Mechanisms of Choroidal Blood Flow Changes During Dark/Light Transitions

Sponsor

Medical University of Vienna (Other)

Overall Status

Completed

CT.gov ID

NCT00431392

Collaborator

(none)

Enrollment

Location

Study Details

Study Description

Brief 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 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.

Condition or Disease	Intervention/Treatment	Phase
Regional Blood Flow Ocular Physiology	Drug: Phenylephrine Drug: NG-Monomethyl-L-Arginine Drug: Propanolol Drug: Atropine	Phase 2

Study Design

Study Type:

Interventional

Allocation:

Randomized

Intervention Model:

Crossover Assignment

Masking:

Double

Primary Purpose:

Treatment

Official Title:

Mechanisms of Choroidal Blood Flow Changes During Dark/Light Transitions

Study Start Date :

Sep 1, 2001

Outcome Measures

Primary Outcome Measures

choroidal blood flow []
fundus pulsation amplitude []

Eligibility Criteria

Criteria

Ages Eligible for Study:

19 Years to 35 Years

Sexes Eligible for Study:

Male

Accepts Healthy Volunteers:

Yes

Inclusion Criteria:

Men aged between 19 and 35 years, nonsmokers
Body mass index between 15th and 85th percentile (Must et al. 1991)
Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant
Normal laboratory values unless the investigator considers an abnormality to be clinically irrelevant
Normal ophthalmic findings, ametropy < 3 Dpt.

Exclusion Criteria:

Regular use of medication, abuse of alcoholic beverages, participation in a clinical trial in the 3 weeks preceding the study
Treatment in the previous 3 weeks with any drug
Symptoms of a clinically relevant illness in the 3 weeks before the first study day
History of hypersensitivity to the trial drug or to drugs with a similar chemical structure
History or presence of gastrointestinal, liver or kidney disease, or other conditions known to interfere with, distribution, metabolism or excretion of study drugs
Blood donation during the previous 3 weeks