II. Anatomy

  1. See Pupil Constriction (Miosis) for Neuroanatomy of Pupil Constriction
  2. Variable sized circular hole in pigmented iris
  3. Images
    1. EyePupillaryReactionNeuroPath.png
    2. EyePupillaryReaction.png
  4. Pupil "Hole" or aperture size controlled by 2 Muscles
    1. Sphincter pupillae
      1. Circular Muscle constricts pupil (Miosis)
      2. Parasympathetic fibers on CN3 from Edinger-Westphal Nucleus innervate the ciliary Ganglion
    2. Dilator pupillae
      1. Radial Muscle dilates pupil (Mydriasis)
      2. Sympathetic inputs via:
        1. Hypothalamus
        2. Ciliospinal center of Budge and Waller

III. Physiology

  1. Pupil is analogous to a camera aperture
    1. Shutter aperture decreases in size under bright light conditions and for sharper focus
    2. Pupil constricts under bright light and with near focus (e.g. reading) known as accomodation
  2. Optic Nerve (CN 2)
    1. Transmits visual signals not only to the visual cortex
    2. Transmits signals via a reflex loop to the pretectal nucleus
      1. Signals then travel onto the Edinger-Westphal Nucleus on each side of the Midbrain
      2. Shining light in one eye will result in a signal to both Edinger-Westphal Nucleii
      3. Signals are then transmitted to the ciliary Ganglion and along the course of Oculomotor Nerve
  3. Oculomotor Nerve (CN 3)
    1. Innervates ciliary Muscle (iris constrictor), resulting in Pupil Constriction
    2. Accomodation (near Vision) also results in signals to the Edinger-Westphal Nucleus
      1. However those signals arise from the visual cortex
    3. Syphilitic Pupil (Argyll-Robertson Pupil, Prostitute's Pupil)
      1. Affected pupil does not react
        1. Lesion in the Midbrain blocks signals from the pretecal nucleus
      2. Syphilitic Pupil does accomodate
        1. Signals follow a different pathway from the visual cortex
    4. Brainstem Herniation
    5. . Oculomotor Nerve (CN 3) is easily compressed
        1. Results in a dilated pupil that does not react (Blown Pupil)
      1. Parasympathetic fibers from the Edinger-Westphal Nucleus to the ciliary Muscle
        1. Found on the outside of the Oculomotor Nerve (CN 3),
        2. Parasympathetic fibers are first to be injured when CN 3 is compressed

IV. Findings

  1. Pupil Normal in
    1. Conjunctivitis
  2. Pupil size changes
    1. Pupil Constriction (Miosis)
    2. Pupil Dilation (Mydriasis)
  3. Pupil distortion
    1. Posterior synechiae
      1. Inflammatory adhesion between lens and iris
    2. Tear drop-shaped pupil
      1. Suggests Globe Rupture with iris prolapse
  4. Pupil fixed, mid-dilated, slightly irregular
    1. Acute Glaucoma
  5. Absent Pupillary Light Reflex
    1. Structural lesion
    2. Hypothermia
    3. Barbiturate or Opiate Overdose

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Related Studies

Ontology: Pupil Disorders (C0034124)

Definition (MSH) Conditions which affect the structure or function of the pupil of the eye, including disorders of innervation to the pupillary constrictor or dilator muscles, and disorders of pupillary reflexes.
Concepts Disease or Syndrome (T047)
MSH D011681
SnomedCT 68633000
Italian Disturbo pupillare, Disturbo pupillare NAS, Disturbi pupillari, Disturbi della pupilla
Dutch pupilafwijking NAO, pupilaandoeningen, pupilafwijking, Pupilstoornis, Pupilstoornissen, Stoornis, pupil-, Stoornissen, pupil-
French Anomalie des pupilles SAI, Trouble pupillaire, Troubles pupillaires
German Pupillenstoerung NNB, Erkrankungen der Pupille, Pupillenstoerung, Störungen der Pupille
Portuguese Alteração pupilar NE, Distúrbios da Pupila, Transtornos da Pupila, Transtornos Pupilares, Alterações da pupila, Anomalia pupilar, Distúrbios Pupilares
Spanish Trastorno pupilar NEOM, trastorno pupilar (trastorno), trastorno pupilar, Trastornos de la pupila, Alteración pupilar, Trastornos de la Pupila
Japanese 瞳孔障害NOS, ドウコウショウガイ, ドウコウショウガイNOS, 遠心性瞳孔反応欠如, 異常瞳孔反応, 瞳孔反応-異常, 求心性瞳孔反応欠如, 瞳孔反応欠如, マ-カス-ガン瞳孔, 瞳孔機能異常, マ-カス・ガン瞳孔, 瞳孔障害, Marcus-Gunn瞳孔
Swedish Pupillstörningar
English PUPILLARY DIS, PUPIL DIS, Pupil disorders, Pupillary disorder NOS, Pupil Disorder, Pupillary Disorder, Pupillary Disorders, Pupil Disorders [Disease/Finding], Pupillary disorder, Disorder of pupil, Pupillary disorder (disorder), Pupillary disorder, NOS, Pupil Disorders
Finnish Mustuaisen sairaudet
Russian ZRACHKA FUNKTSII NARUSHENIIA, ZRACHKA FUNKTSII ANOMAL'NYE, ЗРАЧКА ФУНКЦИИ АНОМАЛЬНЫЕ, ЗРАЧКА ФУНКЦИЙ НАРУШЕНИЯ
Czech Poruchy zornice, Poruchy zornice NOS, Pupilární poruchy, poruchy zornic, pupila - poruchy, poruchy zornice
Croatian Not Translated[Pupil Disorders]
Polish Zaburzenia źreniczne, Odruchy źreniczne nieprawidłowe, Brak reakcji źrenic
Hungarian Pupilla eltérés k.m.n., Pupilla betegségek, Pupillaeltérés
Norwegian Pupillforstyrrelser