Assessment of flow dynamics in retinal and choroidal microcirculation

Wei, Xin; Balne, Praveen Kumar; Meissner, Kenith E.; Barathi, Veluchamy A; Schmetterer, Leopold; Agrawal, Rupesh

doi:10.1016/j.survophthal.2018.03.003

Cited by 67 publications

(52 citation statements)

References 244 publications

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“…Perfusion measurements of the choroidal circulation can be critical for the diagnosis of various diseases such as glaucoma, retinopathy, and macular degeneration. 65 The retina has two separate blood supplies by virtue of the high metabolic activity. The choroidal circulation feeds the choroidal tissues and the outer section of the retina, and the retinal circulation feeds the inner portion of the retina.…”

Section: Ophthalmologymentioning

confidence: 99%

Clinical applications of laser speckle contrast imaging: a review

et al. 2019

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When a biological tissue is illuminated with coherent light, an interference pattern will be formed at the detector, the so-called speckle pattern. Laser speckle contrast imaging (LSCI) is a technique based on the dynamic change in this backscattered light as a result of interaction with red blood cells. It can be used to visualize perfusion in various tissues and, even though this technique has been extensively described in the literature, the actual clinical implementation lags behind. We provide an overview of LSCI as a tool to image tissue perfusion. We present a brief introduction to the theory, review clinical studies from various medical fields, and discuss current limitations impeding clinical acceptance.

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Section: Ophthalmologymentioning

confidence: 99%

Clinical applications of laser speckle contrast imaging: a review

et al. 2019

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“…12 In this context, the assessment of volumetric blood flow in retinal vessels is challenging, especially during experimentally introduced changes in OPP. Although blood flow in retinal arteries and veins has been investigated for many years using techniques such as laser Doppler velocimetry or laser speckle flowgraphy, 13,14 it recently also became possible to study the retinal circulation using Doppler optical coherence tomography (D-OCT). This technique has the advantage of providing retinal blood velocity as well as vessel diameter in absolute values within one measurement, 15 whereas most previous studies investigating retinal autoregulatory properties in humans measured retinal blood velocity and diameters separately or used vessel diameters only.…”

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confidence: 99%

Changes in Retinal Blood Flow in Response to an Experimental Increase in IOP in Healthy Participants as Assessed With Doppler Optical Coherence Tomography

Puchner

Schmidl

Ginner

et al. 2020

Invest. Ophthalmol. Vis. Sci.

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Citation: Puchner S, Schmidl D, Ginner L, et al. Changes in retinal blood flow in response to an experimental increase in IOP in healthy participants as assessed with Doppler optical coherence tomography. Invest Ophthalmol Vis Sci. 2020;61(2):33. https://doi.org/10.1167/iovs.61.2.33 PURPOSE.Blood flow autoregulation is an intrinsic mechanism of the healthy retinal vasculature to keep blood flow constant when ocular perfusion pressure (OPP) is changed. In the present study, we set out to investigate retinal blood flow in response to an experimental decrease in OPP in healthy participants using Doppler optical coherence tomography. METHODS.Fifteen healthy participants aged between 22 and 31 years (mean, 27 ± 3 years) were included in the present open study. IOP was increased stepwise via the suction cup method to induce a decrease in OPP. Retinal blood flow in arteries and veins was assessed using a custom-built Doppler optical coherence tomography system and pressure-flow relationships were calculated to assess autoregulation. RESULTS.Suction cup application induced a pronounced increase in IOP with a maximum value of 50.5 ± 8.0 mm Hg at the highest level of suction. Pressure-flow relationships revealed that blood flow was autoregulated until the OPP was decreased by approximately 21 mm Hg and started to decrease significantly when the OPP was reduced by 30 mm Hg. Retinal blood flow at the last suction period decreased at a maximum of -57.0 ± 22.3% and 65.2 ± 15.4% in retinal arteries and retinal veins, respectively. These changes in retinal blood flow were less pronounced than the decrease in OPP (-75.2 ± 19.2%), indicating retinal autoregulation. CONCLUSIONS.The results of the present study confirm that retinal blood flow is autoregulated in response to changes in the OPP. Doppler optical coherence tomography has the potential to become a clinical tool for the investigation of retinal blood flow autoregulation in the future, because of its ability to assess the blood velocities and diameter of the retinal vessels parallel and therefore also their blood flow in absolute values. (Clinicaltrials.gov number NCT03398616)

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“…10,11 In addition, the techniques have considerable limitations, and no system is currently used in clinical routine. 11,12 Several solutions were proposed to quantify total retinal blood flow (Q) based on Doppler optical coherence tomography (OCT). [13][14][15][16][17][18][19] Recently, a prototype instrument from a commercial company was introduced and good reproducibility was reported.…”

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confidence: 99%

Age-Related Decline of Retinal Oxygen Extraction in Healthy Subjects

Bata

Fondi

Szegedi

et al. 2019

Invest. Ophthalmol. Vis. Sci.

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PURPOSE. To investigate the age-dependence of total retinal blood flow and total retinal oxygen extraction in healthy subjects and determine their possible correlations with structural optical coherence tomography (OCT) parameters. METHODS. This observational cross-sectional study consisted of 68 healthy subjects (mean 6 SD age, 45.6 6 16.3 years; 47% female). Total retinal oxygen extraction was calculated based on measurement of total retinal blood flow using bi-directional Doppler OCT and measurement of oxygen saturation using spectroscopic reflectometry. Retinal nerve fiber layer thickness was measured using OCT, and the total number of retinal ganglion cells was estimated based on a previous published model. Correlation of these parameters with age was studied and the association between structural OCT parameters and hemodynamic vascular parameters was calculated. RESULTS. Both structural and vascular parameters showed a significant decline with increasing age. The correlation coefficients were between r ¼ À0.25 and r ¼ À0.41. Furthermore, structural and vascular parameters were significantly correlated with each other. The strongest association was found between the level of total retinal oxygen extraction and the number of retinal ganglion cells (r ¼ 0.75, P < 0.001). CONCLUSIONS. We showed that there was an age-related decline of retinal oxygen extraction. Levels of retinal oxygen extraction are correlated to retinal nerve fiber layer thickness and number of retinal ganglion cells. Our data partially explain the wide inter-individual variability in retinal blood flow values in healthy subjects. Longitudinal studies are required to study the time course of vascular and neuronal loss in humans.

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Assessment of flow dynamics in retinal and choroidal microcirculation

Cited by 67 publications

References 244 publications

Clinical applications of laser speckle contrast imaging: a review

Clinical applications of laser speckle contrast imaging: a review

Changes in Retinal Blood Flow in Response to an Experimental Increase in IOP in Healthy Participants as Assessed With Doppler Optical Coherence Tomography

Age-Related Decline of Retinal Oxygen Extraction in Healthy Subjects

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