Visual System - Clinical Case Flashcards
58-year-old gentleman has presented to the eye casualty department complaining of inability to open his right eye. You lift his lid up and find that the eye is deviated down and out. He complains of double vision when you do this. On H-test he cannot elevate or adduct his right eye. His left eye has normal movements in all directions. His right pupil is also dilated in comparison to the left. He has a normal direct and consensual light response.
Which cranial nerve may account for this presentation?
Right Oculomotor Nerve (CNIII)
58-year-old gentleman has presented to the eye casualty department complaining of inability to open his right eye. You lift his lid up and find that the eye is deviated down and out. He complains of double vision when you do this. On H-test he cannot elevate or adduct his right eye. His left eye has normal movements in all directions. His right pupil is also dilated in comparison to the left. He has a normal direct and consensual light response.
Which pathologies may cause this?
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Medical lesions:
- Microvascular disease due to hypertension or diabetes mellitus
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Surgical lesions:
- Posterior communicating artery aneurysm
58-year-old gentleman has presented to the eye casualty department complaining of inability to open his right eye. You lift his lid up and find that the eye is deviated down and out. He complains of double vision when you do this. On H-test he cannot elevate or adduct his right eye. His left eye has normal movements in all directions. His right pupil is also dilated in comparison to the left. He has a normal direct and consensual light response.
What treatments may be offered for this presentation?
Treatment will depend on the cause of the cranial nerve palsy
In this case, the cause is likely to be a posterior communicating artery aneurysm. Hence a neurosurgical opinion is advised, and assessment of the aneurysm is needed (this may involve clipping).
For patients with microvascular disease, they will need better metabolic control of their condition.
A 28-year old lady presents with a tonically dilated pupil in the right eye. Upon shining light into the right eye, the pupil is slow to react compared to the left. The left eye reacts when light is shone into the right eye. Addition of pilocarpine drops, however, causes rapid constriction of the right pupil. On further examination, she has an absent knee-jerk reflex and impaired sweating.
What is the site of damage causing the pupil defect?
Damage to parasympathetic ciliary ganglion
Parasympathetic fibres travel with CNIII (oculomotor) to synapse at the ciliary ganglion before innervating the iris and ciliary body.
A 28-year old lady presents with a tonically dilated pupil in the right eye. Upon shining light into the right eye, the pupil is slow to react compared to the left. The left eye reacts when light is shone into the right eye. Addition of pilocarpine drops, however, causes rapid constriction of the right pupil. On further examination, she has an absent knee-jerk reflex and impaired sweating.
What is the site of damage causing the absent reflex and impaired sweating?
Dorsal root ganglia of the spinal cord
A 28-year old lady presents with a tonically dilated pupil in the right eye. Upon shining light into the right eye, the pupil is slow to react compared to the left. The left eye reacts when light is shone into the right eye. Addition of pilocarpine drops, however, causes rapid constriction of the right pupil. On further examination, she has an absent knee-jerk reflex and impaired sweating.
How does pilocarpine work?
Muscarinic receptor agonist that acts on M3 receptors in the iris sphincter muscle -> Contraction of the muscle (miosis) and constriction of the pupil (independent of the parasympathetic tract, hence the response)
A 28-year old lady presents with a tonically dilated pupil in the right eye. Upon shining light into the right eye, the pupil is slow to react compared to the left. The left eye reacts when light is shone into the right eye. Addition of pilocarpine drops, however, causes rapid constriction of the right pupil. On further examination, she has an absent knee-jerk reflex and impaired sweating.
What term can be used to describe this defect?
Adie’s pupil
An Adie’s pupil is described as having light-near dissociation. This is due to reinnervation that takes place as a result of damage to the ciliary ganglion. This process involves up regulation of postsynaptic receptors but the reinnervation is aberrant, causing fibres directed for the ciliary body to end up targeting the iris. As a result, the patient develops more meiosis with near accommodation than they do to light.
