Pupillary reflexes and the control of eye movements
The light reflex arc and the relative afferent pupillary defect, parasympathetic and sympathetic pupil pathways with their pharmacological tests, light-near dissociation, and the gaze centres, MLF and vestibulo-ocular reflex that explain gaze palsies, INO and the doll's eye test.
Tier 2Medical sciences concept
Written with AI assistance and fact-checked against the sources below. For exam study, not clinical decisions. How notes are made
At a glance
- The light reflex has an afferent limb (optic nerve to pretectum) and an efferent limb (Edinger-Westphal nucleus, third nerve, ciliary ganglion, sphincter). Each pretectal nucleus feeds both sides.
- An afferent defect causes a RAPD with equal pupils. An efferent defect causes anisocoria.
- The pupil size reflects a balance: parasympathetic (sphincter, muscarinic M3) and sympathetic (dilator, alpha-1).
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Sources
- Principles of Neural Science (6th ed.)McGraw Hill (Kandel, Koester, Mack, Siegelbaum, 2021), 2021
- Walsh and Hoyt's Clinical Neuro-Ophthalmology (6th ed.)Lippincott Williams and Wilkins (Miller, Newman, Biousse and Kerrison, eds, 2005), 2005
- Leigh RJ, Zee DS. The Neurology of Eye Movements (5th ed.)Oxford University Press, 2015
- Dewan MA, Harrison AR, Lee MS. False-negative apraclonidine testing in acute Horner syndrome. Can J Ophthalmol 2009;44:109-10Canadian Journal of Ophthalmology, 2009
- Last updated
- 14 November 2026
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