Comparison of the Diameter Response of Retinal Arteries and Veins Caused by Flicker Light. A Clinical Study with Healthy Volunteers
Nagel E.1, Vilser W. 2
1Ophthalmic Private Practice, Rudolstadt; 2Technical University, Ilmenau
Purpose: To compare the diameter response of retinal arteries and veins after provocation by flicker light regarding the amplitude and the temporal course.
Method: 26 eyes of 26 healthy volunteers (age 22 to 69 years, mean 44.2) without evidences of systemic or ocular diseases in their medical history were examined. The vessel diameter was automatically and continuously measured by the Retinal Vessel Analyzer (RVA, IMEDOS Weimar). The examination consisted of a baseline measurement (100 s) followed by 5 periods of 20 s flicker light provocation and 80 s follow-up observation. The 5 periods of provocation were averaged. The rectangle luminance flicker worked at 12.5 Hz in a green colour (530 - 600 nm). The blood pressure was measured minutely during the examination.
Results: A diameter dilation was observed immediately after the end of the flicker period in arteries (6.9% ± 2.8) and veins (6.5% ± 2.8, difference n.s.). The av-quotient of arterial dilation / venous dilation was 1.25 ± 0.69 (range 0.2 to 2.8). The arterial diameter reduced faster then the venous and reached a minimum of -2.7% ± 1.4 at 25.9 s ± 10.8 after the end of the flicker phase. The veins were dilated by +0.5% ± 1.3 at this time of the maximal individual arterial constriction (p<0.0001). The blood pressure did not c
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