A 13-SECOND bedside eye test may help doctors predict which patients regain awareness days after severe brain injury, according to research presented at the European Academy of Neurology Congress 2026, by reading a phase of the pupil’s response to light, known as the late light-off response (LOR).
A Persistent Challenge in Intensive Care
Predicting recovery of consciousness after severe brain injury remains one of the hardest problems in intensive care. Automated pupillometry is already widely used in intensive care units (ICUs) to gauge brain function, but existing measures mainly capture the pupil’s instant response to light and say little about longer-term recovery prospects.
Study Design and Pupil Assessment
Researchers from Copenhagen University Hospital Rigshospitalet and the Danish Technical University examined whether the LOR could reveal recovery potential in acute disorders of consciousness. The study enrolled 250 patients with impaired consciousness after traumatic and non-traumatic brain injury, plus 30 age- and sex-matched healthy controls. Patients underwent daily automated pupillometry and neurological assessments for up to 20 days in the ICU. The observational design tested whether pupil measures predicted later changes in awareness rather than applying any treatment.
Late Response Predicts Later Gains
Late LOR latency independently predicted improvement in consciousness seven days later, holding up even after accounting for baseline neurological status, time since injury, sedation, and injury type. By contrast, standard measures already used in ICUs, including the Neurological Pupil Index and pupillary light reflex latency, did not predict later gains. Notably, the late response was not linked to a patient’s responsiveness on the same day, suggesting it may expose recovery potential hidden during routine bedside checks. The association looked strongest in patients off sedation and in those with anoxic-ischaemic brain injury, though the authors stressed these subgroup results were exploratory.
Towards Routine Bedside Use
Lead author Dr Poul Laigaard said current pupil tests show how the brain is responding in the moment, whereas the late light-off response may hint at its capacity to recover in the days ahead. Senior author Professor Daniel Kondziella called the finding important but preliminary, noting that larger multicentre studies are needed before routine use. Because the handheld pupillometer is already common in ICUs and each eye takes only 13 seconds, the team suggested the approach could be practical to adopt if validated, aiding prediction of recovery of consciousness.
Reference
Laigaard P et al. Pupillary light-off latency predicts 7-day improvement in consciousness in patients with acute disorders of consciousness. Abstract A-26-17842. EAN Congress, 27-30 June, 2026.
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