Physical examination maneuver

Physical Exam

Swinging Flashlight Test

also known as Alternating light test
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How to Perform

In a dimly lit room, have the patient fixate on a distant target or your nose. Shine a bright light into one eye for two to three seconds and note the pupillary constriction, then swing the light rapidly across the bridge of the nose to the other eye and observe its response, alternating back and forth every few seconds. Normally each pupil holds its constriction as the light arrives. An abnormal response is when the illuminated pupil dilates as the light swings onto it rather than holding constriction.

How to Interpret

Showing 2 of 7 findings

Glaucoma

Relative afferent pupillary defect, detecting asymmetric cup-to-disc ratio
Rule in
Somewhat helpfulWide CI
Rule out
InconclusiveWide CI
Evidence:Moderate

Multiple Sclerosis

Relative afferent pupillary defect, detecting retinal nerve fiber layer loss
Rule in
Somewhat helpfulWide CI
Rule out
Not helpfulDerived CI
Evidence:Moderate

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Related Systems / Regions

Head, Eyes, Ears, Nose, ThroatNeurological

Related Diagnoses

GlaucomaMacular DiseaseMedia OpacityMultiple SclerosisOptic Nerve DiseaseRhegmatogenous Retinal Detachment

Related Chief Complaints

Blurred VisionBlurred Vision in One EyeCurtain Over VisionDark Spot in VisionDecreased VisionDim VisionFaded Color VisionFlashes of LightFloatersLoss of Vision in One EyeOne Eye Not Seeing WellPain with Eye MovementShadow in VisionSudden Vision ChangesSudden Vision LossVision ChangesVision LossVisual Field LossWashed-out Colors

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. doi:10.1016/s0002-9394(14)74662-8. PMID 7304695.
  • Folk JC, Thompson HS, Farmer SG, O'Gorman TW, Dreyer RF. Relative afferent pupillary defect in eyes with retinal detachment. Ophthalmic Surg. 1987;18(10):757-759. PMID 3431805.
  • Chew SSL, Cunningham WJ, Gamble GD, Danesh-Meyer HV. Retinal nerve fiber layer loss in glaucoma patients with a relative afferent pupillary defect. Invest Ophthalmol Vis Sci. 2010;51(10):5049-5053. PMID: 20445112.
  • Waisbourd M, Lee B, Ali MH, Lu L, Martinez P, Faria B, Williams A, Moster MR, Katz LJ, Spaeth GL. Detection of asymmetric glaucomatous damage using automated pupillography, the swinging flashlight method and the magnified-assisted swinging flashlight method. Eye (Lond). 2015;29(10):1321-1328. doi:10.1038/eye.2015.106. PMID: 26113498. PMCID: PMC4815681.
  • Cettomai D, Hiremath G, Ratchford J, et al. Associations between retinal nerve fiber layer abnormalities and optic nerve examination. Neurology. 2010;75(15):1318-1325. PMID: 20810997.
  • Sadun AA, Bassi CJ, Lessell S. Why cataracts do not produce afferent pupillary defects. Am J Ophthalmol. 1990;110(6):712-714. PMID: 2248346.
  • Levatin P. Pupillary escape in disease of the retina or optic nerve. Arch Ophthalmol. 1959;62:768-779.

Research last updated September 9, 2026.