I built the application, works fine. But now the boss wants the capability for users to concentrate on a point in the screen and it triggers an event. Call me an old fashioned dev but I haven't got a clue. Any insight would be appreciated.
First off, you really need to find out what your boss means by "... users to concentrate on a point in the screen and it triggers an event". There is no eye tracking capability (yet) build into any VR HMD. That might end the vague request right there.
OTOH - what most apps do that need some user input without using any buttons is called "gaze tracking" or "gaze input" but what it really is at this stage of VR development is if the user has centered the screen about some UI trigger, then you can (typically) show some hourglass-like object superimposed on the trigger in an obvious countdown mode. If the countdown goes off, the input is triggered. If the user "gazes away" (i.e. moves their head), you abort the countdown and turn off the UI visuals. Works best if there's a reticule that's either always on, or comes into focus when it's near a trigger. While reasonably intuitive, it's not my favorite technique, and it's got serious problems when you do it in a stereo scene, but a lot of apps currently use it. Get a GearVR and visit the Oculus store/apps, they do it as good as anyone, plus they have some nice documentation of best practices.