RGCs are now known to be affected to an extent in ALS/FTD, albeit without onset of clear visual symptoms in patients (Rojas et al., 2020): loss of RGCs occurred in a model of advanced SOD1-assocciated ALS (Rojas et al., 2021), optic nerve thinning has been observed in FTD patients (Harrison et al., 2019), and neurofilament and TDP-43 inclusions occur in the retina of ALS patients (Fawzi et al., 2014; K. Sharma et al., 2020). Here, SOD1 is linked to amyotrophic lateral sclerosis.