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Momotaz Begum, Daniel Y Tso; Dual Wavelength Oximetry: Noninvasive Measurements of Oxygenation in Mouse Retina. Invest. Ophthalmol. Vis. Sci. 2014;55(13):2094.
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© ARVO (1962-2015); The Authors (2016-present)
Adequate blood supply to the retina is essential for normal retinal function. Quantifying retinal blood oxygenation can be used to provide a better insights to normal metabolic state as well as various pathologies of the retina. Most of the understanding on retinal oxygen saturation using multi-wavelength measurements comes from human and animals, including monkeys and cats. Noninvasive measurements of oximetry based on multi-spectral technique in mouse retina have been rare. This imaging study aims to show retinal vessel oxygenation in mouse.
Animals and Preparation. Mice were sedated and anesthetized using ketamine/xylazine and Brevital. Atropine and phenylephrine were administered to dilate the pupil and inhibit accommodation. Silicone oil was applied to lubricate the eye and prevent corneal drying. Mice were imaged in a stereotaxic frame and physiologically monitored throughout the experiment. Imaging. The retina was illuminated with a simultaneous dual band illumination at ~630nm and ~530nm. Images of mouse retina were collected by using a color CCD camera coupled with custom designed endoscopic retinal imager. This imager was also designed to enable functional intrinsic signal retinal imaging. The dual band images were collected and analyzed to determine oxygen saturation of the mouse retinal vasculature.
The color CCD camera was effective at providing well-separated retina images at the two spectral bands of illumination. ODRs (optical density ratios) obtained comparing inside to outside vessel measurements were comparable to those reported in the literature for other species. The results showed a marked ODR increase (oxygen saturation decrease) in the venules as compared with arterioles.
Using dual wavelength oximetry with the modified functional imager, it was possible to measure the oxygen saturation in wild type mouse retina and show stimulus-driven reflectance change signals similar to those observed in the monkey, cat and human retina. The results demonstrate that multispectral imaging of retinal oxygen saturation is comparable to that observed in another species. This technique promises to be useful in mouse models of retinal diseases.
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