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J.V. Lovasik, H. Kergoat; Blue Flicker Stimulation of the Retina Modulates the Subfoveal Choroidal Blood Flow in Humans . Invest. Ophthalmol. Vis. Sci. 2005;46(13):3918.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Purpose: The objective of the present study was to reveal an interaction between choroidal blood flow (ChBF) and light–induced photoreceptor activity, a physiological coupling that is already proven for retinal blood flow, but not for the ChBF. Methods: Methods: Ten healthy adults volunteered for this study. A real–time recording laser Doppler flowmeter was used to quantify the subfoveal ChBF while the luminance of blue flicker between 1Hz and 64Hz was first increased, then decreased by 4.0 log units in 1.0 log steps between 0.0375 cd/m2and 375 cd/m2. In separate testing, flash electroretinograms (ERGs) provided electrophysiological indices of the relative response of shortwave–cones (s–cones) and rods to blue light stimulation of the retina. Results: Results: Group–averaged, normalized ChBF measurements revealed that it was modulated by an average of ∼9% across flicker frequencies. Increasing the blue flicker luminance from low–to–high decreased the subfoveal choroidal flow, volume (ChBVol), and velocity (ChBVel) by ∼32%, ∼30%, and ∼5% respectively. Decreasing the luminance from high–to–low over the same range had no effect on the subfoveal choroidal hemodynamics. Conclusions: Conclusions: The markedly different effects of reversed directions of change in blue flicker luminance on the subfoveal ChBF were linked to transitions between rod–dominated and s–cone–dominated retinal responses. Overall, the present findings are consistent with neurovascular coupling involving ChBF, and a differential distribution of ChBF across the retina that is driven by the degree and type of photoreceptor activity, and their retinal location.
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