Board Thread:Versus Debates/@comment-26636534-20200129184605/@comment-32685487-20200203231735

Activating on the Third Eye is the same as activating on the users own eyes, all 3 are connected to the optic nerve and genjutsu is done through chakra. I highly doubt Gaara would simply throw sand in somebodies eyes, he had the chance to do that against other dojutsu users and every single time he never even attempted it. Itachi would never just jump into Gaara's sand or let it get on him. That's extremely uncharacteristic of Itachi.