A simple bedside eye test may help predict recovery of consciousness in patients with severe brain injuries, according to new research presented at the European Academy of Neurology Congress 2026.
The study found that a previously overlooked phase of the pupil response to light, known as the late light-off response (LOR), predicted improvements in consciousness seven days later in patients with acute brain injury. Standard pupil measurements already widely used in intensive care units, including the Neurological Pupil Index and pupillary light reflex latency, did not predict later gains in consciousness.
Researchers from Copenhagen University Hospital Rigshospitalet and the Danish Technical University investigated whether a later phase of the pupil response could provide additional insight into recovery potential for patients with acute disorders of consciousness. The study included 250 patients with impaired consciousness following traumatic and non-traumatic brain injury, alongside 30 age- and sex-matched healthy controls. Patients underwent daily automated pupillometry and neurological assessments for up to 20 days in intensive care.
The research found that late LOR latency independently predicted improvement in consciousness seven days later, even after accounting for baseline neurological status, time since injury, sedation, and injury type. Notably, this measure was not associated with patients' level of responsiveness on the same day. Dr. Poul Laigaard from 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. This could help us better understand which patients may improve in the days ahead."
The relationship appeared strongest among patients who were not receiving sedative medication and those with anoxic–ischaemic brain injury; however, researchers said these subgroup findings were exploratory and require confirmation through larger studies. Professor Daniel Kondziella added, "We believe this is an important observation that deserves further investigation. Larger, multicentre studies are needed to determine whether this approach could be used routinely for bedside monitoring and prognosis."
Dr. Laigaard explained that because many intensive care units already have access to automated pupillometry technology, implementing this approach could be relatively straightforward if validated by future research. "The light-off response is measured using a handheld automated pupillometer in much the same way as current pupil measurements. 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."
