To address this issue, electro-retinography was used to measure the changes in retinal light sensitivity, flicker fusion frequency, and spectral sensitivity in black rockfish (Sebastes melanops) subjected to rapid decompression (from 4 atmospheres absolute [ATA] to 1 ATA) and Pacific halibut (Hippoglossus stenolepis) exposed to 15 minutes of simulated sunlight.
Three separate procedures were conducted to test for treatment effects on visual function: responses to increasing light intensities (V-log I response curves), flicker fusion frequency, and spectral sensitivity.
The flicker fusion frequency was determined by comparing the power spectrum of the averaged response at each stimulus frequency (signal) to the power spectrum of a neighboring frequency (noise) and was defined as the frequency at which the power of the signal fell below the power of the noise.
Differences in the mean flicker fusion frequency data collected during the day and night were tested with paired-t tests (SigmaStat 3.
There was also no detectable influence of rapid decompression on flicker fusion frequency for black rockfish, nor an apparent effect of exposure to bright light on the flicker fusion frequency of Pacific halibut.
We found no differences in light sensitivity (V-log I response curves), flicker fusion frequency, or spectral sensitivity between control and experimental fish.
At the second stage ophthalmological status (acuity of vision and refraction) was estimated as well as functional (critical flicker fusion frequency -CFFF) electrophysiological (electrosensitivity threshold -EST; electrolabilityEL), phychophysiological (channel capacity- CC, visual information volume -VIV, visual information speed -VIS, efficiency of visual information analysis -EVIA) investigations were carried out [4, 5].
Negative relation between critical flicker fusion frequency and such parameters of visual perception as channel capacity of visual system and visual information processing may seem to be paradoxical because according to the canon of sensor physiology, the higher is the frequency characteristics of the communication channel, the higher its channel capacity .