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Neurovascular Coupling in Subjects With Amblyopia

This study is not yet open for participant recruitment.
Verified April 2013 by Medical University of Vienna
Sponsor:
Information provided by (Responsible Party):
Gerhard Garhofer, Medical University of Vienna
ClinicalTrials.gov Identifier:
NCT01746693
First received: December 7, 2012
Last updated: April 4, 2013
Last verified: April 2013
  Purpose

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. If changes in retinal neuronal function are also present, is unknown.

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. It has been shown in previous studies that stimulating the retina with diffuse luminant flickering light increases retinal vessel diameter and blood flow. However, it is unknown whether this is also the case in the retina of amblyopic eyes. Additionally, the introduction of blood oxygen level dependent (BOLD) fMRI also makes it possible to directly access the vascular response in the brain to visual stimuli.

Therefore, the aim of the present study is to investigate the effect of luminant flickering light on retinal vessel diameter and retinal blood flow in subjects with amblyopia. Also, oxygen saturation in retinal vessels will be assessed as well as pattern ERG for assessment of retinal function. Additionally, a high resolution image of the visual pathway will be taken with 7 Tesla MRI to investigate whether anatomical or functional alterations are present.


Condition Intervention
Amblyopia ex Strabismus
Amblyopia ex Anisometropia
Device: Dynamic Vessel Analyzer
Other: Laser Doppler Velocimetry
Device: 7-Tesla MRI
Other: Pattern electroretinography

Study Type: Interventional
Study Design: Allocation: Non-Randomized
Endpoint Classification: Safety/Efficacy Study
Intervention Model: Parallel Assignment
Masking: Single Blind (Outcomes Assessor)
Primary Purpose: Basic Science
Official Title: Neurovascular Coupling in Subjects With Amblyopia

Resource links provided by NLM:


Further study details as provided by Medical University of Vienna:

Primary Outcome Measures:
  • Retinal Vessel Diameter in Response to Flickering Light (DVA) [ Time Frame: once on the study day ] [ Designated as safety issue: No ]

Secondary Outcome Measures:
  • Retinal (arterial and venous) oxygen saturation [ Time Frame: once on the study day ] [ Designated as safety issue: No ]
  • Retinal blood velocity in response to flickering light [ Time Frame: once on the study day ] [ Designated as safety issue: No ]
  • High resolution functional and anatomical imaging of the visual pathway [ Time Frame: once on the study day ] [ Designated as safety issue: No ]
  • Inner Retinal Function [ Time Frame: once on the study day ] [ Designated as safety issue: No ]

Estimated Enrollment: 60
Study Start Date: July 2013
Estimated Study Completion Date: October 2014
Estimated Primary Completion Date: July 2014 (Final data collection date for primary outcome measure)
Arms Assigned Interventions
Experimental: amblyopia ex anisometropia
20 male and female volunteers with amblyopia ex anisometropia
Device: Dynamic Vessel Analyzer
retinal vessel diameter, retinal oxygen saturation
Other: Laser Doppler Velocimetry
retinal blood flow velocity, retinal blood flow
Device: 7-Tesla MRI
High resolution functional and anatomical imaging of the visual pathway
Other: Pattern electroretinography
inner retinal function
Experimental: amblyopia ex strabismus
20 male and female volunteers with amblyopia ex strabismus
Device: Dynamic Vessel Analyzer
retinal vessel diameter, retinal oxygen saturation
Other: Laser Doppler Velocimetry
retinal blood flow velocity, retinal blood flow
Device: 7-Tesla MRI
High resolution functional and anatomical imaging of the visual pathway
Other: Pattern electroretinography
inner retinal function
Experimental: control subjects
20 healthy male and female control subjects
Device: Dynamic Vessel Analyzer
retinal vessel diameter, retinal oxygen saturation
Other: Laser Doppler Velocimetry
retinal blood flow velocity, retinal blood flow
Device: 7-Tesla MRI
High resolution functional and anatomical imaging of the visual pathway
Other: Pattern electroretinography
inner retinal function

  Eligibility

Ages Eligible for Study:   18 Years to 35 Years
Genders Eligible for Study:   Both
Accepts Healthy Volunteers:   Yes
Criteria

Inclusion Criteria:

  • Men and women aged between 18 and 35 years
  • Non-smokers (for at least 6 months)
  • Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant
  • Normal ophthalmic findings except amblyopia on one eye resulting from anisometropia or strabismus with a visual acuity of Snellen ≤ 0.3 with best correction on the amblyopic eye and Snellen 0.9 or better in the contralateral eye (for subjects with amblyopia)
  • Normal ophthalmic findings with visual acuity of Snellen ≥ 1.0 in both eyes (for control subjects)

Exclusion Criteria:

  • Symptoms of a clinically relevant illness in the 3 weeks before the first study day
  • Presence or history of a severe medical condition as judged by the clinical investigator
  • Regular use of medication, abuse of alcoholic beverages, participation in a clinical trial in the 3 weeks preceding the study (except oral contraceptives)
  • Blood donation during the previous three weeks
  • Pregnancy, planned pregnancy or lactating
  • Any metallic, electric, electronic or magnetic device or object not removable except dental fillings
  • Claustrophobia
  • Epilepsia, history or family history of seizures
  Contacts and Locations
Please refer to this study by its ClinicalTrials.gov identifier: NCT01746693

Contacts
Contact: Gerhard Garhoefer, MD +43140400 ext 2981 gerhard.garhoefer@meduniwien.ac.at

Locations
Austria
Department of Clinical Pharmacology, Medical University of Vienna Not yet recruiting
Vienna, Austria, 1090
Contact: Gerhard Garhoefer, MD    +43140400 ext 2981    gerhard.garhoefer@meduniwien.ac.at   
Principal Investigator: Gerhard Garhoefer, MD         
Sponsors and Collaborators
Medical University of Vienna
  More Information

No publications provided

Responsible Party: Gerhard Garhofer, Assoc. Prof. PD Dr., Medical University of Vienna
ClinicalTrials.gov Identifier: NCT01746693     History of Changes
Other Study ID Numbers: OPHT-291012
Study First Received: December 7, 2012
Last Updated: April 4, 2013
Health Authority: Austria: Austrian Medicines and Medical Devices Agency

Keywords provided by Medical University of Vienna:
retinal vessel diameter
retinal oxygen saturation
high resolution functional and anatomical imaging
inner retinal function
flicker response

Additional relevant MeSH terms:
Amblyopia
Anisometropia
Strabismus
Brain Diseases
Central Nervous System Diseases
Nervous System Diseases
Vision Disorders
Sensation Disorders
Neurologic Manifestations
Eye Diseases
Signs and Symptoms
Refractive Errors
Ocular Motility Disorders
Cranial Nerve Diseases

ClinicalTrials.gov processed this record on April 14, 2014