Mechanisms of Choroidal Blood Flow Changes During Dark/Light Transitions
There is evidence from a variety of animal studies that choroidal blood flow is under neural control. By contrast, only little information is available from human studies. Recent results indicate that a light/dark transition is associated with a short lasting reduction in choroidal blood flow. We have shown that during unilateral dark/light transition both eyes react with choroidal vasoconstriction strongly indicating a neural mechanism.
The present studies investigate this possibility by using pharmacological interventions. The pharmacological agents tested include a nitric oxide synthase inhibitor, an alpha-receptor agonist (as a control substance for the blood pressure increasing nitric oxide synthase inhibitor), a muscarinic receptor blocker, and a non-specific beta-blocker. These drugs were chosen on the basis of previous animal experiments, as the systems, which are specifically influenced by these substances, are likely involved in neural control of choroidal blood flow.
|Regional Blood Flow Ocular Physiology||Drug: Phenylephrine Drug: NG-Monomethyl-L-Arginine Drug: Propanolol Drug: Atropine||Phase 2|
|Study Design:||Allocation: Randomized
Intervention Model: Crossover Assignment
Primary Purpose: Treatment
|Official Title:||Mechanisms of Choroidal Blood Flow Changes During Dark/Light Transitions|
Please refer to this study by its ClinicalTrials.gov identifier: NCT00431392
|Department of Clinical Pharmacology, Medical University of Vienna|
|Vienna, Austria, 1090|
|Principal Investigator:||Michael Wolzt, MD||Department of Clinical Pharmacology, Medical University of Vienna|