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Akbar Shakoor, Norman P. Blair, Marek Mori, Mahnaz Shahidi; Chorioretinal Vascular Oxygen Tension Changes in Response to Light Flicker. Invest. Ophthalmol. Vis. Sci. 2006;47(11):4962-4965. doi: 10.1167/iovs.06-0291.
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purpose. To investigate oxygen tension (Po 2) changes in the retinal and choroidal vasculatures in response to visual stimulation by light flicker.
methods. A previously developed optical section phosphorescence imaging system was used to measure Po 2 separately in the retinal veins, arteries, and capillaries and in the choroid before and during light flicker. Imaging was performed in rats during light flicker at frequencies between 0 and 14 Hz. Light flicker–induced changes in the chorioretinal vasculature Po 2 and arteriovenous Po 2 differences were determined. Retinal arterial and venous Po 2 were measured along blood vessels as a function of the distance from the optic nerve head.
results. Retinal arterial Po 2 and arteriovenous Po 2 differences increased with increasing light flicker at frequencies up to 10 Hz, after which no further increase was observed. Significant increases in retinal arterial Po 2 (P = 0.009; n =10) and in retinal capillary Po 2 (P = 0.04, n = 10) were measured in response to light flicker at 10 Hz. Retinal arteriovenous Po 2 differences during light flicker were significantly greater than differences before light flicker (P = 0.01; n = 10). Retinal arterial Po 2 decreased significantly with increased distance from the optic nerve head (P ≤ 0.004), whereas retinal venous Po 2 remained relatively unchanged (P ≥ 0.4).
conclusions. Measurement of changes in the chorioretinal vasculature Po 2 can potentially advance the understanding of oxygen dynamics in challenged physiological states and in animal models of human retinal diseases.
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