Fully paralyzed patients could be given a chance to easily express simple "yes" and "no" phrases thanks to a newly developed method of communication. Paralyzed patients who have become "locked in" can't directly control any part of their bodies, but a research team led from the Philipp University of Marburg found that such patients may be able to indirectly control their eyes just enough to get across a message. By training the patients to dilate their pupils, the team found that they could dictate between simple answers.

Instructing patients to dilate their pupils was surprisingly easy: it's long been known that pupils dilate when a person is working through a difficult math problem. The research team took advantage of this by instructing locked-in patients to perform complex arithmetic when they wanted to say "yes" or "no." The only equipment needed was a camera to measure their pupils — making the new method non-invasive and possibly much safer than existing tools that rely on brainwave measurements.

The test was only performed on a small numbers of patients — just seven with "typical" symptoms — but they were able to communicate with an accuracy far above random chance. The test worked by posing a basic question such as, "Is your age 20?" and then presenting two sequential math problems, one for "yes" and another for "no." If their pupils only dilated during one question, the researchers could tell that the patient was selecting that option. It didn't matter if the patient ever solved the math problem, so long as they were working on it, their pupils would enlarge.

Steven Laureys, a researcher who worked on the study, told New Scientist that the research was only a proof of concept, but nonetheless, he was "very excited" to see it in use. Using even the smallest movements to allow locked-in patients to communicate isn't a new strategy though: former Elle editor Jean-Dominique Bauby famously documented his struggle with paralysis after it was discovered that he could communicate by blinking a single eyelid — that method allowed him to dictate an entire book, which was later adapted to film in The Diving Bell and the Butterfly. Even so, this research team's approach could work for patients who can't move at all — and it involves little training and no physical risks.