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Sveinn Hakon Hardarson, David Bragason, Thor Eysteinsson, Einar Stefansson; The Effect of Cataract on Retinal Oximetry. Invest. Ophthalmol. Vis. Sci. 2014;55(13):201.
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© ARVO (1962-2015); The Authors (2016-present)
To determine if and how cataract influences measurements of retinal vessel oxygen saturation with a fundus camera based retinal oximeter.
Individuals, scheduled for cataract surgery, were measured with an Oxymap T1 retinal oximeter, which images the fundus at 570nm and 600nm. The light absorbance of blood vessels at these wavelengths was used to calculate the retinal vessel oxygen saturation. Seventeen subjects, with no major retinal or optic nerve disease, participated in the study. One image of each eye was used (34 images). Oximetry images were ordered in a sequence with respect to image quality by an experienced user of the oximeter. Additionally, the lens status of the subjects was determined with Pentacam and Nidek EAS-1000 anterior segment analysis systems in the right eye of each subject.
A paired comparison was performed of values from each eye of the subjects. Measured oxygen saturation was significantly higher in the eye, which yielded the better image, compared to the worse image/eye of the same subject (see table). Measured oxygen saturation tended to increase with better image quality across the whole set of images (see figure). Oxygen saturation in retinal arterioles and venules correlated with density measurements of the lens, performed with Nidek EAS-1000. Higher density value (worse cataract) yielded lower measured saturation (p<0.029). The Pentacam system gave similar results.
Cataract can lead to lower measured retinal vessel oxygen saturation, which is almost certainly an artifact. Images, that were subjectively determined to be of acceptable quality were less affected. The quality of images must be taken into account when measuring retinal vessel oxygen saturation.
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