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

Medical University of Vienna

Status: Completed

Conditions: Regional Blood Flow; Ocular Physiology

Treatments: Dietary Supplement: Placebo; Dietary Supplement: vitamin C (Mayrhofer) 24mg/min i.v. for 64 min; Other: 100% O2 (AGA) two times for 12 min

Study type: Interventional

Funder types: Other

Identifiers

NCT00712907

OPHT-161202

Details and patient eligibility

About

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.

Enrollment: 12 patients

Sex: Male

Ages: 19 to 35 years old

Volunteers: Accepts Healthy Volunteers

Inclusion criteria

• Men aged between 19 and 35 years, nonsmokers
• Body mass index between 15th and 85th percentile (Must A 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, ametropia < 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

Trial design

Primary purpose: Diagnostic

Allocation: Randomized

Interventional model: Crossover Assignment

Masking: Double Blind

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12 participants in 2 patient groups, including a placebo group

1

Active Comparator group

Description:

vitamin C (Mayrhofer)

Treatment:

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

Other: 100% O2 (AGA) two times for 12 min

2

Placebo Comparator group

Description:

Placebo

Treatment:

Dietary Supplement: Placebo

Other: 100% O2 (AGA) two times for 12 min