Pupillary Disorders Flashcards
What is the round part of the iris that is located just around the pupil
Collarette
What layer of the iris contains the muscle that is involved with miosis
Iris stroma
What layer of the iris contains the muscle that is involved with dilation
Anterior iris epithelium
What does persistent pupillary membrane look like
Strands of iris going across the pupil
What is aniridia
Lack of iris
Keyhole pupil
Iris coloboma
Congenital causes of abnormally shaped pupils
Aniridia Ectopic lentis et papillae Iris coloboma Anterior chamber cleavage anomalies Ectopic pupils Persistent pupillary membranes
Acquired cubes of abnormally shaped pupils
Iritis Truama (accidental or surgical) Iris atrophy (DM, Herpetic disease) Neurological
Aniridia
Congenital -hypoplastic iris creates a large pupillary opening -associated ocular findings often include cataracts, glaucoma, and impaired vision due to macular or optic nerve hypoplasia
Ectopia lentis et papillae
Congenital -rare AR condition -bialteral displacement of the pupil, usually inferotemporally -lens dislocation in the opposite direction -associated ocular anomalies include severe axial myopia, RD, enlarged corneal diameter, cataract, and abnormal iris transillumination -affected patients have microspherophakia, miosis, and poor pupillary dilation with mydriasis
Ectopic pupils
Congenital -may be inherited as an isolated ocular finding -an idiopathic tractional ectopic pupil, in which a fibrous structure tethers the pupillary margin to the peripheral cornea and causes a misplaced pupil
Iris coloboma
Congenital -a notch inferiroly or infranasally in the iris -this anomaly may be accompanied by chorioretinal or optic nerve coloboma -coloboma may occur in isolation in healthy individuals or in patients with chromosomal duplication or deletions -seen in complex congential disorders such as CHARGE syndrome
Anterior chamber cleave anomalies
Congenital -peters (centeral corneal defects) -Rieger syndrome (peripheral defects) -associated with misshapen pupils accompanied by abnormal adhesions between the cornea and iris
Persistent pupillary membrane
Congential -spoke like opacities across the pupil -these derive from persistence of the tunica vasculoa lentis
Normal or abnormal? OD: 4mm bright light; 6mm dim light OS: 5.5mm bright light; 7.5mm dim light Both pupils response briskly to light
Normal
Normal or abnormal? OD: 4mm bright light; 6mm dim light OS:6.5mm bright light; 6.5mm dim light OS dilated when swinging flashlight from OD to OS
Abnormal
Normal or abnormal OD: 4mm bright; 6mm dim OS: 4mm bright, 6mm dim Both pupils respond briskly to light
Normal
Isolated lesions of the lateral geniculate nucleus DO NOT affect pupillary size or light reactivity, T/F
True
The efferent pupillary light pathway has which of the following nerve involved? -long ciliary nerve -CN IV -Short ciliary nerve -CN VI
Short ciliary nerve
Afferent pupillary light pathway
-pupillary fibers travel with visual fibers as far as the posterior option tract, with the nasal fibers crossing the chasm -the pupillary fibers exit in the posterior third of the optic tract and travel within the brachium of the superior colliculus to pretectal nucleus and synapse -the fibers then travel to the two EW nuclei. The fibers that cross to the opposite EW nucleus travel in the posterior commissure
Efferent pupillary light pathway
-the pregnaglionic fibers leave the EW nucleu (midbrain) with the motor fibers of the CN III and follow the inferior deivision of that nerve into the orbit -the parasympathetic fibers leave the inferior division and enter the ciliary ganglion as the parasympathetic root and synapse at the CG -the postganglionic fibers travel with short ciliary nerves to the anterior segment of the eye to innervate the sphincter (constriction)
Disruption in the afferent pathway of light stimulation
RAPD Pretectal pupils Argyll Robertson pupil
RAPD
-disruption in the afferent pathway of light stimulation Causes are large RD, CRAO, CRVO, optics nerve ischemia, optic neuritis, optic compression, asymmetric glaucoma, optic tract lesion (contralateral RAPD) -amaurotic (deafferented) pupil. Associated with vision loss.
Pretectal pupils
-disruption in the afferent pathway if light stimulation –lesions affecting the dorsal midbrain, causing the parinaud syndrome -associated upgaze paresis, head tilt -usually both pupils are involved because the lesion usually takes out both pretectal nuclei, although size and light reactivity may be asymmetric -RAPD is usually contralateral to the lesion -light near dissociation
Accommodation-convergence reaction pathways
Afferent - LGN-striate cortex-FEF-pretectal nucleus Efferent -same as light reflex
Efferent accommodative convergence reaction
-parasympathetic -preganglionic fibers leave the EW nucleus with the motor fibers of the CN III and follow the inferior division of that nerve into the orbit -parasympathetic fibers leave the inferior division and enter the CG as the parasympathetic root and synapse at the CG -the postganglionic fibers travel to the anteiror segment of the eye to innervate the sphincter (constriction) and ciliary muscles ( accommodation)
Argyll Robertson pupil
-bilateral in most causes -interrupt fibers from the pretectal nucleus to the parasympathetic nucleus -shows poor direct and Norma consensual response but does constrict with the near repsosne (light near dissociation) -because the fibers that carry inhibitory feedback to the parasympathetic nucleus also pass through this region, miosis is evident in darkness, with the affected pupil smaller than would be seen in the normal individual -diabetic neuropathy, alcoholic neuropathy, or neurosyphillis
Disruption of the efferent pathway of light stimulation (parasympathetic)
Ocular motility impairment (CN III palsy) Tonic pupil (Adies tonic pupil) Pharmacologically dilated pupils NMJ blockade
Oculomotor motility impairment (CNIII palsy)
Disruption int he efferent pathway of light stimulation (parasympathetic) -para fibers are superficial to CN III as the nerve emerges from the midbrain -the para fibers are especially vulnerable to compression -CN III involvement that includes the pupil is highly suspicious of a compressive intracranial lesion (aneurysm) -emergent CT and CT angiography to MRI scan and MRI angiography can be obtained. Do not dilate this patient, send to ER right away