Fig. 4.

Vitreal, retinal, and choroidal dopamine and DOPAC levels in chickens exposed to flickering light at 1, 10, or 400 Hz at 20 lx (n = 6 in each case), and under laboratory lighting at 470 lx (n = 6). Flickering light, both at 1 and 10 Hz, increased retinal dopamine and DOPAC content more than increasing illuminance from 20 to 470 lx (middle) while 400 Hz flickering light at 20 lx caused a significant decrease in retinal and vitreal DA and DOPAC levels (middle). Flickering light at 20 lx also reduced vitreal dopamine and DOPAC content, compared to laboratory lighting at 470 lx (left). One hertz flickering light also reduced choroidal dopamine and DOPAC content (right). Two-tailed unpaired Student’s t-test; *p < 0.05, **p < 0.01, ***p < 0.001. Colors of asterisks match the color of the data column for comparison