Dopaminergic Modulation of Choroidal Blood Flow Changes During Dark/Light Transitions

Regional Blood Flow Clinical Trial

Official title: Dopaminergic Modulation of Choroidal Blood Flow Changes During Dark/Light Transitions

Status Completed

Clinical Trial Summary

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 reduction in choroidal blood flow due to an unknown mechanism. We have shown that during unilateral dark/light transitions both eyes react with choroidal vasoconstriction strongly indicating a neural mechanism responsible for the blood flow changes.

Dopamine has been discussed as a chemical messenger for light adaptation. However, dopaminergic effects in the eye are not restricted to synaptic sites of release, but dopamine also diffuses to the outer retinal layers and pigment epithelium. Accordingly, dopaminergic effects also include a modulatory role on retinal vessel diameter and animal studies provide evidence for vasodilatory effects in the choroid. There is evidence that during darkness retinal and choroidal dopamine levels decrease. Accordingly, dopamine could provide a modulatory input to the light/dark transition induced changes of choroidal circulation. The aim of the present study is to test this hypothesis.

Clinical Trial Description

n/a

Study Design

Allocation: Randomized, Endpoint Classification: Safety/Efficacy Study, Intervention Model: Crossover Assignment, Masking: Double Blind (Subject, Investigator), Primary Purpose: Treatment

Related Conditions & MeSH terms

• Ocular Physiology
• Regional Blood Flow

• NCT number: NCT00280501
• Study type: Interventional
• Source: Medical University of Vienna
• Status: Completed
• Phase: N/A
• Start date: August 2005
• Completion date: August 2006