title: Morphometric age-related evaluation of small retinal vessels by scanning laser Doppler flowmetry: determination of a vessel wall index.
abstract: BACKGROUND
  Measurement of the retinal vessel wall thickness may contribute to the diagnosis of microvascular diseases. We present a methodical approach to calculate these alterations and to determine age-related differences.
  
  
  METHODS
  One hundred fifty-three subjects without eye or internal diseases (mean age +/- SD, 47.6 +/- 14.9 years) underwent measurement of the retinal temporal superior artery and vein by scanning laser Doppler flowmetry (Heidelberg retina flowmeter). We calculated the difference between the diameter of reflectivity and the Doppler signal (Delta[VD-FD]/2) and determined a "vessel wall index" (VWI) by normalization of Delta(VD-FD)/2 for age and vessel diameter.
  
  
  RESULTS
  Delta(VD-FD)/2 correlated with vessel diameter (artery, r = +0.60, P < 0.001; vein, r = +0.49, P<0.001) and age (artery, r = +0.19, P = 0.02; vein, r = +0.27, P = 0.001) but not with sex, if controlled for the other variables each. The venous, but not the arterial, vessel diameter correlated with age (r = +0.18, P = 0.02), if controlled for sex. The relative statistical weight of these empirical contributions to the variation observed in Delta(VD-FD)/2 was 36.5% (P < 0.001, artery) and 21.7% (P< 0.001, vein), and that of age was 3.6% (P = 0.02, artery) and 7.3% (P = 0.001, vein). The limit value of VWI to pathologic changes (80th percentile) was 1.25 microm/y (artery) and 1.31 microm/y (vein). Delta(VD-FD)/2 normalized for vessel diameter correlated with the 10-year categories of age (artery, r = +0.196, P = 0.017; vein, r = +0.250, P = 0.002).
  
  
  CONCLUSIONS
  In a group of subjects aged 21 years to 70 years, we detected an increase of Delta(VD-FD)/2 in the retinal temporal superior artery and vein with age.
authors.affiliation: Department of Ophthalmology, University of Erlangen-Nürnberg, Erlangen, Germany. Georg.Michelson@rzmail.uni-erlangen.de
authors.forename: Georg
authors.initials: G
authors.lastname: Michelson
authors.forename: Simone
authors.initials: S
authors.lastname: Wärntges
authors.forename: Delia
authors.initials: D
authors.lastname: Baleanu
authors.forename: Jürgen
authors.initials: J
authors.lastname: Welzenbach
authors.forename: Akiko
authors.initials: A
authors.lastname: Ohno-Jinno
authors.forename: Pavel
authors.initials: P
authors.lastname: Pogorelov
authors.forename: Joanna
authors.initials: J
authors.lastname: Harazny
mesh_terms: D000293:Adolescent; D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001160:Arterioles / Q000033:anatomy & histology; D001783:Blood Flow Velocity; D002648:Child; D005260:Female; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008297:Male; D008875:Middle Aged; D012039:Regional Blood Flow; D015203:Reproducibility of Results; D012161:Retinal Artery / Q000033:anatomy & histology*; D012169:Retinal Vein / Q000033:anatomy & histology*; D014699:Venules / Q000033:anatomy & histology