Cone-rod dystrophy (CRD) has an estimated prevalence of 1 in 40,000 individuals. CRD presents first as a macular disease or as a diffuse retinopathy with predominance of the macular involvement. The clinical signs of CRDs reflect the predominant involvement of cones, leading to decreased visual acuity in the first decade of life. However, in some cases, diffuse retinopathy affects simultaneously cones and rods, resulting in both night blindness and loss of visual acuity. The visual field testing shows central scotomas, while the periphery is spared. Fundus examination shows pigment deposits and retinal atrophy in the macular region. At a later stage, patients are legally blind, even though large parts of the peripheral visual field remain preserved. The electroretinogram (ERG), is distinguished by a more distinctive reduction of the photopic cone b-wave amplitude than the scotopic rod b-wave amplitude, compared to rod degeneration.