Structural changes to primary visual cortex in the congenital absence of cone input in achromatopsia

•Anatomy of primary visual cortex (V1) assessed with surface-based morphmetry in those with congenital achromatopsia (ACHM).•Reduction in cortical surface area in foveal, parafoveal and paracentral representations of V1 in those with ACHM.•In ACHM a localized thickening in the area of V1 that represents the region of retina occupied solely by cones.•V1 changes in ACHM may limit its ability to take on normal properties if retinal function were to be restored.•Early intervention, before the development plastic period is over, may offer better restoration of vision in ACHM.