FAF Imaging and Progression of Geographic Atrophy in AMD
By Jean Shaw
Selected By: Andrew P. Schachat, MD
Journal Highlights
Ophthalmology Retina, September 2019
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Holmen et al. used fundus autofluorescence (FAF) imaging to evaluate the sequence of progression leading to geographic atrophy (GA) in patients with age-related macular degeneration (AMD). They found that GA can evolve from a variety of changes as seen on FAF. Moreover, they noted that, in most eyes, predominant hypoautofluorescence appears to be the final step before GA is visible.
This study was a post hoc analysis of images from the Age-Related Eye Disease Study 2 (AREDS2), which evaluated the impact of nutritional supplements on AMD progression. The researchers included 120 eyes (109 participants) with at least two years of FAF images. The first visit at which GA was identified on FAF was considered the incident visit. Images from incident visits were stacked and aligned over previous annual FAF images from the same eye, allowing for pixel-to-pixel correlation between images of sequential visits. Images were graded subjectively and independently by two certified graders at the University of Wisconsin Reading Center.
All precursor images were classified as either 1) minimal change autofluorescence, 2) predominant hypoautofluorescence (decreased autofluorescence), 3) predominant hyperautofluorescence (increased autofluorescence), or 4) mixed autofluorescence. Main outcome measures were GA area and rate of enlargement.
At 1.0 mm2, the mean area of incident visit GA on FAF was significantly smaller than the mean area of incident GA and baseline GA previously described in clinical trials. The mean enlargement rate of incident GA was 0.97 mm2 per year. Although precursor lesion classification was not associated with the area of incident GA, it was associated with enlargement rate, and minimal-change autofluorescence lesions were linked to faster enlargement rates.
Among all types of precursor lesions, predominant hypoautofluorescence lesions were the most common: Three years before GA developed, they accounted for 42% of precursor lesions; this percentage grew to 81% one year before GA developed.
The original article can be found here.