Measurement of Total Retinal Blood Flow During Flicker Stimulation in Healthy Subjects

September 2, 2017 updated by: Gerhard Garhofer, Medical University of Vienna

Neurovascular coupling or functional hyperemia is defined as an essential physiologic mechanism in the brain, which is necessary for the local adaption of blood flow to altered metabolic demands of the tissue. It has been shown that also in the eye, blood flow is considerably coupled to retinal neural activity. The current concept of functional hyperemia is that visual stimulation, as flicker light, effectuates increasing neural activity in the retina, which elevates the metabolic needs of the retinal tissue for oxygen and glucose and consequently induces dilatation and augmented blood flow in the retinal vasculature. In several studies, stimulation with flicker light has been shown to induce an increase of blood flow in major retinal arteries and veins as well as an increase of optic nerve head blood flow. Up until now, flicker induced changes in blood flow were measured solely in the major retinal arteries and veins with systems such as the commercially available dynamic vessel analyzer (DVA) by Imedos and with laser Doppler velocimetry (LDV).

In the present study, the investigators propose to measure the response of total retinal blood flow to diffuse luminance flicker stimulation with bi-directional Fourier Domain Doppler Optical Coherence Tomography (FDOCT) as well as with Laser Speckle Flowgraphy (LSFG) in healthy subjects by assessing vessel diameter, blood velocity and blood flow of all retinal vessels. For comparative reasons, the investigators will furthermore assess the blood flow of major retinal arteries and veins with the dynamic vessel analyzer (DVA) and laser Doppler velocimetry (LDV).

Study Overview

Status

Completed

Conditions

Intervention / Treatment

Study Type

Interventional

Enrollment (Actual)

20

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
        • Department of Clinical Pharmacology, Medical University of Vienna, Austria

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 45 years (Adult)

Accepts Healthy Volunteers

Yes

Genders Eligible for Study

All

Description

Inclusion Criteria:

  • Informed consent for participation
  • Men and women aged between 18 and 45 years
  • Non-smokers
  • Normal findings in the medical history and physical examination unless the investigator considers an abnormality to be clinically irrelevant
  • Systolic blood pressure < 140 mmHg, diastolic blood pressure < 90 mmHg
  • Normal ophthalmic findings, ametropia less than 3 diopters

Exclusion Criteria:

  • History or presence of ocular disease
  • Ametropy ≥ 3 dpt
  • Treatment with any drug in the 3 weeks preceding the first study day
  • Symptoms of a clinically relevant illness in the 3 weeks before the first study day
  • Participation in a clinical trial in the 3 weeks preceding the first study day
  • Blood donation during the 3 weeks preceding the first study day
  • History of family history of epilepsy
  • Abuse of alcoholic beverages
  • Pregnancy

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: N/A
  • Interventional Model: Single Group Assignment
  • Masking: None (Open Label)

Arms and Interventions

Participant Group / Arm
Intervention / Treatment
Experimental: Healthy Subjects
20 healthy female and male volunteers, age 18-45 years, non-smokers. Measurements with FDOCT, DVA, LDV and LSFG will be done in all healthy subjects.
Device: FDOCT
Measurement of retinal blood velocities
Other Names:
  • Fourier Domain Color Doppler Optical Coherence Tomography
Device: LDV
Measurement of retinal blood velocities
Other Names:
  • Laser Doppler Velocimetry
Device: DVA
Measurement of retinal vessel diameters
Other Names:
  • Dynamic Vessel Analyzer
Device: LSFG
Imaging of retinal blood flow
Other Names:
  • Laser Speckle Flowgraphy

What is the study measuring?

Primary Outcome Measures

Outcome Measure
Time Frame
Flicker induced changes in total retinal blood flow (FDOCT)
Time Frame: 1 day
1 day

Secondary Outcome Measures

Outcome Measure
Time Frame
Red blood cell velocity (LDV)
Time Frame: 1 day
1 day
Retinal vessel diameters (DVA)
Time Frame: 1 day
1 day
Retinal oxygen saturation (DVA)
Time Frame: 1 day
1 day
Relative Flow Volume (LSFG)
Time Frame: 1 day
1 day

Collaborators and Investigators

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

Sponsor

Medical University of Vienna

Publications and helpful links

The person responsible for entering information about the study voluntarily provides these publications. These may be about anything related to the study.

General Publications

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)

October 1, 2015

Primary Completion (Actual)

August 1, 2017

Study Completion (Actual)

September 1, 2017

Study Registration Dates

First Submitted

August 20, 2015

First Submitted That Met QC Criteria

August 21, 2015

First Posted (Estimate)

August 24, 2015

Study Record Updates

Last Update Posted (Actual)

September 6, 2017

Last Update Submitted That Met QC Criteria

September 2, 2017

Last Verified

September 1, 2017

More Information

Terms related to this study

Keywords

Other Study ID Numbers

  • OPHT-250315

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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