Parafoveal Retinal Vascular Response to Pattern Visual Stimulation Assessed with OCT Angiography

Eric Wei,Woojhon Choi,David Huang,Benjamin Potsaid,Jonathan J Liu,James G Fujimoto,Yali Jia,Ou Tan,Samuel G Solomon

doi:10.1371/journal.pone.0081343

Abstract

We used optical coherence tomography (OCT) angiography with a high-speed swept-source OCT system to investigate retinal blood flow changes induced by visual stimulation with a reversing checkerboard pattern. The split-spectrum amplitude-decorrelation angiography (SSADA) algorithm was used to quantify blood flow as measured with parafoveal flow index (PFI), which is proportional to the density of blood vessels and the velocity of blood flow in the parafoveal region of the macula. PFI measurements were taken in 15 second intervals during a 4 minute period consisting of 1 minute of baseline, 2 minutes with an 8 Hz reversing checkerboard pattern stimulation, and 1 minute without stimulation. PFI measurements increased 6.1±4.7% (p = .001) during the first minute of stimulation, with the most significant increase in PFI occurring 30 seconds into stimulation (p<0.001). These results suggest that pattern stimulation induces a change to retinal blood flow that can be reliably measured with OCT angiography.

Highlights

The notion that the brain has an intrinsic method to regulate local blood flow in response to a stimulus was first proposed by Roy and Sherrington in 1890 [1]
To measure local microcirculation in the eye, we developed optical coherence tomography (OCT) angiography using a high speed swept-source OCT device [11]
We report the first use of OCT angiography with split-spectrum amplitude-decorrelation angiography (SSADA) to measure the change in blood flow to the parafoveal retina when stimulated with an 8 Hz reversing checkerboard pattern

Summary

Introduction

The notion that the brain has an intrinsic method to regulate local blood flow in response to a stimulus was first proposed by Roy and Sherrington in 1890 [1]. This phenomenon, known as neurovascular coupling, has since been confirmed by brain researchers who have measured changes in cerebral blood flow in response to a variety of stimuli and mapped out the activity of the brain [2]. Neurovascular coupling in the eye was first confirmed in the cat through increased optic nerve head blood flow in response to flicker light, and was later confirmed in primates and human eyes as well [3,4,5]. Techniques used later on, including laser Doppler flowmetry, scanning laser Doppler flowmetry (SLDF), and Doppler OCT, were able to measure vascular changes by measuring the flow rate of moving scatters, such as red blood cells (RBC) [6,8,9,10]

Methods

Results

Conclusion