Alterations of the BEST-1 channel caused by BEST1 gene mutations may account for the diminished light peak–dark trough ratio (Arden ratio typically ≤150%) of the electro-oculogram (EOG) [11,12], which is characteristic of BVMD and associated in most cases with a normal full-field electroretinogram (ERG). This evidence concerns the gene BEST1 and Best vitelliform macular dystrophy.