This was one of the earliest implementation of eye trackers into commercial virtual reality (VR) headsets. Furthermore, it computes not only the X and Y-axis of eye movement, but also the focus depth. When we focus on objects far away, objects closer to our eyes get blurred, and vice versa. We leverage this natural phenomenon to create a VR system that uses the depth of focus to simulate foveated rendering, which renders object not in focus to be more blur. This can overall reduce computational load and create a more natural image that is clear in the focused field.