Bedside eye test may predict consciousness recovery in brain injury patients

Bedside eye test may predict consciousness recovery in brain injury patients

New research presented at the European Academy of Neurology (EAN) Congress 2026 suggests that a simple bedside eye test can help predict when patients with severe brain injuries will regain consciousness. The study identifies a specific phase of pupil response that may reveal recovery potential not visible during routine clinical assessments.

Researchers from the Danish Technical University and Copenhagen University Hospital Rigshospitalet focused on the late light-off response (LOR), a phase of the pupil's reaction to light that occurs after the initial response. The study found that late LOR latency independently predicted improvements in consciousness seven days later. This remained true even after accounting for injury type, sedation, time since injury, and baseline neurological status.

In contrast, standard measurements already common in intensive care units (ICUs) — such as pupillary light reflex (PLR) latency and the Neurological Pupil Index (NPi) — did not predict these later gains. The LOR measure was not associated with a patient's level of responsiveness on the day of the test, suggesting it detects a hidden potential for recovery.

The study involved 30 healthy controls and 250 patients with impaired consciousness resulting from non-traumatic and traumatic brain injuries. These patients underwent neurological assessments and daily automated pupillometry for up to 20 days in the ICU. The relationship between LOR and recovery appeared strongest in patients with anoxic–ischaemic brain injury and those not receiving sedative medication, though researchers noted these specific subgroup findings are exploratory.

Because the test uses handheld automated pupillometers already present in many ICUs, the method is fast and practical, taking only 13 seconds per eye.

"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,"

Dr Poul Laigaard, lead author from Copenhagen University Hospital Rigshospitalet, via Mirage News

Predicting the return of consciousness is a major challenge in critical care. Professor Daniel Kondziella, the study's senior author, stated that larger, multicentre studies are now required to determine if this approach can be used routinely for prognosis and monitoring.

Expanding the Toolkit for "Covert Consciousness"

The LOR findings complement other emerging technologies designed to detect "cognitive motor dissociation" (CMD), a state where patients are conscious but unable to show it. According to a study published in Nature Communications Medicine, up to one quarter of patients labeled as unresponsive may actually be conscious.

To address this, researchers Sima Mofakham and Chuck Mikell, MD, from the Renaissance School of Medicine at Stony Brook University, developed an AI tool called SeeMe. The system uses computer vision and high-resolution video to analyze microscopic facial movements, such as involuntary reactions to commands to smile or open eyes, which are invisible to the human eye.

In a study of 37 comatose patients with acute brain injury, SeeMe detected purposeful movement up to four days before clinical teams recognized physical movements. Patients who showed these early responses were significantly more likely to regain consciousness and achieve better functional outcomes upon discharge.

Mofakham described SeeMe as a noninvasive and inexpensive solution that requires only a camera and open-source software.

"Just because someone can’t move their limbs or speak doesn’t mean they aren’t conscious,"

Sima Mofakham, senior author and associate professor, via Stony Brook Matters

Cellular and Biological Markers

While the LOR and SeeMe focus on physical responses, other researchers are looking for biological signals in the blood to predict recovery. A study in the Journal of Neurotrauma conducted at UPMC Children’s Hospital of Pittsburgh examined DNA methylation in the brain-derived neurotrophic factor (BDNF) gene, which aids brain repair.

The researchers enrolled nearly 300 children, including 189 with traumatic brain injuries (TBI) severe enough to require at least one hospital night. They found that within approximately 30 hours of injury, children with TBI had lower levels of DNA methylation than children with non-head injuries. Notably, these cellular differences did not correlate with brain scans or consciousness evaluations used by clinicians, suggesting that children who appear similar at the bedside may be responding differently at a cellular level.

Alternative Assessment Methods

Other efforts to quantify cognitive function in patients with disorders of consciousness (DOC) include eye-tracking technology (ETT). A clinical multicenter study of 31 DOC patients used the Cognitive Functions Assessment (CFA) scale on the C-EYE X system. The results showed moderate correlations between CFA and the Coma Recovery Scale-Revised (CRS-R), suggesting that ETT can accurately assess language, memory, and abstract thinking without relying on the examiner's experience.

Additionally, a protocol led by researchers at McGill University is testing high-density EEG markers. By recording brain activity in 200 sedated patients during brief interruptions of pharmacological sedation, the team aims to identify network reorganization that predicts long-term cognitive outcomes up to 12 months post-injury.