Our vision isn't what we think it is, with some quite large discrepancies, but it's still completely nuts to say it doesn't exist!

We can't deny "vision exists". But we can say that vision doesn't work anything like people think it works. (Everyone has a mental model of a camera or webcam.)

Your eye is really more like a flashlight in the dark. And it interprets things way to much (see optical illusions.)

It's easy to dismiss these problems, because you are rarely are in situations where the difference matters. This is no coincidence, since people rarely construct things that our eyes can't process. For example, fluorescent lights are actually turning ON and OFF constantly, but we just happen to not be able to see that. There really is no color purple, we just think it exists.

But it's quite easy to mess people up. See "rotating tunnel illusion", or the experiment where subjects fail to notice they are now giving directions to a different person, or the experiment where people fail to notice a guy in a gorilla suit (!) when given a simple task.

So the upshot is "vision is nothing like you think it is". Maybe we should have different words for the way a computers see things (a lot more reality based) vs the way humans see things (with all their foibles.) Ditto for Consciousness.

If our experience itself isn't what we think it is, that would tend to undermine empiricism itself, because we rely on our senses to inform us about the natural world. This includes our sense of whether or not others agree with us, whether they have the same experiences as us, etc.

I think therefore...Answer is Hazy. Ask again later.