Lecture 4: The pupil

Question 1

What does the PNS and SNS do?

Answer 1

SNS: Heightened awareness, dilates pupils

PNS: Relaxed, constricts pupils

Question 2

What are the nuclei of the light relfex?

Answer 2

*Retinal receptor cells
*Bipolar cells
*Ganglion cells
*Optic nerve and tract
*Pretectal nucleus in the midbrain
*Edinger-Westphal nucleus
*Two neurone pathway via the
*Oculomotor nerve
*Sphincter pupillae

Question 3

What is aniscoria?

Answer 3

Difference between pupil size

Question 4

What can cause a difference between pupil size?

Answer 4

• Topical medications:
  o Mydriatics /miotics/other agents
• Trauma:
  o traumatic mydriasis / sphincter rupture / surgical trauma / posterior
  synechiae
• Disease processes:
  o uveitis / acute angle closure glaucoma
• Systemic medications:
  o Narcotics (morphine, pethidine) cause miosis

Question 5

What conditions cause an abnormally small pupil?

Answer 5

Horners
Narcotics
argyll robertson pupil

Question 6

What causes an abnormally large pupil?

Answer 6

*Adie’s tonic pupil
*Pupil involved 3rd nerve palsy
*Bilateral dilated pupils- coma

Question 7

Whats argyll robertson pupil specific for?

Answer 7

• Specific sign of neurosyphilis
• Small and irregular pupils
• Usually bilateral but asymmetric
• Do not respond to light but near
  response normal (light-near dissociation)

Question 8

What are the causes of CN3 nerve palsy?

Answer 8

Microvascular infarction
* Occlusion vasa nervorum
* Risks: diabetes, hypertension, atherosclerosis
Compressive lesion
* Aneurysm (usually post communicating artery)
* Tumour
Trauma

Question 9

Whats evident in a CN3 palsy?

Answer 9

Limited elevation, depression, adduction

Normal abduction

• Ptosis, mydriasis and cycloplegia
• Eye down and out

Question 10

What is RAPD?

Answer 10

Abnormal pupil responds to consensual light but not direct light

Indicates lesion of afferent visual pathway

Question 11

What causes RAPD?

Answer 11

• Optic nerve disorders (optic nerve compression, optic neuritis)
• Chiasma compression
• Retinal detachment
• Large unilateral macular lesion
• Unilateral glaucoma
• RAPD not produced by corneal opacity, cataract, vitreous haemorrhage,
  refractive error, amblyopia.

Question 12

What are mydratics?

Answer 12

Drugs that dilate eyes

Cholinergic antagonists, adrenergic agents,

Question 13

List some anticholinergics:

Answer 13

Cholinergic antagonists,

o Atropine
o Cyclopentolate (Cyclogyl)
o Tropicamide (Mydriacyl)

Question 14

What are some miotics?

Answer 14

Cholinergic (direct): Pilocarpine
* Anticholinesterases (indirect cholinergic): physostigmine, neostigmine
Postganglionic parasympathetic nerves respond to muscarine.
Somatic motor and preganglionic autonomic nerves respond to nicotine