Automatic Retinal Oximetry

Hardarson, Sveinn Hákon; Harris, Alon; Karlsson, Robert Arnar; Halldorsson, Gisli H.; Kagemann, Larry; Rechtman, Ehud; Zoëga, Gunnar Már; Eysteinsson, Þór; Benediktsson, Jón Atli; Thorsteinsson, Adalbjörn; Jensen, Patricia; Beach, J. M.; Stefánsson, Einar

doi:10.1167/iovs.06-0039

Cited by 250 publications

(327 citation statements)

References 41 publications

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“…Oximetry based on differential spectroscopy, on the other hand, is a spatially resolved method that has been successfully applied to retinal vessels. 153,154 Another approach combines Doppler OCT with hyperspectral imaging for assessing blood oxygenation in tumor vasculature. 155 A relatively young biomedical imaging technique that uses absorption as a contrast mechanism is photoacoustic tomography (PAT) or microscopy (PAM).…”

Section: Label-free Optical Angiographymentioning

confidence: 99%

Optical coherence tomography today: speed, contrast, and multimodality

Drexler¹,

Li²,

Kumar³

et al. 2014

J. Biomed. Opt

432

264

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Abstract. In the last 25 years, optical coherence tomography (OCT) has advanced to be one of the most innovative and most successful translational optical imaging techniques, achieving substantial economic impact as well as clinical acceptance. This is largely owing to the resolution improvements by a factor of 10 to the submicron regime and to the imaging speed increase by more than half a million times to more than 5 million A-scans per second, with the latter one accomplished by the state-of-the-art swept source laser technologies that are reviewed in this article. In addition, parallelization of OCT detection, such as line-field and full-field OCT, has shortened the acquisition time even further by establishing quasi-akinetic scanning. Besides the technical improvements, several functional and contrast-enhancing OCT applications have been investigated, among which the label-free angiography shows great potential for future studies. Finally, various multimodal imaging modalities with OCT incorporated are reviewed, in that these multimodal implementations can synergistically compensate for the fundamental limitations of OCT when it is used alone. © 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: Label-free Optical Angiographymentioning

confidence: 99%

Optical coherence tomography today: speed, contrast, and multimodality

Drexler¹,

Li²,

Kumar³

et al. 2014

J. Biomed. Opt

432

264

View full text Add to dashboard Cite

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“…Oxygen cannot be "stored" in tissue so that a constant and adequate supply must be guaranteed to preserve function. Metabolic dysfunction regarding to impaired vascular supply is directly reflected by retinal oxygen saturation which can be detected noninvasively by dual wavelength fundus photography [3]. Normally, the oxygen saturation in retinal vessels differs along vascular segments and is higher in the macular region than retinal periphery [4].…”

Section: Ischemic Tolerance In the Vertebrate Retinamentioning

confidence: 99%

Selected aspects of retinal signaling and energy metabolism and its perspective as a cerebral surrogate model

Albanna¹,

Lüke²,

Alpdogan³

et al. 2018

New Front Ophthalmol

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Purpose: The isolated and superfused retina from vertebrates is routinely used for neurophysiological measurements of basic retinal signal generation and transduction. Such an ex vivo isolated neural network moreover represents a useful model system for the investigation of drugs and toxins and may also be helpful to elucidate molecular mechanisms of CNS diseases. The present overview aims to bring observations to the reader's attention, which, in part, have been made more than 50 years ago and were sparsely followed up upon in subsequent research, but may support the idea that the isolated bovine retina represents a useful system to investigate the physiology and pathophysiology of energy supply to neuronal tissue. Material and methods:Parallel recording of ERGs and pyridine nucleotide oxidation in the isolated and superfused vertebrate retina. The review will focus on topics, which discuss the connection between retinal electrophysiology and underlying energy metabolism.Results: Previous and present reports about (i) transretinal signaling cascades, (ii) the involvement of the pharmacoresistant Cav2.3 / R-type calcium channel in transretinal signaling and (iii) data about the retinal oxygen demands and concentration in different layers are collected, which elucidate that the retina may be used as a cerebral surrogate model in different research areas. Retinal tolerance to ischemia is several times larger than the tolerance in the remaining brain. Conclusions:The retinal energy supply through retinal vessels is regulated and controlled by neurovascular coupling. Classical retinal recording techniques and special retinal abilities in electrical-vascular coupling will be set in perspective with novel recording techniques, currently brought into clinical application for the detection of impaired neurovascular coupling after aneurysmal subarachnoid hemorrhage in the brain. The present review elucidates that important pathophysiological aspects related to the upregulation of pharmacoresistant Cav2.3 / R-type calcium channels during SAH may be investigated in the isolated vertebrate retina. Ischemic tolerance in the vertebrate retinaThe oxygen consumption of the vertebrate retina on a per gram basis has been described as higher than that of the brain [1,2]. Oxygen cannot be "stored" in tissue so that a constant and adequate supply must be guaranteed to preserve function. Metabolic dysfunction regarding to impaired vascular supply is directly reflected by retinal oxygen saturation which can be detected noninvasively by dual wavelength fundus photography [3]. Normally, the oxygen saturation in retinal vessels differs along vascular segments and is higher in the macular region than retinal periphery [4]. Many retinal diseases are caused by a dysfunction of the vascular network. Interestingly, the venous oxygen saturation in diabetic retinopathy was higher in venules draining the macular surroundings than retinal periphery that reflect specific metabolic conditions [5,6].Since a relatively unobstructed light path...

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“…As such it is often, though not always, associated with an increase in intra-ocular pressure. [106,107]. Early detection of retinal abnormalities is considered to be essential in preventing loss of vision [108], and the benefits of early management have been seen to persist for years [101].…”

Section: 6: Retinal Diseasesmentioning

confidence: 99%