Abnormal pupils Flashcards
Normal pupil function
Regulates amount of light entering eye
Pupil anatomy
2 muscles (sphincter and dilator) derived from neural ectoderm
Normal pupil location
Slightly nasal to corneal centre
Pupil physiology
Fine oscillation in size
Physiological anisocoria
Pupil size
Max constriction 1mm
Max dilation 9mm
Physiological vs pathological anisocoria
Pathological anisocoria varies between light and dark
Dilator innervation
Sympathetic
Sphincter innervation
Parasympathetic
PNS route
EWP - 3rd nerve - ciliary ganglion - short ciliary nerves - eyeball - perichoroidal space - ciliaris for accomodation + sphincter for constriction
SNS route
Intermediolateral horn cells from hypothalamus - sympathetic chain spinal cord - superior cervical sympathetic ganglion - carotid plexus - via ciliary ganglion - eyeball - perichoroidal space - radial mm for dilation and Muller’s mm for lid elevation
Causes of unequal pupils
Posterior synechiae Acute glaucoma CNIII palsy Adie's pupil Horner's pupil
Posterior synechiae
Due to iritis
Adhesions form between iris and lens
Present as irregular pupil w normal light reaction therefore difficult to detect
Acute glaucoma
Increased IOP due to overproduction/underdrainage leading to CNII ischaemic damage
Present as vertically oval pupil with poor direct light reflex
CNIII palsy
Dilated pupil that is not reactive to light or accommodation w ptosis + divergent squint Medical causes (DM) = pupil spared Surgical causes (tumour, aneurysm PCA) = pupil involved
Adie’s pupil
Postganglionic sympathetic n damage
80% unilateral
Presents as semi-dilated pupil with decreased light rxn, slow dilation, decreased accommodation
Cause suspected to be viral
Horner’s pupil
Presents as miosis, mild ptosis, ipsiateral facial flushing and decreased perspiration of below SCG
Congenital Horner’s assoc w iris heterochromia
Adie’s pupil diagnostic test
Pilocarpine (0,1%) constriction of abn pupil
Horner’s pupil diagnostic test
Cocaine (4%) abn eye no response
Epinephrine abn eye dilates
Horner’s pupil central causes
Brainstem disease (trauma, vascular, demyelination) Syringomelia Spinal cord trauma Wallenburg syndrome Diabetic autonomic neuropathy
Horner’s pupil
Pancoast tumour
Carotid and aortic aneurysm and dissection
Neck lesion (gland, trauma, postop)
Horner’s pupil
ICA dissection
Nasopharyngeal trauma
Otitis media
Cavernous sinus thrombosis
Differentiate between pre vs postganglionic lesion
Hydroxyamphetamine (1%)
Preganglionic - both pupils dilate
Postganglionic - horner’s pupils won’t dilate
Light near dissociation
Argyll Robertson pupils
React poorly or not at all to light but constrict to near stimulus
Light near dissociation mechanism
EW component of CNIII affected while near reflex pathway spared
Perinaud’s syndrome
Upgaze
Convergence-retraction nystagmus
Light near dissociation
Relative vs total APD
Relative is incomplete CNIII lesion/retinal detachment
Total is complete CNIII lesion
TAPD
Absent direct AND consensual light reflex
Blind eye
Normal near reflex
Efferent defect
Pupil reacts poorly to light
Fixed and dilated
