[Anticlockwise]

Not just multiple companies, multiple approaches. Eye tracking is exhausting, and that's pretty fundamental to the modality - dwell time requires significant control to be usable as a click, and even able bodied people find it exhausting. Some folks have tried doing eye tracking and using something else (EMG for example) as the click, but it doesn't work consistently for the population. ALS is also progressive, and people lose their eye control. Blackrock Neurotech has been working on a brain implant, with spinal cord injury as a first target population (because they're less fragile, among other reasons), and it works for current research patients, but medical devices take a lot of time, money and work to get cleared in the US. The implant itself is cleared, but the FDA wants the entire system to be cleared too.