A 13-second bedside eye test could help clinicians predict whether patients with severe brain injuries are likely to regain consciousness, according to research presented at the European Academy of Neurology Congress 2026 in Geneva.
The findings suggest that a little-studied part of the pupil’s reaction to light, known as the late light-off response, may offer an early sign of recovery potential in people with acute disorders of consciousness. Researchers found that this delayed pupil response predicted improvements in consciousness seven days later, while standard pupil measurements already used in intensive care did not.
The study was led by researchers from Copenhagen University Hospital Rigshospitalet and the Technical University of Denmark. It included 250 patients with impaired consciousness after traumatic and non-traumatic brain injury, as well as 30 healthy controls matched for age and sex. Patients underwent daily automated pupillometry and neurological assessments for up to 20 days while in intensive care.
The late light-off response refers to a later phase of pupil behaviour that occurs after the eye has reacted to light. According to the researchers, this measurement was linked to later improvement even after taking account of baseline neurological status, time since injury, sedation and type of brain injury. Importantly, it was not associated with how responsive patients appeared on the same day, suggesting it may reveal recovery potential not visible during routine bedside checks.
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Lead author Dr Poul Laigaard said current pupil tests show how the brain is functioning at a particular moment, but the late light-off response may provide clues about the brain’s capacity to recover over the following days. The effect appeared strongest in patients who were not receiving sedative medication and in those with anoxic-ischaemic brain injury, although the team stressed that these subgroup findings were exploratory.
Senior author Professor Daniel Kondziella said larger multicentre studies are now needed to confirm whether the method could be used routinely for bedside monitoring and prognosis. Because automated pupillometers are already available in many intensive care units, the researchers believe the test could be relatively straightforward to introduce if future studies support its use.
References
- Laigaard, P., Stückler, S., Eigenbrodt, A. et al. (2026). Pupillary light-off latency predicts 7-day improvement in consciousness in patients with acute disorders of consciousness. Abstract A-26-17842. Presented at the 12th EAN Congress (Geneva, Switzerland).
- Edlow, B.L., Claassen, J., Schiff, N.D., Greer, D.M. (2021). Recovery from disorders of consciousness: mechanisms, prognosis and emerging therapies. Nature Reviews Neurology; 17(3):135–156.
- Messina, Z., Shapshak, A.H., Mills, R. (2023). Anoxic Encephalopathy. StatPearls. NCBI. Available at: https://www.ncbi.nlm.nih.gov/books/NBK539833/.
This news item has been summarised using AI and checked by humans before publication.
Sources
European Academy of Neurology (EAN) Congress 2026
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