title: Age, blood pressure, and vessel diameter as factors influencing the arterial retinal flicker response.
abstract: OBJECTIVE
  The present study investigated whether age, blood pressure (BP), and baseline vessel diameter influence the retinal arterial response to flicker light.
  
  
  METHODS
  Thirty healthy subjects (mean age, 46.3; range, 22-73 years) and 15 patients with untreated essential arterial hypertension (mean, 50.9; range, 26-69 years) were examined. The diameter of the retinal arterioles was measured by a Retinal Vessel Analyzer (RVA; Imedos, Weimar, Germany). Each examination consisted of a 100-second baseline measurement and five 20-second periods of flicker stimulation, followed by an 80-second observation period. The five stimulation periods were then averaged. The rectangular luminance flicker operated at 12.5 Hz at a wavelength of 530 to 600 nm. The baseline-corrected flicker response (bFR) was defined as the difference between the peak dilatation and subsequent constriction after flicker stimulation minus the fluctuation of the baseline. The BP was measured at 1-minute intervals during the examination.
  
  
  RESULTS
  In 26 subjects with normal BP, flicker light induced a bFR of +6.4% +/- 2.7%. The bFR decreased nonsignificantly in healthy subjects with increasing age (y = 8.48-0.048x; r = 0.26). The baseline diameter did not influence the amplitude of the flicker response over a range of 70 to 140 measuring units. The hypertensive patients reacted with a bFR of +2.2% +/- 2.5% (P < 0.001). Four hitherto healthy subjects with elevated BP during the examination were excluded from analysis.
  
  
  CONCLUSIONS
  A significant correlation of age and bFR was not found in the small sample examined. Untreated arterial hypertension appeared to be associated with a reduced flicker response. The value of such functional vessel properties in the screening of vasosclerosis and in diagnostics in arterial hypertension should be examined in further studies.
authors.affiliation: e_a_nagel@t-online.de
authors.forename: Edgar
authors.initials: E
authors.lastname: Nagel
authors.forename: Walthard
authors.initials: W
authors.lastname: Vilser
authors.forename: Ines
authors.initials: I
authors.lastname: Lanzl
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001160:Arterioles / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology*; D005260:Female; D005425:Flicker Fusion / Q000502:physiology*; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D008027:Light; D008297:Male; D008875:Middle Aged; D012161:Retinal Artery / Q000502:physiology*; D012307:Risk Factors