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Effects of Vitamin C on Hyperoxia-Induced Reduction of Retinal Blood Flow

NCT00712907 · Status: COMPLETED · Phase: NA · Type: INTERVENTIONAL · Enrollment: 12

Last updated 2008-07-10

No results posted yet for this study

Summary

High arterial blood oxygen tension leads to vasoconstriction of retinal vessels, possibly related to an interaction between reactive oxygen species and endothelium-derived vasoactive factors. Vitamin C is a potent antioxidant capable of reversing endothelial dysfunction due to increased oxidant stress. Vitamin C appears to have vasodilatory properties, but the underlying mechanisms are not well understood.

In the present study we hypothesized that hyperoxic vasoconstriction of retinal vessels could be diminished by vitamin C.

Ocular blood flow will be determined by non-invasive methods, including laser Doppler velocimetry and the Zeiss retinal vessel analyser.

Conditions

  • Ocular Physiology
  • Regional Blood Flow

Interventions

DIETARY_SUPPLEMENT

vitamin C (Mayrhofer) 24mg/min i.v. for 64 min

Substance: Ascorbic acid (Mayrhofer) Manufacturer: Mayrhofer, Linz, Austria Dosage form: i.v. Dosage: 24mg/min over 64 min Dosage reference: Ting HH 1996

DIETARY_SUPPLEMENT

Placebo

Substance: Physiologic saline solution 0.9% (placebo) Dosage form: i.v. Dosage: 24ml/min over 64 min

OTHER

100% O2 (AGA) two times for 12 min

Substance: 100% oxygen (AGA, Vienna, Austria, gases for human use) Manufacturer: AGA, Vienna, Austria, gases for human use Dosage form: Inhalation through an oxygenmask over a period of 12 minutes two times per study day. Dosage reference: Strenn K 1997

Sponsors & Collaborators

  • Medical University of Vienna

    lead OTHER

Study Design

Allocation
RANDOMIZED
Purpose
DIAGNOSTIC
Masking
DOUBLE
Model
CROSSOVER

Eligibility

Min Age
19 Years
Max Age
35 Years
Sex
MALE
Healthy Volunteers
Yes

Timeline & Regulatory

Start
2003-02-28
Primary Completion
2003-05-31
Completion
2003-05-31

Countries

  • Austria

Study Locations

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Read the full study record

This page highlights key information. For complete eligibility criteria, study locations, investigator contacts, and the full protocol, visit the original record on ClinicalTrials.gov.

View NCT00712907 on ClinicalTrials.gov