I had something similar to this when I was young but it wasn't so much a visual perception change. I'd sometimes lay down to go to sleep and my mind's eye/headspace/whatever felt like it was far away. Like everything I thought about was on the other side of this great chasm. It's very hard to explain since I think part of it is just a feeling. I have certain types of synesthesia that relate to this, so I've attributed it to that, but I guess I could be wrong. Anyway, it happened quite a bit when I was younger and was very scary and uncomfortable, but I think it's only happened once or twice in the past several years.