Measurement of Retinal Blood Flow, Retinal Oxygenation and Retinal Oxygen Extraction in Healthy Subjects During Normoxia and Systemic Hyperoxia

Study Overview
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Brief Summary
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The inner retina is crucially dependent on an adequate retinal blood supply. When the retina becomes ischemic and hypoxic this results in severe vision loss due to retinal neovascularization. Measurement of retinal blood flow and retinal oxygenation is, however, still a difficult task. Information on retinal oxygenation is almost unavailable from human studies. In the present protocol the investigators propose a procedure allowing for the measurement of retinal blood flow, retinal oxygenation and retinal oxygen extraction by combining a number of innovative techniques. Specifically, retinal vessel diameters will be measured with a Retinal Vessel Analyzer, retinal blood velocities with bi-directional laser Doppler velocimetry and retinal oxygenation with spectroscopic evaluation of retinal fundus images. This will allow for the calculation of retinal oxygen extraction, a fundamental parameter of retinal function. Up to now, no data for retinal oxygen extraction are available in the literature.

Official Title
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Measurement of Retinal Blood Flow, Retinal Oxygenation and Retinal Oxygen Extraction in Healthy Subjects During Normoxia and Systemic Hyperoxia

Conditions
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Healthy, Normoxia, Systemic Hypoxia

Intervention / Treatment
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* Drug: Oxygen


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Men and women aged between 18 and 35 years Nonsmokers Body mass index between 15th and 85th percentile 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 except oral contraceptives Symptoms of a clinically relevant illness in the 3 weeks before the first study day Blood donation during the previous 3 weeks Pregnancy

Ages Eligible for Study
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Minimum Age: 18 Years
Maximum Age: 35 Years

Sexes Eligible for Study
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All

Accepts Healthy Volunteers
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Accepts Healthy Volunteers

Study Plan
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How is the study designed?
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Design Details

Primary Purpose: Basic Science
Intervention Model: Single Group Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Healthy subjects<br> | Drug: Oxygen<br>* 100% Oxygen inhalation for 30 minutes<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Retinal blood velocity Retinal vessel diameters Oxygen saturation of retinal vessels Oxygen extraction as calculated from these parameters |  | 20 min ocular blood flow measurement on 1 study day | 

 Terms related to the study
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Keywords Provided by Centre Hospitalier Valida
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Ocular physiology