MAPT and Alzheimer disease: Although this siRNA approach only partially decreased tau levels in the retina, we observed an improvement of axonal transport in 3xTg RGCs (20%) providing strong proof-of-principle for: 1) a detrimental role of tau accumulation on the regulation of anterograde axonal transport in vivo, and 2) early tau-dependent RGC dysfunction preceding overt neurodegeneration in AD.