One of the reasons the Rift can get its enormous FOV into that (relatively) tiny package is that they're using these skinny little lenses that put massive view-

One of the reasons the Rift can get its enormous FOV into that (relatively) tiny package is that they're using these skinny little lenses that put massive view-space distortion on what you see. One of the consequences is that you need to correct for this in software - notice the "fisheye" effect in some parts of the Kickstarter video where it's shown on a regular screen. One of the other consequences is that the pixel density in the centre of your field of view is higher than at the edges. If your eyes are pointing straight ahead, the biggest pixels (due to the lens distortion) are at the edge of the picture.