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H. Kergoat, J.V. Lovasik, C.E. Riva, B.L. Petrig, M. Geiser; Dynamic Interactions between Choroidal Blood Flow, Ocular Perfusion Pressure and Vascular Resistance during and after Aerobic Exercise . Invest. Ophthalmol. Vis. Sci. 2003;44(13):345.
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© ARVO (1962-2015); The Authors (2016-present)
Purpose: For almost 30 years, the dominant viewpoint regarding ocular blood flow has been that the choroidal blood flow (ChBF) is passively determined by the ocular perfusion pressure (OPP). The recent development of a compact confocal laser Doppler flowmetry (cLDF) optical system has allowed us to measure moment-to-moment changes in the ChBF both during and after aerobic exercise used to change the OPP. The objective of the present study was to quantify the interaction among the ChBF, the OPP and vascular resistance during physiologically induced changes in the OPP. Methods: Seven healthy adult (mean age: 29 +/-4.5 years) volunteers were trained to bike on a stationary bicycle (Ergociser) to increase their OPP and simultaneously have their ChBF and systemic BP measured. The latter was quantified with a Colin-7000 NIBP system which provided the BP values required to derive the OPP. The resting IOP was the final variable in the calculation of the OPP. The ChBF and OPP were compared over 20 min of biking and during a 10 min recovery interval. Results: The group average IOP was 13.3 +/- 2.1 mmHg. Within 150 sec. of biking, the OPP exceeded resting values by 43% (p=0.0001) and then decreased slowly to remain ~12% above resting value by the end of biking. In contrast, the ChBF stayed well within 10% of basal value throughout biking but did show a significant increase over time. When biking stopped, the OPP and ChBF decreased by 20% (p=0.0001) and 10% (p=0.0095) respectively in the first 200sec. and remained at those levels during recovery. The calculated vascular resistance (R=OPP/ChBF) was strongly correlated with the OPP (r= 0.962, p= 0.0001) during biking but less so (r= 0.498, p= 0.0001) during the recovery. Conclusions: The divergence between OPP and ChBF during increased / decreased OPP pointed to some mechanism keeping ChBF close to baseline. The increased vascular resistance during aerobic exercise suggested that sympathetic vasoconstriction may be involved in the control of blood flow in the choroid.
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