I tried a freeware open source program like this many years ago!

I have no disability like that, just wanted to test it since it was free. I used my mouse to "track" the marker on the screen.

I remember them writing about how the bottleneck was an affordable setup for actually tracking the eyes, not the software and the screen. But there were up and coming freeware and open source programs for that too.

I imagine that with today's camera quality you can definitively make a basic setup like this at home for free/for the cost of a screen w/camera and something for computing. Be it tablets or other setups.