title: Influence of age on retinal and optic nerve head blood circulation.
abstract: OBJECTIVE
  To quantify the influence of age on the retinal perfusion, the authors investigated the microcirculation of the retina and optic nerve head (ONH) and the blood flow velocity in the central retinal artery (CRA).
  
  
  METHODS
  The authors examined two groups of healthy volunteers. In group 1 (n=36 eyes of 36 subjects; mean age, 41.5 +/- 14.9 years), retinal and ONH microcirculation was analyzed by scanning laser Doppler flowmetry. In group 2 (n=49 eyes from 49 subjects; mean age, 44.4 +/- 15.4 years), CRA blood flow velocity was examined using pulsed Doppler sonography.
  
  
  RESULTS
  Blood flow velocity of the CRA showed a negative correlation to age (systolic velocity, r= -0.47, P=0.001; diastolic velocity r= -0.49, P=0.001). The slope of the linear regression was -0.62 cm/second per 10 years for systolic blood velocity and -0.51 cm/second for diastolic blood velocity. Resistivity index (RI) (RI=[systolic velocity--diastolic velocity]/systolic velocity) as a marker of the rigidity of the vessel increased significantly with age (r=0.40, P=0.004). The slope was 0.03 per 10 years. Retinal microcirculation (flow omega-ret) decreased significantly with age (r= -0.63, P=0.00001). The slope was -34.9[AU] per 10 years. Optic nerve head blood flow showed no significant correlation to age (r= -0.30, P=0.071).
  
  
  CONCLUSIONS
  The authors' data indicate that there is a significant decrease of retinal and CRA blood flow of approximately 6% to 11% per decade. Optic nerve head blood flow seems not to be influenced by age.
authors.affiliation: Ophthalmology and Eye Hospital, University Erlangen-Nuernberg, Germany.
authors.forename: M J
authors.initials: MJ
authors.lastname: Groh
authors.forename: G
authors.initials: G
authors.lastname: Michelson
authors.forename: M J
authors.initials: MJ
authors.lastname: Langhans
authors.forename: J
authors.initials: J
authors.lastname: Harazny
mesh_terms: D000328:Adult; D000368:Aged; D000369:Aged, 80 and over; D000375:Aging / Q000502:physiology*; D001783:Blood Flow Velocity; D001794:Blood Pressure; D006801:Humans; D017078:Laser-Doppler Flowmetry; D008833:Microcirculation; D008875:Middle Aged; D009898:Optic Disk / Q000098:blood supply*; D012161:Retinal Artery / Q000502:physiology*