The Near Response 3- pupil testing

Question 1

What are the pupil reflexes

Answer 1

near reflex and light reflex (not part of near synkinesis)

Question 2

Near reflex

Answer 2

Convergence of visual axis
Increased accommodation and associated constriction of both pupils

Question 3

Light reflex

Answer 3

Refers to the simultaneous and equal constriction of both pupils in response to stimulation of one eye.
Present in low light intensities

Question 4

Afferent pathway- red in pp

Answer 4

1) Light stimulates the retinal ganglionic cells
2) Action potential travels to optic nerve (CN II)
3) Then bilaterally to right and left lateral geniculate bodies
4) Axons synapse at right and left pre-tectal nuclei in midbrain
5) Then projects to Edinger-Westphal nucleus of oculomotor nerve (CN III) via interneurons

• Red line becomes blue as it decussates at optic chiasm.

Question 5

Efferent pathway- green in pp

Answer 5

6) Action potential passes to the right and left ciliary ganglions via inferior division of oculomotor nerve
7) Enters eye by short ciliary nerves
8) Sphincter pupilae and cillaris muscle contract

Question 6

Light reflex

Answer 6

• The pretectal nucleus supplies the right and left Edinger-Westphal nuclei
• So, shining light in one eye causes ipsilateral and contralateral pupil constriction
• This is known as the consensual light reflex.

Near reflex/ synkinesis pathway

Question 7

Afferent pathway course

Answer 7

Retina - LGN -Visual cortex - Frontal eye field - oculomotor nuclear - Edinger Westphal nucleus
(bypasses pretectal nuclei)

Question 8

Efferent pathway course

Answer 8

Parasympathetic fibres
Edinger Westphal nucleus - oculomotor nerve - right and left ciliary ganglions -short ciliary nerve - iris sphincter

Question 9

Near reflex testing

Answer 9

Observe constriction of pupil on stimulus approach
Should be symmetrical and equal
Should occur when BEO or one eye occluded; still see constriction

Recording: Both pupils constrict equally on convergence.

Question 10

Light reflex testing

Answer 10

Patient fixes distance target
Light introduced
Direct: Constriction observed in eye into which light shone
Consensual: Constriction of fellow eye should be equal

Recording: PERL (Pupils equal and reactive to light)
NOTE- Distance fixation avoids near reflex

Question 11

Swinging light test

Answer 11

• Detects relative afferent pupillary defect (RAPD)
• Efferent pathway intact
• Patient fixates in distance
• Light swung from one eye to other and held there for approx 3 secs
• Initial constriction should be seen followed by very slight dilation (pupillary escape)
• RAPD – pupils dilate when light swung from unaffected eye to affected eye

This is relative to a normal eye

• +ve RAPD – due differences between afferent pathways of the eyes
• Pathology is before the optic chiasm e.g. due to retinal or optic nerve disease
• If the light used is sufficiently bright, even a dense cataract or corneal scar will not give a RAPD as long as the retina and optic nerve are healthy (Broadway 2012)

Question 12

Holmes Adie (Tonic) pupil

Answer 12

• Damage: efferent pathway, ciliary ganglion or short ciliary nerves (unilateral)
• Signs: dilated pupil
• Direct light reflex: absent
• Consensual light reflex: absent
• Near reflex: present but slow
• Accommodation: reduced
• Aetiology: unknown (most common in women aged 20-40 yrs), Viral (e.g. herpes zoster), bacterial or inflammatory

Question 13

Holmes Adie is damage to

Answer 13

Efferent pathway, ciliary ganglion or short ciliary nerves (unilateral)

Question 14

RAPD is damage to

Answer 14

Afferent pathway

Question 15

TO KNOW P1,2 &3

Answer 15

Recommended reading on slides
Read how to perform the following tests in preparation for clinical skills:
Accommodative facility
Nott dynamic retinoscopy
Pupils
Conventional and modified push up method