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Rachel E. Annam, Mohamed A. Ibrahim, Long Luu, Yasir J. Sepah, Millena G. Bittencourt, Owhofasa Agbedia, Hyun S. Jang, Jithin Yohannan, Jessica Ramella-Roman, Quan D. Nguyen; Assessment of Oxygen Saturation in Retinal Vessels of Normal Subjects and Diabetic Patients without Retinopathy using the Johns Hopkins Flow Oximetry System. Invest. Ophthalmol. Vis. Sci. 2012;53(14):6838.
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To determine oxygen saturation (SO2) in retinal vessels of normal subjects and diabetic patients without retinopathy using the Johns Hopkins Flow Oximetry System (JHFOS) with novel assessment software and to establish a range of normal retinal oxygen saturation in the venous circulation and analyze the differences across the study groups.
The novel assessment software was used to determine oxygen saturation levels in veins located between 1 to 2 mm from the margin of the optic disc in normal subjects and diabetic patients without retinopathy employing images captured by JHFOS. The retina was divided into 4 quadrants (superior, inferior, temporal, and nasal), although the majority of vessels were in the superior and inferior quadrants. Only those vessels clearly identified as veins by the ophthalmologists were included in the analysis.
21 normal subjects (12 females and 9 males, mean age = 56 years) contributed 21 eyes, and 17 diabetic patients (8 females and 9 males, mean age = 61 years) contributed 17 eyes to the final analysis. The mean (+/-SD) SO2 in retinal veins of normal subjects was 55.2 ± 6.6% (95% CI 52.2 - 58.2) and the mean (+/-SD) venous SO2 in diabetic patients without retinopathy was 59.6 ± 10.4% (95% CI 54.3 - 64.9).
A range of normal venous SO2 has been established using the JHFOS.The mean venous SO2 was found to be higher in diabetic patients without retinopathy compared with normal subjects. The results obtained from the JHFOS are in agreement with previously published data. Further studies with additional subjects are indicated to validate the use of JHFOS in detecting retinal oxygenation as well as to assess levels of retinal oxygenation among normal subjects and diabetics with different stages of retinopathy.
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