Optical lame trick can write with the eyes

It offers new hope for completely paralyzed patients: An amazingly simple optical trick makes it possible to paint with the eyes of handwriting on a screen. The technique could replace invasive brain-computer interfaces, in part.

The eyes are often the only thing that completely paralyzed people to move more can - and then offer the only way to communicate with the environment. So far, affected persons can communicate very slow and cumbersome: you look for it on a computer screen with all the letters of the alphabet, and must in turn fix any letter for a moment and acknowledge by blinking.


But now, a French neuroscientist introduced a technology that could bring a significant improvement: lame were in experiments only by their eye movements, letters, words and numbers painted on a display, such as Jean Lorenceau of the Université Pierre et Marie Curie in Paris in the journal " Current Biology " writes.
So far this kind of writing was impossible eyes, as do the pupils normally constantly twitching, involuntary movements. These so-called saccadic camera programs prevent them from pursuing fine, purposeful movements of the eyes and recognize. The new method eliminates a flashing screen background, the saccades. After a brief training session subjects had learned to control their eye movements and produce readable form, reported Lorenceau. For people who move their limbs no more and no longer able to speak, this could be a quick and easy way of language and creative way.

"The new technology now offers these people a whole range of possibilities that they had not before," explains Lorenceau. They could draw with a pencil as any forms or sign anything. With a little practice you can also write with the eyes of 20-30 letters per minute - as fast as normal handwriting.

Flickering circles fool the visual system

The researcher is currently working on improving his system further. As early as next year, he announces to the first tests carried out with patients suffering from amyotrophic lateral sclerosis (ALS). In this incurable disease, the nerves that control muscles are destroyed gradually. As a result, patients suffering from ever-increasing paralysis and cannot speak for some time. researchers have been working to enable computer-brain interfaces to the patient a better communication with their environment . However, it must usually be implanted electrodes directly to the meninges.
The core of the new system is a wallpaper with many randomly distributed circles. They change 720 times per minute, its contrast and thus produce a rapid flickering. "If the eyes are calm, this background appears only as a static array of discs," says Lorenceau. But if you move his eyes, producing a flicker of that feint: The circles appear in the direction of movement of the eyes to wander. This effect deceive the visual system and make sure that the saccades omitted.

A special camera and a computer program, analyze the eye movements of the person writing it and identify the painted form. To facilitate the training, initially a ring marked with colored dots, where the view of the subject goes straight. However Lorenceau admits that users will see the lines generated by their eye movements immediately. You must therefore learn to write blindly. The go but surprisingly quickly: After only three half-hour training sessions before such a display would have six subjects learned to write numbers, letters and whole words legibly.