Altered sensorium in the Indian ER: what 7 seconds of pupillometry can tell you

Altered sensorium is one of the highest-stakes presentations in any Indian emergency room. Indian tertiary-care series put the prevalence at roughly 3–5 % of all ER visits — a single large government hospital sees 4,500–8,000 such cases a year — and in-hospital mortality across published cohorts sits at 36–42 %. The differential is enormous (metabolic, toxic, infectious, structural) and the time pressure is unforgiving. The pupil exam is one of the very few bedside findings that meaningfully narrows the differential within seconds. The problem is the way we do the exam.

This is a primer for the casualty medical officer and emergency physician on what bilateral, quantitative pupillometry adds when an unconscious patient lands on your trolley.

The Indian altered-sensorium patient is different

Western literature on coma in the ER tends to overweight metabolic and toxic causes. The Indian profile is structurally different. According to PubMed, Budumuru et al.'s 2025 prospective study of 126 patients with GCS < 10 at a South Indian tertiary care hospital found that neurological causes accounted for 36.5 % of presentations — most of them ischaemic stroke — followed by metabolic (25.4 %), multifactorial (14.3 %), infectious (11.1 %), and other (12.7 %, including status, drug overdose, and organophosphate poisoning); in-hospital mortality was 36.5 % (DOI, PMID 41391078). Other Indian tertiary-care series report broadly similar distributions, often with sepsis weighting higher than typical Western datasets — a difference that matters at the bedside because it changes the prior probability you assign at first contact.

The infectious differential carries a distinctly Indian fingerprint. According to PubMed, Aggarwal and colleagues at PGIMER Chandigarh, in 105 adults with febrile encephalopathy, found tuberculous meningitis in 25.7 %, acute pyogenic meningitis in 17.1 %, viral encephalitis in 11.4 %, plus scrub typhus, dengue, leptospirosis, and HSV — a list that no European or US emergency physician would draw up unprompted (PMID 37800084). Toxicology adds another layer: organophosphates account for 30–44 % of poisoning admissions, aluminium phosphide for 9–16 %, and snake envenomation for 26 % in some North-Indian centres. Roughly a quarter of all poisoning patients arrive with altered sensorium.

The clinical implication is uncomfortable. The Indian ER presents a bigger differential than the Western literature trains you for, with higher mortality, and with less imaging headroom — and the patient on your trolley needs you to narrow it now, not after the CT slot opens up.

Why the pupil exam matters here — and why the penlight exam falls short

The pupillary light reflex is one of the few bedside findings that simultaneously interrogates the afferent visual pathway, the dorsal midbrain, the third cranial nerve, and the autonomic balance of the iris. A new anisocoria, a sluggish reaction, a fixed dilated pupil — each points at specific anatomy with extraordinary specificity. The opioid pinpoint pupil, the herniation blown pupil, the metabolic preserved-but-sluggish reflex — these are textbook because they work.

The problem is reproducibility. According to PubMed, Couret et al. (2016), in a prospective double-blinded neuro-ICU study of 406 paired measurements, reported 18 % global discordance between manual and automated PLR assessment, a 39 % error rate for pupils under 2 mm, and nursing staff missed 50 % of anisocoria that the pupillometer detected (DOI, PMID 27072310). Olson et al., across 2,329 paired assessments, measured interrater κ of just 0.54 for size and 0.40 for reactivity; only 33 % of pupils called "non-reactive" by clinicians were confirmed non-reactive by quantitative measurement (DOI, PMID 26381281). Kerr et al. showed that nurses systematically underestimate pupil size and that the underestimation widens as the pupil grows (DOI, PMID 27134226). A 2019 systematic review concluded that automated pupillometry is more precise, more reliable, and detects pupillary change before clinical deterioration is apparent (DOI, PMID 30484008).

If you escalate, image, or transfer a patient based on a pupil exam, the measurement behind that decision should be better than the one we currently use.

"But my patient is intoxicated — does the exam still mean anything?"

This is the most common pushback in the ER. The answer from the published data is reassuring. Jolkovsky et al. (2022), in 325 intoxicated ED patients, compared the Neurological Pupil Index (NPi) between intoxicated patients and controls, including an opioid-positive subset. Raw metrics — pupil size, constriction velocity — were depressed by intoxication, but the NPi composite reactivity score was preserved, and the authors concluded that NPi can be used "without risk of confounding by key intoxicants of abuse" (DOI, PMID 36311337). For the ER physician, this matters: a quantitative reactivity index that holds up in the co-intoxicated patient is worth more than a subjective impression that does not.

What quantitative pupillometry adds to ER triage and disposition

A small but growing body of evidence is beginning to quantify the disposition value of pupillometry in the ED specifically. Gonzalez et al. (2025), in 50 comatose ED patients at a Level-1 trauma centre, found that NPi 3.1–5.0 was associated with 82 % ED discharge, while NPi 0 was associated with 92 % admission — the first published evidence that quantitative pupillometry adds information beyond standard ED clinical assessment for disposition decisions (DOI, PMID 40794983). Godau et al. demonstrated that a minimum NPi < 4 identified non-convulsive status epilepticus in emergency patients with an AUC of 0.93 (DOI, PMID 33215395). Marshall et al. showed superior interrater agreement for automated versus manual PLR assessment in acute stroke (DOI, PMID 30489422).

The under-triage problem is particularly stark in apparent "mild" head injury. Bossers et al., in 808 patients triaged as mild TBI, found that absence of equal and reactive pupils was an independent risk factor (OR 2.1) for being more severely injured than the triage GCS suggested; 12.9 % were eventually reclassified upward (DOI, PMID 29032474). For an Indian casualty officer evaluating a head-injury arrival in a busy bay, that finding is operationally important: a quick, objective pupil reading flags the patient who looks fine but is not.

Smartphone pupillometry has begun to reach into this space directly. According to PubMed, Maxin et al. (2023) reported that a smartphone pupillometer detected PLR alterations in acute large-vessel-occlusion stroke (DOI, PMID 37857150) and, in a separate validation, achieved 87 % accuracy for severe TBI classification (DOI, PMID 37464770).

The medicolegal dimension

Indian ERs face documentation pressures that Western counterparts often do not. A handwritten "PERRL" entry in the case sheet is hard to defend if the patient deteriorates and the family questions whether the pupil exam was done properly, when, and by whom. A time-stamped, two-page bilateral pupil report — produced in seven seconds, by any nurse or resident, in the same way every time — is a categorically different artefact in the case file. It is the same shift quantitative blood pressure measurement made over palpation: not a replacement for clinical judgement, but a defensible, reproducible record that backs the judgement up.

Where PupiLUX fits in the resus bay

PupiLUX is a smartphone-based bilateral pupillometer. Using the rear camera and torch of an iPhone, it performs a 7-second bilateral PLR measurement in a darkened bay and produces a two-page PupiLUX Pro Report with six quantitative parameters per eye — baseline diameter, constriction percentage, latency, maximum constriction velocity, average dilation velocity, and T75 — alongside reference ranges drawn from peer-reviewed literature. Bilateral capture is the architectural choice that matters most for ER work: anisocoria and inter-eye asymmetry carry much of the localising signal, and these are exactly what single-eye devices cannot measure.

PupiLUX is a measurement and screening tool — not a diagnostic device. The report surfaces quantitative data and reference ranges; the emergency physician interprets. We deliberately do not offer clinical impressions, diagnoses, or decision rules. That is your job, and the document the app produces exists to support that work, not to replace it.

Disclaimer. PupiLUX is a measurement tool, not a diagnostic device. For informational and screening purposes only.

Closing

The bedside pupil exam in the Indian ER deserves the same modernisation that the BP cuff and the SpO₂ probe got a generation ago. If you run an emergency department and would like to evaluate PupiLUX in your practice, write to us at info@pupilux.ai. The deeper write-up of where pupillometry fits in emergency medicine lives at pupilux.ai/clinical/emergency-medicine, and the longer clinical primer is at pupilux.ai/clinical/introduction.

References

All references verified against PubMed on 2026-04-27. DOI links included per PubMed attribution requirements.

1. Budumuru U, Sowmini PR, Pramod KS, et al. A Study of the Etiology, Clinical Profile, and Outcome of Nontraumatic Cases of Impaired/Altered Sensorium in Patients Attending the Emergency Department in a South Indian Tertiary Care Hospital. J Assoc Physicians India. 2025;73(12):34–36. DOI · PMID 41391078.
2. Aggarwal A, et al. Aetiology, clinical profile and outcome of patients with febrile encephalopathy. Trop Doct. 2023. PMID 37800084.
3. Couret D, et al. Reliability of standard pupillometry practice in neurocritical care. Crit Care. 2016;20:99. DOI · PMID 27072310.
4. Olson DM, et al. Interrater Reliability of Pupillary Assessments. Neurocrit Care. 2016;24(2):251–257. DOI · PMID 26381281.
5. Kerr RG, et al. Underestimation of Pupil Size by Critical Care and Neurosurgical Nurses. Am J Crit Care. 2016;25(3):213–219. DOI · PMID 27134226.
6. Phillips SS, et al. A Systematic Review Assessing the Current State of Automated Pupillometry in the NeuroICU. Neurocrit Care. 2019;31(1):142–161. DOI · PMID 30484008.
7. Jolkovsky EL, et al. Impact of acute intoxication on quantitative pupillometry assessment in the emergency department. J Am Coll Emerg Physicians Open. 2022;3(5):e12825. DOI · PMID 36311337.
8. Gonzalez H, Chen Y, Addo N, Madhok DY. Pupillometry in the Emergency Department: A Tool for Predicting Patient Disposition. West J Emerg Med. 2025;26(4):1078–1085. DOI · PMID 40794983.
9. Godau J, Bierwirth C, Rösche J, Bösel J. Quantitative Infrared Pupillometry in Nonconvulsive Status Epilepticus. Neurocrit Care. 2021;35(1):113–120. DOI · PMID 33215395.
10. Marshall M, Deo R, Childs C, Ali A. Feasibility and Variability of Automated Pupillometry Among Stroke Patients and Healthy Participants. J Neurosci Nurs. 2019;51(2):84–88. DOI · PMID 30489422.
11. Bossers SM, et al. Discrepancy between the initial assessment of injury severity and post hoc determination of injury severity in patients with apparently mild TBI. Eur J Trauma Emerg Surg. 2017;44(6):889–896. DOI · PMID 29032474.
12. Maxin AJ, et al. A smartphone pupillometry tool for detection of acute large vessel occlusion. J Stroke Cerebrovasc Dis. 2023;32(12):107430. DOI · PMID 37857150.
13. Maxin AJ, et al. Validation of a Smartphone Pupillometry Application in Diagnosing Severe Traumatic Brain Injury. J Neurotrauma. 2023;40(19-20):2118–2125. DOI · PMID 37464770.