Abstract
Purpose::
The purpose of this work was to compare the parameters of the electroretinogram (ERG) recovery during the course of a dark-adaptation after moderate intensity photobleach in three strains of mice.
Methods::
Full-field ERGs were recorded from male CD-1, BALB/c and C57BL/6 mice at 8 to 12 weeks of age (weight 20 - 45 g). Two stimulation intensities were used throughout the recording: 0.01 cd.s/m2 and 1 cd.s/m2. After recording baseline dark-adapted ERG responses, ~400 lux white light was presented for 45 sec to provide ~45% photobleaching of rhodopsin. ERG recordings from both intensities were recorded every 5 min up to 45 min after bleach. A-wave was measured at a fixed time point after flash, whereas b-wave amplitudes were measured from the trough of the a-wave to the peak of the b-wave after elimination of the superimposed oscillatory potentials (OP) with digital filtering.
Results::
The amplitude of the a-wave was measurable only at 1 cd.s/m2 intensity and also exhibited full recovery (118 to 143%) without any strain difference. The amplitude of the b-wave fully recovered in all three strains by the end of the 45 minute follow-up period (101-113% for 0.01 cd.s/m2 and 111-126% for 1 cd.s/m2) and there were no significant differences between the strains. The coefficient of variation (CV) for a- and b-wave amplitude recovery was considerably lower in C57BL/6 mice (5-21%) compared to either CD-1 (35-38%) or BALB/c mice (43-48%). Dark-adapted a- and b-wave amplitudes did not differ significantly between the strains.
Conclusions::
Despite the disparity in ocular pigmentation (lack of retinal/choroidal melanin in CD-1 and BALB/c vs. presence of melanin in C57BL/6), the amplitude of the ERG a- and b-waves fully recovered in all three strains at 45 min after moderate bleach. However, the variability of the response was less in. pigmented strains than in albinos.
Keywords: electrophysiology: non-clinical • electroretinography: non-clinical • photoreceptors: visual performance