Well, then there's this -- when Keith starts talking about the "floaties," I started seeing ... stuff in my field of vision too.
Still real, to me.
I've been thinking from the opposite direction lately -- when I look at something and see red, and you see red, because that light stimulated certain cones in our eyes, its really not different from any other sensation; rather, its just one we happen to (reproducibly) share.
Not that the sunset isn't red (among other things).
But that it exists for us as the experience of a red sunset, which it's not.
Keith, I hope you are recovering.