The non-invasive innovation enables physicians to track the eye movement and dilation of a patient’s eyes, even when closed, offering the promise of improving clinical responses to patients in unresponsive conditions.

Pupil dilation — the process by which the pupils expand or widen to allow more light to enter the eyes — can provide critical insights into a patient’s physiological state. The pupil size fluctuates not only in response to light but also as a reaction to emotional and physical stimuli, such as pain or sudden events. These changes are driven by the autonomic nervous system, which prepares the body to react to external stimuli.

However, until now, monitoring these changes was only possible when patients had their eyes open.

But a Tel Aviv University research team, led by doctoral student Omer Ben Barak-Dror and supervised by Prof. Yuval Nir and Prof. Israel Gannot, demonstrated that changes in pupil size and gaze direction can be monitored without the need for the patient’s eyes to be open. The findings were recently published in the peer-reviewed Communications Medicine journal.

“It is often said that the eyes are the windows to the soul,” said Nir, who heads the Department of Physiology at Tel Aviv University’s Faculty of Medical and Health Sciences.

The new technology uses short-wave infrared (SWIR) imaging combined with deep learning algorithms, allowing clinicians to track the pupillary light reflex (PLR) behind closed eyelids. PLR refers to the way pupils constrict in response to a flash of light and then return to their normal size. The researchers conducted experiments that demonstrated their system’s ability to accurately monitor the reflex even when the eyes are shut, matching the accuracy of open-eye data.

“Our method can successfully track the precise dynamics of the pupillary light reflex in closed-eye conditions,” said Ganot, of the university’s Department of Biomedical Engineering. He added that the technology can even estimate the direction of the patient’s gaze with remarkable accuracy, providing additional insights into a patient’s cognitive state.

The researchers explained that the technology could be used to monitor the depth of sedation during surgeries or identify intraoperative awareness, a rare but traumatic condition where patients regain consciousness during anesthesia but are unable to move or speak.

Another potential use is in the intensive care unit (ICU), where patients are often unresponsive. In these cases, tracking pupil size could help detect signs of pain, seizures, or other neurological responses that may otherwise go unnoticed. It could also prove useful in sleep medicine by providing insights into various sleep disorders and helping detect nightmares in real-time.

The researchers have already filed a patent application.

PHOTO: Use according to Section 27 A