Technological breakthrough can help identify clinical responses in unresponsive conditions

Closed eye imaging can track arousal, awareness, and pain in unresponsive conditions such as sleep, anesthesia, and intensive care, say Tel Aviv University researchers

A new technological development allows, for the first time, to monitor changes in pupil size and gaze direction behind closed eyes using touchless infrared imaging. In the future, tracking changes in pupil size will help identify arousal in sleep, anesthesia, and intensive care and help track the depth of sedation, detect seizures and nightmares, and recognize pain or responsiveness that may occur after trauma and in intensive care departments. The investigators anticipate that this technology has strong potential to become an important tool in clinical care.

The breakthrough was achieved with a team of investigators led by Omer Ben Barak-Dror, under joint supervision of Prof. Yuval Nir from the department of physiology, faculty of medical and health sciences, Sagol school of neuroscience, and the department of biomedical engineering, and Prof. Israel Gannot from the department of biomedical engineering. Other team members include Dr. Michal Tepper, Dr. Barak Hadad, Dr. Hani Barhum and David Haggiag. The research was published in the journal Communications Medicine.

Prof. Nir explains that “it is often said that the eyes are the windows to the soul”. Indeed, pupil size changes all the time, dilating or contracting to regulate the amount of incoming light, while providing valuable clinical information. We all know that our pupils get smaller in bright light and larger in darkness. But this is only one reason why the pupils change size. They also dilate when we’re aroused, for example when we react to a sudden event or when we are in pain. In such cases, our autonomic nervous system serves as an alarm and prepares us to take action. Tracking pupil size and eye movements can be critical in many clinical situations. However, until now this has been limited to open-eye scenarios. There was no method that allowed to do this in a touchless continuous manner when the eyes are closed, so that it can be used in domains such as sleep medicine, anesthesia, and intensive care.

The new research describes innovative technology that combines short wave infrared (SWIR) imaging with deep learning algorithms to perform touchless pupillometry and eye tracking behind closed eyelids.  “To establish and validate our technology, we focused on the pupillary light reflex (PLR) when the pupil constricts in response to a sudden flash of light, and then dilates back to normal. This is a basic reflex that occurs symmetrically across the two eyes in healthy people. We performed experiments testing our technology on the closed eye while comparing the results to the open eye data”, said Omer Ben Barak-Dror, lead author of the study at Tel Aviv University (TAU).

Profs. Nir and Gannot add that “Our method can successfully track the precise dynamics of the pupillary light reflex in closed-eye conditions, revealing the changes in pupil size following each light flash in individual subjects, and also accurately estimating where the eye gaze is directed to, with few degrees accuracy”, “the system operates at wavelengths where light has its maximum depth of penetration in biological tissue, and by analyzing the data using deep learning algorithms, we could go beyond what is typically possible with standard methods of near-infrared imaging”.

Ramot, the technology transfer company of Tel Aviv University, has filed a patent and is in the process of commercializing this groundbreaking new technology. "We believe in this technology's potential to revolutionize the diagnosis and treatment of neurological disorders," said Dr. Ronen Kreizman, CEO of Ramot. "This collaboration is part of Ramot's mission to bridge academia and industry, fostering innovations that address critical healthcare challenges."

Dr. Tepper adds that the information collected using continuous touchless monitoring is a critical element of the patient’s electronic medical record (EMR) and help with decisions concerning optimal medical treatment.

The investigators conclude: “our technology, backed by a patent application, paves the way for developing devices with wide-ranging clinical and commercial applications in domains ranging from sleep medicine, through monitoring sedation level and intraoperative awareness in anesthesia, to assessing pain and reactivity in unresponsive patients or in neurology intensive care and trauma”.

The study was supported by grants from the Zimin Foundation at Tel Aviv University and the breakthrough technology program of the Israeli Ministry of Science and Technology.