There is the focal distance, which is the distance at which your eyes need to focus. I'm pretty near-sighted, so my focal distance is short. There is also the

There is the focal distance, which is the distance at which your eyes need to focus. I'm pretty near-sighted, so my focal distance is short. There is also the focal angle, which is the angle your eyes have to be at to focus at a particular point which is a given distance away. As we evolved over millions of years, the focal angle corresponded to the focal distance the angle would get get closer and closer to zero (where your eyes are angled parallel to each other), the further away something was. But with modern VR systems, they feed different images to each eye, and they give you different focal angles (to make things appear further away or closer together), but the focal distance doesn't change -- it's still that screen that is millimeters away from your eyeballs. So, your visual systems get all kinds of screwed up. So far as I know, this problem is not something that can be corrected with any modern VR system. AR is different, since you're layering one generated visual image with one screen that both eyeballs are looking at and that gets put on top of the actual real world image that you can see.