A 13-second bedside eye test could help predict recovery of consciousness in patients with severe brain injuries, according to research presented at the European Academy of Neurology Congress 2026.
The study found that a previously overlooked part of the pupil’s response to light, known as the late light-off response, predicted improvements in consciousness seven days later in patients with acute brain injury. By contrast, standard pupil measurements already used in intensive care units, including the Neurological Pupil Index and pupillary light reflex latency, did not predict later recovery.
Researchers from Copenhagen University Hospital Rigshospitalet and the Technical University of Denmark studied 250 patients with impaired consciousness following traumatic and non-traumatic brain injury, alongside 30 age- and sex-matched healthy controls. Patients received daily automated pupillometry and neurological assessments for up to 20 days in intensive care.
The late light-off response remained independently associated with later improvement in consciousness after researchers accounted for baseline neurological status, time since injury, sedation, and injury type. The measure was not linked to responsiveness on the same day, suggesting it may detect recovery potential not visible during routine bedside assessment.
Lead author Poul Laigaard, of Copenhagen University Hospital Rigshospitalet, said: "Current tests of pupillary function tell us how the brain is responding in the moment, but the late light-off response may provide clues about the brain's potential for recovery.”
The association appeared strongest in patients not receiving sedatives and in those with anoxic-ischemic brain injury, though researchers said these findings needed confirmation in larger studies.
Because handheld automated pupillometers are already available in many ICUs, the researchers said the approach could be practical to implement if validated in future multicenter studies. “The entire assessment takes only 13 seconds per eye, making it a fast and practical bedside tool that could potentially be integrated into routine ICU care,,"added Laigaard.
Source: European Medical Journal.
