title: Complete blood count and retinal vessel calibers.
abstract: OBJECTIVE
  The influence of hematological indices such as complete blood count on microcirculation is poorly understood. Retinal microvasculature can be directly visualized and vessel calibers are associated with a range of ocular and systemic diseases. We examined the association of complete blood count with retinal vessel calibers.
  
  
  METHODS
  Cross-sectional population-based Blue Mountains Eye Study, n = 3009, aged 49+ years. Complete blood count was measured from fasting blood samples taken at baseline examination, 1992-4. Retinal arteriolar and venular calibers were measured from digitized retinal photographs using a validated semi-automated computer program.
  
  
  RESULTS
  All analyses adjusted for age, sex, systolic blood pressure, diabetes, smoking and fellow vessel caliber. Higher hematocrit, white cell count and platelet count were associated with narrower arteriolar caliber (p = 0.02, 0.03 and 0.001 respectively), while higher hemoglobin, hematocrit, red cell count, white cell count and platelet count were associated with wider venular caliber (p<0.0001 for all). Each quintile increase in hematocrit, white cell count and platelet count was associated with approximately 0.5 µm narrower arteriolar caliber; whereas each quintile increase in all of the complete blood count components was associated with approximately 1-2 µm wider venular caliber.
  
  
  CONCLUSIONS
  These associations show that elevated levels of hematological indices can have adverse effects on the microcirculation.
authors.affiliation: Centre for Vision Research, University of Sydney, Sydney, New South Wales, Australia; Centre for Eye Research Australia, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Gerald
authors.initials: G
authors.lastname: Liew
authors.affiliation: Centre for Vision Research, University of Sydney, Sydney, New South Wales, Australia; Centre for Eye Research Australia, University of Melbourne, Melbourne, Victoria, Australia.
authors.forename: Jie Jin
authors.initials: JJ
authors.lastname: Wang
authors.affiliation: Centre for Vision Research, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Elena
authors.initials: E
authors.lastname: Rochtchina
authors.affiliation: Centre for Eye Research Australia, University of Melbourne, Melbourne, Victoria, Australia; Singapore Eye Research Institute, Yong Loo Lin School of Medicine, National University of Singapore, Singapore, Singapore.
authors.forename: Tien Yin
authors.initials: TY
authors.lastname: Wong
authors.affiliation: Centre for Vision Research, University of Sydney, Sydney, New South Wales, Australia.
authors.forename: Paul
authors.initials: P
authors.lastname: Mitchell
mesh_terms: D000368:Aged; D001160:Arterioles / Q000166:cytology / Q000473:pathology; D001772:Blood Cell Count; D005260:Female; D006801:Humans; D008297:Male; D008875:Middle Aged; D012171:Retinal Vessels / Q000166:cytology* / Q000473:pathology; D014699:Venules / Q000166:cytology / Q000473:pathology