AIF1 and Abnormal retinal morphology: We first investigated the presence of microglia/macrophages in postmortem human specimens of nondiabetic retina and NPDR, using immunohistochemical analysis with IBA1, which is a more specific marker for detecting both quiescent and activated MPs in the CNS (25), and has been a useful marker of microglia in retinal studies, including retinal disease models (13, 26, 27).