The initial discovery of tau in the adult mammalian retina dates back to 1988. In this early study, tau was predominantly found in horizontal cells residing in the OPL of adult rat retinas (Tucker and Matus, 1988). On the other hand, disease-associated pTau species were detected somatodendritically in RGCs of a commonly studied double transgenic mouse model of AD, known as the APPSWE/PS1ΔE9 mouse (Yang et al., 2013), and in the GCL to ONL of Tg2576 ADtg mice (Liu et al., 2009). In line with these observations, intracellular aggregates of pTau have also been detected in retinas of the APPSWE/PS1M146L/L286V mouse model of AD (Zhao et al., 2013). Further, recent analyses of young, pre-symptomatic 3xTg mouse retinas showed retinal Aβ plaques and tau tangles in the RGC layer (Grimaldi et al., 2018).