Methods to measure blood flow and vascular reactivity in the retina

Böhm, Elsa Wilma; Pfeiffer, Norbert; Wagner, Félix; Gericke, Adrian

doi:10.3389/fmed.2022.1069449

Cited by 8 publications

(3 citation statements)

References 187 publications

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“…Retinal arteriole reactivity was measured in retinal vascular preparations in vitro by using video microscopy as described previously [ 36 , 37 ]. First, mice were sacrificed by CO 2 inhalation, and eyes were isolated and put into cold Krebs-Henseleit buffer.…”

Section: Methodsmentioning

confidence: 99%

Effects of Resveratrol on Vascular Function in Retinal Ischemia-Reperfusion Injury

et al. 2023

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Ischemia-reperfusion (I/R) events are involved in the development of various ocular pathologies, e.g., retinal artery or vein occlusion. We tested the hypothesis that resveratrol is protective against I/R injury in the murine retina. Intraocular pressure (IOP) was elevated in anaesthetized mice to 110 mm Hg for 45 min via a micropipette placed in the anterior chamber to induce ocular ischemia. In the fellow eye, which served as control, IOP was kept at a physiological level. One group received resveratrol (30 mg/kg/day p.o. once daily) starting one day before the I/R event, whereas the other group of mice received vehicle solution only. On day eight after the I/R event, mice were sacrificed and retinal wholemounts were prepared and immuno-stained using a Brn3a antibody to quantify retinal ganglion cells. Reactivity of retinal arterioles was measured in retinal vascular preparations using video microscopy. Reactive oxygen species (ROS) and nitrogen species (RNS) were quantified in ocular cryosections by dihydroethidium and anti-3-nitrotyrosine staining, respectively. Moreover, hypoxic, redox and nitric oxide synthase gene expression was quantified in retinal explants by PCR. I/R significantly diminished retinal ganglion cell number in vehicle-treated mice. Conversely, only a negligible reduction in retinal ganglion cell number was observed in resveratrol-treated mice following I/R. Endothelial function and autoregulation were markedly reduced, which was accompanied by increased ROS and RNS in retinal blood vessels of vehicle-exposed mice following I/R, whereas resveratrol preserved vascular endothelial function and autoregulation and blunted ROS and RNS formation. Moreover, resveratrol reduced I/R-induced mRNA expression for the prooxidant enzyme, nicotinamide adenine dinucleotide phosphate oxidase 2 (NOX2). Our data provide evidence that resveratrol protects from I/R-induced retinal ganglion cell loss and endothelial dysfunction in the murine retina by reducing nitro-oxidative stress possibly via suppression of NOX2 upregulation.

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Section: Methodsmentioning

confidence: 99%

Effects of Resveratrol on Vascular Function in Retinal Ischemia-Reperfusion Injury

et al. 2023

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“…Another limitation of CDI is its inability to provide volumetric blood flow data. Accurate calculation of blood flow requires the determination of vascular diameter [39]. However, CDI does not provide quantitative data on vessel diameter.…”

Section: Technical Aspectsmentioning

confidence: 99%

“…Moreover, to perform experiments in laboratory animals using CTA or MRI, general anesthesia is required, which may influence the results of the study. Therefore, myography may represent a feasible method for performing vascular studies in these small animals, where diameter changes of 1-3% are detectable in ex vivo studies and no general anesthesia is required [39]. However, using this method, no longitudinal studies can be performed and experienced investigators are mandatory.…”

Section: Clinical and Scientific Relevance Of Measuring Retrobulbar B...mentioning

confidence: 99%

Measurement of Retrobulbar Blood Flow and Vascular Reactivity—Relevance for Ocular and Cardiovascular Diseases

Böhm,

Grauhan,

Pfeiffer

et al. 2023

Diagnostics

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Abnormal retrobulbar hemodynamics have been linked to the development of various ocular diseases, including glaucoma, age-related macular degeneration, and diabetic retinopathy. Additionally, altered retrobulbar blood flow has been observed in patients with severe cardiovascular diseases, including carotid artery occlusion, stroke, heart failure, and acute coronary syndrome. Due to the complex and intricate anatomy of retrobulbar blood vessels and their location behind the eyeball, measurement of retrobulbar blood flow and vascular reactivity, as well as the interpretation of the findings, are challenging. Various methods, such as color Doppler imaging, computed tomography angiography or magnetic resonance imaging, have been employed to assess retrobulbar blood flow velocities in vivo. Color Doppler imaging represents a fast and non-invasive method to measure retrobulbar blood flow velocities in vivo. While no information about vessel diameter can be gained performing this method, computed tomography angiography and magnetic resonance imaging provide information about vessel diameter and detailed information on the anatomical course. Additionally, ex vivo studies, such as myography, utilizing genetically modified animal models may provide high optical resolution for functional vascular investigations in these small vessels. To our best knowledge, this is the first review, presenting a detailed overview of methods aiming to evaluate retrobulbar blood flow and vascular reactivity in both humans and laboratory animals. Furthermore, we will summarize the disturbances observed in retrobulbar blood flow in retinal, optic nerve, and cardiovascular diseases.

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Quantitative study of spatial and temporal variation in retinal capillary network perfusion in rat eye by in vivo confocal imaging

Yu,

Mehnert,

Dickson

et al. 2023

Sci Rep

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Microvascular dysfunction is the underlying pathological process in many systemic diseases. However, investigation into its pathogenesis is impeded by the accessibility and complexity of the microvasculature within different organs, particularly for the central nervous system. The retina as an extension of the cerebrum provides a glimpse into the brain through which the microvasculature can be observed. Two major questions remain unanswered: How do the microvessels regulate spatial and temporal delivery to satisfy the varying cellular demands, and how can we quantify blood perfusion in the 3D capillary network? Here, quantitative measurements of red blood cell (RBC) speed in each vessel in the field were made in the in vivo rat retinal capillary network using an ultrafast confocal technique with fluorescently labelled RBCs. Retinal RBC speed and number were found to vary remarkably between microvessels ranging from 215 to 6641 microns per second with significant variations spatially and temporally. Overall, the RBC speed was significantly faster in the microvessels in the superficial retina than in the deep retina (estimated marginal means of 2405 ± 238.2 µm/s, 1641 ± 173.0 µm/s respectively). These observations point to a highly dynamic nature of microvasculature that is specific to its immediate cellular environment and is constantly changing.

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Methods to measure blood flow and vascular reactivity in the retina

Cited by 8 publications

References 187 publications

Effects of Resveratrol on Vascular Function in Retinal Ischemia-Reperfusion Injury

Effects of Resveratrol on Vascular Function in Retinal Ischemia-Reperfusion Injury

Measurement of Retrobulbar Blood Flow and Vascular Reactivity—Relevance for Ocular and Cardiovascular Diseases

Quantitative study of spatial and temporal variation in retinal capillary network perfusion in rat eye by in vivo confocal imaging

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