The Effect of Hyperoxia and Hypoxia on Fluorescence Lifetime Imaging Ophthalmoscopy in Healthy Subjects- a Randomized, Double Blind, Crossover Study

Study Overview
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Brief Summary
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The present study aims to investigate whether FLIO can also detect shorttime changes in retinal metabolism induced by hyperoxia and hypoxia. For this purpose, 48 healthy subjects will be included in the present study and changes in FLIO will be assessed during breathing of 100% oxygen to induce hyperoxia as well as during breathing of 12% oxygen in nitrogen to induce hypoxia. Since stimulation with flickering light also induces a higher metabolic demand in the retina (functional hyperemia), thisprovocation test will also applied during breathing of the different gas mixtures and compared to baseline. To gain information about retinal blood flow, optical coherence tomography angiography (OCT-A) will be performed. The results of the present study can help to gain more insight into the physiology of the retinal metabolism and might give grounds to establish new biomarkers in future studies.

Official Title
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The Effect of Hyperoxia and Hypoxia on Fluorescence Lifetime Imaging Ophthalmoscopy in Healthy Subjects- a Randomized, Double Blind, Crossover Study

Conditions
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To Investigate the Effect of 100% Oxygen Breathing on Fluorescence Lifetime Imaging Ophthalmoscopy (FLIO) in Healthy Subjects

Intervention / Treatment
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* Drug: SAUERSTOFF
* Drug: STICKSTOFF


Participation Criteria
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Eligibility Criteria
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Inclusion Criteria: Men and women aged between 18 and 35 years Normal ophthalmic findings Ametropia ≤ 6 diopters Normal findings in the medical history and physical examination including ECG unless the investigator considers an abnormality to be clinically irrelevant Nonsmokers Exclusion Criteria: Regular use of medication, abuse of alcoholic beverages or drugs Participation in a clinical trial in the 3 weeks preceding the study Treatment in the previous 3 weeks with any drug (except contraceptives) Symptoms of a clinically relevant illness in the 3 weeks before the first study day Blood donation during the previous 3 weeks History or family history of epilepsy Pregnant or breast-feeding women Women of childbearing potential (neither menopausal, nor hysterectomized, nor sterilized) not using effective contraception

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
Allocation: Randomized
Intervention Model: Crossover Assignment
Masking: Double


Arms and Interventions

| Participant Group/Arm | Intervention/Treatment |
| --- | --- |
| Experimental: 1<br> | Drug: SAUERSTOFF<br>* SAUERSTOFF medizinisch, Messer GmbH, Industriestrasse 5, 2352 Gumpoldskirchen, Austria Dose: min. 95.5%, breathing for 30 minutes<br>Drug: STICKSTOFF<br>* STICKSTOFF medizinisch, Messer GmbH, Industriestrasse 5, 2352 Gumpoldskirchen, Austria Dose: 88% with 12% oxygen, breathing for 30 minutes<br>|
| Experimental: 2<br> | Drug: SAUERSTOFF<br>* SAUERSTOFF medizinisch, Messer GmbH, Industriestrasse 5, 2352 Gumpoldskirchen, Austria Dose: min. 95.5%, breathing for 30 minutes<br>Drug: STICKSTOFF<br>* STICKSTOFF medizinisch, Messer GmbH, Industriestrasse 5, 2352 Gumpoldskirchen, Austria Dose: 88% with 12% oxygen, breathing for 30 minutes<br>|

What is the study measuring?
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Primary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in FLIO induced by hyperoxia |  | 15 minutes | 

Secondary Outcome Measures

| Outcome Measure | Measure Description | Time Frame |
| --- | --- | --- |
| Changes in FLIO induced by hypoxia |  | 15 minutes | 
| Changes in FLIO induced by flicker stimulation |  | 15 minutes | 
| Changes in OCT-A induced by hyperoxia |  | 15 minutes | 
| Changes in OCT-A induced by hypoxia |  | 15 minutes | 
| Changes in OCT-A induced by flicker stimulation |  | 15 minutes | 
| Retinal oxygen saturation |  | 15 minutes | 
| Retinal vessel diameter |  | 15 minutes | 
| Changes in peripheral oxygen saturation |  | 15 minutes | 
| Changes in blood gas parameters (pH, pCO2, PO2 and SaO2) |  | 15 minutes |