The Response of Intraocular Pressure to Systemic Hypercapnia & Hyperoxia

Status Not yet recruiting

Clinical Trial Summary

The purpose of this study is to determine how intraocular pressure responds to changes in the levels of carbon dioxide or oxygen that a healthy individual inspires.

Clinical Trial Description

In response to changes in the composition of inhaled gases, blood vessels will dilate or constrict. As a result, hypercapnia or hyperoxia may affect the production and drainage of aqueous humour in the anterior chamber of the eye. The balance between the production and drainage of the aqueous humour determines the intraocular pressure. As this system is hydrodynamic, it is expected that any increase or decrease in the production of aqueous humour due to dilation or constriction of the capillaries within the ciliary body will be compensated by increased or decreased drainage at the trabecular meshwork. Therefore intraocular pressure is not expected to show a response to hypercapnia or hyperoxia, but this supposition needs to be tested in a stably controlled manner of inducing inhaled gas provocations. This study will measure the intraocular pressure at varying levels of hypercapnia and hyperoxia using a sequential rebreathing circuit and automated gas blender. This will allow the precise targeting and stable control of end-tidal partial pressure values of carbon dioxide and oxygen.

In this study, intraocular pressure will be measured at seven different inhaled gas stages. The seven stages are as follows:

1. Baseline, measured in eye A (PETCO2=38mmHg and PETO2=100mmHg)

2. 10% hypercapnic increase, measured in eye A (PETCO2=42mmHg and PETO2=100mmHg)

3. 20% hypercapnic increase, measured in eye A (PETCO2=46mmHg and PETO2=100mmHg)

4. Baseline, measured in both eyes (PETCO2=38mmHg and PETO2=100mmHg)

5. 250% hyperoxic increase, measured in eye B (PETCO2=38mmHg and PETO2=250mmHg)

6. 500% hyperoxic increase, measured in eye B (PETCO2=38mmHg and PETO2=500mmHg)

7. Baseline, measured in eye B (PETCO2=38mmHg and PETO2=100mmHg) ;

Study Design

Observational Model: Case-Only, Time Perspective: Cross-Sectional

Related Conditions & MeSH terms

Clinical Trial Details

NCT number	NCT01325285
Study type	Observational
Source	University of Toronto
Contact	Alanna Adleman, BSc
Phone	416-603-5694
Email	aadleman@uhnresearch.ca
Status	Not yet recruiting
Phase	N/A
Start date	August 2011
Completion date	September 2011

View Details

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Clinical trials are conducted in a series of steps, called phases - each phase is designed to answer a separate research question.

Phase 1: Researchers test a new drug or treatment in a small group of people for the first time to evaluate its safety, determine a safe dosage range, and identify side effects.
Phase 2: The drug or treatment is given to a larger group of people to see if it is effective and to further evaluate its safety.
Phase 3: The drug or treatment is given to large groups of people to confirm its effectiveness, monitor side effects, compare it to commonly used treatments, and collect information that will allow the drug or treatment to be used safely.
Phase 4: Studies are done after the drug or treatment has been marketed to gather information on the drug's effect in various populations and any side effects associated with long-term use.

The Response of Intraocular Pressure to Systemic Hypercapnia and Hyperoxia

Clinical Trial Summary

Clinical Trial Description

Study Design

Related Conditions & MeSH terms