title: Retinal vascular fractal dimension and its relationship with cardiovascular and ocular risk factors.
abstract: OBJECTIVE
  To examine the influence of a range of cardiovascular risk factors and ocular conditions on retinal vascular fractal dimension in the Singapore Malay Eye Study.
  
  
  METHODS
  Population-based cross-sectional study.
  
  
  METHODS
  Fractal analysis of the retinal vessels is a method to quantify the global geometric complexity of the retinal vasculature. Retinal vascular fractal dimension (D(f)) and caliber were measured from retinal photographs using a computer-assisted program. D(f) and arteriolar caliber were combined to form a retinal vascular optimality score (ranging from 0 to 3). Data on cardiovascular and ocular factors were collected from all participants based on a standardized protocol.
  
  
  RESULTS
  Two thousand nine hundred thirteen (88.8% of 3280 participants) persons had retinal photographs of sufficient quality for the measurement. The mean D(f) was 1.405 (standard deviation, 0.046; interquartile range, 1.243 to 1.542). In the multiple linear regression analysis, after controlling for gender, serum glucose, intraocular pressure, anterior chamber depth, and retinal vascular caliber, smaller D(f) was associated independently with older age (standardized regression coefficient [sβ] = -0.311; P < .001), higher mean arterial blood pressure (sβ = -0.085; P < .001), a more myopic spherical equivalent (sβ = 0.152; P < .001), and presence of cataract (sβ = -0.107; P < .001). Retinal vascular optimality score was associated significantly with higher mean arterial blood pressure (P > .001 for trend).
  
  
  CONCLUSIONS
  Age, blood pressure, refractive error, and lens opacity had significant influence on retinal vascular fractal measurements. A new score of retinal vascular optimality combining fractals and caliber showed strong association with blood pressure. Quantitative analysis of retinal vasculature therefore may provide additional information on microvascular architecture and optimality.
authors: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore. carol.cheung.y.1@seri.com.sg
authors: Carol Y
authors: CY
authors: Cheung
authors: George N
authors: GN
authors: Thomas
authors: Wanting
authors: W
authors: Tay
authors: M Kamran
authors: MK
authors: Ikram
authors: Wynne
authors: W
authors: Hsu
authors: Mong Li
authors: ML
authors: Lee
authors: Qiangfeng Peter
authors: QP
authors: Lau
authors: Tien Yin
authors: TY
authors: Wong
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure / Q000502:physiology; D015992:Body Mass Index; D002318:Cardiovascular Diseases / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D003430:Cross-Sectional Studies; D005128:Eye Diseases / Q000453:epidemiology* / Q000209:etiology / Q000503:physiopathology; D005260:Female; D017709:Fractals; D006801:Humans; D007091:Image Processing, Computer-Assisted; D007429:Intraocular Pressure / Q000502:physiology; D008297:Male; D008875:Middle Aged; D010781:Photography; D012171:Retinal Vessels / Q000473:pathology*; D012307:Risk Factors; D012846:Singapore / Q000453:epidemiology