From field to ICU: quantifying the pupillary response
In traumatic brain injury, pupillary changes are among the earliest signs of deterioration. Quantitative pupillometry provides objective, reproducible measurements at every stage of the trauma pathway.
The challenge of serial neurological assessment in trauma
Traumatic brain injury affects over 50 million people worldwide each year. In the acute phase, pupillary examination is one of the few neurological assessments available — especially in pre-hospital and resource-limited settings.
The Glasgow Coma Scale and pupillary reactivity together form the basis of acute TBI assessment. But while GCS has a standardized scoring system, pupillary assessment remains subjective. A 'briskly reactive' pupil to one clinician may be 'sluggish' to another.
This subjectivity compounds across handoffs: field paramedic to ER physician to ICU nurse. Each transition loses fidelity. Quantitative measurements that travel with the patient solve this problem.
A quantitative baseline that follows the patient
PupiLUX creates a PDF report at each measurement point — a quantitative record that transfers across care settings without degradation.
- 7-second test works in ambulances, ERs, trauma bays, and ICUs
- Bilateral measurement establishes quantitative baseline on first contact
- PDF report transfers across care settings — no verbal handoff degradation
- Latency (LAT) and Maximum Constriction Velocity (MCV) detect subtle slowing
- RAPD scoring identifies asymmetry that suggests unilateral pathology
- No specialized equipment to carry — the clinician's phone is the device
Key Evidence
In settings without ICP monitoring, pupillary reactivity is the primary available indicator of intracranial hypertension.
Chesnut RM, Temkin N, Dikmen S, et al.. “A method of managing severe traumatic brain injury in the absence of intracranial pressure monitoring” J Neurotrauma, 2018.
Quantitative pupillary changes preceded ICP spikes by up to 15.9 hours, providing an early warning window for intervention.
Jahns FP, Miroz JP, Messerer M, et al.. “Quantitative pupillometry for the monitoring of intracranial hypertension in patients with severe traumatic brain injury” Crit Care, 2019.
Manual pupil assessment has inter-observer agreement as low as 50% for intermediate reactions — precisely the range most clinically relevant in TBI monitoring.
Couret D, Boer W, Chabrier S, et al.. “Reliability of standard pupillometry practice in neurocritical care” Crit Care, 2016.
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Frequently Asked Questions
Can PupiLUX be used in the pre-hospital setting?
Yes. PupiLUX runs entirely on an iPhone with no network connection required. The 7-second test can be performed in an ambulance, at the scene, or in any setting where the patient's pupils are accessible.
How does PupiLUX help with trauma handoffs?
Each PupiLUX measurement generates a PDF with quantitative data. This PDF accompanies the patient through care transitions — from paramedic to ER to ICU — providing an objective record rather than subjective notes.
Does PupiLUX work with periorbital swelling?
PupiLUX requires visibility of the pupil. In cases of severe periorbital edema where the pupil cannot be visualized, the test cannot be performed — the same limitation as any pupil assessment method.
PupiLUX is not a diagnostic device. For informational and screening purposes only. All clinical decisions must be made by qualified healthcare professionals.