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Pupillary Response

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Topic updated on 08/24/16 8:24am

Pathway
  • Constriction (miosis) 
    • pupillary sphincter muscle
    • parasympathetic innervation
      • CN II → pretectal area → bilateral Edinger-Westphal nuclei → ciliary ganglion → short ciliary nerves (CN III) to pupillary sphincter
        • averaging of input from both eyes results in normal uniform diameters between both pupils 
    • can be a response to light or to convergence of eyes
  • Dilation (mydriasis)
    • radial muscle
    • sympathetic innervation
      • T1 preganglionic sympathetic → superior cervical ganglion long ciliary nerve (CN III) to radial muscle
  • Clinical note
    • pupillary reflexes should still be present in patients who are cortically blind as well as someone who is unconscious (unless cause of unconsciousness effects the pupillary pathway
Defects in pupil response
  • Marcus Gunn pupil
    • afferent pupillary defect
      • e.g. due to optic nerve damage (MS), retinal detachment
    • diagnosis made by swinging light between eyes
      • when light shines in affected eye both eyes do not constrict fully
      • swing light to normal eye and both eyes constrict
      • swing light back to affected eye and both eyes dilate
  • Argyll Robertson pupil
    • pupils constrict with accommodation but do not react to light
    • see in neurosyphilis
      • prostitute's pupil (they accommodate but do not react)
    • also seen in diabetes
  • Horner syndrome
    • loss of sympathetic input to pupil
    • results in constricted and unreactive pupil
    • also present with ipsilateral ptosis
  • Adie pupil
    • slowly reacting pupil that is dilated
      • response better to accommodation than to reaction
    • common in young females who lack knee jerk reflexes
  • Transtentorial (uncal) herniation
    • blown-pupil
      • fixed and dilated pupil
    • due to ↑ in intracerebral pressure and compression of CN III


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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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