Competency 3.1.9

Question 1

Pupils Testing Procedure

Answer 1

1. Ask patient to take off their glasses, and look at the target.
2. TARGET: letter on distance VA acuity chart or spotlight if VA worse than 6/18 in poorer eye.
3. Sit in front and to the side of the patient.
4. Keep the room lights on and check the size, shape and location of both pupils.
   
   • If the pupil sizes are unequal in bright light, measure the pupil sizes with a millimetre ruler.
   • Then, dim the room lights and measure the size of the pupils again.
5. DIRECT AND CONSENSUAL:
   - Ask the patient to remain fixating on the letter or spotlight at the distance.
   - Shine a penlight into the right pupil and observe speed and extent of constriction of the right pupil (direct light reflex) and left pupil (consensual reflex). Check this several times as dramatic fatigue can occur in an abnormal eye that at first shows a normal response.
   - Repeat (b) with left eye.
6. SWINGING FLASHLIGHT TEST:
   - Ask the patient to remain fixating on the letter or spotlight at the distance.
   - Shine the penlight into the right eye from the patient’s eyes from a distance of 5-10cm. Pause for 2-3sec on each eye, and look for any change in pupil size as the light is alternated.
   
   • Normal response = both pupils constrict.
   • An eye with a relative afferent pupillary defect (RAPD) will dilate as the light is first shone on it
7. NEAR REFLEX:
   - Ask the patient to remain fixating on the letter or spotlight at the distance.
   - Ask the patient to then look at a target such as a pen at about 15cm from their eyes.
   - Observe the extent and speed of pupillary constriction as the patient changes fixation from distance to near.
   - Ask the patient to look back at the distance target and observe the dilation as this occurs.
8. RECORD: PERRLA = pupils equally round and respond to light and accommodation

Question 2

Appearance of a Normal Pupil

Answer 2

• A normal patient’s pupils should be round, symmetrical, and centred within the iris

Question 3

Causes of Non-Round Pupil

Answer 3

• surgical complication
• posterior synechia from intraocular inflammation
• iris atrophy from age, ischemia, inflammation, or trauma

Question 4

Other Pupil Gross Abnormalities

Answer 4

• corectopia (displaced pupil)
• polycoria (multiple pupils)
• leukocoria (white pupil due to retinoblastoma)
• iris heterochromia (difference in iris colours)

Question 5

Pupil Sizes Normal Values

Answer 5

• Under normal illumination, the average adult’s pupil size measures around 3.5 mm but can range from 1.0 mm to 8 mm
• decreases as one ages due to senile miosis.
• Pupils should be within 1 mm in size of each other

Question 6

The Afferent Pupil Pathway

Answer 6

• Light enters the pupil and stimulates the retina.
• Retinal ganglion cells transmit the light signal to the optic nerve
• The optic nerve enters the optic chiasm where the nasal retinal fibres cross to contralateral optic tract, while the temporal retinal fibres stay in the ipsilateral optic tract
• Fibres from the optic tracts project and synapse in the pretectal nuclei which is located in the superior colliculus.
• The pretectal nuclei project fibres to the ipsilateral and contralateral Edinger-Westphal nuclei

Question 7

The Efferent Pupil Pathway

Answer 7

• Information from the Edinger-Westphal nucleus innervates the parasympathetic oculomotor nerve (3rd) – synapses at the ciliary ganglion.
• Ciliary ganglion within the orbit (short ciliary nerves) innervates the iris sphincter (miosis) and ciliary muscle (accommodation).

Question 8

The Pupillary Light Pathway

Answer 8

• Consists of two components: the afferent fibres and the efferent pathway
• Afferent is via CN II
• Efferent is via CN III

Question 9

The Function of Pupillary Dark Pathway

Answer 9

• This dilates the pupil in the dark.
• Can also occur due to other sympathetic stimuli such as a sudden noise etc.

Question 10

Dilation Lag in Horner Syndrome

Answer 10

• Dilation lag may occur in patients with Horner syndrome who have an issue with sympathetic innervation of the pupil
• Associated with pupillary dark pathway
• can be seen when there is greater anisocoria 5s after light removed compared to after 15 seconds.

Question 11

The Pupillary dark Pathway

Answer 11

• Retinal fibres send signals to the hypothalamus from where the signal descends down to T1-T3
• From here in the lateral horn sympathetic send signals to the superior cervical ganglion
• From the superior cervical ganglion innervation is sent via the long ciliary nerve to the iris dilator

Question 12

Types of Afferent Defects

Answer 12

• Retinal artery occlusion
• Retinal vein occlusion
• Macular disease
• Retinal detachment
• POAG
• Optic neuritis

Question 13

Types of Efferent Defects

Answer 13

• Horner’s syndrome
• 3rd nerve palsy
• Adie’s pupil
• Argyll-Robertson Pupil

Question 14

Marcus Gunn Pupil

Answer 14

• Known as RAPD
• This occurs due to asymmetry in the afferent response from one eye compared to the other
• During the swinging flashlight test the affected eye will continue dilating when the light is shone onto it

Question 15

Physiological Anisocoria

Answer 15

• This is relatively normal
• seen in around 1 in 5 patients
• If physiological it will be the same difference between differing levels of illumination

Question 16

Pathological Anisocoria

Answer 16

• Pathological anisocoria is due to a defect in the efferent pathway.

Question 17

If there is a greater amount of anisocoria in the bright light…

Answer 17

• IF the larger pupil is not constricting as usual
• likely parasympathetic pupil problem
• Examples:
  
  • Adie’s tonic pupil
  • cranial nerve III palsy
  • pharmacologic dilation

Question 18

If there is a greater amount of anisocoria in the dark…

Answer 18

• IF the smaller pupil is not dilating like it should
• likely dealing with a sympathetic pupil problem
• Examples:
  
  • Horner’s syndrome
  • Argyll-Robertson pupils
  • pharmacologic constriction

Question 19

Amaurotic Pupil

Answer 19

• occurs in a blind eye
• If the light is shone in the affected eye then both pupils will remain unresponsive
• If the light is shone in the other eye then there will be a normal and equal pupil response
• The near reflex will be normal

Question 20

What is Adie’s Pupil?

Answer 20

• Unresponsive to light
• most often unilateral but can be bilateral

Question 21

Adie’s Pupil Symptoms

Answer 21

• Blurring of vision, especially at near (due to paralysis of ciliary muscle)
• Glare (due to dilated pupil)

Question 22

Adie’s Pupil Causes

Answer 22

• Possibly a viral infection of the orbital ciliary ganglion causing lack of parasympathetic supply to the eye
• The iris sphincter muscle (which causes pupil constriction) is paralysed
• more common in young women who don’t have a patellar reflex
• should be more concerned with Adie’s in a young patient as Adie’s in an older individual is likely to be caused by damage to the pupil pathway by viral infections throughout life

Question 23

Adie’s Pupil Signs

Answer 23

• Dilated pupil with very poor constriction to light but which constricts slowly when the patient is asked to look at a near target (‘light-near dissociation’).
• No ptosis, normal eye movements.

Question 24

What is Argyll-Robertson Pupil

Answer 24

• This is due to a disorder with the CNS causing both pupils to appear constricted
• These already constricted pupils do not react to light (reaction can be present but will be poor)
• they will exhibit a near response

Question 25

Argyll-Robertson Pupil Causes

Answer 25

• Tertiary syphilis
• Alcoholism
• DM

Question 26

What is Horner’s Syndrome?

Answer 26

• interruption of the sympathetic nerve supply on one side of the face
• tell-tale marker is the anisocoria being greater in dark light due ot the lack of sympathetic innervation to the pupil dilator muscle
• The signs of Horner’s syndrome are usually slight and difficult to detect
• If there is associated neck pain then this could be carotid artery dissection and should be referred as an emergency

Question 27

Horner’s Syndrome Causes

Answer 27

• Head or neck tumour
• Trauma brainstem stroke
• Apical lung tumour
• Aneurysm of the internal carotid

Question 28

Horner’s Syndrom Signs

Answer 28

• Anhidrosis (decreased sweating from one side of the face)
• Miosis
• Ptosis
• Heterochromia (if congenital)

Question 29

Horner’s Syndrome Symptoms

Answer 29

• patient will usually be asymptomatic
• changes are usually noticed by chance by friend or family, or at a routine check-up

Question 30

Third Nerve Palsy

Answer 30

• can either present as pupil-sparing or pupil-involving
• 3rd nerve palsy with pupil-sparing is mostly benign and usually secondary to microvascular diseases such as DM (can resolve in 3 months)
• 3rd nerve palsies with pupil-involvement are caused by compressive diseases such as an expanding aneurysm

Question 31

Third Nerve Palsy Causes

Answer 31

• Compression of the 3rd nerve by aneurysm or tumour.
• Can occur in adults of any ages.
• An expanding posterior communicating artery aneurysm is a common cause of partial or complete 3rd nerve palsy – this can kill the patient within hours of onset of the double vision if it is not detected and treated before it ruptures
• Ischaemia of the nerve: overall the most common cause of 3rd nerve palsy in adults.
  
  • Atherosclerosis, diabetes, hypertension.
  • Temporal arteritis (less common but more serious cause – patients over age 50).
• Inflammation of the nerve, e.g., viral infections or post-viral auto immune reaction.
• Raised ICP
• Trauma

Question 32

Third Nerve Palsy Management

Answer 32

• Liase with the Forth Valley Advice line in all cases
• many will be referred on an emergency basis due to the seriousness of potential causes
• Microvasculature related palsies will be reviewed and monitored as many spontaneously resolve
• In these cases Fresnel prism can be used for diplopia and surgery only considered if there is no improvement in 6 to 12 months

Question 33

Third Nerve Palsy Symptoms

Answer 33

• new onset diplopia vertically and horizontally
• If complete ptosis then the patient may not complain of diplopia due to the lid covering the affected eye

Question 34

Third Nerve Palsy Signs

Answer 34

• Eye is abducted and intorted (due to LR and SO)–down and out
• Limited add (MR), elevation (SR) and depression (IR)
• Ptosis (levator palsy)
• Dilated pupil and defective accommodation
• On motility: affected eye cannot turn in, up.