Virtual reality therapy.

graphic and content of the system, although the significant savings in rehabilitation can offset such costs. Also, VR rehabilitation, except for the CAVE-like technology, is portable and easier to distribute. Therapists can take VR equipment around with them and carry out sessions in people’s homes. This is particularly useful for patients, like people with agoraphobia, who due to their condition cannot leave their homes. The development of the content is ultimately what makes the therapy work, and should only be developed in close consultation with the therapist. As the success of the therapy often relies on skills learned virtually, it is important that something is not learned in the computer-generated environment that is not applicable to the real world, or that represents a distorted version of reality. Prolonged immersion in computer-generated worlds causes what is generally referred to as VR sickness. The reported symptoms are vertigo, motion sickness, flashbacks, spontaneous seizures, and excessively nervous and antisocial behaviour. People prone to epileptic seizures also are subject to a condition called ‘flicker vertigo’ that usually occurs when computer screens are not regenerated at least 15 times per second. This limitation is generally not a problem with the latest displays. VR sickness usually occurs after an exposure of 30 minutes or more. Fortunately, due to the costs associated with the development, it is unlikely that a simulation runs for more than a minute. Despite the downsides, VR therapy solutions are widely used and promise a lot of benefit for rehabilitation.