A study in monkeys has recently provided evidence for the involvement of mRGCs in blue color sensitivity (Dacey et al., 2005). AD patients are reported to experience altered color vision with a selective and severity-independent deficiency in blue hue discrimination (Cronin-Golomb et al., 1993; Wijk et al., 1999; Rizzo et al., 2000; Chang et al., 2014; Polo et al., 2017). Interestingly, impaired blue color discrimination also manifests in patients with other neurodegenerative disorders (Paulus et al., 1993; Haug et al., 1995; Birch et al., 1998; Rodnitzky, 1998; Melun et al., 2001; Anssari et al., 2020).