Effect of Stimulus Contrast on Simultaneous Steady-State Pattern Reversal Electroretinogram and Visual Evoked Response

Abstract

We studied the effect of stimulus pattern contrast on the simultaneously recorded pattern reversal electroretinogram (PERG) and pattern reversal visual evoked response (PVER) at 5 check sizes. The stimulus contrast ranged from 24 to 95 % in 6 steps of 0.1- or 0.15-log unit increments. PERG amplitude showed a linear increase with an increase in pattern contrast at all check sizes. PVER amplitude showed an increase up to a certain pattern contrast, but was saturated upon further increase in stimulus contrast at all check sizes. The PERG amplitude-check size function curve showed a flattened, inverted-U shape only with the highest contrast and low-pass filter shape or flat shape with lower contrasts. The PVER amplitude-check size function curve showed an inverted-U shape (bandpass filter shape) at all contrasts. These characteristics to the changes in contrast and the spatial frequency tuning suggest that PVER is processed in a different location of visual pathway than PERG.

Effect of Hemifield Stimulation on Simultaneous Steady-State Pattern Reversal Electroretinogram and Visual Evoked Response

“…The stimulus pattern was a square-wave checker board with a check size of 40 min of arc. The contrast levels and the check size were selected based upon the results of previous studies [25]. The temporal fre quency (reversal rate) was 6 Hz (12 reversals/s), and analysis time was 500 ms.…”

“…Since the report by Maffei and Fiorentini [4], clinical applications of PERG have been reported in several patho logic conditions such as amblyopia [5]. dia betic retinopathy [6][7][8], glaucoma [9][10][11][12], macular degeneration [13.14], and optic neu ritis [15][16][17], An increasing number of para metric studies analyzed the PERG character istics [18][19][20][21][22][23][24][25], To investigate these character istics more extensively, we simultaneously re corded PERG and PVER. using common stimulus patterns [24.…”

“…Tetsuka cl al. [25] studied PERG/PVER re sponses to contrast changes and found that PERG amplitudes increased linearly with an increase in the pattern contrast, unlike PVER that showed saturation.…”

Impact of luminance and spatial parameters on the generation of the human pattern electroretinogram.

“…An interaction between contrast and spatial tuning has also been suggested by some investigations. Generally, spatial selectivity seems to be more prevalent when stimuli are of higher contrast levels, with lower contrast levels showing little to no spatial selectivity (Korth & Rix, 1984;Sokol et al, 1983;Tetsuka, Katsumi, Mehta, Tetsuka, & Hirose, 1992), though some evidence points to this only being the case for P50, with N95…”