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I. M. Lanzl, C. v. Düring, S.-F. Seidova, K. Kotliar; Spontaneous and Flicker Induced Dynamic Retinal Vessel Reaction in Primary Open Angle Glaucoma. Invest. Ophthalmol. Vis. Sci. 2008;49(13):3266.
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Impaired vascular regulation might contribute to glaucomatous damage. Whether retinal branch arteries and veins of healthy persons and primary open angle glaucoma (POAG) patients show different dynamic behaviour and different reactions in response to flickering light is investigated.
Vessel diameters of retinal vessel segments were assessed by Dynamic Vessel Analyzer (DVA) in 28 POAG patients (stage I, 54.3±9.9 years old) after 4 week wash-out of eye drops and in 28 age and gender matched medically healthy volunteers. After baseline measurement (50 s) monochromatic rectangular flicker stimulation (530-600 nm, 12.5 Hz, 20 s) was applied 3 consecutive times. Mathematical and statistical data analysis independent from the commercial DVA program was performed. Baseline vessel reactions were analyzed for periodic pulsations using signal analyzing (1). Vessel diameter reaction was analyzed in its temporal sequence following the stimulus (2).
(1) We found a significant difference in low-frequency oscillations in arteries at baseline between both groups: mean period 3.6±3.0 s in POAG and 7.7±3.8 s in the control group (p<0.05). In veins high-frequency oscillations show a significantly decreased periodicity in POAG vs. normals (p<0.05; U-test). The rate of periodicity amounted to 0.140±0.100 and 0.255±0.145 respectively.(2) In most subjects prompt vessel dilation in response to flicker and an ensuing reactive arterial constriction were observed. No significant differences in arterial or venous dilation in response to the stimulation were found between the groups. Reactive arterial constriction occurred later in the POAG group (49.9±26.7 s vs. 25.5±18.1 s; p<0.01). Venous restoration occurred faster in POAG: area under the venous curve following the stimulation in POAG amounted to -1.1±16.9 s*% vs. 27.9±34.3 s*% in normals.
(1) Low-frequency oscillations with a period of 6-15 s reflect myogenic vasomotion. They are well expressed in healthy seniors and almost absent in POAG. High-frequency changes in venous diameter corresponding to venous pulsation were decreased in POAG group. (2) Reactive arterial constriction following the flicker stimulation appeared later and venous restoration occurred faster in POAG than in healthy controls. These findings in dynamic vessel behaviour (1) and the time course of vessel reaction to flicker (2) in POAG might be an indication for alterations in vessel wall rigidity (1), autonomous vessel regulation (1,2) and vascular endothelial function (1,2) in glaucoma.
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