The Choroidal Eye Oximeter: An Instrument for Measuring Oxygen Saturation of Choroidal Blood In Vivo

Laing, Ronald A.; Danisch, L.; Young, Laurence R.

doi:10.1109/tbme.1975.324558

Cited by 19 publications

(18 citation statements)

References 6 publications

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“…Gloster 19 measured changes in choroidal reflectometry with altered oxygenation. Laing 20 developed a 'choroidal eye oximeter' to measure the OS of choroidal blood. Hickam et al 21 described a photographic method to estimate the OS of the retinal veins in humans.…”

Section: Principles Of Retinal Oximetrymentioning

confidence: 99%

Spectral imaging of the retina

Mordant

Alabboud

Muyo

et al. 2011

Eye

107

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Introduction The work described here involved the use of a modified fundus camera to obtain sequential hyperspectral images of the retina in 14 normal volunteers and in 1 illustrative patient with a retinal vascular occlusion. Methods The paper describes analysis techniques, which allow oximetry within retinal vessels; these results are presented as retinal oximetry maps. Results Using spectral images, with wavelengths between 556 and 650 nm, the mean oxygen saturation (OS) value in temporal retinal arterioles in normal volunteers was 104.3 ( ± 16.7), and in normal temporal retinal venules was 34.8 (±17.8). These values are comparable to those quoted in the literature, although, the venular saturations are slightly lower than those values found by other authors; explanations are offered for these differences. Discussion The described imaging and analysis techniques produce a clinically useful map of retinal oximetric values. The results from normal volunteers and from one illustrative patient are presented. Further developments, including the recent development of a 'snapshot' spectral camera, promises enhanced non-invasive retinal vessel oximetry mapping.

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Section: Principles Of Retinal Oximetrymentioning

confidence: 99%

Spectral imaging of the retina

Mordant

Alabboud

Muyo

et al. 2011

Eye

107

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“…Combining measurements of blood flow (Cunha-Vaz and Lima, 1978;Oswald et al, 1983;Riva et al, 1972;Sato et al, 2006;Vilser et al, 1986) and of arterial oxygen saturation (Beach et al, 1999;Delori et al, 1981;Hickham et al, 1963;Laing et al, 1975;Schweitzer et al, 1999Schweitzer et al, , 1995 the supply of the tissue with oxygen can be calculated. Additionally, the arterio-venous difference of the oxygen saturation enables an estimation of the oxygen consumption in the tissue.…”

Section: Introductionmentioning

confidence: 99%

Towards metabolic mapping of the human retina

Schweitzer

Schenke

Hammer

et al. 2007

Microscopy Res & Technique

205

240

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Functional alterations are first signs of a starting pathological process. A device that measures parameter for the characterization of the metabolism at the human eye-ground would be a helpful tool for early diagnostics in stages when alterations are yet reversible. Measurements of blood flow and of oxygen saturation are necessary but not sufficient. The new technique of auto-fluorescence lifetime measurement (FLIM) opens in combination with selected excitation and emission ranges the possibility for metabolic mapping. FLIM not only adds an additional discrimination parameter to distinguish different fluorophores but also resolves different quenching states of the same fluorophore. Because of its high sensitivity and high temporal resolution, its capability to resolve multi-exponential decay functions, and its easy combination with laser scanner ophthalmoscopy, multi-dimensional time-correlated single photon counting was used for fundus imaging. An optimized set up for in vivo lifetime measurements at the human eye-ground will be explained. In this, the fundus fluorescence is excited at 446 or 468 nm and the time-resolved autofluorescence is detected in two spectral ranges between 510 and 560 nm as well as between 560 and 700 nm simultaneously. Exciting the fundus at 446 nm, several fluorescence maxima of lifetime t1 were detected between 100 and 220 ps in lifetime histograms of 40 degrees fundus images. In contrast, excitation at 468 nm results in a single maximum of lifetime t1 = 190 +/- 16 ps. Several fundus layers contribute to the fluorescence intensity in the short-wave emission range 510-560 nm. In contrast, the fluorescence intensity in the long-wave emission range between 560 and 700 nm is dominated by the fluorescence of lipofuscin in the retinal pigment epithelium. Comparing the lateral distribution of parameters of a tri-exponential model function in lifetime images of the fundus with the layered anatomical fundus structure, the shortest component (t1 = 190 ps) originates from the retinal pigment epithelium and the second lifetime (t2 = 1,000 ps) from the neural retina. The lifetime t3 approximately 5.5 ns might be influenced by the long decay of the fluorescence in the crystalline lens. In vitro analysis of the spectral properties of expected fluorophores under the condition of the living eye lightens the interpretation of in vivo measurements. Taking into account the transmission of the ocular media, the excitation of NADH is unlikely at the fundus.

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“…Pulse oximetry is a well-known noninvasive medical detection technique that is used for measuring the oxygen saturation of blood and the pulse rate of patients [5], [6]. Oxygenated hemoglobin and reduced hemoglobin have different absorption properties at specific wavelengths.…”

Section: Experimental Methods and Setupmentioning

confidence: 99%

“…Pulse oximetry is a well-known noninvasive technique that can detect respiratory signals, pulsation signals, and chemicals in the blood [5], [6]- [12]. It is an electrooptical method and detects blood volume changes in the finger arterial tree.…”

Section: Introductionmentioning

confidence: 99%

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Advanced Spectroscopic Characterization of Impact of Alcoholic Intake on Variation in Blood-Pulse Waveform

Shimizu

Ōmura

2011

IEEE Sensors J.

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We spectroscopically investigate the impact of alcohol intake on photoplethysmogram (PPG) signal and confirm that alcohol intake can be discerned by optoelectronic sensors. This paper focuses on specific spectra of the PPG signal and demonstrates the importance of observing the harmonics ratio of the PPG signal. In contrast to past studies, it is strongly suggested that the best light source for detecting alcohol intake is a green-LED. An analysis of the time evolution of the harmonic ratio shows that it includes important information from which the intake of alcohol can be discerned despite the complexity involved. This assessment is strongly supported by the physical model and the mathematical formulation provided herein.

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The Choroidal Eye Oximeter: An Instrument for Measuring Oxygen Saturation of Choroidal Blood In Vivo

Cited by 19 publications

References 6 publications

Spectral imaging of the retina

Spectral imaging of the retina

Towards metabolic mapping of the human retina

Advanced Spectroscopic Characterization of Impact of Alcoholic Intake on Variation in Blood-Pulse Waveform

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