Writing and painting with the eyes

New procedure allows paralyzed people to write with their eyes

07/27/2012

French scientists have found a way that allows fully paralyzed people to write and paint with their eyes. "This system could help to improve the quality of life of patients with limb paralysis," researchers Jean Lorenceau of the Paris University Pierre et Marie Curie write in the journal Current Biology..

Letters, numbers and simple drawings were no longer a problem with the new system for fully paralyzed patients. They use their eyes to create the shapes they want on a computer screen. The French scientists have found a way to improve the so-called method of eye tracking, in which a camera detects the movement of the pupil, so that even paralyzed people who suffer from a speech loss can communicate with it.

Writing by eye movement was previously not possible
According to the researchers, fully paralyzed patients often only use their eyes as a means of communication. Previous methods were relatively complicated. Affected had to fix on a computer screen individual letters of the alphabet with their eyes in the correct order and confirm their inputs by blinking. Writing directly over the eye movement seemed out of the question, as the eyes can effectively track a moving object but are "unable to perform movements smoothly and regularly against a static background," according to Lorenceau and colleagues. The constant involuntary twitching of the pupils - so-called saccades - made it impossible for camera programs to implement fine, targeted movements in writing.

Optical trick prevents twitching of the pupils
To suppress the irregular twitching of the pupil, the French researchers now used a relatively simple optical trick. A flashing screen background prevents the saccades, so that the subjects based on the eye-tracking could draw letters, numbers and simple shapes. The screen background of the novel system is provided with a multitude of randomly distributed circles which change their contrast 720 times per minute and thus produce a continuous flicker. When the screen is stationary, the circles appear static, but as soon as "the view moves, there is a clear impression that the discs are moving with the eye movements," reports Lorenceau. Through this effect, the saccades are prevented. The pupil movement can by means of. Eye tracking and a relatively simple software will be displayed as an onscreen display.

New procedure can be used for communication after a short training
A short workout of "two to four 30-minute sessions" was enough for the subject to control their eye movements so that readable words appeared on the computer display, Jean Lorenceau explained. Initially, the gaze of the subject was marked by a ring of colored dots to facilitate training. This allowed the subjects to better control what they were doing. However, not all users were immediately aware of which line they created with their eye movement, explained Lorenceau. This was for the subjects as if they were writing blind. However, the users got used to it surprisingly fast, so that they were able to present numbers, letters, whole words and drawings after just a short training period.

Patients write with their eyes as fast as with their hands
To the paralyzed patient, "this provides a quick, creative and personal aid to the linguistic and emotional expression," explained Jean Lorenceau. According to the French brain researchers, "a well-trained person can use the new system to write with his eyes at about the same speed as with his hand." Twenty to 30 letters per minute are not a problem if trained accordingly. The system may also be used to train pilots, surgeons, athletes and other activities that require accurate oculomotor control, Lorenceau continues.

Trial planned in patients with amyotrophic lateral sclerosis
First and foremost, however, the novel system is currently intended for use in patients with limb paralysis and speech loss. As a next step, the French scientists are planning to test in people with amyotrophic lateral sclerosis (ALS). This degenerative disease of the motor nervous system causes a progressive and irreversible destruction of nerve cells required for muscle movement. Accordingly, patients suffer from increasing paralysis, which also causes speech loss as the disease progresses. Therefore, the ability of ALS patients to communicate significantly could benefit from the invention of French brain researchers. (Fp)

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