Abstract
Purpose: :
By image analysis it is possible to observe retinal vessels in their dynamic state online. Vessel diameters can be measured continuously along a given vessel segment with the Dynamic Vessel Analyzer (DVA, Fa. IMEDOS, Jena). Continuous signals can be mathematically analyzed using cross- and autocorellation analysis. The aim is to investigate a difference in spontaneous dynamic behaviour of retinal vessels in healthy persons of different age.
Methods: :
Time dependent retinal vessel reaction was measured in the right eye of 28 medically healthy volunteers. The volunteers were divided in 2 age groups of 14 persons each: youngs (21-32 years) and seniors (52-70 years). Vessel diameters of a retinal arterial and venous vessel segment were examined with DVA during 40 seconds in all subjects. Temporal vessel behavior was evaluated using methods of signal analysis. Oscillatory temporal changes of vessel diameter were divided into high-frequent (period < 1.5 s) and low-frequent (period ≥ 1.5 s).
Results: :
Phase difference between temporal arterial and venous vessel diameter changes was significantly higher in the young group (0.6(0.1;3.3) s (median(1. quartile;3. quartile)) compared to the senior group (0.1(-0.4;0.3) s) (p<0.03). In veins there was a significant difference in the rate of periodicity (RP) between the groups (p<0.01). In the senior group there was a significant difference in RP between arteries and veins (p<0.01).
Conclusions: :
High-frequency oscillations of vessel diameter correspond to the heart pulse rate and were more expressed in the senior group. We were able to see high-frequency changes in venous diameter (spontaneous venous pulse) in the majority of healthy subjects independent of age. Low-frequency oscillations with a period of 6-15 s were well expressed in healthy youngs. Our results show significant difference between arterial and venous temporal vessel behavior as well as between vessel reactions in both age groups. These findings in dynamic vessel behaviour in aging might be an indication for age-specific changes of vascular endothelium and vessel wall rigidity leading to alterations in the retinal autoregulation.
Keywords: aging • blood supply • retina