Intraocular PressureNCT01325285
The Response of Intraocular Pressure to Systemic Hypercapnia and Hyperoxia
An observational study of Intraocular Pressure, run by University of Toronto at 1 site in Canada.
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. Read more about this study
- Who is it for?
- Ages 18 to 30 yearsHealthy volunteers can take part
- Conditions the study is for
- Intraocular Pressure
- What is being tested?
- RespirAct
- Type of treatment
- Medical device
- How many people
- 14 participants
- Where
- 1 siteCanada
- Study dates
- Aug 2011to Sep 2011
- Phase
- Observational
- Are there results?
- None posted in the registry
Key requirements
Who can take part, as listed by the sponsor. Only the study team can confirm whether you are eligible, so take this list to your doctor.
- Ages 18 to 30 years
- All sexes
- Healthy volunteers accepted
- Adult
Study population: Healthy young individuals (age 18-30)
Who may be able to join
- Age range 18-30 years old
- Visual acuity of 20/20 or better
Who cannot join
- Refractive error >±6.00 DS and/or ± 2.00 DC
- History or presence of ocular disease
- Family history of diabetes or glaucoma
- History of intraocular or refractive surgery
- Nursing or pregnant women
- History of clinically diagnosed endocrine disease
Show all 10Show fewer
- History of vascular disease, cardiovascular disease, or any treated respiratory disorders (seasonal asthma excluded from this so long as subject not taking Rx at the time)
- History of systemic hypertension
- Habitual smoking
- Use of medications that affect blood flow
Trial locations and contacts
1 site in 1 country.
Canada1 site
Toronto Western Hospital
Toronto, Ontario
Alanna Adleman, BSc, 416-603-5694, aadleman@uhnresearch.ca
Tien Wong, BSc, 416-603-5694, twong@uhnresearch.ca
About this study
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.
Read the detailed 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:
- Baseline, measured in eye A (PETCO2=38mmHg and PETO2=100mmHg)
- 10% hypercapnic increase, measured in eye A (PETCO2=42mmHg and PETO2=100mmHg)
- 20% hypercapnic increase, measured in eye A (PETCO2=46mmHg and PETO2=100mmHg)
- Baseline, measured in both eyes (PETCO2=38mmHg and PETO2=100mmHg)
- 250% hyperoxic increase, measured in eye B (PETCO2=38mmHg and PETO2=250mmHg)
- 500% hyperoxic increase, measured in eye B (PETCO2=38mmHg and PETO2=500mmHg)
- Baseline, measured in eye B (PETCO2=38mmHg and PETO2=100mmHg)
- Conditions
- Intraocular Pressure
- Being tested
- RespirAct
- Keywords
- Intraocular pressure, Hypercapnia, Hyperoxia, Rebreathing circuit
- Medical subject headings
- Hypercapnia, Hyperoxia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
RespirActDevice
Also called Inhaled gas provocations
Participants will breathe through a mask connected to a sequential rebreathing circuit and gas blender. The following seven gas stages will be targeted for about 10 minutes each:
- Baseline, measured in eye A (PETCO2=38mmHg and PETO2=100mmHg)
- 10% hypercapnic increase, measured in eye A (PETCO2=42mmHg and PETO2=100mmHg)
- 20% hypercapnic increase, measured in eye A (PETCO2=46mmHg and PETO2=100mmHg)
- Baseline, measured in both eyes (PETCO2=38mmHg and PETO2=100mmHg)
- 250% hyperoxic increase, measured in eye B (PETCO2=38mmHg and PETO2=250mmHg)
- 500% hyperoxic increase, measured in eye B (PETCO2=38mmHg and PETO2=500mmHg)
- Baseline, measured in eye B (PETCO2=38mmHg and PETO2=100mmHg)
What is being measured
The primary outcome is the main question the study is designed to answer.
Intraocular pressure
Intraocular pressure will be measured using Goldmann applanation tonometry.
Measured: Intraocular pressure will be measured during the study visit, ten minutes into each of the seven inhaled gas provocation stages
Secondary outcomes (1)
Retinal blood flow
Retinal blood flow will be measured using the Canon Laser Blood Flowmeter in a subset of participants asked to return for a second visit. This will demonstrate that retinal blood flow behaves as the study claims that it does.
Measured: Retinal blood flow will be measured during the second (optional) study visit, ten minutes into each of the seven inhaled gas provocation stages
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted29 Mar 2011 (estimated)
- Study startAug 2011
- Primary completionSep 2011 (estimated)
- Study completionSep 2011 (estimated)
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Publications (2)Papers the sponsor has linked to this study.
- Other trials for Intraocular PressureStudies of the same condition, open and under way.
- More trials run by University of TorontoThe sponsor's other registered studies.
- What the trial phases meanHow a treatment moves from first tests in people to approval.
More details
For doctors and researchers: how the study is designed, who runs it, and its registry IDs.
Study design
- Study type
- Observational
- Observational model
- Case only
- Time perspective
- Cross-sectional
- Enrolment
- 14 participants (estimated)
Sponsor and investigators
- Lead sponsor
- University of Toronto
- Sponsor type
- University, hospital or other
- Collaborators
- University Health Network, Toronto, Thornhill Research
- Investigators
- Christopher Hudson, PhD, Principal investigator, University of Toronto
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT01325285
- Sponsor's protocol ID
- 10-0655
- Status last verified
- Nov 2010
- First submitted
- 15 Feb 2011
- Last updated
- 18 Aug 2011
- Results posted
- No
- Data monitoring committee
- No
Publications
Hosking SL, Harris A, Chung HS, Jonescu-Cuypers CP, Kagemann L, Roff Hilton EJ, Garzozi H. Ocular haemodynamic responses to induced hypercapnia and hyperoxia in glaucoma. Br J Ophthalmol. 2004 Mar;88(3):406-11. doi: 10.1136/bjo.2002.008995.
PubMed 14977778Slessarev M, Han J, Mardimae A, Prisman E, Preiss D, Volgyesi G, Ansel C, Duffin J, Fisher JA. Prospective targeting and control of end-tidal CO2 and O2 concentrations. J Physiol. 2007 Jun 15;581(Pt 3):1207-19. doi: 10.1113/jphysiol.2007.129395. Epub 2007 Apr 19.
PubMed 17446225
Study at a glance
From the registry record, last updated by the sponsor on 18 Aug 2011. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- The Response of Intraocular Pressure to Systemic Hypercapnia and Hyperoxia
- ClinicalTrials.gov ID
- NCT01325285
- Acronym / sponsor ID
- 10-0655
- Conditions
- Intraocular Pressure
- Keywords
- Intraocular pressure, Hypercapnia, Hyperoxia, Rebreathing circuit
- Study type
- Observational
- Recruitment status
- Unknown status
- Enrolment
- 14 participants (estimated)
- Lead sponsor
- University of TorontoUniversity, hospital or other
- Collaborators
- University Health Network, Toronto, Thornhill Research
- Study start
- Aug 2011
- Primary completion
- Sep 2011 (estimated)
- Study completion
- Sep 2011 (estimated)
- First posted
- 29 Mar 2011 (estimated)
- Results
- Not posted in the source record
Clinical summary
The research question as the sponsor registered it. This describes what the study plans to test, not what it found.
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.
Detailed 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:
- Baseline, measured in eye A (PETCO2=38mmHg and PETO2=100mmHg)
- 10% hypercapnic increase, measured in eye A (PETCO2=42mmHg and PETO2=100mmHg)
- 20% hypercapnic increase, measured in eye A (PETCO2=46mmHg and PETO2=100mmHg)
- Baseline, measured in both eyes (PETCO2=38mmHg and PETO2=100mmHg)
- 250% hyperoxic increase, measured in eye B (PETCO2=38mmHg and PETO2=250mmHg)
- 500% hyperoxic increase, measured in eye B (PETCO2=38mmHg and PETO2=500mmHg)
- Baseline, measured in eye B (PETCO2=38mmHg and PETO2=100mmHg)
Study design
- Observational model
- Case only
- Time perspective
- Cross-sectional
Who may qualify
- Ages
- 18 to 30 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
- Study population
- Healthy young individuals (age 18-30)
Key inclusion criteria (2 listed)
- Age range 18-30 years old
- Visual acuity of 20/20 or better
Key exclusion criteria (10 listed)
- Refractive error >±6.00 DS and/or ± 2.00 DC
- History or presence of ocular disease
- Family history of diabetes or glaucoma
- History of intraocular or refractive surgery
- Nursing or pregnant women
Eligibility is decided by the study team after screening; this overview does not establish that a patient qualifies. Full inclusion and exclusion criteria.
Interventions
| Intervention | Type | Arms |
|---|---|---|
| RespirActAlso: Inhaled gas provocationsParticipants will breathe through a mask connected to a sequential rebreathing circuit and gas blender. The following seven gas stages will be targeted for about 10 minutes each: 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) | Device | – |
Primary outcome
Intraocular pressure
Time frame: Intraocular pressure will be measured during the study visit, ten minutes into each of the seven inhaled gas provocation stages
Intraocular pressure will be measured using Goldmann applanation tonometry.
1 secondary outcome
Retinal blood flow
Time frame: Retinal blood flow will be measured during the second (optional) study visit, ten minutes into each of the seven inhaled gas provocation stages
Results and safety
Results are not available in the source record.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 18 Aug 2011.
- Background: PubMed 14977778Hosking SL, Harris A, Chung HS, Jonescu-Cuypers CP, Kagemann L, Roff Hilton EJ, Garzozi H. Ocular haemodynamic responses to induced hypercapnia and hyperoxia in glaucoma. Br J Ophthalmol. 2004 Mar;88(3):406-11. doi: 10.1136/bjo.2002.008995.
- Background: PubMed 17446225Slessarev M, Han J, Mardimae A, Prisman E, Preiss D, Volgyesi G, Ansel C, Duffin J, Fisher JA. Prospective targeting and control of end-tidal CO2 and O2 concentrations. J Physiol. 2007 Jun 15;581(Pt 3):1207-19. doi: 10.1113/jphysiol.2007.129395. Epub 2007 Apr 19.
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Referral and contact
AzTrials does not enrol participants or take referrals. Contact the study team or a site listed below; they decide who can take part. This study is not recruiting at the moment.
Christopher Hudson, PhD principal investigator
University of Toronto
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
An observational study of Intraocular Pressure, run by University of Toronto at 1 site in Canada.
The full registered description is in the About this study section and the official record.
Who may be eligible to take part?
The sponsor lists 2 inclusion and 10 exclusion criteria. Eligibility is decided by the study team after screening, so read the full criteria and contact a listed site.
Is this clinical trial currently recruiting?
The record says: status not confirmed, as of the sponsor's last update on 18 Aug 2011. Status can change between updates, so confirm with the study contact before making plans.
Where is the study taking place?
The record lists 1 site in Canada. Whether a site is taking part right now should be confirmed with that site. See every site.
What are the possible benefits and risks?
They depend on the study and the treatment, and no study can promise a benefit. The study team explains the known risks during informed consent, before anyone joins; the record itself does not list them.
Are results available for this study?
Results are not available in the source record.
How can a doctor refer a patient or contact the research team?
Contact Alanna Adleman, BSc (416-603-5694, aadleman@uhnresearch.ca), or a site near the patient. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Intraocular pressure (time frame: Intraocular pressure will be measured during the study visit, ten minutes into each of the seven inhaled gas provocation stages). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
On the ClinicalTrials.gov record for NCT01325285, which also lists 2 linked publications.
Does a listing mean the treatment is approved or proven to work?
No. A listing means the study is registered. It does not show that the treatment is safe, works, or is approved by a regulator.
How often is this information updated?
AzTrials copies changed records from ClinicalTrials.gov every night and reloads the whole registry every week. The sponsor last updated this record on 18 Aug 2011.