  Latest developments in computer hardware, sensor technologies, and artificial
intelligence can make virtual reality (VR) and virtual spaces an important part
of human everyday life. Eye tracking offers not only a hands-free way of
interaction but also the possibility of a deeper understanding of human visual
attention and cognitive processes in VR. Despite these possibilities,
eye-tracking data also reveal privacy-sensitive attributes of users when it is
combined with the information about the presented stimulus. To address these
possibilities and potential privacy issues, in this survey, we first cover
major works in eye tracking, VR, and privacy areas between the years 2012 and
2022. While eye tracking in the VR part covers the complete pipeline of
eye-tracking methodology from pupil detection and gaze estimation to offline
use and analyses, as for privacy and security, we focus on eye-based
authentication as well as computational methods to preserve the privacy of
individuals and their eye-tracking data in VR. Later, taking all into
consideration, we draw three main directions for the research community by
mainly focusing on privacy challenges. In summary, this survey provides an
extensive literature review of the utmost possibilities with eye tracking in VR
and the privacy implications of those possibilities.
