Eye Gaze Technology for AAC: Looking at the Hardware

We live in such an exciting time! Leaps in technology have opened doors for computer access in ways that we didn’t even know to dream about just a few years ago.
(Creepy picture...I couldn't find a copyright-free image
of a child using eye gaze on a device, sorry!)
Eye gaze technology can be a miracle for people with severe motor impairments who cannot touch a screen or control a mouse or joystick. When coupled with a voice output device, it may give “voice” to someone who is otherwise unable to speak.
Regularly, the question comes up in circles where I hang out about how to pair up a child with one of the eye gaze systems to access an AAC device. It’s such a big question; let’s look at it over the next few Thursdays in smaller parts.
Disclaimer:  I speak from personal experience and my own research. All children, even those sharing the same diagnosis, are unique individuals with specific strengths and needs that must be considered in evaluating the different systems available.
Please keep in mind that technology changes daily. Current specs that apply to today’s devices (3/10/2011) will be replaced by specs for new devices tomorrow.
Also, I am not affiliated with any manufacturer and receive no compensation for expressing my views.
Today let’s look at the eye gaze hardware used to access computerized voice output devices.
Eye gaze not the same as head tracking, where a camera watches a point on the head or other body part as the person moves. Instead, this technology watches eye movement independent of what the head does. This allows access for people who have no other movement, as well as people with uncontrolled movements in the rest of their bodies.
Experience by any number of clinicians working with girls with Rett syndrome have shown eye gaze to be an effective means of input for many of their clients. The same findings are true for children with other diagnoses who have severely limited motor output.
I personally recommend having the option of eye gaze on AAC devices for girls with Rett whenever possible, even if a child is currently capable of using touch to access a device. There is no way of knowing what skills will stay strong in Rett syndrome and which will decline. Unfortunately, touch skills tend to be one of the skills that are difficult to maintain in the long term. As well, when kids are sick, any access method is demanding and eye gaze is often easier than touch access  during that period. Since an AAC device is a 5-year commitment before insurance funding can be accessed again, if it is at all possible to include the eye gaze function (an additional option of about $7,000, unfortunately, and thereby requiring lots of justification for funding), I do suggest that. At this time, the eye gaze units can be disconnected so they don't need to travel with the device when not needed.

As far as which devices to evaluate, try to arrange trials with several manufacturers. Sometimes one will "click" with a student over the others in a very obvious way right from the initial exposure.
My experience is limited to three major manufacturers distributing in our area:  Dynavox, Tobii, and Prentke-Romich. Other companies also manufacture eye gaze devices, but I have no experience with these. If anyone can add their experience in the comments section with these other companies, we can all learn from you.
The eye gaze hardware and software is different between the three main devices (Dynavox’s Eyemax, Tobii's C-12 with CEye, and PRC's ECOpoint). Each one includes a touch screen and a removable eye gaze unit. Weights for the computers and their eye gaze units differ somewhat, with the Dynavox Eyemax being the heaviest at 9 lbs. 2 oz. The PRC ECOpoint combination is 7 lbs. 4 oz. Tobii lists only the base weight of the C12 as 6 lbs. 8 oz., with the CEye unit not specified (though I would guess it to be somewhere in the 7-8 oz range). Weight may not be an issue for a device that will be mounted on a wheelchair or carried by an assistant.

Prentke-Romich has one of the best descriptions of eye gaze range and tolerance for movement that I have read. They describe an imaginary "box" surrounding your head. So long as your head stays inside that "box," the unit can read your eyes. Move outside that "box" and your gaze will be lost. It is also possible that the calibration to the unit may be lost, depending on the device, and require that the child complete the calibration exercise again.
Each manufacturer's device has a uniquely sized and shaped box. One "box" may be preferable for your student than another (i.e.: if she rocks back and forth, then depth may be a more critical dimension than side-to-side or height). I'll share these with you as height (up and down motions) x width (side to side) x depth (back and forth).

On to the three eye gaze devices I have used with children, and my own daughter in particular:

a) Dynavox's Eyemax was an early arrival on the eye gaze market. It is the eye gaze accessory that combines with the VMax or Vmax+. I found it to be fairly particular about positioning. It's "box" is
6" high x  9.4" wide  x 11” deep for a person sitting 17-24" from the device.
While it stayed calibrated well for my daughter, the small "box" did not accommodate the large movements she makes. I would expect someone with much smaller head movements to have greater success.

b) Tobii has 2 different eye gaze units, each accompanying a specific device. The MyTobii P-10 has a built-in eye gaze function and, while portable, is mainly intended for stationary use in bed or at a desk. It is purported to have extremely exact eye reading capabilities (I haven't personally tried it, so I can't comment). It's tolerance for movement is
12” high x 16” wide x 8” deep at a distance of 20 to 28 inches The CEye is the eye gaze unit for their portable C-12 device and is very forgiving of movement. It allows movements 12” high x 16” wide x 8” deep at a distance of 18 to 26 inches. In our experience, it was the most accommodating of large head movements and of leaving/returning without requiring recalibration. Tobii’s new C-15 voice output device is due to be released to the public market any day; it appears to use the same CEye unit for eye gaze as the C-12 (I could be wrong; please check with your local rep if you are interested).
c) PRC's ECOpoint is an eye gaze unit manufactured by Tobii to be used with PRC's ECO2 or Essense PRO. Its "eyebox" measures 10" x 15" x 8" at a distance of 20-24". We personally had less success with it’s eye gaze than with the Tobii CEye unit. For us, it didn't accomodate large head movements as well and seemed to require recalibrating more often. However, some kids do better with the PRC eye gaze, which underscores the importance of trying many devices. One SLP I talked with said in her experience, mobile girls and those with large movements tend to have better success using the Tobii and girls in wheelchairs tend to have better success on the ECOpoint. 
At www.AACTechConnect.com, you can print off a comparison chart of the three devices with a greater number of specs, including computer and operating system specifications, touch screen size, battery performance, along with the types of drives and ports each has. These take on a bit more importance if the device will also be used in a computer capacity instead of just for communication.

I hope that gives you a start on thinking about hardware issues. The first step to using any AAC device is being able to access it. After all, the most wonderful language systems are only as useful as a child’s ability to access them. Your team’s occupational therapist can be GOLD in helping to determine the best unit for access for your child.
Next week, on to language access software!
What questions do you have about evaluating eye gaze technology with AAC? Please leave a comment below…I greatly appreciate comments!
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You might find these other posts useful:


sam said...

Thank you so very much for posting this wonderful information. It has been a great starting point for me.

Rose-Marie said...

Sam, I'm so glad this was helpful. Thanks for letting me know. I hope the other posts in this “mini-series” will be useful to you as well.

Just a head's up...PRC had made some upgrades in the past few months that are reported to solve the head movement issues we had. In a couple weeks we'll be trying an upgraded unit and are excited to see how it goes!