Abstract
Purpose :
Vascular risk factors contribute to the development of Alzheimer's disease (AD). We demonstrated previously that functional retinal arterial reaction to flicker stimulation and retinal arterial vasomotions changed in mild-to-moderate AD. The spatial structure of the retinal artery blood column measured along the vessel axis is termed longitudinal arterial profile (LAP). It reflects configuration of internal retinal arterial wall and can be assessed with modern in-vivo retinal imaging. Whether LAP is altered in retinal arteries of AD patients and whether it changes during vascular constriction/dilation is investigated.
Methods :
Two groups of participants were examined by Dynamic Vessel Analyzer (IMEDOS Systems): 13 patients, 72.7(67.1 – 78,6) y.o. [median (1st. quartile – 3rd quartile)], with mild-to-moderate dementia due to probable AD fulfilling the standard diagnostic criteria (ADD); and 15 anamnestic healthy control subjects 69.2(60.9 – 71.1) y.o. without cognitive impairment (HC). In retinal arterial segments of approximately 1 mm in length vessel diameters were measured with a spatial resolution of 10µ in order to obtain LAP at different stages of arterial reaction to flicker. Differences in amplitude and frequency of spatial vessel diameter changes were analysed using Fourier transformation.
Results :
The magnitude of spatial arterial diameter changes did not differ between the groups during all stages of the arterial response. At the baseline it amounted to: 21(16 – 29) µm in HC and to 20(6 – 22) µm in AD. Compared to the arteries of HC power spectra of LAP in AD patients showed pronounced waves with a period of 170 – 250 µm during vasodilation but not during baseline and constriction phases (parameter: area under the power spectra at certain frequency ranges, p<0.05, Mann-Whitney test). In the meantime low spatial frequencies with a period of 330 – 500 µm tended to be less emphasized in AD patients in comparison to HC during vasodilation (p <0.1).
Conclusions :
Dynamic functional alterations of retinal arteries in AD dementia are shown using a non-invasive in-vivo technique. Retinal arteries of AD patients tended to change their internal microstructure during vasodilation. Since dynamic retinal vessel analysis provides a direct non-invasive assessment of microcirculatory damage, it could allow for additional diagnostic characterization of AD.
This is an abstract that was submitted for the 2018 ARVO Annual Meeting, held in Honolulu, Hawaii, April 29 - May 3, 2018.