The S2 Eye Tracker can work with people wearing glasses. The eye tracker has been tested with corrective glasses, anaglyph, polarized and shutter 3D glasses. Of all the types of glasses, the eye tracker works best with 3D glasses.
The S2 Eye Tracker also performs well with IR (anti-reflective coatings). This does depend on the thickness of the coating. There should be no difficulty if the coating blocks around 50% or less of the light coming through the glasses.
The video below shows a demonstration of an eye tracking study with a subject wearing glasses. You can see the person looking around the screen represented by the lines, and where the person hovers, represented by the red dots. On the right-hand side you see a recording of the subject looking at the computer screen; for the experiment he is moving his head around quite vigorously to demonstrate that the S2 Eye Tracker maintains calibration on the eyes, even at angles where the glasses are no longer covering the eyes.