Age-dependent variations in the drusen fluorescence on indocyanine green angiography.

Purpose: To examine the fluorescence patterns of macular drusen using indocyanine green (ICG) angiography in human subjects of different ages.
Methods: A total of 180 eyes in 100 consecutive patients aged 34-90 years with macula drusen were evaluated with ICG angiography using the Topcon 1024 ImageNet system. Eyes were divided into two groups depending on age. The older group (subjects over the age of 55 years) comprised 170 eyes. The younger group (subjects 55 years or younger) comprised 10 eyes. The fluorescence patterns of the drusen were graded as hyper-fluorescent (brighter than the background fluorescence), hypofluorescent (darker than the background fluorescence) or isofluorescent (unable to be distinguished from the background fluorescence). The ICG angiogram appearances were correlated with the clinical types of drusen in differing age groups.
Results: An age-dependent difference in the fluorescence pattern of drusen was observed. Drusen in the older group were hypofluorescent or isofluorescent (169/170 eyes). In contrast, drusen in the younger group (55 years or younger) were hyperfluorescent (10/10 eyes).
Conclusions: This study defines the distinct age-dependent differences in the ICG fluorescence pattern of drusen. This heterogeneity might be due to differential binding of extravasated ICG to the constituents and histological site of the drusen deposits. Furthermore, ICG angiography is able to differentiate drusen types not possible by clinical and fluorescein angiographic evaluation.