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 corneal 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 flash 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.