Access and apraxia
Someone living with Rett Syndrome often has more physical movement than eyegaze users with other conditions. As a professional, it may feel unusual to consider eyegaze for someone who can walk, move their hands and hit buttons.
However, we now know that it is unusual for someone with Rett Syndrome to use their hands in a functional way or for them to develop good switch skills. This is due to apraxia and the stereotypical involuntary hand movement.
Apraxia is best described as “a motor disorder caused by damage to the brain which someone has difficulty with the motor planning to perform tasks or movements when asked, provided that the request or command is understood and he/she is willing to perform the task.”
Apraxia often becomes heightened on request. Simply put, someone with Rett Syndrome would find it difficult to hit a switch with any consistent timing. The involuntary hand movement make direct access to a touchscreen extremely difficult.
Eyegaze is considered the best access method for someone with Rett Syndrome. The apraxia does not seem to affect the eye movement as much, although there are often periods of delay before a selection is made. Proper training, patience, short eye dwell times for selection on the eyegaze system are the keys to successful access.