AutoregulationNCT00812526
Regulation of Choroidal Blood Flow During Combined Changes in Intraocular Pressure and Arterial Blood Pressure
A study testing Suction cup application and Squatting in people with Autoregulation, run by Medical University of Vienna at 1 site in Austria.
Trial summary
Autoregulation is the ability of a vascular bed to maintain blood flow despite changes in perfusion pressure. For a long time it had been assumed that the choroid is a strictly passive vascular bed, which shows no autoregulation. Read more about this study
- Who is it for?
- Ages 19 to 35 years, men onlyHealthy volunteers can take part
- Conditions the study is for
- Autoregulation
- What is being tested?
- Suction cup application and Squatting
- Type of treatment
- Surgery or procedure
- How many people
- 18 participants
- Where
- 1 siteAustria
- Study dates
- Sep 2002to Sep 2004
- Phase
- Interventional
- 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 19 to 35 years
- Men only
- Healthy volunteers accepted
- Adult
Who may be able to join
- Men aged between 19 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 ophthalmic findings, ametropia < 1 Dpt.
Who cannot join
- 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
- Symptoms of a clinically relevant illness in the 3 weeks before the first study day
- Blood donation during the previous 3 weeks
- Presence of intraocular pathology: ocular hypertension, glaucoma, retinal vasculopathy or other retinal diseases
Trial locations and contacts
1 site in 1 country.
Austria1 site
Department of Clinical Pharmacology, Medical University of Vienna
Vienna, 1090
About this study
Autoregulation is the ability of a vascular bed to maintain blood flow despite changes in perfusion pressure. For a long time it had been assumed that the choroid is a strictly passive vascular bed, which shows no autoregulation. However, recently several groups have identified some autoregulatory capacity of the choroid. Choroidal autoregulation was first shown in a rabbit model where intraocular pressure (IOP) and arterial blood pressure could be varied independently. In these experiments regulation of choroidal blood flow was not only dependent on ocular perfusion pressure, but was also dependent on the value of IOP. This indicates that a myogenic mechanism contributes to choroidal autoregulation, because the regulatory capacity is dependent on the transmural pressure. In the model of myogenic autoregulation arterioles change their vascular tone depending on the pressure inside the vessel and outside the vessel. The present experiments are designed to test whether a myogenic mechanism may also be involved in choroidal autoregulation in humans. For this purpose the investigators perform experiments during which the IOP and the arterial blood pressure is increased. According to the myogenic theory of autoregulation one would expect stronger vasoconstriction at lower IOPs for the same increase in ocular perfusion pressure.
- Conditions
- Autoregulation
- Being tested
- Suction cup application, Squatting
- Keywords
- Choroid, Regional blood flow, Autoregulation, Laser Doppler flowmetry
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
Suction cup applicationProcedure or surgery
SquattingProcedure or surgery
What is being measured
The primary outcome is the main question the study is designed to answer.
Relationship between ocular perfusion pressure and choroidal blood flow
Measured: 4 study days
Secondary outcomes (4)
Choroidal blood flow
Measured: 4 study days
Mean arterial pressure
Measured: 4 study days
Intraocular pressure
Measured: 4 study days
Systolic/diastolic blood pressure
Measured: 4 study days
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted22 Dec 2008 (estimated)
- Study startSep 2002
- Primary completionSep 2004
- Study completionSep 2004
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for AutoregulationStudies of the same condition, open and under way.
- More trials run by Medical University of ViennaThe 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
- Interventional
- Phase
- Phase N/A
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
- Enrolment
- 18 participants (actual)
Sponsor and investigators
- Lead sponsor
- Medical University of Vienna
- Sponsor type
- University, hospital or other
- Investigators
- Elzbieta Polska, MD, Study director, Department of Clinical Pharmacology, Medical University of Vienna
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT00812526
- Sponsor's protocol ID
- OPHT-190702
- Status last verified
- Dec 2008
- First submitted
- 18 Dec 2008
- Last updated
- 22 Dec 2008
- Results posted
- No
Study at a glance
From the registry record, last updated by the sponsor on 22 Dec 2008. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Regulation of Choroidal Blood Flow During Combined Changes in Intraocular Pressure and Arterial Blood Pressure
- ClinicalTrials.gov ID
- NCT00812526
- Acronym / sponsor ID
- OPHT-190702
- Conditions
- Autoregulation
- Keywords
- Choroid, Regional blood flow, Autoregulation, Laser Doppler flowmetry
- Study type
- Interventional
- Recruitment status
- Completed
- Enrolment
- 18 participants (actual)
- Lead sponsor
- Medical University of ViennaUniversity, hospital or other
- Study start
- Sep 2002
- Primary completion
- Sep 2004 (actual)
- Study completion
- Sep 2004 (actual)
- First posted
- 22 Dec 2008 (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.
Autoregulation is the ability of a vascular bed to maintain blood flow despite changes in perfusion pressure. For a long time it had been assumed that the choroid is a strictly passive vascular bed, which shows no autoregulation. However, recently several groups have identified some autoregulatory capacity of the choroid. Choroidal autoregulation was first shown in a rabbit model where intraocular pressure (IOP) and arterial blood pressure could be varied independently. In these experiments regulation of choroidal blood flow was not only dependent on ocular perfusion pressure, but was also dependent on the value of IOP. This indicates that a myogenic mechanism contributes to choroidal autoregulation, because the regulatory capacity is dependent on the transmural pressure. In the model of myogenic autoregulation arterioles change their vascular tone depending on the pressure inside the vessel and outside the vessel. The present experiments are designed to test whether a myogenic mechanism may also be involved in choroidal autoregulation in humans. For this purpose the investigators perform experiments during which the IOP and the arterial blood pressure is increased. According to the myogenic theory of autoregulation one would expect stronger vasoconstriction at lower IOPs for the same increase in ocular perfusion pressure.
Study design
- Primary purpose
- Basic science
- Allocation
- Non-randomised
- Intervention model
- Single group
- Masking
- None (open label)
Who may qualify
- Ages
- 19 to 35 years
- Sex
- Male only
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (4 listed)
- Men aged between 19 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 ophthalmic findings, ametropia < 1 Dpt.
Key exclusion criteria (5 listed)
- 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
- Symptoms of a clinically relevant illness in the 3 weeks before the first study day
- Blood donation during the previous 3 weeks
- Presence of intraocular pathology: ocular hypertension, glaucoma, retinal vasculopathy or other retinal diseases
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 |
|---|---|---|
| Suction cup application | Procedure or surgery | – |
| Squatting | Procedure or surgery | – |
Primary outcome
Relationship between ocular perfusion pressure and choroidal blood flow
Time frame: 4 study days
4 secondary outcomes
Choroidal blood flow
Time frame: 4 study days
Mean arterial pressure
Time frame: 4 study days
Intraocular pressure
Time frame: 4 study days
Systolic/diastolic blood pressure
Time frame: 4 study days
Results and safety
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 22 Dec 2008.
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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.
Elzbieta Polska, MD study director
Department of Clinical Pharmacology, Medical University of Vienna
1 site in 1 country: see every site and its status.
Questions about this trial
What is this clinical trial studying?
A study testing Suction cup application and Squatting in people with Autoregulation, run by Medical University of Vienna at 1 site in Austria.
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 4 inclusion and 5 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: finished, as of the sponsor's last update on 22 Dec 2008. 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 Austria. 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?
The study is completed, but results are not available in the source record. That does not mean the treatment did or did not work.
How can a doctor refer a patient or contact the research team?
The record lists no contact. The official record names the sponsor, who can be asked directly. AzTrials does not enrol participants or take referrals.
What does the primary outcome measure?
Relationship between ocular perfusion pressure and choroidal blood flow (time frame: 4 study days). It is what the study was designed to measure, not a finding.
Where can I read the original study information?
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 22 Dec 2008.