[Voltbishop]

Bring a old cell phone that's sensitive to IR light and place it in front of a tobii system. You'll see they're pulsing at a high frequency something like 30 lights at a >60 refresh rate per second, to the point you can actually see the light on the users face (using sensitive camera). Not all eye tracking companies put this much light on your eye's, but Tobii seems to be cutting corners - to make up for short coming in image processing. It's a brute force method to eye tracking.

The sensation you get after running a tobii is feeling like you've been up past midnight staring at a bright screen. Most people don't get that it's the eye tracker that makes you feel this way. Some of the other more respected companies take the amount of IR light placed on your eye balls seriously and try to drastically reduce it.

Talk to Tobii about it and they'll just bury it and say "there are no none health risks, or regulations about having that much IR light on your eye". Basically no one has set a threshold for how much IR light should be on a person's eye thus it isn't a problem "we should worry about".