The Mechanisms of Diameter Changes in Retinal Vessels During Hypoxia

Study Overview
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Brief Summary
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The primary objective is to study if a stimulation of nitric oxide and/or prostaglandin affect the diameter changes of retinal vessels during hypoxia. Diameter changes are studied using the Dynamic Vessel Analyzer.

Official Title
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The Underlying Mechanisms of Diameter Changes in Retinal Vessels During Hypoxia

Conditions
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Retinal Hypoxia

Intervention / Treatment
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* Drug: COX-inhibitor
* Drug: Nitroglycerin
* Drug: COX-inhibitor + Nitroglycerin


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Age between >19 and <61 years No known systemic or ocular diseases Exclusion Criteria: Cardio-vascular disease Lung disease Epilepsy Previous ocular disease Previous treatment with medications influencing the intraocular pressure or the metabolism of nitric oxide or prostaglandins Daily intake of medicine except contraceptive pills Pregnancy or breastfeeding Known allergy against any of the drugs used in the interventions

Ages Eligible for Study
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Minimum Age: 20 Years
Maximum Age: 60 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
Allocation: Non-Randomized
Intervention Model: Crossover Assignment
Masking: None (Open Label)


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: Hypoxia<br>Inhaling hypoxic gas mixture to induce hypoxemia during recordings of diameter changes of retinal vessels. Recording are performed during hypoxia alone and in combination with the associated interventions over two examination days | Drug: COX-inhibitor<br>* Administration of 1 drop voltaren 45 minutes before recordings of diameter changes of retinal vessels are initiated<br>* Other names: Voltaren eye drops;Drug: Nitroglycerin<br>* Oral administration of tablet nitroglycerin 0,5mg 5 minutes before recordings of diameter changes of retinal vessels are initiated<br>* Other names: Glyceryl Nitrate;Drug: COX-inhibitor + Nitroglycerin<br>* Combination of COX-inhibitor and nitroglycerin interventions.<br>|
| Experimental: Normoxia<br>Breathing atmospheric air during recordings of diameter changes of retinal vessels. Recording are performed during normoxia alone and in combination with the associated interventions over two examination days | Drug: COX-inhibitor<br>* Administration of 1 drop voltaren 45 minutes before recordings of diameter changes of retinal vessels are initiated<br>* Other names: Voltaren eye drops;Drug: Nitroglycerin<br>* Oral administration of tablet nitroglycerin 0,5mg 5 minutes before recordings of diameter changes of retinal vessels are initiated<br>* Other names: Glyceryl Nitrate;Drug: COX-inhibitor + Nitroglycerin<br>* Combination of COX-inhibitor and nitroglycerin interventions.<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Diameter changes of retinal vessels | Comparing the differences of diameter changes occuring during each of interventions | Examination day 1 and 2 |