Progression of GA in Dry AMD

Finally returning from a long holiday break. Happy new year to everybody! Now back to business...

The previous case provides a good example of the progression of geographic atrophy (GA) in dry AMD. We see a set of color fundus photos and FA taken approximately 1.75 years apart. The discs look grossly normal with no significant cupping. There is some peripapillary atrophy, that is not out of the ordinary if seen on its own. The vessels look grossly normal. What we see in the macular region are areas of RPE atrophy which appear as areas where the choroidal details are more distinct. Notice, also, areas of hyperpigmentation along the margin of atrophic areas. As the atrophy progresses in the later set of images, the region becomes more distinct, larger, and more delineated. Note that the ideal imaging modality to evaluate GA is fundus auto-fluorescence, which would clearly demonstrate a rim of hyperfluorescent RPE surrounding black regions of atrophy (non-fluorescent, since RPE is absent).

Dry AMD may progress to an advanced form in a minority of patients. GA represents this advanced form. GA tends to occur in older patients than those with neovascular or wet AMD at the time of presentation. GA is closely associated with pigmentary changes and drusen within the macula. The development of GA is especially linked to large soft drusen. Large, confluent drusen over 125 microns are considered a risk factor for progression to GA. There is often a high degree of symmetry between fellow eyes. Peripapillary atrophy is very common in eyes with GA. The precise pathophysiologic mechanism for the progression of GA, which affects the RPE, choriocapillaris and neurosensory retina is poorly understood.

(Laud K, Mukkamala SK, Brue C, Slakter J. "The Future of Non-neovascular Age-related Macular Degeneration." Ho AC, Regillo CD (eds.) Age-related Macular Degeneration Diagnosis and Treatment, Springer Science+Business Media, LLC. 2011)