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Jessica C. Ramella-Roman, M A. Ibrahim, Y J. Sepah, D D. Duncan, B Cho, T A. Nguyen, A Basiri, B E. Munoz, S K. West, Q D. Nguyen; Measurement Of Macular Blood Flow And Oxygen Saturation In Normal Subjects And In Patients With Diabetes Mellitus With And Without Diabetic Retinopathy Using The Flow Oximetry System. Invest. Ophthalmol. Vis. Sci. 2011;52(14):4417.
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© ARVO (1962-2015); The Authors (2016-present)
To compare in vivo measurements of macular blood flow (MBF) and oxygen saturation (SO2) acquired from normal subjects, patients with diabetes mellitus (DM) and no diabetic retinopathy (DR), and patients with non-proliferative diabetic retinopathy (NPDR)
MBF and SO2 measurements were acquired from 31 normal subjects (Group-1), 25 patients with DM and no DR (Group-2), and 21 patients with NPDR (Group-3) using a novel video-based 60-frames/second system (The Johns Hopkins Flow Oximetry System, FOS). The measurements were acquired from two retinal areas: zone-1 and 2 (2-to-3 and 4-to-5mm from the center of fovea, respectively). The measurements from arteries and veins were summarized separately using descriptive statistics.
The differences in the mean arterial oxygen saturation (SaO2) and venous oxygen saturation (SvO2) among the study groups were calculated in the measured zones. In group-1, the mean SaO2 was 84.6% and 91.5% (SD=13.8 and 9.6), in zones 1 and 2 respectively, compared to 88.4% (SD=11.3) and 90.5% (SD=6.9) in group-2 and 87.2% (SD=9.5) and 92.7% (SD=4.5) in group-3 in the same zones. Mean SvO2 was 55% (SD=13.3) and 58.6% (SD=9.3) in group-1, 52.1% (SD=8.2) and 55% (SD=11.6) in group-2, and 54.8% (SD=8.8) and 62.2% (SD=8.3) in group-3. Mean arterial MBF ranged from 2.7mm/sec in group-1 (zone-1) to 3.1mm/sec in group-2 (zone-1); mean venous MBF ranged from 2.6mm/sec in group-2 (zone-1) to 3mm/sec in group-3 (zone-2).
We have successfully developed the first device that can simultaneously measure retinal oxygenation and blood flow. Our results suggest, although not statistically significant, that patients with diabetes and no DR have lower retinal SO2 and higher MBF than normal subjects and subjects with NPDR in certain regions of the retina. Once patients develop DR, as initial physiologic response, MBF and SO2 return toward normal levels. Longitudinal studies and studies including patients with advanced DR are needed to detect the statistical significance of the observed trends.
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