Increase In B-wave Amplitude Research Articles

ERG off-effects produced by short duration stimuli.

Variable duration square wave pulses of 633-nm light were used to produce electroretinograms (ERG's) in a human subject. When the stimuli were presented on a white light background, the records obtained for stimulus durations greater than 70 msec showed a clearly separated off-response while those of shorter durations did not. By subtracting a common "on-effect" from the ERG's produced by short duration stimuli, the previously unseen off-effect was isolated from records produced by stimulus pulses as short as 5 msec. It appears that the marked increase in b-wave amplitude associated with these short duration stimuli can be attributed to an interaction between "on" and "off" components of the ERG.

A study on the effects of constant polarizing current on the human electroretinogram and visual sensitivity.

1. The constant current running across the human retina from outside into inside of the eyeball (polarizing current with “cornea cathode”) brings about an enhancement of ERG, i. e., an increase in amplitude of b-wave and an decrease in its latency, while the current of the reverse direction (“cornea anode”) causes its depression, i. e., a decrease in amplitude of b-wave and an increase in its latency.2. Both of the enhancement and the depression of ERG depend not only upon the intensity of the polarizing current but also upon the intensity of the stimulus (white light). When the light intensity is kept constant, both changes in amplitude and latency of b-wave due to polarization are approximately in a linear relation to the intensity of the polarizing current.3. The visual sensitivity of the fovea centralis to the white light improved also with increase in intensity of the polarizing current with “cornea cathode”, while it weakens with increase in intensity of the current with “cornea anode”. These results are quite similar to the changes in cone sensitivity to orange-red spectral rays in Kravkov and Galochkina's experiments.4. The effects of polarization on the visual mechanism were proved consistently by two different methods of electrophysiological and psychophysical experiments.