title: Short-term retinal vessel diameter variability in relation to the history of cold extremities.
abstract: OBJECTIVE
  To test whether the regularity and short-term changes of retinal vessel diameter are related to the history of cold hands and feet and to nailfold circulatory response to cooling.
  
  
  METHODS
  In 13 vasospastic and 13 nonvasospastic young healthy women (based on their history of cold extremities and nailfold capillaroscopy) 20- to 30-second recordings of the ocular fundus was obtained with a retinal vessel analyzer. The spatial regularity of arterioles and venules was analyzed by means of the coefficient of variation of vessel diameter and by exploratory Fourier analysis of spatial frequencies. Temporal variability was analyzed as excursion amplitude of the vessel diameter, as a correlation of means and standard deviations of vessel diameter within a defined time period, and by Fourier analysis of temporal diameter change in the heartbeat frequency range.
  
  
  RESULTS
  Mean diameters of selected segments of arterioles (129.9 +/- 15.3 and 124.4 +/- 24.4 microm) and venules (150.8 +/- 14.6 and 149.3 +/- 19.6 microm) were not different between the vasospastic and nonvasospastic groups, respectively. Spatial variability: The coefficient of variation in arterioles was 8.8% +/- 2.8% and 6.1% +/- 1.7%, in venules 3.8% +/- 1.4%, and 3.6% +/- 0.9% in the vasospastic and nonvasospastic groups, respectively (difference by ANOVA, P = 0.017). Fourier analysis revealed differences between arterioles in the two groups, with relative Fourier power spectrum amplitudes of spatial frequencies higher in vasospastic eyes (Mann-Whitney P = 0.029). Temporal variability: The excursion amplitudes of vessel diameters were comparable in the two groups. Individual coefficients of correlation of successive means and standard deviations of the vessel diameter were 0.11 +/- 0.23 and 0.09 +/- 0.23 in the nonvasospastic group, and 0.25 +/- 0.40 and 0.24 +/- 0.22 in the vasospastic group, in the arterioles and venules, respectively (ANOVA: vasospastic versus nonvasospastic; P = 0.038). Fourier analysis in the heartbeat frequency range revealed differences in relative power spectrum amplitudes of temporal frequencies between arterioles in the two groups (higher in the vasospastic group, Mann-Whitney P = 0.029).
  
  
  CONCLUSIONS
  Retinal arterioles in healthy vasospastic women show higher spatial irregularity and an increased vessel diameter variation within the temporal frequency of the heartbeat than do arterioles in nonvasospastic women.
authors.affiliation: University Eye Clinic, Basel, Switzerland.
authors.forename: Asan
authors.initials: A
authors.lastname: Kochkorov
authors.forename: Konstantin
authors.initials: K
authors.lastname: Gugleta
authors.forename: Claudia
authors.initials: C
authors.lastname: Zawinka
authors.forename: Robert
authors.initials: R
authors.lastname: Katamay
authors.forename: Josef
authors.initials: J
authors.lastname: Flammer
authors.forename: Selim
authors.initials: S
authors.lastname: Orgul
mesh_terms: D000328:Adult; D000886:Anthropometry; D001160:Arterioles / Q000473:pathology; D001783:Blood Flow Velocity; D003080:Cold Temperature; D003941:Diagnostic Techniques, Ophthalmological; D005260:Female; D005583:Fourier Analysis; D006801:Humans; D009262:Nails / Q000098:blood supply*; D012039:Regional Blood Flow; D012161:Retinal Artery / Q000473:pathology*; D012169:Retinal Vein / Q000473:pathology*; D014661:Vasoconstriction; D014699:Venules / Q000473:pathology