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

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: Healthy
• Intervention / Treatment: Device: FDOCT; Device: LDV; Device: DVA; Device: LSFG

• Study Type: Interventional
• Enrollment (Actual): 20
• Phase: Not Applicable

Contacts and Locations

Study Locations

• Austria
  • Vienna, Austria, 1090
    • Department of Clinical Pharmacology, Medical University of Vienna, Austria

Participation Criteria

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

How is the study designed?

Design Details

• Primary Purpose: Basic Science
• Allocation: N/A
• Interventional Model: Single Group Assignment
• Masking: None (Open Label)

Number of Arms

1

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)	1 day

Secondary Outcome Measures

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

Collaborators and Investigators

• Sponsor: Medical University of Vienna

Publications and helpful links

General Publications

• Fondi K, Aschinger GC, Bata AM, Wozniak PA, Liao L, Seidel G, Doblhoff-Dier V, Schmidl D, Garhofer G, Werkmeister RM, Schmetterer L. Measurement of Retinal Vascular Caliber From Optical Coherence Tomography Phase Images. Invest Ophthalmol Vis Sci. 2016 Jul 1;57(9):OCT121-9. doi: 10.1167/iovs.15-18476.

Study record dates

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: flicker induced changes; total volumetric retinal blood flow
• Other Study ID Numbers: OPHT-250315