the surface of the cornea or on the skin under the eye.

This method is used to determine an Electroretinogram (ERG): essentially the Spectral Sensitivity of the Retina. This ERG will have a number of peaks generally equal to the number of different Cone types in the Retina, and each peak will correspond to the Peak Sensitivity of one of the Opsins.

This is one method for determining the type of Color Vision (or deficiency thereof) of an individual. It is used on both humans and animals, though it can be more difficult than behavioral testing.