Optical coherence tomography angiography of stimulus evoked hemodynamic responses in individual retinal layers

Abstract

Blood flow changes are highly related to neural activities in the retina. It has been reported that neural activity increases when flickering light stimulation of the retina is used. It is known that blood flow changes with flickering light stimulation can be altered in patients with vascular disease and that measurement of flicker-induced vasodilatation is an easily applied tool for monitoring functional microvascular alterations. However, details of distortions in retinal neurovascular coupling associated with major eye diseases are not well understood due to the limitation of existing techniques. In this study, flickering light stimulation was applied to mouse retinas to investigate stimulus evoked hemodynamic responses in individual retinal layers. A spectral domain optical coherence tomography (OCT) angiography imaging system was developed to provide dynamic mapping of hemodynamic responses in the ganglion cell layer, inner plexiform layer, outer plexiform layer and choroid layer before, during and after flickering light stimulation. Experimental results showed hemodynamic responses with different magnitudes and time courses in individual retinal layers. We anticipate that the dynamic OCT angiography of stimulus evoked hemodynamic responses can greatly foster the study of neurovascular coupling mechanisms in the retina, promising new biomarkers for retinal disease detection and diagnosis.

In vivooptical coherence tomography of stimulus-evoked intrinsic optical signals in mouse retinas

“…Light-induced hemodynamic change may also partially contribute to the slow IOS. 46 Further investigation is required to understand the origination of slow IOS.…”

Concurrent OCT imaging of stimulus evoked retinal neural activation and hemodynamic responses

“…The hemodynamic image sequence indicated the SV changes relative to baseline (pre-stimulation recording). A detailed data processing procedure has been reported previously [3, 12]. Doppler OCT, which is not shown in the results, was calculated to differentiate large blood (artery and vein) vessels from capillaries.…”

“…It is well known that early stages of eye diseases often affect specific retinal layers. Different morphological abnormalities, impaired physiological responses and blood vascular distortions can occur with different eye diseases [3]. Advanced and objective evaluations of retinal physiological functions are important for a better understanding of vision, which will allow better prevention of vision losses, early disease detection and improved treatment evaluation.…”

“…Both in vitro and in vivo studies have shown that fast IOSs have different polarities and mainly originate from the photoreceptor outer segments in the retina. Light stimulus-evoked hemodynamic changes have also been demonstrated in the retina using time-lapse OCT angiography, which is a functional extension of OCT [3]. Parafoveal retinal blood flow changes have been reported by visual stimulation with a reversing checkerboard pattern using the split-spectrum amplitude-decorrelation angiography (SSADA) algorithm [13].…”

Optical coherence tomography angiography: A comprehensive review of current methods and clinical applications

“…These studies show preferential changes in the plexiform layers presumably due to the increased metabolic demand from synaptic activity (Son, Wang et al 2016). With an experimental OCTA-based parafoveal flow index and a SS-OCTA device, flicker stimulation of the retina seems to increase the parafoveal blood flow by a modest, but significant amount (~6%) (Wei, Jia et al 2013).…”