Eye tracking software for sufferers of ALS/MND can cost tens of thousands of dollars, so I've spent 3.5 years of my spare time writing a free & open-source alternative - meet OptiKey (C#, Rx, WPF) (x-post from r/Software) : programming

https://www.reddit.com/r/programming/comments/3ke7ug/eye_tracking_software_for_sufferers_of_alsmnd_can/