Pupil Evaluation

Question 1

what are the afferent pathways evaluated in a pupil exam?

Answer 1

• eye to midbrain (pupillary light reflex)

- eye to cortex (pupillary near reflex)

Question 2

what are the efferent pathways evaluated in a pupil exam?

Answer 2

-brain to pupils (CN III to pupillary sphincter muscle and oculosympathetic pathway to pupillary dilator)

Question 3

describe the afferent pathway (from eye to brain)

Answer 3

• pre-geniculate visual pathways (optic nerve and anterior portion of optic tracts)
• projections to midbrain

Question 4

describe efferent pathway (from brain to eye)

Answer 4

• CN III to pupillary sphincter

- oculosympathetic pathway to pupillary dilator

Question 5

fibers from nasal retina go where

Answer 5

cross to the opposite side at the chiasm

Question 6

percent of fibers that are nasal are

Answer 6

53-55%

Question 7

percent of fibers that are temporal are

Answer 7

45-47%

Question 8

what is the anatomical basis for the consensual pupillary light reflex

Answer 8

crossing over in optic chiasm and posterior commissure

Question 9

a lesion in the afferent pathway produces

Answer 9

• impaired pupillary light reflex (but not near reflex)
• light-near dissociation
• APD (if unilateral or asymmetric damage to the 2 afferent pathways)

Question 10

what is light-near dissociation?

Answer 10

near reflex is stronger and quicker than light reflex

Question 11

damage to afferent pathway does NOT cause:

Answer 11

• anisocoria

- change in near reflexes

Question 12

3rd cranial nerve efferent pathway involved what input and what structure?

Answer 12

parasympathetics to pupillary sphincter

Question 13

oculosympathetic pathway involves what input and what structure?

Answer 13

sympathetics to pupillary dilator

Question 14

efferent pathway damage causes

Answer 14

• changes in pupil size (if asymmetric or unilateral damage)
• reduced pupil function (of some type)

Question 15

if CN III efferent pathway damage, what affect on pupil function?

Answer 15

reduced response of light and near

Question 16

if oculosympathetic pathway (efferent) damage, what affect on pupil function?

Answer 16

reduced or slower dilation in dark

Question 17

oculosympathetic pathway:

1st order neuron

Answer 17

• hypothalamus
• brainstem
• upper spinal cord
• ciliospinal center of budge (C8, T1, T2)

Question 18

oculosympathetic pathway:

2nd order neuron

Answer 18

• white rami communicantes
• stellate ganglion (no synapse)
• over the apex of the lung
• joins common carotid artery (CCA)
• superior cervical ganglion (synapse)

Question 19

oculosympathetic pathway

3rd order neuron (facial sweating)

Answer 19

• follows the external carotid artery

- goes to sudomotor (sweating) and vasomotor control in face

Question 20

oculosympathetic pathway

3rd order neuron (eye/globe)

Answer 20

• follows internal carotid artery
• cavernous sinus
• cranial nerve V, ophthalmic division, nasociliary
• long ciliary nerves

Question 21

lid retractors and their innervations:

Answer 21

• mueller’s muscle (sympathetic)

- levator palpebrae superioris (CN III)