Amblyopia and Neurovascular Coupling in the Retina of Humans
NCT ID: NCT00312390
Last Updated: 2014-12-08
Study Results
The study team has not published outcome measurements, participant flow, or safety data for this trial yet. Check back later for updates.
Basic Information
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WITHDRAWN
NA
INTERVENTIONAL
2003-07-31
Brief Summary
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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.
Detailed Description
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Conditions
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Keywords
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Study Design
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NON_RANDOMIZED
PARALLEL
DIAGNOSTIC
NONE
Study Groups
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Healthy Control Subjects
Flicker
Retinal Vessel Diameter
Retinal Blood Flow
Subjects with amblyopia
Flicker
Retinal Vessel Diameter
Retinal Blood Flow
Interventions
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Flicker
Retinal Vessel Diameter
Retinal Blood Flow
Eligibility Criteria
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Inclusion Criteria
* 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
* 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
* 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
Exclusion Criteria
* 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
18 Years
60 Years
ALL
Yes
Sponsors
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Medical University of Vienna
OTHER
Responsible Party
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Department of Clinical Pharmacology, Medical University of Vienna
Principal Investigators
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Gabriele Fuchsjaeger-Mayrl, MD
Role: PRINCIPAL_INVESTIGATOR
Department of Clinical Pharmacology, Medical University of Vienna
Locations
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Department of Clinical Pharmacology
Vienna, , Austria
Countries
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Other Identifiers
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OPHT-070503
Identifier Type: -
Identifier Source: org_study_id