Week 1.06 Pupils

Question 1

What muscles do you have in the pupil and what do they do

Answer 1

Concentric muscles (sphincter) cause pupil CONSTRICTION

Radial muscles (dilator) cause pupil DILATION

Question 2

What is the iris sphincter muscle innervated by

Answer 2

Parasympathetic division

Question 3

What is the radial muscles innervated by

Answer 3

Sympathetic division

Question 4

What is the neurotransmitter, receptor, location and effect of stimulation of the parasympathetic branch

Answer 4

Acetylcholine
Muscarinic
Sphincter muscle
Miosis

Question 5

What is the neurotransmitter, receptor, location and effect of stimulation of the sympathetic branch

Answer 5

Noradrenaline
Alpha 1 & 2 adrenal receptors
Dilator muscle
Mydriasis

Question 6

What are the two main neural pathways

Answer 6

Afferent neural pathway = from eye to brain
Efferent neural pathway = from brain to eye

Question 7

What to look out for when doing pupil assessment

Answer 7

• non round pupils
• Differential pupil sizes (anisocoria)
• differential responses to light
• differential coloured irides (heterochromia)

Question 8

What are the causes of non -round pupils

Answer 8

• trauma - blunt or penetrating
• post operative cataract
• iris clip or anterior chamber intra -ocular lens implants
• sectorial dilation - some types of drops applied to certain region

Question 9

Polycoria

Answer 9

• presence of multiple pupils in the same eye
• may be congenital, genetic disease or trauma
• peripheral iridectomy - done to allow aqueous humour

Question 10

Anisocoria: physiological or pathological?

Answer 10

Need to determine if present in both bright and in dim illuminations.

Physiological – difference in size between right and left (in both dim and bright) remains constant

Pathological – difference is more pronounced in with bright or dim light then could mean there is problem with neurological pathway supplying to iris.

Question 11

Before dynamic tests (direct and consul) what should you check

Answer 11

Pupil size
Position
Iris colour

Question 12

Swinging flashlight tests test which pathway

Answer 12

Afferent pathway - eye to brain

Question 13

Swinging flashlight test

Answer 13

room lights half
- position light 10cm from eyes below lone of sight roughly on the midline
- illuminate re 2 seconds
- quickly swing pen torch to illuminate LE 2 seconds
- swing back to RE and repeat
- look for change in pupil size as light is moved between eyes

In a patient with RAPD (relative afferent pupillary defect) there eye will dilate when the pen torch lands on that eye. This is because signals leaving that eye aren’t getting through. Only the opposite eyes signals get through telling the eye to dilate.

Question 14

What does it mean by RAPD and how to quantify

Answer 14

Means there’s is a lesion in the Afferent pathway of illuminated eye causing dilation

Quantifying the RAPD
- ND filter in front of good eye
- increase till normal swinging flashlight response achieved
Record at +ve RAPD, 0.2log

Question 15

What does PERRLA stand for

Answer 15

Pupils equal, round, respond to light and accomodation

Question 16

What conditions can lead to RAPD

Answer 16

• Optic neuritis – demyelinating inflammation of optic nerve
• Retro-bulbar neuritis
• Multiple sclerosis
• Optic atrophy – e.g. due to long standing untreated glaucoma that’s asymmetric (one eye more severe than the other)
• Retinal vascular disorder

Question 17

What are 4 defects of the efferent pathway

Answer 17

• third nerve palsy
• Horner’s syndrome
• Argyll-Robertson pupil
• Adie’s tonic pupil