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Pupillary Response

Topic updated on 07/01/17 11:53pm

Overview
 

 
Introduction
  • Basic principle
    • the parasympathetic and sympathetic nervous system control the pupil
      • parasympathetic fibers lead to pupillary constriction (miosis)
      • sympathetic fibers lead to pupillary dilation (mydriasis)
        • as well as controlling the
          • superior tarsal muscle 
            • elevates the upper lid
          • smooth muscle orbitalis 
            • prevents eye sinking into the orbit
          • facial and neck cutaneous arteries and sweat glands
  • Miosis
    • light enters the eye which activates
      • retinal ganglion cells that will project axons into the optic nerve → optic chiasm → optic tract and then reach the
        • pretectal nucleus
    • fibers from the pretectal nucleus project to the Edinger-Westphal nucleus
      • pre-ganglionic parasympathetic fibers exit the Edinger-Westphal nucleus and synapse in the
        • ciliary ganglion
    • post-ganglionic parasympathetic fibers from the ciliary ganglion innervate the
      • pupillary constrictor muscles causing uniform bilateral miosis
  • Mydriasis
    • sympathetic fibers from many hypothalamic nuclei descend and reach T1 and T2 spinal cord levels
      • pre-ganglionic sympathetic fibers exit the T1 and T2 spinal cord level to join the paravertebral sympathetic chain (via the white ramus) and
        • synapse to the superior cervical ganglion
    • post-ganglionic sympathetic fibers ascend via the carotid plexus of the internal carotid artery, goes through the cavernous sinus, and synapses to the
      • pupillary dilator muscle
 
Select Pupillary Defects
Pupillary Defect
Comments
Horner syndrome
  • Pathogenesis inolves impairment in sympathetic pathways to the eye and face which results in
    • ptosis
      • secondary to impaired innervation into the upper lid smooth muscles
    • miosis
      • secondary to impaired innervation into the pupillary dilator muscles
    • anhidrosis
Marcus Gunn pupil
  • Describes an afferent pupillary defect resulting in
    • the affected eye is not sensitive to the light
      • there is minimal or absent pupillary constriction of the affected eye to light
  • A lesion may affect
    • eye
    • retina
    • optic nerve
  • Afferent pupillary defects can be detected with
    • swinging flashlight test which will show
      • the affected pupil dilate when exposed to the penlight
Argyll Robertson pupil
  • A type of light-near dissociation where
    • the eye does not constrict in response to light as much as it does with accomodation
  • Associated with neurosyphilis
Adie's myotonic pupil
  • A type of light-near dissociation where
    • the eye does not constrict in response to light as much as it does with accomodation
  • Secondary to
    • degeneration of the
      • ciliary ganglion
      • postganglionic parasympathetic neurons
 


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Qbank (1 Questions)

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(M1.NE.31) A 50-year-old woman with Systemic Lupus Erythematosus (SLE) presents to your clinic with complaints of left eye pain and reduced vision. She notes that she was in her usual state of health until 3 days prior to presentation when she noticed some mild tenderness around her left eye, unrelieved by any pain relievers. This morning when she woke up she was unable to see out of her left eye and made an appointment to come see you. Other than SLE, her medical history is unremarkable. She has had no additional symptoms other than pain and vision loss. Her vital signs are all within normal limits. On exam, she has no vision in her left eye, but 20/30 visual acuity in her right eye. When you shine a light in her left eye there is no response. What response would you expect when you shine a light in her right eye? Topic Review Topic

1. Bilateral mydriasis
2. Bilateral miosis
3. Miosis of the right eye only
4. Miosis of the left eye only
5. Mydriasis of the left eye

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