Cone properties of the light-adapted murine ERG

Purpose: Because the mouse lacks a typical Purkinje shift, we have examined its light-adapted ERG to determine whether there was other evidence in addition to tolerance to background light, that could be used to identify cone function in the ERG. Methods: Full field comeal ERGs to white flashes, double flashes and flash trains were examined in the presence of a strong full field light adaptation and compared with the human cone ERG. Results: The following cone-like properties could be identified. (1)The light-adapted murine ERG increases in amplitude gradually during the first 10 minutes of light-adaptation (2) It is capable of responding to a 50 Hz stimulus, although its overall frequency response is slower than that of the human cone ERG; (3) A corneal positive d-wave occurs to the termination of a Bash train; (4) The response increases linearly with light intensity. Conclusion: The light adapted murine ERG has several properties of cones but it has a slower response than the human cone ERG.