title: Determinants of retinal microvascular architecture in normal subjects.
abstract: BACKGROUND
  Recent studies have shown that changes in the retinal microvasculature predict cardiovascular disease (CVD); however, little is known regarding influences on the retinal microvasculature in healthy people without overt cardiovascular or metabolic disease.
  
  
  METHODS
  We used a semiautomated computerized technique to analyze digitized retinal photographs from a total of 167 healthy people (age range, 45-75 years; 83 female), without clinical CVD, diabetes, or hypertension, randomly sampled from the population-based Beaver Dam Eye Study. We assessed arteriolar and venular narrowing, arteriolar optimality deviation, and other quantitative aspects of the retinal microvasculature.
  
  
  RESULTS
  Arterioles were significantly narrower and longer, had wider branching angles, and were more tortuous than venules. Increased arteriolar length to diameter ratio (an index of ratio arteriolar narrowing) was positively and independently associated with older age and elevated systolic blood pressure. Arteriolar optimality deviation (an index of microvascular endothelial dysfunction) increased with greater body mass index. Current smoking and increased white blood cell (WBC) count was associated with wider venules. After controlling for smoking, WBC was no longer a significant predictor of venular diameter.
  
  
  CONCLUSIONS
  CVD risk factors are associated with retinal microvascular changes in healthy individuals without evidence of CVD, diabetes, or hypertension. CVD risk factors have different influences on the arteriolar and venular bed.
authors.affiliation: Clinical Pharmacology, NHLI Division, International Centre for Circulatory Health, Faculty of Medicine, Imperial College London, UK. a.hughes@imperial.ac.uk
authors.forename: Alun D
authors.initials: AD
authors.lastname: Hughes
authors.forename: Tien Y
authors.initials: TY
authors.lastname: Wong
authors.forename: Nicholas
authors.initials: N
authors.lastname: Witt
authors.forename: Richard
authors.initials: R
authors.lastname: Evans
authors.forename: Simon A Mcg
authors.initials: SA
authors.lastname: Thom
authors.forename: Barbara E
authors.initials: BE
authors.lastname: Klein
authors.forename: Nish
authors.initials: N
authors.lastname: Chaturvedi
authors.forename: Ronald
authors.initials: R
authors.lastname: Klein
mesh_terms: D000368:Aged; D001160:Arterioles / Q000033:anatomy & histology / Q000502:physiology; D001794:Blood Pressure / Q000502:physiology; D002318:Cardiovascular Diseases / Q000097:blood / Q000473:pathology / Q000503:physiopathology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007958:Leukocyte Count; D008297:Male; D008833:Microcirculation / Q000502:physiology*; D008875:Middle Aged; D012160:Retina / Q000033:anatomy & histology / Q000502:physiology*; D012171:Retinal Vessels / Q000033:anatomy & histology / Q000502:physiology*; D014699:Venules / Q000033:anatomy & histology / Q000502:physiology