title: Does refractive error influence the association of blood pressure and retinal vessel diameters? The Blue Mountains Eye Study.
abstract: OBJECTIVE
  To determine if refractive errors influence the association of blood pressure and retinal vessel diameters.
  
  
  METHODS
  Population-based, cross-sectional study.
  
  
  METHODS
  Retinal photographs from the right eyes of participants (n = 3,654, aged 49+ years) in the Blue Mountains Eye Study taken during baseline examinations (1992 to 1994) were digitized. The diameter of all retinal vessels located half to one disk diameter from the disk margin was measured using a computer-assisted imaging program. These measurements were combined to provide the average diameters of retinal arterioles and venules of that eye, and the ratio of their diameters, the arteriole-to-venule ratio (AVR). The association of blood pressure and retinal vessel diameters was analyzed before and after correction for refraction using the Bengtsson formula.
  
  
  RESULTS
  Before correction, each 10-mm Hg increase in mean arterial blood pressure was associated with a 3.7-microm (95% confidence interval [CI], 3.2-4.3) decrease in arteriolar diameter and a 0.9-microm (95% CI, 0.3-0.9) decrease in venular diameter. After correction for refraction, each 1-mm Hg increase in mean arterial blood pressure was associated with a 3.7-microm (95% CI, 3.2-4.2) decrease in arteriolar diameter and a 0.8-microm (95% CI, 0.3-0.9) decrease in venular diameter. Refraction was not associated with the AVR and had no effect on the association of blood pressure and AVR.
  
  
  CONCLUSIONS
  Refraction had no appreciable effect on the association of blood pressure and retinal vessel diameters or on the AVR. Correction for refraction is important for quantifying absolute retinal vessel caliber, but may not be particularly important in epidemiologic studies investigating the association of generalized retinal arteriolar narrowing and hypertension.
authors.affiliation: Centre for Eye Research Australia, University of Melbourne, East Melbourne.
authors.forename: Tien Yin
authors.initials: TY
authors.lastname: Wong
authors.forename: Jie Jin
authors.initials: JJ
authors.lastname: Wang
authors.forename: Elena
authors.initials: E
authors.lastname: Rochtchina
authors.forename: Ronald
authors.initials: R
authors.lastname: Klein
authors.forename: Paul
authors.initials: P
authors.lastname: Mitchell
mesh_terms: D000368:Aged; D000369:Aged, 80 and over; D001794:Blood Pressure / Q000502:physiology*; D002318:Cardiovascular Diseases / Q000503:physiopathology; D003430:Cross-Sectional Studies; D005260:Female; D006801:Humans; D006973:Hypertension / Q000503:physiopathology; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D009517:New South Wales; D012030:Refractive Errors / Q000503:physiopathology*; D012171:Retinal Vessels / Q000503:physiopathology*