Another unit is the FRS Solutions product, but it has the same problems.
The FRS laptop computer system is large for two reasons: First, it's bullet-proof and ruggedized. Second, they have added input/output devices for use with infrared, allowing for home automation like opening the door, changing the channel, adjusting their own bed positions, turning on lights and such. Some of the input devices include the eye-gaze attachment and a switch that is activated by the tiniest movement of the PALS' last remaining muscle.
There is a stand made up of poles inserted together so the computer can hover over the patient while lying in a hospital bed. It is mobile--can roll around from room to room. But if there is any movement at all, the eye gaze unit needs to be realigned to the PALS' eyeballs. The poles were too flexible, just because they had to extend up 6 feet from the floor, then over to the patient 3 feet to the left. Any unit would bounce around flexibly in those conditions, which results in needing to realign the eye gaze unit.
If I were taking care of a PALS again, I would rig my own system using home automation stuff from Home Depot, use voice command, then generate the voice by switches or by gazing at a section of the screen. The big part--the computer--would go somewhere else in the house, and I would dangle the eye gaze unit from the ceiling instead of on a roll-around stand.
Big lesson learned: It takes a LOT of practice for the PALS to learn to use the software and hardware, so it's important to start early--before it is needed.
BTW, the voice software used by Stephen Hawking is now free to the public.