Retinal Oxygen Metabolism During Normoxia and Hyperoxia in Healthy Subjects

Palkovits, Stefan; Lasta, Michael; Told, Reinhard; Schmidl, Doreen; Boltz, Agnes; Napora, Katarzyna J; Werkmeister, René M.; Popa-Cherecheanu, Alina; Garhöfer, Gerhard; Schmetterer, Leopold

doi:10.1167/iovs.14-14593

Cited by 63 publications

(75 citation statements)

References 63 publications

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“…It is worth noting that our measured sO 2 of retinal veins are at the higher range compared to previously reported values [39, 40,45,46]. All these results were obtained by the less accurate multiple wavelength diffusive fundus imaging, which has intrinsic vulnerability due to lack of axial resolution and strong influences from vessels diameter and RPE pigmentation variations [22].…”

Section: Discussionsupporting

confidence: 46%

Retinal oximetry in humans using visible-light optical coherence tomography [Invited]

Chen

Xiao

Nesper

et al. 2017

Biomed. Opt. Express

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Abstract:We measured hemoglobin oxygen saturation (sO 2 ) in the retinal circulation in healthy humans using visible-light optical coherence tomography (vis-OCT). The measurements showed clear oxygenation differences between central retinal arteries and veins close to the optic nerve head. Spatial variations at different vascular branching levels were also revealed. In addition, we presented theoretical and experimental results to establish that noises in OCT intensity followed Rice distribution. We used this knowledge to retrieve unbiased estimation of true OCT intensity to improve the accuracy of vis-OCT oximetry, which had inherently lower signal-to-nose ratio from human eyes due to safety and comfort limitations. We demonstrated that the new statistical-fitting sampling strategy could reduce the estimation error in sO 2 by three percentage points (pp). The presented work aims to provide a foundation for using vis-OCT to achieve accurate retinal oximetry in clinical settings. G. Garhöfer, and L. Schmetterer, "Retinal oxygen metabolism during normoxia and hyperoxia in healthy subjects," Invest.

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Section: Discussionsupporting

confidence: 46%

Retinal oximetry in humans using visible-light optical coherence tomography [Invited]

Chen

Xiao

Nesper

et al. 2017

Biomed. Opt. Express

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“…In anesthetized cats, average inner retinal PO 2 does not decrease until PaO 2 is below about 40 mmHg (Enroth-Cugell et al, 1980; Linsenmeier and Braun, 1992). Limited evidence, discussed further in section 5, indicates that IR-QO 2 is also maintained to relatively low PaO 2 (Yi et al, 2015a; Palkovits et al 2014a). Because of the regulation, the b-wave is also relatively resistant to hypoxia, but it begins to change before the a-wave (e.g.…”

Section: Retinal Po2 In Hypoxia and Hyperoxiamentioning

confidence: 99%

Retinal oxygen: from animals to humans

Linsenmeier

Zhang

2017

Progress in Retinal and Eye Research

192

150

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This article discusses retinal oxygenation and retinal metabolism by focusing on measurements made with two of the principal methods used to study O2 in the retina: measurements of PO2 with oxygen-sensitive microelectrodes in vivo in animals with a retinal circulation similar to that of humans, and oximetry, which can be used non-invasively in both animals and humans to measure O2 concentration in retinal vessels. Microelectrodes uniquely have high spatial resolution, allowing the mapping of PO2 in detail, and when combined with mathematical models of diffusion and consumption, they provide information about retinal metabolism. Mathematical models, grounded in experiments, can also be used to simulate situations that are not amenable to experimental study. New methods of oximetry, particularly photoacoustic ophthalmoscopy and visible light optical coherence tomography, provide depth-resolved methods that can separate signals from blood vessels and surrounding tissues, and can be combined with blood flow measures to determine metabolic rate. We discuss the effects on retinal oxygenation of illumination, hypoxia and hyperoxia, and describe retinal oxygenation in diabetes, retinal detachment, arterial occlusion, and macular degeneration. We explain how the metabolic measurements obtained from microelectrodes and imaging are different, and how they need to be brought together in the future. Finally, we argue for revisiting the clinical use of hyperoxia in ophthalmology, particularly in retinal arterial occlusions and retinal detachment, based on animal research and diffusion theory.

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“…22 During hyperoxia, a significant decrease in RBF, vessel diameter, and velocity observed as well as SO 2 increased in retinal arteries and veins by þ4.4% and þ19.6%, respectively. 50 One must note that, in their studies, RBF measurements were achieved from one single vein compared to TRBF reported in the current study. Also, the vessel diameter and blood flow measurements were acquired using two different instruments, unlike simultaneous acquisition using Doppler SD-OCT.…”

Section: Discussionmentioning

confidence: 76%

“…In this study, alongside the TRBF measurements, retinal arteriolar and venular blood SO 2 also was achieved using the MHRC. Recently, Palkovits et al 22,50 reported retinal blood SO 2 and RBF during hypoxia and hyperoxia in humans. Retinal blood flow increased while retinal blood SO 2 decreased during two levels of hypoxia studied.…”

Section: Discussionmentioning

confidence: 99%

Intervisit Repeatability of Retinal Blood Oximetry and Total Retinal Blood Flow Under Varying Systemic Blood Gas Oxygen Saturations

Rose

Kulasekara

Hudson

2016

Invest. Ophthalmol. Vis. Sci.

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Citation: Rose K, Kulasekara SI, Hudson C. Intervisit repeatability of retinal blood oximetry and total retinal blood flow under varying systemic blood gas oxygen saturations. Invest Ophthalmol Vis Sci. 2016;57:188-197. DOI:10.1167/iovs.15-17908 PURPOSE. The aim of the study is to validate and calibrate the Doppler spectral-domain optical coherence tomography (SD-OCT) derived total retinal blood flow (TRBF) and metabolic hyperspectral retinal camera (MHRC) derived oxygen saturation (SO 2 ) of major retinal vessels in human volunteers using a novel and exact provocation technique (RespirAct) that allows the precise control of the end-tidal partial pressure of oxygen (P ET O 2 ). Between visit repeatability of the TRBF and retinal blood SO 2 also were studied.METHODS. One eye of 11 young healthy subjects was chosen randomly for the study. Total retinal blood flow and retinal SO 2 measurements were obtained under conditions of normoxia, hyperoxia, and hypoxia. The order of hyperoxia and hypoxia was randomized between subjects. The measurements were repeated after a week interval.RESULTS. When the arterial P ET O 2 was increased from baseline (P ET O 2 ¼ 100 mm Hg) to 200 and 300 mm Hg, the TRBF significantly reduced (P ¼ 0.02) from 44.60 (68.9) to 40.28 (68.9) and 36.23 (64.6) lL/min. Lowering the arterial P ET O 2 , from baseline to 80, 60, and 50 mm Hg, TRBF significantly increased (P ¼ 0.04) from 43.17 (612.7) to 45.19 (65.5), 49.71 (613.4), and 52.89 (610.9) lL/min with simultaneous reduction in the arterial blood SO 2 content from 99.3% (65.8) to 95.6% (65.1), 89.6% (62.8), and 83.3% (63.9), respectively (P ¼ 0.00). The coefficient of repeatability (COR) of TRBF, retinal arterial, and venous blood SO 2 values are 21.8 lL/min, 18.4%, and 15.2%, respectively. CONCLUSIONS.Total retinal blood flow and retinal blood SO 2 measurements performed under safe levels of hypoxia and hyperoxia were repeatable in healthy adults over the range of SO 2 investigated.

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Retinal Oxygen Metabolism During Normoxia and Hyperoxia in Healthy Subjects

Cited by 63 publications

References 63 publications

Retinal oximetry in humans using visible-light optical coherence tomography [Invited]

Retinal oximetry in humans using visible-light optical coherence tomography [Invited]

Retinal oxygen: from animals to humans

Intervisit Repeatability of Retinal Blood Oximetry and Total Retinal Blood Flow Under Varying Systemic Blood Gas Oxygen Saturations

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