First Author: M.Biarnés SPAIN
Co Author(s): J. Mones
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To determine if there are subgroups of patients with geographic atrophy secondary to age-related macular degeneration (GA) defined by their fundus features using cluster analysis.
Institut de la Màcula (Barcelona, Spain).
We retrospectively included patients with GA and a minimum follow-up of 6 months. Multimodal imaging was used to characterize the ocular fundus based on the presence of: heavy soft drusen and reticular pseudodrusen (RPD) load, foveal atrophy, increased fundus autofluorescence (FAF), a grey atrophy on FAF and subfoveal choroidal thickness (SFCT). Cluster analysis, a data-driven method used to identify subgroups within a population, was used to determine the optimal number of groups (phenotypes). Atrophy enlargement rate was compared between the emerging phenotypes.
We included 77 eyes of 77 patients. Cluster analysis identified 3 groups: phenotype 1 was characterized by high soft drusen load, foveal atrophy and slow growth; phenotype 3, by high RPD load, extrafoveal location of atrophy, grey atrophy and thin SFCT. The features of phenotype 2 were intermediate between those of groups 1 and 3. Atrophy enlargement rate differed between groups 1, 2 and 3 (0.63, 1.91 and 1.73 mm2/year, respectively; p=0.0005).
Three phenotypes were identified, and one of them showed a particularly slow growth. These results may be relevant for patient prognosis, eligibility criteria in clinical trials and, hopefully, improved phenotype-genotype correlation.