title: Influence of refractive error and axial length on retinal vessel geometric characteristics.
abstract: OBJECTIVE
  To evaluate the influence of refractive error and axial length (AL) on retinal vascular network geometry measurements in an adult Asian population.
  
  
  METHODS
  This was a population-based, cross-sectional study on 2882 persons with diabetes in the Singapore Malay Eye Study. Spherical equivalent refraction was assessed using an autokeratorefractometer and subjective refraction. AL retinal vascular caliber, tortuosity, and branching characteristics were quantified from retinal fundus photographs using a semiautomated computer-assisted program according to a standardized protocol.
  
  
  RESULTS
  In multivariate analyses adjusting for age, sex, education, smoking, blood pressure, diabetes status, and antihypertensive medication use, longer AL and more myopic refraction were associated with narrower retinal arterioles and venules (P ≤ 0.001 for all) and less tortuous (straighter) arterioles (P < 0.001 for both). Longer AL and more myopic refraction were also associated with increased branching coefficients in both arterioles (P < 0.001 for both) and venules (P = 0.02 and P < 0.001, respectively). Longer AL and more myopic refraction were associated with more acute branching angles in arterioles (P < 0.001 for both) but not venules.
  
  
  CONCLUSIONS
  Myopic refractive errors and longer AL are associated with narrower retinal arterioles and venules, less tortuous arterioles, and increased branching coefficients in both arterioles and venules. These findings provide insights into ocular blood flow in myopia and also suggest that future studies evaluating these retinal parameters should account for the influence of AL and refractive error.
authors.affiliation: Singapore Eye Research Institute, Singapore National Eye Centre, Singapore.
authors.forename: Laurence Shen
authors.initials: LS
authors.lastname: Lim
authors.forename: Carol Yim-lui
authors.initials: CY
authors.lastname: Cheung
authors.forename: Xiaoyu
authors.initials: X
authors.lastname: Lin
authors.forename: Paul
authors.initials: P
authors.lastname: Mitchell
authors.forename: Tien Yin
authors.initials: TY
authors.lastname: Wong
authors.forename: Seang
authors.initials: S
authors.lastname: Mei-Saw
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000959:Antihypertensive Agents / Q000627:therapeutic use; D001160:Arterioles / Q000473:pathology; D044466:Asian People; D058452:Axial Length, Eye / Q000503:physiopathology*; D001783:Blood Flow Velocity; D001794:Blood Pressure / Q000502:physiology; D003430:Cross-Sectional Studies; D048909:Diabetes Complications / Q000503:physiopathology; D005260:Female; D006801:Humans; D007091:Image Processing, Computer-Assisted; D008297:Male; D008875:Middle Aged; D012030:Refractive Errors / Q000503:physiopathology*; D012039:Regional Blood Flow / Q000502:physiology; D012171:Retinal Vessels / Q000473:pathology*; D012846:Singapore; D014699:Venules / Q000473:pathology
chemical_list: D000959:Antihypertensive Agents