EYE and DRUGs Flashcards

1
Q

what nerves innervate the eye?

A

optic nerve = 2
movement = 3,4 and 6
parasympathetic - carried by CN 3
sympathetic via superior cervical ganglia

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2
Q

what does the different eye muscles do?

A

occulomotor nerve = all rectus muscles except lateral, inferior oblique. up and in

trochea nerve = superior oblique = down and out

abducens = lateral rectus

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3
Q

what does the parasympathetic supply of the eye do?

A

pupil constriction
cilliary muscles involved in accomadation

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4
Q

what is the normal intraoccular pressure?

A

10-20mmHg

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5
Q

what are the causes of raised IOP?

A

intraocular
-blocked canal of schlem - aqueous humour cant be reabsorbed e.g. glaucoma
- choroidal blood volume - head down, high CO2
- tumour
- foregin body

extraoccluar
- muscle tone - succinylcholine
- retrobulbar haematoma
- tumour or abscess

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6
Q

how is aqueous humour produced?

A

cilliary bodies
flows over lens into anterior chamber and then through canal of schlemm.

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7
Q

drugs that reduce intraoccular pressure?

A

B blockers - timolol - reduces secretion of aqueous humour
parasympathomimetics - pupil constriction helps with drainage e.g. pilocarpine
prostaglandin antagonists - latanoprost
carbonic anhydrase inhibitors
mannitol
volatiles and induction agents (except ketamine and N20)

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8
Q

what is the occulocardic reflex?

A

bradycardia when eye is pulled on
vagal response

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9
Q

how can anaesthetist avoid raised intraocular pressure?

A

selection of anaesthetic drugs - avoid sux, ketamine and N20. avoid cyclizine (use ondansetron instead)
use volatiles and benzos and opioids

positioning - avoid head down, prone positon

avoid HTN

gentle extubation

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10
Q

what drugs give side effects that efect the eye? (other than Raised occular pressure)

A

amiodarone - corneal deposits
digoxin - green vision
ethanbutol - optic nerve damage
steroids -cataracts

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