There is a great deal of excitement around virtual reality (VR) headsets that display a computer-simulated world and augmented reality (AR) glasses that overlay computer-generated elements with the real world. Although AR and VR devices are starting to hit the market, they remain mostly a novelty because eye fatigue makes them uncomfortable to use for extended periods. A new type of 3D display could solve this long-standing problem by greatly improving the viewing comfort of these wearable devices.