Here is an example of messing with the optical mind. If someone has enough time and creative energy, they can create convincing illusions, inside our empirical realm. Actually, the whole world is an illusion, not in the sense that it doesn't exist, but in that we take it for one thing and it is another. It is reality versus Reality. Temporary versus eternal. The illusion is we think it will last as it is, and that it is all that is.
It would be a mistake to ignore reality, that is only another kind of illusion. I mean ignore it in the sense of "I don't need to floss my teeth because this is all temporary." That sort of reasoning is a young (usually) person's misapplication of the concept of illusion. While it is true we are not our body, our body IS our body and needs care. So floss your teeth, your future self will thank you for it.
To see several photos of real illusions in rooms like the above, and to see how it was done, click here.