-_- He didn't Photoshop it.. Geesh. Go look :P
But notice in the first and middle frame, blood comes down from the other side of his eye at the same time.... I'm not sure if that means Sasuke's eyelid transfered some of it overto the other side (running along the surface of the eye is scientifically plausible).
Personally, I think maybe... Itachi's blood contaminated Sasuke's eye.. So, it might take on a MS Property. Or the whole Rivalry brings along MS... Who knows ^.^
edit: there is also some Japanese symbols to the side pointing at the drop... I don't know what they mean unfortunately..