Detection of Reticular Pseudodrusen (RPD) in Early- and Late-Phase Fluorescein Angiography (FA)

Abstract

 

Purpose

 

To evaluate the sensitivity of early- and late-phase FA in detecting RPD.

 

Methods

 

We retrospectively identified age-related macular degeneration (AMD) patients from a single institution who had advanced disease in only one eye. We diagnosed RPD in the fellow eye by the presence of characteristic lesions on both autofluorescence (AF) and late-phase indocyanine green angiography (ICG). Color fundus photographs were used to detect soft drusen. Two readers analyzed early-phase FA (<30 seconds after injection) and late-phase FA (~10 minutes after injection) from the same session for the presence of multiple, grouped, focal, hypofluorescent lesions, the pattern observed for RPD in ICG. Each reader graded the image as hypofluorescence present, absent, or unclear due to drusen. Any image with a grading disagreement was re-categorized to “unclear”.

 

Results

 

A total of 19 patients with RPD were identified on AF and ICG (Table 1). Four eyes had only RPD, and 15 eyes had both RPD and drusen. Of the 4 eyes with only RPD, 2 showed RPD in early-phase FA and 3 showed them in late-phase FA. Of the 15 eyes with both RPD and drusen, 7 showed RPD in early-phase FA and 6 showed them in late-phase FA. The areas largely overlapped, and there was on average only 7.95% difference in the percentage areas occupied by RPD between ICG and FA (Figure 1).

 

Conclusions

 

Although less sensitive than AF or late-phase ICG, early- and late-phase FA can detect RPD. While previous studies noted the difficulty in detecting RPD in FA due to low contrast, this is the first systematic study of RPD in FA, particularly to show that characteristic hypofluorescence can persist into the late-phase FA. The variable appearance of these lesions in the early-phase FA may be consistent with either subretinal deposits or a choroidal vascular process masked by patchy filling. However, the persistence of hypofluorescence in the late-phase FA, when fluorescein has equilibrated across the extravascular space, suggests blocking defects, possibly from subretinal deposits.

 

 

Table 1. Summary of number of patients with hypofluorescence indicative of RPD on early- and late-phase FA.

 

 

Figure 1. Example of AF (A), late-phase ICG (B), early-phase FA (C), and late-phase FA (D). The yellow boundary demarcated the area with RPD.

 

Keywords: 412 age-related macular degeneration • 504 drusen • 552 imaging methods (CT, FA, ICG, MRI, OCT, RTA, SLO, ultrasound)