Pupil Disorders

Question 1

How does the pupil constrict?

Answer 1

• Circular muscles in the iris allow the pupil to constrict

- They are stimulated by the parasympathetic nervous system using acetylcholine as a neurotransmitter

Question 2

How does the pupil dilate?

Answer 2

• Dilator muscles in the iris which allow the pupil to dilate
• These are stimulated by the sympathetic nervous system, using adrenaline as a neurotransmitter

Question 3

What can cause an abnormal pupil shape?

Answer 3

• Trauma to the muscles of the iris
• Anterior uveitis
• Acute angle closure glaucoma
• Coloboma (congenital)
• Tadpole pupil (associated with migraines)

Question 4

What is miosis?

Answer 4

Constriction of the pupil

Question 5

What is mydriasis?

Answer 5

Dilation of the pupil

Question 6

Give three causes of miosis

Answer 6

• Horner’s syndrome
• Argyll-Robertson pupil (prostitute’s pupil)
• Drugs (opiates)

Question 7

Give three causes of mydriasis

Answer 7

• Third nerve palsy
• Holmes-Adie pupil
• Drugs (cocaine)

Question 8

What are the three features of a third nerve palsy?

Answer 8

• Ptosis
• Fixed dilated pupil
• Down and out position of the eye

Question 9

Give three causes of a third nerve palsy

Answer 9

Three T’s:

• Tumour
• Trauma
• Thrombosis (cavernous sinus)

Question 10

What are the three features of Horner’s syndrome?

Answer 10

• Ptosis
• Miosis
• Anhidrosis

Question 11

How can you determine the cause of the Horner’s syndrome based on examination findings?

Answer 11

The cause can be determined by the anhidrosis:

• Central lesions = anhidrosis of face, arm and trunk
• Preganglionic lesions = anhidrosis of face only
• Postganglionic lesions = no anhidrosis

Question 12

Give 4 central causes of Horner’s syndrome

Answer 12

4 S’s (S for “sentral”):

• Stroke
• Sclerosis (MS)
• Swelling (tumour)
• Syringomyelia (cyst in the spinal cord)

Question 13

Give 4 preganglionic causes of Horner’s syndrome

Answer 13

4 T’s (T for torso = preganglionic):

• Tumour (Pancoast’s tumour)
• Trauma
• Thyroidectomy
• Top rib

Question 14

Give 4 postganglionic causes of Horner’s syndrome

Answer 14

4 C’s (C for cervical = postganglionic):

• Carotid aneurysm
• Carotid artery dissection
• Cavernous sinus thrombosis
• Cluster headache

Question 15

Congenital Horner’s syndrome is associated with which finding on examination?

Answer 15

Heterochromia

Question 16

What is a Holmes-Adie pupil? What causes this?

Answer 16

• Unilateral dilated pupil that is sluggish to react to light
• Exact cause is unknown, but thought to be viral

Question 17

What is an Argyll-Robertson pupil? What causes this?

Answer 17

• Unilateral constricted pupil which accommodates but does not react to light
• Caused by neurosyphilis (AKA prostitute’s pupil)