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Amblyopia and Neurovascular Coupling in the Retina of Humans

The safety and scientific validity of this study is the responsibility of the study sponsor and investigators. Listing a study does not mean it has been evaluated by the U.S. Federal Government. Read our disclaimer for details.
 
ClinicalTrials.gov Identifier: NCT00312390
Recruitment Status : Withdrawn
First Posted : April 10, 2006
Last Update Posted : December 8, 2014
Sponsor:
Information provided by:
Medical University of Vienna

Tracking Information
First Submitted Date  ICMJE April 6, 2006
First Posted Date  ICMJE April 10, 2006
Last Update Posted Date December 8, 2014
Study Start Date  ICMJE July 2003
Primary Completion Date Not Provided
Current Primary Outcome Measures  ICMJE
 (submitted: December 5, 2014)
  • Retinal vessel diameter [ Time Frame: 10 minutes ]
  • Time course of diameter changes induced by flicker light stimulation [ Time Frame: 10 minutes ]
Original Primary Outcome Measures  ICMJE
 (submitted: April 6, 2006)
  • Retinal vessel diameter
  • Time course of diameter changes induced by flicker light stimulation
Change History Complete list of historical versions of study NCT00312390 on ClinicalTrials.gov Archive Site
Current Secondary Outcome Measures  ICMJE Not Provided
Original Secondary Outcome Measures  ICMJE Not Provided
Current Other Pre-specified Outcome Measures Not Provided
Original Other Pre-specified Outcome Measures Not Provided
 
Descriptive Information
Brief Title  ICMJE Amblyopia and Neurovascular Coupling in the Retina of Humans
Official Title  ICMJE Amblyopia and Neurovascular Coupling in the Retina of Humans
Brief 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), 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.

Detailed Description Not Provided
Study Type  ICMJE Interventional
Study Phase  ICMJE Not Applicable
Study Design  ICMJE Allocation: Non-Randomized
Intervention Model: Parallel Assignment
Masking: None (Open Label)
Primary Purpose: Diagnostic
Condition  ICMJE
  • Amblyopia
  • Regional Blood Flow
Intervention  ICMJE
  • Procedure: Flicker
  • Procedure: Retinal Vessel Diameter
  • Procedure: Retinal Blood Flow
Study Arms  ICMJE
  • Healthy Control Subjects
    Interventions:
    • Procedure: Flicker
    • Procedure: Retinal Vessel Diameter
    • Procedure: Retinal Blood Flow
  • Subjects with amblyopia
    Interventions:
    • Procedure: Flicker
    • Procedure: Retinal Vessel Diameter
    • Procedure: Retinal Blood Flow
Publications * Not Provided

*   Includes publications given by the data provider as well as publications identified by ClinicalTrials.gov Identifier (NCT Number) in Medline.
 
Recruitment Information
Recruitment Status  ICMJE Withdrawn
Actual Enrollment  ICMJE
 (submitted: December 5, 2014)
0
Original Enrollment  ICMJE
 (submitted: April 6, 2006)
76
Study Completion Date  ICMJE Not Provided
Primary Completion Date Not Provided
Eligibility Criteria  ICMJE

Inclusion Criteria:

  • Inclusion criteria for healthy subjects:
  • 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
  • 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:

  • 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
Sex/Gender  ICMJE
Sexes Eligible for Study: All
Ages  ICMJE 18 Years to 60 Years   (Adult)
Accepts Healthy Volunteers  ICMJE Yes
Contacts  ICMJE Contact information is only displayed when the study is recruiting subjects
Listed Location Countries  ICMJE Austria
Removed Location Countries  
 
Administrative Information
NCT Number  ICMJE NCT00312390
Other Study ID Numbers  ICMJE OPHT-070503
Has Data Monitoring Committee Yes
U.S. FDA-regulated Product Not Provided
IPD Sharing Statement  ICMJE Not Provided
Responsible Party Gerhard Garhöfer, MD, Department of Clinical Pharmacology, Medical University of Vienna
Study Sponsor  ICMJE Medical University of Vienna
Collaborators  ICMJE Not Provided
Investigators  ICMJE
Principal Investigator: Gabriele Fuchsjaeger-Mayrl, MD Department of Clinical Pharmacology, Medical University of Vienna
PRS Account Medical University of Vienna
Verification Date November 2014

ICMJE     Data element required by the International Committee of Medical Journal Editors and the World Health Organization ICTRP