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E. Nagel, W. Vilser; Age and Retinal Arterial Flicker Response: Preliminary Results . Invest. Ophthalmol. Vis. Sci. 2003;44(13):348.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: Flicker stimulation is known to increase retinal arterial diameter in humans. The aim of the present study was to investigate the influence of age on the response of retinal arteries to stimulation by luminance flicker. Methods: In the study were enclosed 28 healthy volunteers (age 22 to 73 y, mean 45) without any history of systemic or eye diseases and without drug therapy. Diameter of retinal arteries was measured continuously by Retinal Vessel Analyzer (IMEDOS, Germany). Each examination consisted of 100 sec baseline measurement and 5 periods of 20 sec flicker stimulation followed by 80 sec of observation. The square wave luminance flicker works at 12.5 Hz and 530 - 600 nm. The amplitude of the flicker response (FR) was calculated as the difference of maximal dilatation and consecutive constriction of the vessel diameter after flicker stimulation by averaging of the 5 repetitions. Blood pressure (BP) was measured minutely. Results: Flicker stimulation induced a FR of 9.7%± 2.8 (mean ± SEM) in 24 volunteers with normotensive BP during examination. FR decreases slowly with increasing age (linear regression y=13.11-0.08x, R=0.4). The variance of FR enlarged with age ≥ 40 y (p=0.05). 4 volunteers with hypertensive BP during examination showed a reduced FR of 4.2% ± 1.3 (p=0.0029). Conclusions: The relationship between FR and age is nearly -1% per decade. There were observed distinctive responses in volunteers older than 60 y. Increased variance of FR in elderly persons could be caused by subclinical or unknown vascular diseases in some cases especially with small FR. Increasing BP during the examination could be the reason of the reduced FR of these 4 volunteers caused by myogenic vasoconstriction (Bayliss effect).
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