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J.M. Beach, J. Ning, B. Khoobehi; Quantitative Assessment of Oxygen Saturation in the Primate Optic Nerve Head by Hyperspectral Image Analysis . Invest. Ophthalmol. Vis. Sci. 2006;47(13):4798.
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To provide quantitative measures of oxygen saturationin the primate optic nerve head (ONH) and overlying retinalvessels at a controlled baseline IOP.
Cynomolgus monkeys were anesthetized with intramuscularketamine/xylazine and intravenous pentobarbital, to obtain stageIV anesthesia. IOP was set to 10 mmHg with a saline reservoirconnected to a needle that was inserted into the anterior chamber.Reflected light spectroscopy was performed in both eyes of twomonkeys with a dispersive hyperspectral imager attached to afundus camera. Images were taken after holding IOP steady for10 minutes. Image areas were assigned to artery and veins overlyingthe ONH, and to six regions including the cup and rim of theONH. Oxygen saturation of areas was found using linear least–squarescurve fits between spectral curves and reference spectra foroxygenated and deoxygenated blood whose saturation was confirmedwith a blood gas analyzer.
(mean ± SE%, N = number of images)
Deviation from ONH average (%):
With controlled IOP near a baseline level, oxygensaturation measurements were repeatable in the artery and ONHaveraged data. The relatively low artery saturations were likelydue to the deep stage of anesthesia. In veins, a larger rangeof saturations may reflect differing metabolic activities ineach eye. The AV saturation difference was greater for OS inboth monkeys. Areas of highest ONH saturation were the temporalaspects of the cup and rim and lowest were the superior andinferior rim. Hyperspectral imaging is shown to give quantitativeassessments of oxygen saturation in distinct structures of theONH.
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