Purpose <p>This study allows the functional evaluation of all retinal layers in individuals with extensive macular atrophy with pseudodrusen. The findings may contribute to the elucidation of the disease's pathophysiology. The purpose of this retrospective observational study is to determine ganglion cell function in individuals with extensive macular atrophy with pseudodrusen by measuring the photopic negative response.</p> Methods <p>Retrospective observational study included patients with EMAP who were seen at a visual electrophysiology laboratory.</p> Results <p>Fifty-four patients with extensive macular atrophy with pseudodrusen were evaluated, with 39% having normal visual acuity, 41% bilateral visual impairment, and 20% unilateral impairment; all had characteristic retinal findings, including retinal pigment epithelium atrophy and pseudodrusen. Full-field electroretinogram responses showed significantly reduced amplitudes in all groups compared to reference ranges, with no significant differences between better and worse eyes. The photopic negative response amplitudes (BT and PT) were reduced in all patients, indicating functional loss of retinal ganglion cells, while photoreceptor responses were less affected.</p> Conclusion <p>This study highlights the importance of assessing retinal ganglion cell function through the Photopic Negative Response as a potential functional biomarker and suggests that extensive macular atrophy with pseudodrusen may involve broader retinal and systemic dysfunction beyond photoreceptor impairment.</p>