For the longest time, the medical community hasn't had any idea what to do with people who have locked-in  syndrome, 
 the condition of being completely paralyzed from head-to-toe. Sometimes doctors don't even know if they're even  conscious. The answer to communicating, it turns out, is to look in their eyes.
Thanks to a cutting edge piece of technology developed by researchers in Germany, these patients can now offer the outside world a yes or no based simply on the size of their pupils. It comes in the form of smart glasses that direct a camera into the patient's eyes. The patient's then given a question with a "yes" or "no" answer. After the question is asked a robotic voice says "yes" and then a math problem is displayed on a screen in front of them. A few moments later, the same robotic voice says "no," and another math problem is presented.


Pupil size is affected by thought processes, so the patient had been instructed to solve the math problem that came after their preferred answer. If their answer is "yes," for instance, their pupils will grow larger when the math problem is displayed after the word "yes." It doesn't even matter if they solve the problem, they just need to exert the mental effort. Said author of a paper on the experiment Dr. Wolfgang Einhäuser, a neurophysicist at Philipps-Universität Marburg in Germany, "It is remarkable that a physiological system as simple as the pupil has such a rich repertoire of responses that it can be used for a task as complex as communication."It is remarkable, but it needs work. While the experiment worked well on six healthy volunteers, it saw slightly less success on patients with locked-in syndrome. Nevertheless, it gives doctors hope that patients might earn some ability to communicate after being hit with what was once thought to be a once hopeless condition. Of course, if researchers keep making progress with brain-to-computer interfaces, these folks may soon be able to communicate simply by thinking about what they want to say.