OPA1 and hereditary optic atrophy: RGCs are long projection neurons with an initial long unmyelinated intraretinal segment that is thought to be particularly vulnerable to insults, at least in cases of LHON and OPA1 mutations, the major forms of optic atrophy described so far (Lenaers et al, 2012; Chun & Rizzo, 2017; Jurkute & Yu‐Wai‐Man, 2017).