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Leopold Schmetterer, Mozhgan Sharifizad, Gerold Aschinger, Doreen Schmidl, Gerhard Garhofer, Rene Marcel Werkmeister; Flicker-Induced Retinal Vasodilation in Healthy Subjects. Invest. Ophthalmol. Vis. Sci. 2017;58(8):3038.
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© ARVO (1962-2015); The Authors (2016-present)
The aim of the present study was to analyze factors associated with retinal arterial and venous responses to stimulation with diffuse luminance flicker in healthy subjects.
We analyzed results obtained in 374 healthy subjects who had previously participated in clinical studies. A total of 153 subjects underwent a protocol in which flicker stimulation was delivered at a frequency of 8 Hz (protocol 1). In this protocol measurement and stimulation light are separated based on the wavelength. Another 221 subjects underwent a protocol in which diffuse luminance flicker was delivered at 12.5 Hz (protocol 2). Modulation depth in this protocol was almost 100%. We investigated whether sex, systemic blood pressure, baseline vessel size, blood plasma concentration of fasting glucose and hematocrit, and serum concentration of cholesterol, triglycerides, creatinine and C-reactive protein were associated with the retinal arterial and venous in response to flicker stimulation.
Flicker responses in arteries and veins were more pronounced in protocol 2 as compared to protocol 1 (P < 0.001, each). In both protocols the vascular response to stimulation with diffuse luminance flicker was larger in smaller vessels (P between 0.001 and 0.016). In protocol 2 the retinal arterial flicker response was negatively associated with cholesterol serum levels (P = 0.033). In protocol 1, only a tendency toward this effect was observed (P = 0.056).
The present analysis indicates that retinal arterial and venous responses to stimulation with diffuse luminance flicker depend on the way the stimulation is delivered through the fundus camera. The protocol providing a modulation depth of almost 100% resulted in a more pronounced vascular response. In addition, the flicker response varied with vessel size: the smaller the vessel width, the larger the flicker response. Finally, our data indicate that, even within the normal range, higher cholesterol serum levels are associated with lower hyperemic flicker responses.
This is an abstract that was submitted for the 2017 ARVO Annual Meeting, held in Baltimore, MD, May 7-11, 2017.
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