I read an article today saying that Toshii eye tracking technology is being implemented in some of the next-gen VR hats.
For those unfamiliar, Toshii has developed a system that uses infrared sensors to track eye movement. This has been implemented in a sensor bar that can be mounted on a monitor, or installed adjacent to a laptop screen. The sensor essentially acts as a supplement to the mouse, allowing faster and more accurate clicks. In some instances, like certain video games, the sensor can completely replace the mouse, allowing you to interact with world items just by looking at them.
Toshii has also developed a set of glasses utilizing this technology, feeding precise information about what the user is looking at to a computer, and has touted it's potential use in marketing research and field studies.
Mounting these sensors inside a VR hat would allow for all manner of amusing magic tricks, where you interact with things just by looking at them without the need to aim your controllers.
But more importantly, these sensors seem to have significant implications when it comes to foveated rendering. As many gamers already know, most graphic-intensive video games do not actively render geometry behind the user, thus effectively cutting the GPU usage in half. Toshii's technology takes this to the next level, only fully rendering the small area that a person is actually looking at, and gradually reducing the resolution of graphics further into the users peripheral vision.
Early testers have claimed that they never even notice the diminished graphics, because it gets upscaled to full resolution the instant they move their gaze. NVidia has made the bold claim that this degree of foveated rendering can effectively improve graphic card performance by a full generation; which is to say, last gen cards will perform like current gen cards, and current gen cards will perform like next gen cards. Considering that VR hats need to render each scene twice, once for each eye, and it absolutely has to be the highest definition possible for a satisfying VR experience, this kind of technology could significantly advance what is possible in VR.