Pupil Disorders

Question 1

What causes pupil constriction and what is the responsible nerve pathway?

Answer 1

1. Circular muscles in the iris that cause constriction.
2. Parasympathetic nervous system - acetylcholine
3. Fibres travels along oculomotor nerve (CN III)

Question 2

What causes pupil constriction?

Answer 2

1. Dilator muscles of the pupil arranged like spokes on a bike.
2. Sympathetic nervous system - adrenaline

Question 3

Which conditions can cause an abnormal pupil shape?

Answer 3

1. Sphincter muscle trauma (cataract surgery)
2. Anterior uveitis (adhesions)
3. Acute angle-closure glaucoma (ischaemic damage to muscles)
4. Rubeosis iridis (neovascularisation)
5. Coloboma (congenital malformation)
6. Tadpole pupil (spasm associated with migraines)

Question 4

What are the causes of mydriasis?

Answer 4

1. Third nerve palsy
2. Holmes-Aide syndrome
3. Raised intra-ocular pressure
4. Congenital
5. Trauma
6. Stimulants (cocaine)
7. Anticholinergics

Question 5

What are the causes of miosis?

Answer 5

1. Horner’s syndrome
2. Cluster headaches
3. Argyll-Robertson pupil (neurosyphilis)
4. Opiates
5. Nicotine
6. Pilocarpine

Question 6

What is this a presentation of:

Ptosis, dilated non-reactive pupil, strabismus, down and out position of eye?

Answer 6

Third nerve palsy

Question 7

What causes the down and out position in third nerve palsy?

Answer 7

Oculomotor nerve supplies all extraocular muscles except the lateral rectus and the superior oblique.

Question 8

What causes the ptosis in third nerve palsy?

Answer 8

Oculomotor nerve supplies the levator palpebrae superioris, responsible for lifting upper eyelid.

Question 9

What causes the dilated fixed pupil in third nerve palsy?

Answer 9

Oculomotor nerve contains parasympathetic fibres that innervate the sphincter muscle of the iris.

Question 10

Which vessel abnormalities can cause compression of the oculomotor and a subsequent third nerve palsy?

Answer 10

Cavernous sinus thrombosis and posterior communicating artery aneurysm.

Question 11

What are the causes of a microvascular third nerve palsy (pupil sparing)?

Answer 11

Diabetes, hypertension, ischaemia.

Question 12

What are the causes of a surgical third nerve palsy (involving the pupil)?

Answer 12

Idiopathic, tumour, trauma, cavernous sinus thrombosis, posterior communicating artery aneurysm, raised ICP.

Question 13

What is this a presentation of:

Ptosis, miosis, anhidrosis, enophthalmos?

Answer 13

Horner’s syndrome

Question 14

What is damaged to cause Horner’s syndrome?

Answer 14

Damage to sympathetic nerves supplying the face.

Question 15

What are the causes of Horner’s syndrome (4 Ss, 4 Ts, 4 Cs) and what is the lesion location for each?

Answer 15

1. Central lesion - Stroke, multiple Sclerosis, Swelling (tumours), Syringomyelia (cyst in spinal cord)
2. Pre-ganglionic lesion - Tumour (Pancoast’s), Trauma, Thyroidectomy, Top rib
3. Post-ganglionic lesion - Carotid aneurysm, Carotid artery dissection, Cavernous sinus thrombosis, Cluster headache.

Question 16

How can the location of a Horner’s syndrome lesion be identified?

Answer 16

Anhidrosis.

1. Central lesion - anhidrosis of arm and trunk as well as face.
2. Pre-ganglionic lesion - anhidrosis of face only
3. Post-ganglionic lesion - no anhidrosis

Question 17

What is the pathway of the sympathetic nerves responsible for Horner’s syndrome?

Answer 17

Arise from spinal cord (pre-ganglionic), enter sympathetic ganglion and exit as post-ganglionic nerves. Travel to the head alongside the internal carotid artery.

Question 18

What is congenital Horner’s syndrome associated with?

Answer 18

Heterochromia - different coloured iris on affected side

Question 19

What are the diagnostic tests for Horner’s syndrome and how do they work?

Answer 19

1. Cocaine eye drops - stops NA re-uptake at NM junction, normal eye dilates, Horner’s pupil no reaction.
2. Low concentration adrenaline eye drop - does not dilate normal pupil, dilates Horner’s pupil.

Question 20

What is this a presentation of:

Unilateral dilated pupil sluggish to react to light with slow dilation of the pupil after constriction?

Answer 20

Holmes-Adie pupil

Question 21

What is Holmes-Adie syndrome?

Answer 21

Holmes-Adie pupil with associated absent ankle and knee reflexes.

Question 22

What is the cause of Holmes-Adie pupil?

Answer 22

Damage to post-ganglionic parasympathetic fibres, exact cause unknown.

Question 23

What is this a presentation of:
Constricted pupil that accommodates when focussing on near objects but does not react to light, irregularly shaped, history of syphilis?

Answer 23

Argyll-Robertson pupil (prostitutes pupil)