AmblyopiaNCT00312390
Amblyopia and Neurovascular Coupling in the Retina of Humans
A study testing Flicker, Retinal Vessel Diameter and Retinal Blood Flow in people with Amblyopia and Regional Blood Flow, run by Medical University of Vienna at 1 site in Austria.
Trial summary
The visual disorder of amblyopia affects 2% to 3% of the population. Amblyopia is a developmental condition that is characterized by reduced vision of the eye due to the presence of a sensory impediment during visual development, such as strabismus (ocular misalignment) or anisometropia (unequal refractive error)… Read more about this study
- Who is it for?
- Ages 18 to 60 yearsHealthy volunteers can take part
- Conditions the study is for
- Amblyopia, Regional Blood Flow
- What is being tested?
- Flicker, Retinal Vessel Diameter and Retinal Blood Flow
- Type of treatment
- Surgery or procedure
- Could I receive a placebo?
- No, everyone receives an active treatment
- How many people
- 0 participants
- Where
- 1 siteAustria
- Study dates
- Jul 2003to not given
- 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 18 to 60 years
- All sexes
- Healthy volunteers accepted
- Adult
Who may be able to join
- Women and men, aged between 18 and 60 years
- Matched with regard to age, sex and smoking status
- Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant
- Normal ophthalmic findings, ametropia of less than 3.0 dpt
- Inclusion criteria for patients with amblyopia as a result of anisometropia or strabismus:
- Normal ophthalmic findings except amblyopia on one eye resulting from anisometropia or strabismus with a visual acuity between log Mar 0.3 and 0.7 (Snellen 0.2-0.5) with best correction on the amblyopic eye and 0.1 (Snellen 0.9) or better on the contralateral eye
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- Anisometropia of more 3 dpt (patients with anisometropia)
- Women and men, aged between 18 and 60 years
- Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant
Who cannot join
- Regular use of medication, abuse of alcoholic beverages, participation in a clinical trial in the 3 weeks preceding the study
- pregnancy
- 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
Trial locations and contacts
1 site in 1 country.
About this study
The visual disorder of amblyopia affects 2% to 3% of the population. Amblyopia is a developmental condition that is characterized by reduced vision of the eye due to the presence of a sensory impediment during visual development, such as strabismus (ocular misalignment) or anisometropia (unequal refractive error), occurring early in life. Recent studies in humans and animals point towards a cortical locus for the processing deficit in amblyopia, revealing sensory deficits at the signal cell level that include reduced spatial resolution, reduced contrast sensitivity, and a reduced number of binocular neural cells. In the retina, however, no abnormalities have yet been reported.
Like in the brain blood flow in the retina is coupled to neuronal activity. This phenomenon has been measured by different study groups with non invasive techniques in the brain and retina. We therefore use a Zeiss fundus camera for the assessment of retinal vessel diameters. This so called retinal vessel analyzer (RVA) is a combination of a fundus camera connected to a high resolution video camera equipped with a software based analyzing system. An unprecedented reproducibility and sensitivity of retinal vessel diameter measurements is attained with this system. In addition this system allows real time analysis of retinal vessels as well as off-line determinations from video tape. A special provocation test, which minimizes risk and discomfort to the subject under study is applied through the illumination pathway of the fundus camera: Diffuse luminance flicker is used as a stimulus to augment intrinsic mechanisms by which the retina can vary the vascular supply, in correspondence with local variations of functional activity. This system allows to study the flicker response of retinal vessels, which is within a magnitude of 6 to 8%.
Read more
However, the exact mechanisms underlying this phenomenon are not fully understood. Especially in the eye it is not clear whether it is an exclusive metabolic effect within the retina and the surrounding blood vessels or dependent of central regulatory brain functions.
The purpose of the current study is to improve our understanding of the mechanisms underlying flicker evoked responses of retinal blood vessels in humans. It is not clear whether the retina of amblyopic eyes can regulate retinal blood flow in response to increased metabolic demands as induced during flicking light stimulation. A detail understanding of the metabolic and functional processes within the retina of patients with amblyopia is a prerequisite for further research to prevent amblyopia.
- Conditions
- Amblyopia, Regional Blood Flow
- Being tested
- Flicker, Retinal Vessel Diameter, Retinal Blood Flow
- Keywords
- Amblyopia, Retinal vessel diameters, Retinal blood flow, Flicker
- Medical subject headings
- Amblyopia, photopsia
What participants receive
What participants receive. In a randomised study each person is assigned to one group by chance.
FlickerProcedure or surgery
Retinal Vessel DiameterProcedure or surgery
Retinal Blood FlowProcedure or surgery
| Study group | Role | What they receive |
|---|---|---|
| Healthy Control Subjects | Other | Not described Receives: Procedure: Flicker; Procedure: Retinal Vessel Diameter; Procedure: Retinal Blood Flow |
| Subjects with amblyopia | Other | Not described Receives: Procedure: Flicker; Procedure: Retinal Vessel Diameter; Procedure: Retinal Blood Flow |
What is being measured
The primary outcome is the main question the study is designed to answer.
Retinal vessel diameter
Measured: 10 minutes
Time course of diameter changes induced by flicker light stimulation
Measured: 10 minutes
Timeline
From the start of the study to its completion; the mark is today. Estimated dates are the sponsor’s plan.
- First posted10 Apr 2006 (estimated)
- Study startJul 2003
Resources
- Official record on ClinicalTrials.govThe registry entry this page is built from, with its full change history.
- Other trials for AmblyopiaStudies 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
- Diagnosis
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Enrolment
- 0 participants (actual)
Sponsor and investigators
- Lead sponsor
- Medical University of Vienna
- Sponsor type
- University, hospital or other
- Investigators
- Gabriele Fuchsjaeger-Mayrl, MD, Principal investigator, Department of Clinical Pharmacology, Medical University of Vienna
IDs, dates and publications
- ClinicalTrials.gov ID
- NCT00312390
- Sponsor's protocol ID
- OPHT-070503
- Status last verified
- Nov 2014
- First submitted
- 6 Apr 2006
- Last updated
- 8 Dec 2014
- Results posted
- No
- Data monitoring committee
- Yes
Study at a glance
From the registry record, last updated by the sponsor on 8 Dec 2014. Recruitment status is as the sponsor reported it: confirm with the study team.
- Official title
- Amblyopia and Neurovascular Coupling in the Retina of Humans
- ClinicalTrials.gov ID
- NCT00312390
- Acronym / sponsor ID
- OPHT-070503
- Conditions
- Amblyopia, Regional Blood Flow
- Keywords
- Amblyopia, Retinal vessel diameters, Retinal blood flow, Flicker
- Study type
- Interventional
- Recruitment status
- Withdrawn
- Enrolment
- 0 participants (actual)
- Lead sponsor
- Medical University of ViennaUniversity, hospital or other
- Study start
- Jul 2003
- First posted
- 10 Apr 2006 (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 visual disorder of amblyopia affects 2% to 3% of the population. Amblyopia is a developmental condition that is characterized by reduced vision of the eye due to the presence of a sensory impediment during visual development, such as strabismus (ocular misalignment) or anisometropia (unequal refractive error), occurring early in life. Recent studies in humans and animals point towards a cortical locus for the processing deficit in amblyopia, revealing sensory deficits at the signal cell level that include reduced spatial resolution, reduced contrast sensitivity, and a reduced number of binocular neural cells. In the retina, however, no abnormalities have yet been reported.
Like in the brain blood flow in the retina is coupled to neuronal activity. This phenomenon has been measured by different study groups with non invasive techniques in the brain and retina. We therefore use a Zeiss fundus camera for the assessment of retinal vessel diameters. This so called retinal vessel analyzer (RVA) is a combination of a fundus camera connected to a high resolution video camera equipped with a software based analyzing system. An unprecedented reproducibility and sensitivity of retinal vessel diameter measurements is attained with this system. In addition this system allows real time analysis of retinal vessels as well as off-line determinations from video tape. A special provocation test, which minimizes risk and discomfort to the subject under study is applied through the illumination pathway of the fundus camera: Diffuse luminance flicker is used as a stimulus to augment intrinsic mechanisms by which the retina can vary the vascular supply, in correspondence with local variations of functional activity. This system allows to study the flicker response of retinal vessels, which is within a magnitude of 6 to 8%.
However, the exact mechanisms underlying this phenomenon are not fully understood. Especially in the eye it is not clear whether it is an exclusive metabolic effect within the retina and the surrounding blood vessels or dependent of central regulatory brain functions.
The purpose of the current study is to improve our understanding of the mechanisms underlying flicker evoked responses of retinal blood vessels in humans. It is not clear whether the retina of amblyopic eyes can regulate retinal blood flow in response to increased metabolic demands as induced during flicking light stimulation. A detail understanding of the metabolic and functional processes within the retina of patients with amblyopia is a prerequisite for further research to prevent amblyopia.
Study design
- Primary purpose
- Diagnosis
- Allocation
- Non-randomised
- Intervention model
- Parallel groups
- Masking
- None (open label)
- Number of arms
- 2
| Arm | Type | Receives |
|---|---|---|
| Healthy Control Subjects | Other | Procedure: Flicker, Procedure: Retinal Vessel Diameter, Procedure: Retinal Blood Flow |
| Subjects with amblyopia | Other | Procedure: Flicker, Procedure: Retinal Vessel Diameter, Procedure: Retinal Blood Flow |
Who may qualify
- Ages
- 18 to 60 years
- Sex
- All
- Healthy volunteers
- Accepted
- Age groups
- Adult
Key inclusion criteria (9 listed)
- Women and men, aged between 18 and 60 years
- Matched with regard to age, sex and smoking status
- Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant
- Normal ophthalmic findings, ametropia of less than 3.0 dpt
- Inclusion criteria for patients with amblyopia as a result of anisometropia or strabismus:
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
- pregnancy
- 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
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 |
|---|---|---|
| Flicker | Procedure or surgery | Healthy Control Subjects, Subjects with amblyopia |
| Retinal Vessel Diameter | Procedure or surgery | Healthy Control Subjects, Subjects with amblyopia |
| Retinal Blood Flow | Procedure or surgery | Healthy Control Subjects, Subjects with amblyopia |
Primary outcome
Retinal vessel diameter
Time frame: 10 minutes
Time course of diameter changes induced by flicker light stimulation
Time frame: 10 minutes
Results and safety
The study was withdrawn before enrolling participants, so there are no results.
Research links
- Official record on ClinicalTrials.govLast updated by the sponsor 8 Dec 2014.
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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.
Gabriele Fuchsjaeger-Mayrl, MD principal investigator
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 Flicker, Retinal Vessel Diameter and Retinal Blood Flow in people with Amblyopia and Regional Blood Flow, 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 9 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: withdrawn, as of the sponsor's last update on 8 Dec 2014. 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 was withdrawn before enrolling participants, so there are no results.
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?
Retinal vessel diameter (time frame: 10 minutes). The study lists 2 primary outcomes in all. 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 8 Dec 2014.