title: Diffuse luminance flicker increases retinal vessel diameter in humans.
abstract: OBJECTIVE
  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 is 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.
authors.affiliation: Institut de Recherche en Ophtalmologie, Sion, Switzerland.
authors.forename: F
authors.initials: F
authors.lastname: Formaz
authors.forename: C E
authors.initials: CE
authors.lastname: Riva
authors.forename: M
authors.initials: M
authors.lastname: Geiser
mesh_terms: D000293:Adolescent; D000328:Adult; D001158:Arteries / Q000502:physiology; D005260:Female; D006801:Humans; D008029:Lighting; D008297:Male; D010775:Photic Stimulation / Q000379:methods; D015203:Reproducibility of Results; D012171:Retinal Vessels / Q000502:physiology* / Q000528:radiation effects*; D014664:Vasodilation / Q000502:physiology*; D014680:Veins / Q000502:physiology