Implication fix needed: "optical illusion" should not imply "modern art"

Well, I didn’t expect that to happen.
 
optical illusion currently implies modern art. This is nonsensical.
 
I guess that something got renamed from op art, because that’s the only overlap I can think of. Anyway, can someone with powers please fix the implication?

There’s not much of it, and I do appreciate a good proof that my eyes are lying to me all the time, so I’ll fix the wrong ones.

Tag tweaking done. Various bits of fallout…
 
keeps both tags, given the obvious MC Escher reference.
 
>>1133808 too, for the same reason. Not as clear an homage.
 
Otherwise, optical illusion clearly gets used a lot for not what it looks like stuff, or for accidental juxtaposition wins in single images. Both have better tags.