[Recording rod ON and OFF responses in ERG and multifocal ERG].

PURPOSE

To investigate feasibility and recording conditions of recording rod on and off responses in electroretinograms (ERG) and multifocal electroretinograms (mf-ERG), and observe character and influence factors of these responses.

METHODS

ERG responses were recorded using the rectangle stimulus, sawtooth rapid-on and rapid-off stimulus in normal subjects after dark adaptation. Flash frequency and flash intensities varied to obtain appropriate recording conditions for clinical use. Mf-ERG responses were recorded in using simulated rectangle stimulus, saw tooth rapid-on and rapid-off stimulus.

RESULTS

A large positive wave was found in ERG of rectangle stimulus and rapid-on stimulus. Increasing flash frequency decreased response amplitudes, however, the latency time changed little. A small negative wave with 80 ms latency time was found in ERG of rapid-off stimulus, and a very small positive wave with 75 ms latency time was found in the downhill of the negative wave. Increasing flash frequency increased latency time of the negative wave, but decreased the amplitude of the small positive wave. Oscillatory wave-like waves were found in the responses when flash frequency increased to 3 Hz. A large negative wave following a positive wave was found in mf-ERG of simulated rapid-off stimulus, which was difference from the wave of simulated rectangle stimulus and rapid-on stimulus.

CONCLUSIONS

Rod on and off responses of ERG can be recorded with sawtooth rapid-on and rapid-off stimulus. There is a small positive wave in downhill of negative wave in rod off response. Rod on response of mf-ERG can be recorded with simulated rapid-on stimulus. The flash frequency of 0.5-1 Hz and small flash intensity were suggested to appropriate conditions for recording rod on and off responses in ERG. The simulated rapid-on, sawtooth rapid-on and rapid-off stimulus can be used to investigate retinal disease.