Diffuse luminance flicker increases blood flow in major retinal arteries and veins

Garhöfer, Gerhard; Zawinka, Claudia; Resch, Hemma; Huemer, Karl-Heinz; Dorner, Guido T.; Schmetterer, Leopold

doi:10.1016/j.visres.2003.11.013

Cited by 87 publications

(90 citation statements)

References 12 publications

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“…This is in good agreement with human data indicating that most of the vasodilator response occurs in the microvasculature. 58 A reduction in the retinal response to flicker stimulation can be seen in diabetic patients before any change in pattern electro-retinography becomes evident. 59 In diabetic rats, the abnormal retinal flicker response can be normalized by inhibition of inducible nitric oxide synthase.…”

Section: Discussionmentioning

confidence: 99%

Measurement of retinal blood flow in the rat by combining Doppler Fourier-domain optical coherence tomography with fundus imaging

et al. 2014

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Abstract. A wide variety of ocular diseases are associated with abnormalities in ocular circulation. As such, there is considerable interest in techniques for quantifying retinal blood flow, among which Doppler optical coherence tomography (OCT) may be the most promising. We present an approach to measure retinal blood flow in the rat using a new optical system that combines the measurement of blood flow velocities via Doppler Fourier-domain optical coherence tomography and the measurement of vessel diameters using a fundus camera-based technique. Relying on fundus images for extraction of retinal vessel diameters instead of OCT images improves the reliability of the technique. The system was operated with an 841-nm superluminescent diode and a charge-coupled device camera that could be operated at a line rate of 20 kHz. We show that the system is capable of quantifying the response of 100% oxygen breathing on the retinal blood flow. In six rats, we observed a decrease in retinal vessel diameters of 13.2% and a decrease in retinal blood velocity of 42.6%, leading to a decrease in retinal blood flow of 56.7%. Furthermore, in four rats, the response of retinal blood flow during stimulation with diffuse flicker light was assessed. Retinal vessel diameter and blood velocity increased by 3.4% and 28.1%, respectively, leading to a relative increase in blood flow of 36.2%. The presented technique shows much promise to quantify early changes in retinal blood flow during provocation with various stimuli in rodent models of ocular diseases in rats. © The Authors. Published by SPIE under a Creative Commons Attribution 3.0 Unported License. Distribution or reproduction of this work in whole or in part requires full attribution of the original publication, including its DOI.

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Section: Discussionmentioning

confidence: 99%

Measurement of retinal blood flow in the rat by combining Doppler Fourier-domain optical coherence tomography with fundus imaging

et al. 2014

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“…Manganese ions are likely localized in the intracellular space of the retinal pigment epithelium and the endothelial cells outlining choroidal vessels, which are unlikely to differ between light and dark conditions. Choroid BF is generally unresponsive to visual stimulation, and light and dark adaptation as detected by using laser Doppler flowmetry techniques in humans, 42 although exception has been noted. 3 Others have also suggested that choroid is not regulated by local metabolic controls.…”

Section: Discussionmentioning

confidence: 99%

“…Other functional imaging techniques of the retina include intrinsic optical imaging, 47 laser Doppler flowmetry, 42 laser speckle imaging, 48,49 and depth-resolved functional optical coherence tomography. 50,51 Intrinsic optical imaging measures reflectance associated with visual stimulation, albeit without laminar resolution.…”

Section: Discussionmentioning

confidence: 99%

Layer-Specific Manganese-Enhanced MRI of the Retina in Light and Dark Adaptation

Garza

Shih

et al. 2012

Invest. Ophthalmol. Vis. Sci.

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“…30 In humans, a flickering light results in blood flux increases of 30-38% in the optic nerve head 31,32 and flux increases of 59% in retinal arterioles. 33 In the cat optic nerve head, flux increases of 27-59% are observed. 27,34 As originally noted by Roy and Sherrington, 20 the localized nature of blood flow control is a hallmark of the functional hyperemia response.…”

Section: Introductionmentioning

confidence: 99%

Functional Hyperemia and Mechanisms of Neurovascular Coupling in the Retinal Vasculature

Newman

2013

J Cereb Blood Flow Metab

196

162

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The retinal vasculature supplies cells of the inner and middle layers of the retina with oxygen and nutrients. Photic stimulation dilates retinal arterioles producing blood flow increases, a response termed functional hyperemia. Despite recent advances, the neurovascular coupling mechanisms mediating the functional hyperemia response in the retina remain unclear. In this review, the retinal functional hyperemia response is described, and the cellular mechanisms that may mediate the response are assessed. These neurovascular coupling mechanisms include neuronal stimulation of glial cells, leading to the release of vasoactive arachidonic acid metabolites onto blood vessels, release of potassium from glial cells onto vessels, and production and release of nitric oxide (NO), lactate, and adenosine from neurons and glia. The modulation of neurovascular coupling by oxygen and NO are described, and changes in functional hyperemia that occur with aging and in diabetic retinopathy, glaucoma, and other pathologies, are reviewed. Finally, outstanding questions concerning retinal blood flow in health and disease are discussed. In lower vertebrates that have thinner retinas, including amphibians, reptiles, and some mammals, the retinal vasculature is absent and the choroidal circulation supplies the entire retina. 2 The choroidal circulation is supplied by the long and short ciliary arteries and the anterior ciliary arteries, which feed the large arteries in the outer portion of the choroid. 3 These arteries branch into smaller vessels, which, in turn, feed the highly anastomosed choriocapillaris network lying at the inner border of the choroid, adjacent to the retinal pigment epithelium and retinal photoreceptors. The total blood flow supplying the choroid is much greater than that supplying the retina (606 vs. 25 mg/min/ whole tissue 4 ), to meet the high metabolic demands of the photoreceptors. 5 The retinal vasculature is supplied by the central retinal artery, which enters the retina with the optic nerve at the optic disc. The artery branches into radial arterioles and smaller vessels on the vitreal surface of the retina. 3 Pre-capillary arterioles and capillaries ramify from these surface vessels and form anastomotic networks in the ganglion cell layer, just beneath the retinal surface, and deeper in the inner nuclear layer, supplying horizontal cells, bipolar cells, amacrine cells, and Mü ller glial cells. Blood is returned through radial venules on the retinal surface that empty into the central retinal vein in the optic nerve. Journal of Cerebral BloodThe retinal and choroidal vasculatures differ in several respects. Retinal vessels lack autonomic innervation, 6,7 whereas the choroidal circulation is innervated by both sympathetic and parasympathetic

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Diffuse luminance flicker increases blood flow in major retinal arteries and veins

Cited by 87 publications

References 12 publications

Measurement of retinal blood flow in the rat by combining Doppler Fourier-domain optical coherence tomography with fundus imaging

Measurement of retinal blood flow in the rat by combining Doppler Fourier-domain optical coherence tomography with fundus imaging

Layer-Specific Manganese-Enhanced MRI of the Retina in Light and Dark Adaptation

Functional Hyperemia and Mechanisms of Neurovascular Coupling in the Retinal Vasculature

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