Eyes Don't Lie: Patient Pupils May Help Answer Tough Questions
Patients may soon be able to answer questions using only the pupils of their eyes.
Scientists have invented a simple system that allows patients who can't communicate to answer yes or no questions with their eyes. Researchers said the system consists of just a laptop and camera that measures nothing but the size of pupils.
The latest technology takes advantage of changes in pupil size that naturally occur when people do mental arithmetic. What's more the latest system requires no specialized equipment or training at all.
Besides helping severely motor-impaired patients communicate, researchers say the new pupil response system may also help assess the mental state of patients whose state of consciousness is still unclear.
"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," researcher Wolfgang Einhäuser of Philipps-Universität Marburg in Germany said in a news release.
In a study, researchers asked healthy participants to solve math problems only when the correct answer to a yes or no question was shown to them on a screen. Researchers found that the mental load associated with solving that problem caused an automatic increase in pupil size, which researchers showed they could measure and translate into an accurate answer to questions like "Are you 20 years old?"
Afterwards, researchers tested out their pupil response algorithm on seven "typical" locked-in patients who had suffered brain damage following a stroke. Researchers said that in many cases, they were able to discern an answer based on pupil size alone.
"We find it remarkable that the system worked almost perfectly in all healthy observers and then could be transferred directly from them to the patients, with no need for training or parameter adjustment," Einhäuser said.
While the new pupil response system could still be improved in terms of speed and accuracy, researchers say those are technical hurdles that they can easily overcome. Einhäuser stressed that the latest measure of pupil response could already make an important difference for those who need it most.
"For patients with altered state of consciousness-those who are in a coma or other unresponsive state-any communication is a big step forward," he said.
The findings are published in the journal Current Biology.