title: Retinal vascular tortuosity, blood pressure, and cardiovascular risk factors.
abstract: OBJECTIVE
  To examine the relationship of retinal vascular tortuosity to age, blood pressure, and other cardiovascular risk factors.
  
  
  METHODS
  Population-based, cross-sectional study.
  
  
  METHODS
  A total of 3280 participants aged 40 to 80 years from the Singapore Malay Eye Study (78.7% response rate).
  
  
  METHODS
  Retinal arteriolar and venular (vascular) tortuosity were quantitatively measured from fundus images using a computer-assisted program. Retinal vascular tortuosity was defined as the integral of the curvature square along the path of the vessel, normalized by the total path length. Data on blood pressure and major cardiovascular disease (CVD) risk factors were collected from all participants.
  
  
  METHODS
  Retinal arteriolar and venular tortuosity.
  
  
  RESULTS
  A total of 2915 participants contributed data to this study. The mean (standard deviation) and median were 2.99 (1.40) and 2.73 for retinal arteriolar tortuosity (×10(4)), and 4.64 (2.39) and 4.19 for retinal venular tortuosity (×10(4)), respectively. Retinal venules were significantly more tortuous than retinal arterioles (P<0.001). In multivariable-adjusted linear regression models, less arteriolar tortuosity was independently associated with older age, higher blood pressure, higher body mass index (BMI), and narrower retinal arteriolar caliber (all P<0.05); greater venular tortuosity was independently associated with younger age, higher blood pressure, lower high-density lipoprotein (HDL) cholesterol level, and wider retinal venular caliber (all P<0.05).
  
  
  CONCLUSIONS
  Retinal arteriolar tortuosity was associated with older age and higher levels of blood pressure and BMI, whereas venular tortuosity was also associated with lower HDL level. The quantitative assessment of retinal vascular tortuosity from retinal images may provide further information regarding effects of cardiovascular risk factors on the retinal vasculature.
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore. carol.cheung.y.l@seri.com.sg
authors.forename: Carol Yim-Lui
authors.initials: CY
authors.lastname: Cheung
authors.forename: Yingfeng
authors.initials: Y
authors.lastname: Zheng
authors.forename: Wynne
authors.initials: W
authors.lastname: Hsu
authors.forename: Mong Li
authors.initials: ML
authors.lastname: Lee
authors.forename: Qiangfeng Peter
authors.initials: QP
authors.lastname: Lau
authors.forename: Paul
authors.initials: P
authors.lastname: Mitchell
authors.forename: Jie Jin
authors.initials: JJ
authors.lastname: Wang
authors.forename: Ronald
authors.initials: R
authors.lastname: Klein
authors.forename: Tien Yin
authors.initials: TY
authors.lastname: Wong
mesh_terms: D000328:Adult; D000367:Age Factors; D000368:Aged; D000369:Aged, 80 and over; D044466:Asian People / Q000208:ethnology; D001794:Blood Pressure / Q000502:physiology*; D002318:Cardiovascular Diseases / Q000208:ethnology / Q000503:physiopathology*; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006973:Hypertension / Q000503:physiopathology*; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D012164:Retinal Diseases / Q000175:diagnosis* / Q000208:ethnology; D012171:Retinal Vessels / Q000473:pathology*; D012307:Risk Factors; D012846:Singapore / Q000453:epidemiology; D014505:Urban Population / Q000706:statistics & numerical data