These photopic ffERG findings are similar to those seen in inherited retinal dystrophies characterised by a loss of cone photoreceptor to bipolar cell transmission such as incomplete congenital stationary night blindness [20] associated with mutations in CACNA1F [21] and other cone-rod synaptic disorders caused by mutations in CABP4 [22] and CACNA2D4 [23]. Here, CACNA2D4 is linked to inherited retinal dystrophy.