Kerotan said:
Lafiel said:

Eyetracking cams usually work with an array of infra-red lights around the eyes and infra-red cams tracking the pupil movements (~250Hz seems to be the magic number to enable FovR). Smartphone (visible light) cams probably won't get enough light to reliably track the pupil, especially at 240+ images per sec. Btw I've yet to see a phone with cams at both ends of the display.

Is that not bad for your eyes having infra-red lights shining into them? 

Sun light contains infra-red....
Point a remote at your eyes, it doesn't hurt :)