To characterize structural and clinical alterations preceding the diffuse macular atrophy in extensive macular atrophy with pseudodrusen (EMAP) and their evolution towards atrophic changes. A retrospective chart review was performed of patients with early-onset reticular pseudodrusen (i.e., pre-EMAP) under 55 years of age and EMAP with foveal sparing. Patients were included if they had complete medical records and multimodal imaging. A total of 12 cases were reviewed, of whom 4/12 patients (7 eyes) presented a pre-EMAP stage, characterized by the presence of pseudodrusen-like deposits without atrophic changes, while the remaining 8/12 cases (10 eyes) exhibited EMAP with foveal sparing (60.1+/-6.4 years). Subretinal deposits of various stages tended to fade, leaving sub-retinal pigment epithelium (RPE) accumulation of hyperreflective material with a physical separation between the RPE-basal lamina (BL) and Bruch's membrane (BrM), along with the persistence of hyperreflective material after RPE loss. These findings preceded atrophy development in a pre-EMAP stage and the EMAP stage with foveal sparing. Our findings presented distinct multimodal imaging features in eyes with reticular pseudodrusen depicting a peculiar phenotype of rapidly progressing atrophy in midlife. The disease spectrum may include other forms of geographic atrophy allied by thickened basal laminar deposits.