Unit 2 - Pupil Defects

Question 1

What does the sympathetic pathway control?

Answer 1

Dilator muscle

Question 2

What muscle does the parasympathetic pathway innervate?

Answer 2

Sphincter muscle

Question 3

What pathway does the sympathetic pathway take?

Answer 3

First order neuron: hypothalamus to ciliary centre of bulge
Second order neuron: enters sympathetic chain at level of stellate ganglion, synapse at superior cervical ganglion
Third order neuron: Fibres to eye run along the ICA as it enters cavernous sinus, most run along ophthalmic division of trigeminal nerve to innervate dilator pupillae and Muller’s muscle

Question 4

What pathway does the efferent branch of the parasympathometic nervous system follow?

Answer 4

Starts at Edinger-Westphal nucleus
Follows third nerve, following inferior division at cavernous sinus
Synapses at ciliary ganglion
Goes on to innervate the sphincter and anterior segment

Question 5

What is the afferent pathway of the parasympathometic system?

Answer 5

Follows optic nerve
Synapses at pretectal synapse in occipital lobe
Goes on to Edinger-Westphal nucleus

Question 6

What percentage of patients have anisocoria?

Answer 6

20%

Question 7

How can you differentiate between physiological and pathological anisocoria?

Answer 7

Pathological becomes more pronounced in either dim or bright light whilst physiological stays the same.

Question 8

How much of a difference in pupils is required for it to be termed anisocoria?

Answer 8

0.4mm

Question 9

What causes a RAPD/Marcus Gunn pupil?

Answer 9

Severe damage to retina, optics nerve, chiasm, optic tract or mid-brain pre-tectal area.

Question 10

What are the signs of Horner’s syndrome?

Answer 10

Miosis
Ptosis
Facial anhydrosis (only if lesion is close to superior cervical ganglion)

Dilation lag in the affected pupil
Heterchromia may be present in congenital form.

Question 11

What tests are used to diagnose a Horner’s syndrome?

Answer 11

Apraclonidine (alpha 2 agonist and weak alpa 1 agonist) will reverse miosis. (Need to wait a full 40 mins and you need a full reversal for the test to be considered positive.

Cocaine: prevent reuptake of noradernaline at pre-synaptic neuron thus exacerbating antisocoria. It would dilate it in a normal pupil

Question 12

Compression of 3rd cranial nerve will compress with pupillary nerve fibres?

Answer 12

Efferent

Question 13

What ocular signs would you get with a 3rd nerve palsy?

Answer 13

1. Ptosis
2. Diplopia due to vertical and exo deviation on affected side
3. Mydriasis of affected eye

Question 14

Will a third nerve anisocoria increase or decrease in bright light?

Answer 14

Increase as normal pupil mioses normally

Question 15

What is a common cause for a 3rd nerve palsy?

Answer 15

Enlarging aneurysm of the posterior communicating artery.

Question 16

What path of the pathway is affected in Adie’s tonic pupil?

Answer 16

Parasympathetic denervation at the level of the ciliary ganglion

Question 17

What are the signs of Adie’s tonic pupil?

Answer 17

1. Affected pupil larger with segmental paralysis leading to abnormal shape
2. Light reaction is slow
3. Near reaction is present but slow
4. Loss of sweating, tendon reflexes and accommodation
5. Corneal anaesthesia may be present

Question 18

What does corneal anaesthesia confirm in Adie’s tonic pupil?

Answer 18

that ciliary ganglion is the site of the lesion.

Question 19

What are the causes of Adie’s tonic pupil?

Answer 19

May be idiopathic or due to an unknown viral cause. E.g. varicella?

Question 20

What test can be done to confirm Adie’s tonic pupil?

Answer 20

1. Pilocarpine 0.125%, a genuine Adie’s is super sensitive and there will be a marked miosis.
2. Unaffected eye won’t constrict. BUT an absent super sensitivity does not rule out Adie’s especially if it is acute and regeneration of nerves has not occurred.

Question 21

What is the prognosis with Adie’s pupil?

Answer 21

Accommodation will often improve with time

Question 22

What is a cause of unilateral mydriasis often associated with headache

Answer 22

Benign episodic unilateral mydriasis.

Question 23

What are the symptoms of benign episodic unilateral mydriasis

Answer 23

Isolated unilateral mydriasis. Pupils are not tonic and light responses are normal.
Attack can last 12 hours but can be 10mins to 1 week.
May be associated with headaches, visual blue and orbital discomfort.

Question 24

When should phenylephrine (alpha -1 agonist) be used with caution?

Answer 24

Alpha 1 receptors are found in blood vessel walls, heart muscle and the neck of the bladder.

1. Coronary artery disease - can reduce cardiac output and slow heart rate
2. Heart disease
3. Artherosclerosis - can cause chest pain
4. Overactive thyroid - more likely to get cardiac side-effects
5. Diabetes - long standing insulin dependent more likely to get high BP
6. High BP
7. Enlarged prostate - can cause urine retention

Question 25

What does tropicamide do?

Answer 25

Restricts action of sphincter causing dilation.

Question 26

What does 2.5% phenylephrine do?

Answer 26

Stimulates dilator muscle

Question 27

In a congenital Horner’s syndrome which eye will be lighter and why?

Answer 27

Affected eye is lighter. Melanin production is thought to be under sympathetic control.

Question 28

Why does apraclonidine test work with Horner’s?

Answer 28

Denervation in Horner syndrome results a-1 receptors in the iris becoming supersensitive. This causes mydriasis but will have with little or no effect on normally innervated eyes.

Question 29

Why does cocaine test work with Horner’s?

Answer 29

It block re-uptake of noradrenaline. In a normal pupil this will cause dilation but in a Horner’s pupil less noradrenaline is produced so there will be minimal change and anisocoria will be exacerbated.

Question 30

What do we need to be aware of if a child presents with horner’s?

Answer 30

Neuroblastoma, 2% present with Horner’s

Question 31

What causes are there of Horner’s in adults?

Answer 31

1st neuron: Stroke, tumour, cervical spondylitis, neck trauma
2nd neuron: apical lung tumour, cardiothoracic surgery
3rd neuron: carotid dissection or aneurysm, cavernous sinus tumour