AD-related tauopathies have also been investigated in a limited number of non-murine animal models of aging or AD. Selective expression of normal human tau in adult drosophila retina leads to progressive loss of ERG responses without a considerable effect on retinal structure or neuronal density, although TEM analysis later revealed signs of tau-induced retinal synaptotoxicity and abnormal photoreceptor morphology (Chouhan et al., 2016). In the same study, human Aβ expression in a separate group of flies caused an age-dependent loss of retinal neurons without altering ERG signals (Chouhan et al., 2016). In the UAS-Gal4 drosophila model of AD, species of pTau, phosphorylated at different epitopes to varying degrees and in a cell type-specific manner, have also been detected in both the retina and brain (Grammenoudi et al., 2006). In a small number of young and aged primates, total tau expression in the outer retina was observed in the OPL, ONL and inner segment of photoreceptors, whereas AT8-positive pTau was localized predominantly in the OPL and cones (Aboelnour et al., 2017). In older primates, pTau staining in retinal cones also appeared stronger compared with younger animals (Aboelnour et al., 2017). Altogether, it is apparent that tau expression and pTau accumulation may vary across several species commonly used to model human AD, and future studies should aim to elucidate these differences.