MAPT and Alzheimer disease: Next, IHC analysis of T22+ Oligo-tau in the retina of MCI and AD patients compared to CN controls identified oligo-tau deposition within swollen RBPMS+ RGCs (Fig. 4a, white arrows) and prominent Oligo-tau staining in the GCL (Fig. 4b; T22+ RGCs are indicated by morphology and location with white arrows).