Effects of flickering light stimulation on retinal blood flow and full-field electroretinogram in mice

Purpose: To investigate the effects of brief flickering light stimulation (FLS) on retinal electrophysiology and retinal blood flow (RBF) in normal C57BL6J mice. Methods: RBF and full-field electroretinography (ffERG) were measured before and after a 60 second FLS (12 Hz, 0.1 cd·s/m2) in a cohort of 8-12-weeks old C57BL6J mice (n=10) under anaesthetic and light-adapted conditions. A separate set of age-matched mice (n=9) underwent RBF and ffERG measurements before and after steady light stimulation (SLS) at 1 cd/m2 under similar conditions. The changes in RBF (arterial and venous flow) as well as the amplitudes and implicit times of the a-wave, b-wave, oscillatory potentials (OPs), and photopic negative response (PhNR) were analyzed. Results: FLS significantly increased both arterial (p=0.003) and venous (p=0.018) blood flow as well as b-wave amplitudes (p=0.017) compared to SLS, which did not have any significant changes in either RBF or ERG. However, no significant differences were found in other ffERG responses (amplitudes and implicit times of a-wave, OPs, and PhNR, as well as b-wave implicit time) between the two groups after light stimulation. An increase in b-wave amplitude was positively associated with an increase in both arterial (r=0.655, p=0.040) and venous blood flow (r=0.638, p=0.047) in the FLS group. Conclusions: Our results suggest that transient FLS not only increases RBF but also enhances electro-retinal responses of the middle retinal layer, as shown by ffERG, thus demonstrating its substantial effects on both the vascular and neuronal components of retinal neurovascular coupling in mice.