Abstract: Nowadays, the widespread access to Internet has made the shift from traditional classroom learning to virtual e-learning more accessible than ever. Online education has developed a whole industry both in the private and the public sector. E-learning is either a substitute for tradition learning, usually chosen independently by students, or a complementary for it, the institutions adding online materials to the traditional curricula. The shift to online learning brings the advantage of having the possibility to accurately assess user behavior and understand where the pain points are in the elearning process. Therefore, the researchers are able to prescribe the most efficient calibration methods for this process. One of the most accurate methods to record user behavior is through eye tracking technology. Eye tracking is a method that records real, natural and objective user behavior. Eye movements are fast, subconscious movements, which reveal information that is not accessible even to the responder. The human gaze can tell exactly what has been seen, in what order and for how long and, on the other side, what has been missed. Therefore, eye tracking data gives valuable insights for improving the learning process. Moreover, eye data can reveal valuable information about the emotional and cognitive processes of the student. In this paper, we review the studies that used eye tracking technology in e-learning. We aim to discuss the findings until the present date and to discover the current gaps in knowledge.