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Sindri Traustason, Jens F. Kiilgaard, Robert A. Karlsson, Sveinn H. Hardarson, Einar Stefansson, Morten D. de La Cour; Validation of Snap-shot Retinal Oximetry by Porcine Experiments. Invest. Ophthalmol. Vis. Sci. 2012;53(14):2198.
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© ARVO (1962-2015); The Authors (2016-present)
To validate snapshot spectrophotometric retinal oxygen saturation measurements, by comparison to femoral arterial saturation over a wide range of oxygen saturation.
Female domestic pigs were used for all experiments. Oxygen concentrations in inspired air were changed using a mixture of room air, pure oxygen and pure nitrogen, ranging from 5 % to 100 % oxygen concentration. At each level of inspiratory oxygen concentration, femoral arterial blood gas analysis and retinal oximetry was performed.Retinal oximetry was made using a commercial instrument (Oxymap Retinal Oximeter T1, Oxymap ehf, Reykjavik, Iceland). The instrument consists of a fundus camera (Topcon TRC-50DX, Topcon, USA) coupled with a beam splitter and two digital cameras. Images are acquired simultaneously at two wavelengths (570 nm and 600 nm) and specialized software automatically detects retinal blood vessels.
Regression analysis (fig. 1) reveals a highly significant linear relationship between femoral arterial saturation and retinal artery ODR values (R2 = 0.965, p <0.001).Analysis of the data using human calibration values resulted in abnormally high saturation values. The retinal oxygen saturation measurements were recalibrated by comparing femoral arterial saturation and retinal arterial saturation at 5-21% inspiratory vO2 percentage.Results for femoral blood gas analysis and retinal vessel oximetry are presented in table 1.
Spectrophotometric snapshot oximetry is sensitive to systemic oxygen saturation changes over a wide range. Care should be taken when comparing measurements between humans and animal models.
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