Dye Dependent Differences in Arteriovenous Passage Times: A Comparison of ICG and Fluorescein

Abstract

Abstract: : Purpose: To evaluate the difference in arteriovenous passage time calculated from angiograms using fluorescein sodium and indocyanine green in healthy individuals. Methods: All procedures were approved by an IRB, and informed consent obtained. Examinations of eight healthy subjects, recruited for a pharmaceutical study, were analyzed. Each subject had four consecutive visits two weeks apart. Both ICG and fluorescein angiography were performed using scanning laser ophthalmoscopy and angiograms were obtained sequentially, ICG before fluorescein. Arteriovenous passage (AVP) times, the time elapsed between dye arrival in the artery and its corresponding vein, were calculated from the videotaped angiograms by means of digital image analysis on a Mac G4 image processing workstation. Results: AVP times calculated from ICG angiography recordings were significantly shorter than fluorescein AVP times when compared across all study groups (p < 0.0001). Mean ICG AVP time was 1.417 seconds while mean fluorescein AVP time was 2.539 seconds and intragroup variability was similar. There was no significant difference in superior versus inferior AVP time with either dye. Conclusions: ICG AVP times were expected to be longer than fluorescein AVP times, but were found to be significantly shorter in this study. The current data suggest that fluorescence from the early choroidal filling may alter the analysis of ICG angiograms.

Keywords: imaging methods (CT, FA, ICG, MRI, OCT, RTA, S • blood supply • retina