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A. Wiermann, M. Klemm, J. Mayer, D. Hufnagel, P. Galambos, L. Wagenfeld, G. Richard, O. Zeitz; Analysis of the Spectral Waveform of Doppler Measurements of the Short Posterior Ciliary Artery After Flicker Stimulation. Invest. Ophthalmol. Vis. Sci. 2008;49(13):4134.
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© ARVO (1962-2015); The Authors (2016-present)
To assess alterations of the regulation of ocular perfusion, methods are required which combine measurements of ocular perfusion with the provocation of hemodynamic regulation. For this purpose we propose a combination of retinal flicker stimulation with color Doppler imaging (CDI). In the present, an analysis of the spectral waveform of CDI measurements is provided. This analysis gives more detailed insight into the CDI results than the classic evaluation of peak systolic and end-diastolic velocity does (ARVO posters 2006:487 and 2007:2296).
9 glaucoma patients and 9 healthy volunteers were enrolled in the study. Color Doppler Imaging was performed with a Siemens Elegra set-up (transducer 7.5L40 at 6.5 MHz). The short posterior ciliary artery (SPCA) was investigated. Through the closed eye lids the retina was stimulated by a 10 Hz flicker after a baseline measurement. CDI measurements were repeated after 15s of flicker stimulation, as well as 60 and 120s after termination of the flicker light stimulation. Spectral waveforms were analyzed with an image analysing computer program (DigitizeIT®). The time of visible blood flow was determined as percentage of the whole cardiac cycle. For statistics an ANOVA model was applied.
Flicker light led to an increase of visible blood flow from 88.0±8.0 to 96.7±3.3% of the cardiac cycle in healthy volunteers. Glaucoma patients had reduced visible blood flow at baseline, and the increase observed in presence of flicker was less pronounced (83.3±7.3 vs. 88.2±5.1%). After termination of the flicker, the visible blood flow remained higher than at baseline in healthy volunteers (93.3±7.0% after 15s and 92.4±5.1% after 120s), whereas in glaucoma patients the blood flow decreased to values below baseline (79.0±8.0% after 15s and 82.0±6.8% after 120s).
The present study shows an increased retinal perfusion due to flicker stimulation in healthy volunteers in the SPCA. The flicker response in glaucoma patients deviates from that of healthy volunteers, which may indicate altered regulation of ocular perfusion in the glaucoma population of this study.
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