Pupillary Reflexes

Question 1

Light Reflex Pathway

Answer 1

1. Travels from retina and this portion follows nerve, chiasm and tract CN II
   a. Small portion bypasses the LGN and synapses in the Pre-Tectal Nucleus
2. From Pretectal to Edinger-Westphal Nucleus
3. From Edinger-Westphal Nucleus (Parasympathetic) to the Ciliary Ganglion via CN III
4. From Ciliary Ganglion to the Sphincter Pupillae Muscle

Question 2

Accommodation Reflex Pathway

Answer 2

Accommodation Reflex
Afferent
• Perception of an object by visual cortex
○ Retinal Ganglion Cells to the LGN
○ LGN to the Primary Visual Cortex
○ V1 to the Visual Association Cortices
○ These association cortices to the Midbrain Reticular Formation
Efferent
• Accommodation Center Neurons (from Midbrain Reticular Formation) project to the following places
○ Edinger-Westphal for changes in lens shape CN III
○ Edinger-Westphal for pupil constriction CN III
○ Oculomotor for convergence of eyes CN III

Question 3

Argyll Robertson Pupil

Answer 3

ARP but PRA

Accommodation Reflex Present but the Pupillary Reflex is Absent

Question 4

Pupillary Dilation Reflex

Answer 4

Pupillary Dilation Reflex
Afferent
• Perception of the extra light or perhaps a stimulus that merits dilated pupils is received through the eyes and goes to the Visual Cortex
• From the Visual Cortex signal is sent to the Hypothalamus
Efferent
• From the Hypothalamus the signal is projected down to the Lateral Horn of the Spinal Cord
• From Lateral Horn to the Superior Cervical Ganglion
• From the Superior Cervical Ganglion to the Internal Carotid Nerve Plexus
• From the Internal Carotid Nerve Plexus to the Long and Short Ciliary Nerves
From these nerve to the Dilator Pupillae Muscle

Question 5

Horner’s Syndrome

Answer 5

Horner’s Syndrome
Sympathetic Nerve Pathway Injury

• Miosis (pupil constriction)
• Ptosis (drooping eyelid)
• Anhidrosis (lack of sweating) Erythematosis (blushing of the skin)

Question 6

What do you call clinically found pupil asymmetry?

Answer 6

Anisocoria – pupil asymmetry

Question 7

Marcus Gunn Pupil

Answer 7

Marcus Gunn Pupil
• There is a problem is afferent light detection
Problem with the Left Eye, Marcus Gunn Pupil
• Both eyes appear normal in light and normal in darkness
• Shine light into the left eye and neither eye has constriction
• Shine light into the right (unaffected) eye
○ Direct light reflex constricts the right eye
○ Consensual Light Reflex constricts the left eye (the effected eye)

Use the Swinging light Test