Apple VR headset may use fluid-filled lenses to counter a user's bad eyesight.

An Apple VR or AR headset may be able to automatically adjust the lenses placed in front of the user’s eyes by using fluids to deform the shape of the lens to improve the user’s eyesight.
The fundamental part of augmented reality and virtual reality is that the user must be able to see the virtual content. Given this typically involves the use of a display very close to the user’s eyes, a position that may be hard to focus on for long periods of time, VR headset producers use optical lenses positioned between the eyes and the screen, adjusting the perceived focal distance for the user and making it more comfortable to look at.