SmartNav is a head-tracking device that uses your head motion to move the mouse cursor. It is installed on top of the monitor and the user has to place a dot on the forehead I’m not sure why they couldn’t track the eyes, but the dot is probably more precise, may be because the SmartNav uses a light reflection of some sort.
If you wonder, the head only moves the cursor. To click, the user has to install another accessory, such a foot pedal. Many options are available. I’ll stick to the mouse for now, but this could be useful to someone who has arm/hand/wrist related health issues.