writes "This nifty gizmo was actually made of a popular gaming console camera that is fast enough to track the movements of a human eye, which can move 10 to 20 times a second. Such parts a made in bulk, so they are much cheaper than previous types of eye-tracking technology that cost upwards of $8000. This device, the GT3D, is made up of a pair of glasses, two attached cameras, and the elastic band to keep the cameras focused on the pupils.
The accuracy of this gadget is pretty incredible at this stage of development, as said by its creators:
"...is so accurate that if you were in a normal-sized room and wearing the device it would be able to locate where you were looking to within the size of a grapefruit.""Link to Original Source