He seems far different nowadays but I think that's because we had a long time to see him public. If there's a surgery, I would place it around 2001. He seems different in Rock in Rio (2001) and different in VMAs (2002) as well. But that could be because of the braids.
I don't think it's bottox, in bottox you can't blink your eyes easily.
Btw, I've found this picture. I don't think he's done anything...