Yamen Saraiji et al., have developed the Layered Telepresence system - a layered-based approach to create a seamless interaction between multiple users from multiple locations to engage in the same conversation.
The system combines multiple locations and arranges them as layers that are presented in the same virtual space. The concept allows users to achieve multiple types of compound presence in both physical and virtual environments.
Their system employs eye tracking to determine the user's gaze position; which in turn is used to inform the saliency of the layer. Pupil hardware is used in the VR headsets, and the demo was used by over 300 participants at SIGGRAPH 2016.
As part of the development process, Yamen created a Unity3d plugin, that talks to Pupil Service over the network and coordinates calibration within the VR headset. Check out Yamen's Unity3d calibration plugin here on github.
Check out Yamen Saraiji et al.'s, SIGGRAPH 2016 poster - Layered Telepresence