When I visit someone at home for a eyegaze assessment I’ll take along a whole selection of eye trackers. That’s because I often find that some perform much better than others based on the individual, their preferred activities and their environment.
I find it useful to order the trackers in my head from most to least likely to help. This is important when facilitating traditional in-person assessments as you don’t want to take too much time and tire everybody out. It is even more important when performing remote assessments as you can’t possibly mail out every tracker in your collection.
This diagram represents a simplistic view of my thought process when thinking about the trackers. The following information comes from my best efforts to research the difference between the camera technologies, and is largely based on my experience in the field and feedback from eyegaze users.
For people with significantly atypical eyes then the Eyegaze trackers work very well. They are also good for people who want very fast access, such as if they are writing a book. However they are technically a bit difficult so require good support from caregivers and family.
If the person wishes to use their eyegaze system in rooms filled with natural light or outdoors (particularly AAC users) then the PCEye 5 from Tobii Dynavox is really the only option, although the Irisbond can work outside too, albeit on less sunny days.
For those with glasses I find the trackers that provide an infra-red video feed to be most useful as you can control for glare, reflections and frames. They are also perfect for remote assessments as it helps the clinician observe and fix problems. The Alea and the Irisbond perform well here.
The TM5 gets a mention because the eye status dots on the tracker are very useful to indicate something is wrong, but the TM5 doesn’t provlide a video throughput. The same company make a unit called the EyeOn which uses a similar tracker with video feed, but this camera isn’t available for other devices.
Features that are not accounted for here but are important for some users include the headbox size (the amount someone can move their head and the versatility of positioning) which is a real strength for the Tobii Dynavox line of trackers.
Please see this diagram for what it is, and with a big pinch of salt! You might find that the first tracker you try works perfectly, but usually a few are needed for comparison.