Physical examination maneuver

Physical Exam

Pupillary Light Reaction

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How to Perform

In dim lighting, ask the patient to fixate on a distant target or your nose. Shine a bright light into one eye and watch that pupil constrict (direct response) while the opposite pupil constricts at the same time (consensual response); repeat for the other eye.

How to Interpret

Showing 8 of 20 findings

Intracranial Aneurysm

Anisocoria or abnormal light reaction in a patient with a third nerve palsy
Rule in
Not helpfulWide CI
Rule out
Not helpfulDerived CI
Evidence:Moderate

Poor Neurologic Outcome

Absent pupillary light reflex in a comatose patient after cardiac arrest
Rule in
Helpful
Rule out
Minimally helpful
Evidence:Moderate
Both pupils nonreactive to light in a patient undergoing craniotomy for acute subdural hematoma
Rule in
Somewhat helpfulDerived CI
Rule out
Somewhat helpfulDerived CI
Evidence:Moderate
Bilateral unreactive pupils in a patient with established traumatic brain injury, predicting a poor 6-month neurologic outcome
Rule in
—
Rule out
—
Evidence:Moderate

Serious Eye Disease

Photophobia on indirect (consensual) illumination in a patient with a red eye
Rule in
Very helpful
Rule out
Minimally helpful
Evidence:Moderate
Photophobia on direct illumination in a patient with a red eye
Rule in
Helpful
Rule out
Somewhat helpful
Evidence:Moderate

Structural Brain Lesion

Anisocoria greater than 1 mm in a patient with impaired consciousness
Rule in
HelpfulDerived CI
Rule out
Minimally helpfulDerived CI
Evidence:Moderate
Absent light reflex in at least one eye in a patient with impaired consciousness
Rule in
Somewhat helpfulDerived CI
Rule out
Somewhat helpfulDerived CI
Evidence:Moderate

Related Bedside Tests

Extraocular MovementsMembers
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Extraocular Movements
Rule in:VHStroke, SHHyperthyroidism, SHMyasthenia Gravis +9 more
Rule out:HMyasthenia Gravis, SHHyperthyroidism, NHOrbital Fracture +9 more
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Gait Assessment
Rule in:VHStroke, HFalls, HVascular Parkinsonism +24 more
Rule out:SHDementia, SHVascular Parkinsonism, MHFalls +24 more
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Pronator Drift
Rule in:VHBrain Tumor, VHFunctional Neurologic Disease, HUpper Motor Neuron Lesion +5 more
Rule out:VHFunctional Neurologic Disease, VHUpper Motor Neuron Lesion, MHBrain Tumor +5 more
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Babinski Reflex
aka Plantar reflex
Rule in:VHUpper Motor Neuron Lesion, VHVascular Parkinsonism, HMultiple System Atrophy +4 more
Rule out:SHUpper Motor Neuron Lesion, MHMultiple System Atrophy, NHVascular Parkinsonism +4 more
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Alternate Cover Test
aka Cross-cover test, Test of skew
Rule in:VHSkew Deviation, VHVestibular Dysfunction, HStroke +1 more
Rule out:VHStroke, VHVestibular Dysfunction, HSkew Deviation +1 more
Eye InspectionMembers
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Eye Inspection
Rule in:VHHyperthyroidism, VHStroke, HSerious Eye Disease +18 more
Rule out:HConjunctivitis, SHHypovolemia, MHAnemia +18 more

Related Systems / Regions

Head, Eyes, Ears, Nose, ThroatNeurological

Related Diagnoses

Acute Angle-closure GlaucomaAdie Tonic PupilAnticholinergic ToxicityBrain InjuryCholinergic ToxicityCranial Nerve III PalsyIntoxicationIntracranial AneurysmNeurosyphilisOptic Nerve DiseasePoor Neurologic OutcomeSerious Eye DiseaseStrokeStructural Brain Lesion

Related Chief Complaints

AgitationBalance ProblemsBlurred VisionCardiac ArrestCognitive DeclineColor Vision LossComaConfusionDecreased VisionDiarrheaDifficulty SpeakingDifficulty SwallowingDifficulty WalkingDifficulty with Daily TasksDilated PupilDizzinessDouble VisionDrooping EyelidDrowsinessDry MouthDry SkinExcessive SalivationEye MisalignmentEye Pain with MovementEye RednessFacial DroopFacial WeaknessFeverFloatersFlushed SkinHallucinationsHead InjuryHeadacheLight SensitivityLoss of ConsciousnessMemory LossMuscle TwitchingNumbness on One SidePalpitationsPersonality ChangePinpoint PupilsRed EyeSeizureShooting Leg PainsShortness of BreathSlowed BreathingSlurred SpeechSmall PupilsSudden Vision LossSweatingTearingUnequal PupilsUnresponsivenessUnsteady GaitUrinary IncontinenceUrinary RetentionVertigoVision ChangesVision LossVomitingWeaknessWeakness on One Side

References

Research in progress on one or more findings above; ratings may change.

  • Cox TA, Thompson HS, Corbett JJ. Relative afferent pupillary defects in optic neuritis. Am J Ophthalmol. 1981;92(5):685-690. PMID: 7304695.
  • Hoffman JR, Schriger DL, Luo JS. The empiric use of naloxone in patients with altered mental status: a reappraisal. Ann Emerg Med. 1991;20(3):246-252. PMID: 1996818.
  • Brennan PM, Murray GD, Teasdale GM. Simplifying the use of prognostic information in traumatic brain injury. Part 1: The GCS-Pupils score: an extended index of clinical severity. J Neurosurg. 2018;128(6):1612-1620. PMID 29631516. DOI 10.3171/2017.12.JNS172780
  • Wang CH, Wu CY, Liu CC, Hsu TC, Liu MA, Wu MC, Tsai MS, Chang WT, Huang CH, Lee CC, Chen SC, Chen WJ. Neuroprognostic Accuracy of Quantitative Versus Standard Pupillary Light Reflex for Adult Postcardiac Arrest Patients: A Systematic Review and Meta-Analysis. Crit Care Med. 2021;49(10):1790-1799. PMID 34259437. DOI 10.1097/CCM.0000000000005045
  • Kim KH. Predictors for functional recovery and mortality of surgically treated traumatic acute subdural hematomas in 256 patients. J Korean Neurosurg Soc. 2009;45(3):143-150. doi:10.3340/jkns.2009.45.3.143. PMID: 19352475. PMCID: PMC2666115.
  • Narayana S, McGee S. Bedside diagnosis of the 'red eye': a systematic review. Am J Med. 2015;128(11):1220-1224.e1. doi:10.1016/j.amjmed.2015.06.026. PMID: 26169885.
  • Narayana S, McGee S. Bedside diagnosis of the 'red eye': a systematic review. Am J Med. 2015;128(11):1220-1224.e1. PMID: 26169885.
  • Tokuda Y, Nakazato N, Stein GH. Pupillary evaluation for differential diagnosis of coma. Postgrad Med J. 2003;79(927):49-51. PMID: 12566553.
  • Harrison MJG. Clinical distinction of cerebral haemorrhage and cerebral infarction. Postgrad Med J. 1980;56:629-632. PMID: 7465470.
  • Fang C, Leavitt JA, Hodge DO, Holmes JM, Mohney BG, Chen JJ. Incidence and etiologies of acquired third nerve palsy using a population-based method. JAMA Ophthalmol. 2017;135(1):23-28. doi:10.1001/jamaophthalmol.2016.4456. PMID: 27893002. PMCID: PMC5462106.
  • Yoo YJ, Hwang JM, Yang HK. Dilute pilocarpine test for diagnosis of Adie's tonic pupil. Sci Rep. 2021;11(1):10089. PMID: 33980910.
  • Bickley LS, Szilagyi PG, Hoffman RM, Soriano RP. Bates' Guide to Physical Examination and History Taking. 13th ed. Philadelphia, PA: Wolters Kluwer; 2021.
  • Swartz MH. Textbook of Physical Diagnosis: History and Examination. 9th ed. Philadelphia, PA: Elsevier; 2025.

Research last updated September 9, 2026.