Mutual gaze has a diverse and essential role in guiding human social behavior. It not only eases communicational and collaborative tasks but also modulates mental and affective states. During mutual gazing, interpersonal synchronization of eye parameters occurs concurrently with synchronization of brain activity. Also, increased synchrony in eye parameters corresponds to higher evaluations of trustworthiness, interest, and engagement among individuals. However, the eye-tracking studies in question lack ecological validity as, to the best of our knowledge, they did not recruit real-world face-to-face dyadic pairs but used static images or videos as stimuli. Thus, targeting this challenge in literature, our study presents the first experimental setup to investigate interpersonal synchronization of eye movements during sustained mutual gazing in dyadic settings using mobile eye-tracking devices. We recruited dyads to make eye contact without any explicit verbal communication for one minute under three conditions: looking at each other face-to-face, looking at each other through a mirror, and self-gazing through a mirror. Participants also reported how connected they felt with their partners in each condition. The results revealed varying levels of interpersonal eyeblink synchronization and sense of connectedness across conditions: In the face-to-face mutual gazing condition, a higher synchronization of eyeblinks was observed along with higher ratings of perceived connectedness. These results emphasize the critical importance of investigating mutual gaze dynamics in the context of direct versus mediated interaction. The present study also calls for further investigation of eye parameters such as the correlation of gaze position and pupil size changes in real-person settings.