Monogenic diseases affecting these structures including the anatomy of BrM (Sorsby Fundus Dystrophy [SFD], Pseudoxanthoma elasticum [PXE]), the function of enzymes in the RPE (RPE65-related Retinitis pigmentosa, Late-onset retinal degeneration [LORD]), or rod structure (RHO-associated Retinitis pigmentosa), all cause delays in dark adaptation [26,58,59,65,66,67,68]. Here, RPE65 is linked to pseudoxanthoma elasticum (inherited or acquired).