Atypical Autofluorescence Findings in Geographic Atrophy: The Influence of Age-Related Choroidal Atrophy

Purpose: To describe atypical fundus autofluorescence (FAF) patterns in geographic atrophy (GA) secondary to age-related macular degeneration (AMD) with associated age-related choroidal atrophy (ARCA). Methods: Multimodal imaging of two cases using (pseudo-)color fundus photography, optical coherence tomography (OCT), fluorescein and indocyanine green angiography, and FAF employed with blue- and green excitation wavelengths on several devices ( Spectralis, Heidelberg and (ultra-)widefield [UWF] FAF [ California, Optos and EIDON, iCare ]). Results: Two female patients, with foveal-involving GA secondary to AMD, were assessed. All eyes demonstrated concurrent features indicative of ARCA on multimodal imaging including a paucity of choroidal vasculature, reduced choroidal pigmentation, macular pigmentary changes, peripapillary atrophy, and subretinal drusenoid deposits. Clinically, progression of GA with coalescence of lobular lesions was observed. Notably, UWF FAF with green-( California ) and blue excitation wavelengths ( California and EIDON ) revealed atypical patterns characterized by isofluorescent FAF signals (indistinguishable from surrounding tissue) or hyperautofluorescent GA lesions. In these cases, blue excitation wavelengths were more effective than green light for delineating GA, owing to increased contrast from hypoautofluorescence related to macular pigment surrounding the lesion. Conclusion: In patients with GA and concomitant ARCA, atypical FAF patterns on UWF imaging complicate the accurate delineation and monitoring of GA. Atypical FAF patterns appear due to the properties of the confocal apertures and postprocessing features of UWF imaging that allow for the detection of scleral autofluorescence in patients with reduced choroidal vasculature, pigment and thickness. In patients with concomitant ARCA, multimodal imaging plays a crucial role in precisely identifying and tracking GA progression.