Institut de Recherche en Ophtalmologie, Sion, Switzerland - Ecole d'Ingénieurs du Valais, Sion, Switzerland
Purpose. To determine retinal vessel diameter variations in response
to neuronal activity induced by diffuse luminance flicker.
Methods. The diameter of retinal arteries and veins was measured
in 9 normal subjects by computer analysis of fundus pictures taken in monochromatic
light under normal conditions of illumination and after 1 min of sinusoidally
varying diffuse luminance flicker at 10 Hz.
Results. The diameter immediately after flicker was significantly
larger than the pre-stimulus diameter by 4.2 ± 2.2% for the retinal
arteries and 2.7 ± 1.7% for the retinal veins (mean ± SD).
Six seconds after cessation of the flicker, arterial diameter was not significantly
different from that of pre-flicker value.
Conclusions. Diffuse luminance flicker induces an increase in
retinal vessel diameter. This increase most probably reflects an increase
in retinal blood flow previously evidenced in humans by the blue field
simulation technique. The technique needs to be optimized in terms of flicker
parameters to determine whether flicker-evoked retinal diameter changes
could represent a useful clinical measure of the capability of the retinal
vascular system to vasodilate.
Key Words: Retinal diameter; flicker; neuronal activity; retinal blood flow.