Neurovascular Coupling in Subjects With Amblyopia

Not Applicable

• Conditions: Amblyopia ex Strabismus; Amblyopia ex Anisometropia
• Interventions: Device: Dynamic Vessel Analyzer; Other: Laser Doppler Velocimetry; Device: 7-Tesla MRI; Other: Pattern electroretinography; Other: Fourier domain optical coherence tomography

• Registration Number: NCT01746693
• Lead Sponsor: Medical University of Vienna

Brief Summary

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.

Detailed Description

Not available

Basic Information
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Recruitment & Eligibility
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Study & Design
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Trial Locations

Study Timeline

• Study First Submitted: 2012-12-07
• Study First Submitted QC: 2012-12-07
• Study First Posted: 2012-12-11
• Study Start: 2014-03
• Status Verified: 2022-04
• Last Update Submitted: 2022-04-06
• Last Update Posted: 2022-04-07
• Primary Completion: 2023-09
• Study Completion: 2023-09-02

Recruitment & Eligibility

• Status: UNKNOWN
• Sex: All
• Target Recruitment: 60

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)

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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

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Study & Design

• Study Type: INTERVENTIONAL
• Study Design: PARALLEL

Arm && Interventions

Group	Intervention	Description
control subjects	Dynamic Vessel Analyzer	20 healthy male and female control subjects
amblyopia ex anisometropia	Dynamic Vessel Analyzer	20 male and female volunteers with amblyopia ex anisometropia
amblyopia ex anisometropia	7-Tesla MRI	20 male and female volunteers with amblyopia ex anisometropia
amblyopia ex strabismus	Dynamic Vessel Analyzer	20 male and female volunteers with amblyopia ex strabismus
amblyopia ex strabismus	Pattern electroretinography	20 male and female volunteers with amblyopia ex strabismus
amblyopia ex strabismus	Fourier domain optical coherence tomography	20 male and female volunteers with amblyopia ex strabismus
control subjects	Pattern electroretinography	20 healthy male and female control subjects
amblyopia ex anisometropia	Laser Doppler Velocimetry	20 male and female volunteers with amblyopia ex anisometropia
control subjects	Laser Doppler Velocimetry	20 healthy male and female control subjects
control subjects	7-Tesla MRI	20 healthy male and female control subjects
control subjects	Fourier domain optical coherence tomography	20 healthy male and female control subjects
amblyopia ex anisometropia	Pattern electroretinography	20 male and female volunteers with amblyopia ex anisometropia
amblyopia ex anisometropia	Fourier domain optical coherence tomography	20 male and female volunteers with amblyopia ex anisometropia
amblyopia ex strabismus	Laser Doppler Velocimetry	20 male and female volunteers with amblyopia ex strabismus
amblyopia ex strabismus	7-Tesla MRI	20 male and female volunteers with amblyopia ex strabismus

Primary Outcome Measures

Name	Time	Method
Retinal Vessel Diameter in Response to Flickering Light (DVA)	once on the study day

Secondary Outcome Measures

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

Trial Locations

Locations (1)

Department of Clinical Pharmacology, Medical University of Vienna; 🇦🇹 Vienna, Austria