Neurovascular Coupling in Subjects With Amblyopia

April 6, 2022 updated by: Gerhard Garhofer, Medical University of Vienna

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.

Study Overview

Status

Recruiting

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Anticipated)

60

Phase

  • Not Applicable

Contacts and Locations

This section provides the contact details for those conducting the study, and information on where this study is being conducted.

Study Locations

  • Austria
      • Vienna, Austria, 1090
        • Recruiting
        • Department of Clinical Pharmacology, Medical University of Vienna
        • Principal Investigator:
          • Gerhard Garhoefer, MD

Participation Criteria

Researchers look for people who fit a certain description, called eligibility criteria. Some examples of these criteria are a person's general health condition or prior treatments.

Eligibility Criteria

Ages Eligible for Study

18 years to 55 years (Adult)

Accepts Healthy Volunteers

No

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Men and women aged between 18 and 55 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

Study Plan

This section provides details of the study plan, including how the study is designed and what the study is measuring.

How is the study designed?

Design Details

  • Primary Purpose: Basic Science
  • Allocation: Non-Randomized
  • Interventional Model: Parallel Assignment
  • Masking: Single

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
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
Other: Fourier domain optical coherence tomography
Blood flow in retina.
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
Other: Fourier domain optical coherence tomography
Blood flow in retina.
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
Other: Fourier domain optical coherence tomography
Blood flow in retina.

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Retinal Vessel Diameter in Response to Flickering Light (DVA)
Time Frame: once on the study day
once on the study day

Secondary Outcome Measures

Outcome Measure
Time Frame
Retinal (arterial and venous) oxygen saturation
Time Frame: once on the study day
once on the study day
Retinal blood velocity in response to flickering light
Time Frame: once on the study day
once on the study day
High resolution functional and anatomical imaging of the visual pathway
Time Frame: once on the study day
once on the study day
Inner Retinal Function
Time Frame: once on the study day
once on the study day

Collaborators and Investigators

This is where you will find people and organizations involved with this study.

Sponsor

Medical University of Vienna

Study record dates

These dates track the progress of study record and summary results submissions to ClinicalTrials.gov. Study records and reported results are reviewed by the National Library of Medicine (NLM) to make sure they meet specific quality control standards before being posted on the public website.

Study Major Dates

Study Start (Actual)

March 1, 2014

Primary Completion (Anticipated)

September 1, 2023

Study Completion (Anticipated)

September 2, 2023

Study Registration Dates

First Submitted

December 7, 2012

First Submitted That Met QC Criteria

December 7, 2012

First Posted (Estimate)

December 11, 2012

Study Record Updates

Last Update Posted (Actual)

April 7, 2022

Last Update Submitted That Met QC Criteria

April 6, 2022

Last Verified

April 1, 2022

More Information

Terms related to this study

Keywords

Additional Relevant MeSH Terms

Other Study ID Numbers

  • OPHT-291012

This information was retrieved directly from the website clinicaltrials.gov without any changes. If you have any requests to change, remove or update your study details, please contact register@clinicaltrials.gov. As soon as a change is implemented on clinicaltrials.gov, this will be updated automatically on our website as well.

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