Pupil Disorders - Week 4

Question 1

What type of pupil defect affects the afferent pathway?

Answer 1

RAPD

Question 2

Does anisocoria result from an afferent or efferent pathway innervational problem?

Answer 2

Efferent

Question 3

What is the difference between afferent and efferent pathway?

Answer 3

Afferent: eye to CNS
Efferent: CNS to eye via ANS (autonomic nervous system)

Question 4

Describe the parasympathetic pathway for iris innervation

Answer 4

EW nucleus – cil. ganglion – short cil. nerve – sphincter pupillae constrict

Question 5

What neurotransmitter is used for the parasympathetic iris innervation pathway? And what receptors are used?

Answer 5

ACh. Muscarinic or nicotinic receptors

Question 6

Describe the sympathetic pathway for iris innervation

Answer 6

Midbrain – piggyback on long cil. nerve – exit at T1 spino-centre (pre-ganglionic fibres) – sup. cerv. gang. (post-ganglionic fibres) – follow carotid – through carvernous sinus – dilator muscle

Question 7

What neurotransmitter and receptors does the sympathetic iris innnervation pathway use?

Answer 7

ACh. Adregnergic or nicotinic.

Question 8

Where does the pathology occur in RAPD/Marcus-Gunn pupil?

Answer 8

Before the chiasm

Question 9

What type of pathology could occur to cause RAPD?

Answer 9

• large retinal detachment
• CRAO or CRVO (central retinal artery/vein occlusion)
• O.N ischaemia, asymetric glaucoma
• Optic neuritis, optic nerve compression

Question 10

Do any of the following result in RAPD?

• cataract
• vitreous haemmorhage
• amblyopia

Answer 10

NO. (though amblyopia may cause very mild RAPD)

Question 11

Is anisocoria a feature of RAPD?

Answer 11

No. (though that doesn’t mean you can’t have both)

Question 12

During the swinging light test, how do complete RAPD patients react? (in general)

Answer 12

normal side: regular small relaxation after initial constriction
affected side: both pupils dilate

Question 13

How does flash luminance effect constriction and escape?

Answer 13

Brigher luminance: more constriction, less relative escape
Dimmer: less constriction, more relative escape

Note: when flashing a light on diseased RAPD eyes, it’s as if less light was delivered to them. because they have less constriction and more relative escape

Question 14

What do you use to record video pupillometry?

Answer 14

infrared video camera

Question 15

How does the escape and constriction compare for mild vs severe RAPD patients?

Answer 15

Mild: some constriction and early escape
Severe: No constriction

Question 16

How do you grade RAPD? Name and describe the grades

Answer 16

No RAPD: pupils constrict and show equal physiological escape
Grade 1+: when light shone onto affected eye, escape apparent @ 3 seconds only
Grade 2+: escape apparent at 2 seconds
Grade 3+: escape apparent at 1 second
Grade 4+: Immediate dilation

Question 17

Does an afferent defect ever give anisocoria?

Answer 17

No. Never

Question 18

How many interneurones are there?

Answer 18

2 CNS, 1 peripheral

Question 19

What does anisocoria in the dark vs light indicate?

Answer 19

More anisocoria in dark: sympathetic (because dilator is weak)
More anisocoria in light: parasympathetic problem

Question 20

Describe the pupil light reflex in Horner’s syndrome

Answer 20

Anisocoria with dilation lag (i.e. greater anisocoria in dark)

Question 21

How does Horner’s syndrome affect the following: lids, sweat, IOP, conjunctiva, accommodation, iris

Answer 21

• lid ptosis (apparent enophthalmos)
• facial anhydrosis (lack of sweating)
• IOP reduced on affected side (1-2mm Hg)
• conjunctival flash
• increased accommodation (1D)
  iris heterochromia (in congenital/ long standing)

Question 22

Why does congenital horner’s present with iris heterochromia?

Answer 22

Because sympathetic innervation is needed to develop iris pigmentation and horner’s is an efferent sympathetic problem

Question 23

Name the 2 causes of congenital horner’s

Answer 23

• brachial plexus trauma

- forceps delivery at birth

Question 24

How can you assess congenital horner’s?

Answer 24

Family album test (to see change from youth)

Question 25

for parasympathetic dysfunction, how does a mid-brain lesion vs peripheral lesion affect light and near response?

Answer 25

Mid-brain lesion: poor light response, normal near

Peripheral lesion: both responses poor

Question 26

What type of light and near response might Percy Grainger’s Mum be likely to present with?

Answer 26

Poor/No light, but good (or brisk) near response

Because she has syphilis, which can cause a mid-brain lesion

Question 27

List 2 examples of mid-brain lesion pupil problems

Answer 27

• Parinaud’s syndrome (large pupil)

- Argyll Robertson pupil (small pupil)

Question 28

Describe parinaud’s syndrome: pupil size, gaze, what type of lesion

Answer 28

Large pupil, nystagmus on attempted upgaze, posterior brain stem lesion (still midbrain)

Question 29

What is the effect of the posterior brain stem lesion? Possible cause of lesion?

Answer 29

• reduced pupil input gives dilated state

- pineal tumour

Question 30

Describe argyll robertson pupil

Answer 30

Pupils: irregular and miotic (small)

• total absence of light reaction
• brisk near response

Question 31

What type of lesion causes argyll robertson?

Answer 31

supra nuclear (EW) lesion in descending pathways

Question 32

Can syphillis cause argyll robertson pupil?

Answer 32

yes

Question 33

What type of issue would no light response but with near response indicate?

Answer 33

Mid-brain problem

Question 34

Which type of lesion is a greater cause for concern? Mid-brain or Peripheral

Answer 34

Mid-brain lesion

Question 35

What type of lesion does Adies Tonic Pupil have, and what does this mean for the light and near response?

Answer 35

Peripheral lesion. Therefore affected eye has no light or near response (still get consensual in other eye though)

Question 36

What proportion of central ANS defects are sinister?

Answer 36

60%

Question 37

What proportion of peripheral ANS defects are benign?

Answer 37

80% benign

Question 38

How does an abnormal peripheral neuron affect neurotransmitter release

Answer 38

reduced basal rate of neurotransmitter. leads to up-regulation in post0synaptic receptors

Question 39

What type of drug is horner’s supersensitive to? What about Adies?

Answer 39

Horners: adrenergic drugs (2.5% PE)
Adies: cholinergic drugs (1% pilocarpine)

Question 40

What type of sympathetic drugs can you use to confirm if there’s a problem with sympathetic receptors?

Answer 40

• phenylephrine 2.5% (diluted to 0.1%)

- apracholonidine 0.5%

Question 41

What type of parasympathetic drugs can you use to confirm if there’s a problem with parasympathetic receptors?

Answer 41

• pilocarpine 1% (0.125%)