Oxygen Saturation in Human Retinal Vessels Is Higher in Dark Than in Light

Hardarson, Sveinn Hákon; Basit, S.; Jonsdottir, Thora Elisabet; Eysteinsson, Þór; Halldorsson, Gisli H.; Karlsson, Robert Arnar; Beach, J. M.; Benediktsson, Jón Atli; Stefánsson, Einar

doi:10.1167/iovs.08-2576

Cited by 83 publications

(70 citation statements)

References 25 publications

(44 reference statements)

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“…Also, the human retinal vein oxyhemoglobin saturation is thought to be ∼60%. 1,13,14,16,27,40,41 We estimated the oxyhemoglobin saturation in the enucleated swine retinal vein and in the in vivo human retinal vein using the calibration line from our intravitreal retinal illumination experiments 1 and the measured minima in Fig. 6.…”

Section: Discussionmentioning

confidence: 99%

“…The calculated oxyhemoglobin saturation in the enucleated swine vessel was very near 0 as expected (-1 ± 2.0% Sat), and the human vein oxyhemoglobin saturation (63 ± 2.3% Sat) was also in the range reported elsewhere. 1,13,14,16,27,40,41 …”

Section: Discussionmentioning

confidence: 99%

“…In our earlier work evaluating the use of the BGO technique in hemoglobin solutions 4,40 and blood in transmission, 1,26 we calculated the scattering component of the loss of light using the model equation developed by Steinke and Sheppard. 38 The scattering component was linear with wavelength, had a negative slope, and had a positive intercept.…”

Section: Backscattering Of Light From the Eye In The Blue-green Spectmentioning

confidence: 99%

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Retinal oximeter for the blue-green oximetry technique

et al. 2011

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Abstract. Retinal oximetry offers potential for noninvasive assessment of central venous oxyhemoglobin saturation (SO 2 ) via the retinal vessels but requires a calibrated accuracy of ± 3% saturation in order to be clinically useful. Prior oximeter designs have been hampered by poor saturation calibration accuracy. We demonstrate that the bluegreen oximetry (BGO) technique can provide accuracy within ± 3% in swine when multiply scattered light from blood within a retinal vessel is isolated. A noninvasive on-axis scanning retinal oximeter (ROx-3) is constructed that generates a multiwavelength image in the range required for BGO. A field stop in the detection pathway is used in conjunction with an anticonfocal bisecting wire to remove specular vessel reflections and isolate multiply backscattered light from the blood column within a retinal vessel. This design is tested on an enucleated swine eye vessel and a retinal vein in a human volunteer with retinal SO 2 measurements of ∼1 and ∼65%, respectively. These saturations, calculated using the calibration line from earlier work, are internally consistent with a standard error of the mean of ± 2% SO 2 . The absolute measures are well within the expected saturation range for the site (-1 and 63%). This is the first demonstration of noninvasive on-axis BGO retinal oximetry. C 2011 Society of Photo-Optical Instrumentation Engineers (SPIE).

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Section: Discussionmentioning

confidence: 99%

Section: Discussionmentioning

confidence: 99%

Section: Backscattering Of Light From the Eye In The Blue-green Spectmentioning

confidence: 99%

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Retinal oximeter for the blue-green oximetry technique

et al. 2011

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“…It has been well established in brain studies that 1/T1r in blood is much shorter than in tissue, and this forms the basis of its use in functional brain studies (13)(14)(15)(16). Furthermore, it is known that outer retinal oxygen consumption is significantly larger in dark than in light and ;10% of the oxygen needs of the outer retina are supplied from the inner retinal circulation (42,(49)(50)(51). Thus, we speculated that the decrease in net 1/T1r in the well-vascularized inner retina that we measure in the dark (vs. light) reflected an increase in inner retinal blood volume (13)(14)(15)(16).…”

Section: D1/t1r Mri Is Sensitive To Light-evoked Changes In Inner Retmentioning

confidence: 99%

Development of an MRI biomarker sensitive to tetrameric visual arrestin 1 and its reduction via light‐evoked translocation in vivo

Berkowitz¹,

Gorgis²,

Patel

et al. 2014

FASEB j.

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Rod tetrameric arrestin 1 (tet-ARR1), stored in the outer nuclear layer/inner segments in the dark, modulates photoreceptor synaptic activity; light exposure stimulates a reduction via translocation to the outer segments for terminating G-protein coupled phototransduction signaling. Here, we test the hypothesis that intraretinal spin-lattice relaxation rate in the rotating frame (1/T1r), an endogenous MRI contrast mechanism, has high potential for evaluating rod tet-ARR1 and its reduction via translocation. Dark-and light-exposed mice (null for the ARR1 gene, overexpressing ARR1, diabetic, or wild type with or without treatment with Mn 2+ , a calcium channel probe) were studied using 1/T1r MRI. Immunohistochemistry and single-cell recordings of the retinas were also performed. In wild-type mice with or without treatment with Mn 2+ , 1/T1r of avascular outer retina (64% to 72% depth) was significantly (P < 0.05) greater in the dark than in the light; a significant (P < 0.05) but opposite pattern was noted in the inner retina (<50% depth). Light-evoked outer retina D1/T1r was absent in ARR1-null mice and supernormal in overexpressing mice. In diabetic mice, the outer retinal D1/T1r pattern suggested normal darkto-light tet-ARR1 translocation and chromophore content, conclusions confirmed ex vivo. Light-stimulated D1/ T1r in inner retina was linked to changes in blood volume. Our data support 1/T1r MRI for noninvasively assessing rod tet-ARR1 and its reduction via protein translocation, which can be combined with other metrics of retinal function in vivo.-Berkowitz, B. A., Gorgis, J., Patel, A., Baameur, F., Gurevich, V. V., Craft, C. M., Kefalov, V. J., Roberts, R. Development of an MRI biomarker sensitive to tetrameric visual arrestin 1 and its reduction via light-evoked translocation in vivo. FASEB J. 29, 554-564 (2015). www.fasebj.org

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“…In our simulation, we assumed that Hb tot ¼ 150 g∕L, 41 and set the sO 2 as 90% in blood of retinal vessel segment 42 and 95% in choroidal blood. 33,36 As a simplified, yet, effective way of modeling, optical absorption within retinal blood and choroid blood layer is contributed only by hemoglobin (μ H a ); optical absorption within the RPE and the 2 suprachoroidea layers are only from melanin (μ M a ).…”

mentioning

confidence: 99%

Monte Carlo investigation on quantifying the retinal pigment epithelium melanin concentration by photoacoustic ophthalmoscopy

2015

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Abstract. The retinal pigment epithelium (RPE) melanin plays an important role in maintaining normal visual functions. A decrease in the RPE melanin concentration with aging is believed to be associated with several blinding diseases, including age-related macular degeneration. Quantifying the RPE melanin noninvasively is therefore important in evaluating the retinal health and aging conditions. Photoacoustic ophthalmoscopy (PAOM), as an optical absorption-based imaging technology, can potentially be applied to measure variations in the RPE melanin if the relationship between the detected photoacoustic (PA) signal amplitudes and the RPE melanin concentrations can be established. In this work, we tested the feasibility of using PA signals from retinal blood vessels as references to measure RPE melanin variation using Monte Carlo (MC) simulation. The influences from PAOM axial resolution, the depth and diameter of the retinal blood vessel, and the RPE thickness were examined. We proposed a calibration scheme by relating detected PA signals to the RPE melanin concentrations, and we found that the scheme is robust to these tested parameters. This study suggests that PAOM has the capability of quantitatively measuring the RPE melanin in vivo.

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Oxygen Saturation in Human Retinal Vessels Is Higher in Dark Than in Light

Abstract: Oxygen saturation in retinal blood vessels is higher in dark than in 80 or 100 cd/m(2) light in human retinal arterioles and venules. The authors propose that this is a consequence of increased oxygen demand in the outer retina in the dark.

Cited by 83 publications

References 25 publications

Retinal oximeter for the blue-green oximetry technique

Retinal oximeter for the blue-green oximetry technique

Development of an MRI biomarker sensitive to tetrameric visual arrestin 1 and its reduction via light‐evoked translocation in vivo

Monte Carlo investigation on quantifying the retinal pigment epithelium melanin concentration by photoacoustic ophthalmoscopy

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