The ultra-late phase of indocyanine green angiography for healthy subjects and patients with age-related macular degeneration

Purpose: To compare the characteristics of residual fundus fluorescence observed in the ultra-late phase of indocyanine green (ICG) angiography, in normal subjects and in patients with age-related macular degeneration (ARMD). Methods: ICG angiography was performed on 38 patients, 21 had ARMD, 9 were normal subjects aged >62, and 8 were normal subjects aged <36. The intensity and pattern of fluorescence from angiograms obtained in the ultra-late phase, 24 hours after dye injection, was also recorded and analyzed. Results: In the ultra-late phase, 95% of ARMD eyes with CNV showed geographic hypofluorescent lesions. All of the CNV that could be delineated with fluorescein and/or ICG angiography were located in these geographic lesions. In 73% of ARMD eyes without CNV, these hypofluorescent lesions occurred, while age-matched normal subjects had no hypofluorescent lesions. The mean intensity of fluorescence in the normal older subject group was significantly higher than that seen in the normal young subject group. Conclusions: Increased fluorescence, associated with older subjects, in the ultra-late phase of ICG angiography may reflect aging changes in the chorioretinal complex. Geographic hypofluorescent areas, demonstrated only in the ultra-late phase, associate with ARMD and may represent areas predisposed to CNV development.