[Effect of light on choroidal blood flow in the fovea centralis].
OBJECTIVE
To investigate whether light and dark exposures induce a response of choroidal blood flow (ChBF) in the foveal region in humans.


METHODS
In a group of healthy volunteers (age 25-60 years) ChBF was measured using a new confocal laser Doppler flowmeter (probing laser at 785 nm, power at the cornea = 90 microW). ChBF was recorded at room light, in darkness, at room light following dark adaptation, and during strong light exposure following room light.


RESULTS
While ChBF was stable during room light condition, it decreased significantly by 15% (p < 0.01) during darkness. After 6 min of room light following darkness, ChBF was back to baseline. Strong diffuse, green light exposure over a field of 45 degrees had no detectable effect on ChBF. In all the experiments, no significant change of blood pressure was detected.


CONCLUSIONS
Our findings did not confirm the presence of an active process of ChBF regulation in response to strong light exposure in humans. They demonstrate, however, a reversible decrease in ChBF occurring after a transition from room light to darkness.
Longo
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Institut de Recherche en Ophtalmologie, Sion, Suisse.
Geiser
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Riva
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D000221:Adaptation, Ocular / Q000502:physiology*; D000328:Adult; D002829:Choroid / Q000098:blood supply* / Q000502:physiology; D003623:Dark Adaptation / Q000502:physiology*; D005584:Fovea Centralis / Q000098:blood supply* / Q000502:physiology; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008875:Middle Aged; D012039:Regional Blood Flow
Effet de la lumière sur le flux sanguin de la choroïde dans la région de la fovea centralis.