Artifactual reduction in oxygen saturation readings affected by indocyanine green in ophthalmic angiography

Purpose To investigate time-dependent changes in oxygen saturation (SpO 2 ) readings during fluorescein angiography (FA) or simultaneous fluorescein and indocyanine green angiography (F/I). Study design A prospective observational study. Methods One hundred twenty-five consecutive patients underwent FA or F/I. After application of the exclusion criteria, 67 patients (28 underwent FA, 39 underwent F/I) were included in the study. During angiography, SpO 2 was measured by using a pulse oximeter and recording each second. The arm-to-retina circulation time (ARCT) was measured on the angiography video images. Latency time was defined as the time from intravenous injection of the dye to observation of a 3% decrease in the SpO 2 reading, and variation SpO 2 , as the difference between baseline SpO 2 and the lowest SpO 2 value. Results The mean variation SpO 2 was − 1.0 ± 0.6 during FA, and − 6.1 ± 1.5 during F/I. Variation SpO 2 was within 2% during FA and > 3% during F/I. No corresponding changes were observed in the other vital signs or subjective symptoms. The mean latency time was 33.3 ± 6.4 s. Latency time was positively correlated with the ARCT in the F/I group (r s = 0.766, P