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Richard B. Rosen, Nicole Scripsema, Chavaki Bhoomibunchoo; Patterns Of Oxygen Saturation In Retinal Vein Occlusions As Measured With Oxymap. Invest. Ophthalmol. Vis. Sci. 2012;53(14):2173.
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To determine how oxygen saturation is altered in the setting of retinal vein occlusions.
This was a retrospective review of patients being treated for RVO who were imaged with Oxymap (Oxymap EPH, Reykjavik, Iceland). Exclusion criteria included previous ocular surgeries and concurrent ocular conditions. Images were excluded when the presence of heme obscured the identification of the primary and secondary retinal vessels. Oxymap uses uses two wavelength differential analysis (600 and 570nm) of images captured simultaneously to determine relative retinal vessel oxygenation. For each patient imaged, fluorescein angiographies were referenced to determine the precise area of occlusion and mean arterial and venous oxygenation of this region was measured. The same values were computed in the corresponding region of the normal eye. In BRVO and HRVO patients, the area of occlusion identified as within the superior or inferior arcade. Mean oxygen saturation in the unaffected arcade was also analyzed. We used paired t-tests to compare mean oxygen saturation in affected and unaffected vessels in normal and diseased eyes.
7 patients were included in the analysis. All of the patients were male. There were 2 CRVOs, 3 BRVOs, and 2 HRVOs. Mean age was 56.86±10.32 years. 43% were Hispanic, 29% Asian, 14% African American and 14% Caucasian. Imaging was complete an average of 4.71±3.80 months after the occlusion, with a range from 2 weeks to 10 months.Mean arterial oxygen saturation were significantly higher in the affected region of the diseased eye (107.43±7.89%) compared to the corresponding region in the normal eye (98.29±2.21%, p=0.016). Mean venous oxygen saturation was significantly lower in the affected region (55.00±13.64%) versus the normal eye (68.29±3.55%,p= 0.047). In the BRVO and HRVO patients, the arterial O2 sat in the unaffected vessels of the occluded eye was similar to that of the normal eye (100.20±2.86% and 99.20±1.79%, p=0.486). Mean venous O2 Sat in the unaffected vessels of the occluded eye (75.40±6.02%) was significantly higher than both normal eyes (68.40±3.78, p=0.008) and the area of occlusion (61.60±6.58%, p=0.014).
We found a significant increase in arterial oxygen saturation and a decrease in venous oxygen saturation in the region of retinal vein occlusions, consistent with prior reports. In the case of branched and hemi-spheric retinal vein occlusions, the venous saturation was higher in the unaffected region of the occluded eye. It is possible that this is a result of compensatory mechanisms attempting to maintain perfusion of the occluded region. We also noted that independent of the time imaged after the occlusion, all patients demonstrated a similar pattern of oxygen saturation.
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