title: Ageing effect on flicker-induced diameter changes in retinal microvessels of healthy individuals.
abstract: OBJECTIVE
  To compare flicker-induced retinal vessel diameter changes in varying age groups with low cardiovascular risk.
  
  
  METHODS
  Retinal vascular reactivity to flicker light was assessed by means of dynamic retinal vessel analysis in 57 participants aged 19-30 years, 75 participants aged 31-50 years and 62 participants aged 51-70 years participants. Other assessments included carotid intima-media thickness (c-IMT), augmentation index (AIx), blood pressure profiles, blood lipid metabolism markers and Framingham risk scores (FRS).
  
  
  RESULTS
  Retinal arterial dilation amplitude (DA) and postflicker percentage constriction (MC%) were significantly decreased in the oldest group compared to the middle-aged (p = 0.028; p = 0.021) and youngest group (p = 0.003; p = 0.026). The arterial constriction slope (SlopeAC ) was also decreased in the oldest group compared to the youngest group (p = 0.027). On the venous side, MC% was decreased in the middle-aged and oldest groups in comparison with the youngest group (p = 0.015; p = 0.010, respectively). Additionally, men exhibited increased arterial DA (p = 0.007), and percentage dilation (MD%, p < 0.001) in comparison with women, but only in the youngest age group. Both AIx and c-IMT scores increased with age (both p < 0.001); however, no correlations were found between the observed differences in the measured retinal vascular function and systemic parameters.
  
  
  CONCLUSIONS
  In individuals with low cardiovascular risk, there are age-related differences in flicker-induced retinal vessel diameter changes throughout the entire functional response curve for arteries and veins. Gender differences mainly affect the arterial dilatory phase and are only present in young individuals.
authors.affiliation: Vascular Research Laboratory, Ophthalmic Research Group, School of Life and Health Sciences, Aston University, Birmingham, UK.
authors.forename: Swathi
authors.initials: S
authors.lastname: Seshadri
authors.affiliation: School of Engineering and Applied Sciences, Aston University, Birmingham, UK.
authors.forename: Aniko
authors.initials: A
authors.lastname: Ekart
authors.affiliation: Vascular Research Laboratory, Ophthalmic Research Group, School of Life and Health Sciences, Aston University, Birmingham, UK.
authors.forename: Doina
authors.initials: D
authors.lastname: Gherghel
mesh_terms: D000328:Adult; D000368:Aged; D000375:Aging / Q000502:physiology*; D001794:Blood Pressure / Q000502:physiology; D059168:Carotid Intima-Media Thickness; D005260:Female; D064368:Healthy Volunteers; D006801:Humans; D008027:Light; D008055:Lipids / Q000097:blood; D008297:Male; D055806:Microvessels / Q000502:physiology / Q000528:radiation effects; D008875:Middle Aged; D010775:Photic Stimulation; D012161:Retinal Artery / Q000502:physiology* / Q000528:radiation effects; D012169:Retinal Vein / Q000502:physiology* / Q000528:radiation effects; D014664:Vasodilation; D055815:Young Adult
chemical_list: D008055:Lipids
keywords: ageing; cardiovascular risk; dynamic retinal vessel analysis; retina; vascular function