Eye tracking (or gaze tracking) is a technology for measuring the gaze direction of the user. When combined with positional head tracking, one can determine the exact point the user is looking at in the real or virtual world.

Eye tracking is already widely utilized in many fields of research, including marketing, psychology, medical, usability, and user behavior. It also has many important use cases in VR/AR and is rapidly becoming a standard feature in high-end headsets. Examples include automatic inter-pupillary distance (IPD) adjustment, detecting when a headset is worn, and automated user detection through iris recognition. It can also be used as a control mechanism in user interfaces, and to improve the realism of social avatars.

As the human eye has a reduced acuity in the peripheral vision, it is possible to utilize eye tracking to improve graphics performance by reducing the number of pixels rendered in areas where the user cannot see them clearly. This technique is known as foveated rendering, and Varjo headsets can also exploit this phenomenon with the human-eye resolution Bionic Display.

Apart from detecting the Point of Interest, an eye tracking system provides information about fixations (whether a user is focusing on something), saccades and other eye motion patterns, blinking, and pupil dilation. Varjo provides a simple API that applications can use to query the relevant information about each eye at any given moment.

The integrated 20/20 Eye Tracker in Varjo HMD can be used for interacting with human-eye resolution VR content in various training scenarios.