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G. Weigert, G. T. Dorner, J. Kolodjaschna, M. Wolzt, L. Schmetterer, G. Garhofer; Role of Adenosine in the Control of Choroidal Blood Flow During Changes in Ocular Perfusion Pressure. Invest. Ophthalmol. Vis. Sci. 2007;48(13):2284.
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Adenosine has been demonstrated to play an important role in several physiological and pathophysiological processes of the eye. The present study investigated whether adenosine plays a role in choroidal autoregulation during a decrease in ocular perfusion pressure.
A randomized double masked, placebo-controlled, two way cross-over study was performed in 8 young, healthy volunteers. Placebo (NaCl 0.9%) or adenosine (40µg/kg/min) was administered intravenously over 30 minutes. The increase in ocular pressure was achieved by the application of a suction cup. The suction force was increased in 3 consecutive steps from 50 mmHg up to 125 mm Hg. Each step was maintained for 2 minutes. Choroidal blood flow was measured continously during baseline and during the different suction levels. After a resting period a suction cup was applied again and IOP was measured at each incremental step. Finally, the blood flow measurements were performed again during suction, in presence or absence of adenosine in the selected dose. Systemic blood pressure was measured in 2 minutes intervals during the study period and ECG and heart rate were monitored continously.
Intraocular pressure (IOP) increased during suction from 11±2 to 25±2, 30±2, 33±2 and 37±2 mmHg, respectively. Choroidal blood flow decreased during the suction cup period in both groups reaching a maximum of -40% (p<0.05). However, this effect was not altered by the administration of adenosine (p=0.1).
Our study confirms that a pronounced increase of IOP significantly decreases choroidal blood flow. Additionally, administration of adenosine did not influence the effect of increased IOP on choroidal blood flow.
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