MAPT and Schnyder corneal dystrophy: Decreased contrast sensitivity in mild cognitive impairment (MCI) or subjective cognitive decline (SCD) has been associated with p-tau and Aβ deposition in parietal, temporal, and especially occipital brain regions [47].Studies in patients with MCI have reported a significant general decrease of contrast sensitivity in all frequencies across the visual field, when measured by frequency doubling technology [47–49].