Purpose: To further characterize a previously described phenotypic variant of geographic atrophy (GA) associated with rapid progression and a diffuse-trickling appearance on fundus autofluorescence (FAF).
Methods: Thirty-six patients (60 eyes; 72.2% women; mean age, 69.4 ± 10.7 years) with this distinct phenotype were examined by simultaneous confocal scanning laser ophthalmoscopy (cSLO) and spectral-domain optical coherence tomography (SD-OCT) imaging. Images were qualitatively and quantitatively analyzed and compared with 60 eyes (38 patients) with non diffuse-trickling GA.
Results: The atrophic area in the diffuse-trickling phenotype showed a grayish FAF signal and characteristic coalescent lobular configuration at the lesion boundaries. SD-OCT revealed a marked splitting of band 4 (the presumptive retinal pigment epithelium (RPE)/Bruch's membrane (BM) complex) in all 240 analyzed border sections of diffuse-trickling GA eyes (four borders/eye) with a mean distance between the inner and outer parts of band 4 of 23.2 ± 7.5 μm. This finding was present in only 13.8% (33/240) of analyzed border sections in non diffuse-trickling GA.
Conclusions: Patients with the rapidly progressing diffuse-trickling GA phenotype exhibited a characteristic marked separation within the RPE/BM complex on SD-OCT-imaging. The presumed histopathologic correlates are basal laminar deposits. Such deposits may promote RPE cell death and, thus, contribute to rapid GA progression. The persistence of these deposits within the atrophic lesion may account for the distinct grayish FAF appearance, which differs from the markedly reduced signal in other forms of GA. Identification of such alterations based on FAF and SD-OCT imaging may be helpful in future interventional trials directed toward slowing GA progression. (ClinicalTrials.gov number, NCT00393692.).