EYE and DRUGs Flashcards
what nerves innervate the eye?
optic nerve = 2
movement = 3,4 and 6
parasympathetic - carried by CN 3
sympathetic via superior cervical ganglia
what does the different eye muscles do?
occulomotor nerve = all rectus muscles except lateral, inferior oblique. up and in
trochea nerve = superior oblique = down and out
abducens = lateral rectus
what does the parasympathetic supply of the eye do?
pupil constriction
cilliary muscles involved in accomadation
what is the normal intraoccular pressure?
10-20mmHg
what are the causes of raised IOP?
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
how is aqueous humour produced?
cilliary bodies
flows over lens into anterior chamber and then through canal of schlemm.
drugs that reduce intraoccular pressure?
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)
what is the occulocardic reflex?
bradycardia when eye is pulled on
vagal response
how can anaesthetist avoid raised intraocular pressure?
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
what drugs give side effects that efect the eye? (other than Raised occular pressure)
amiodarone - corneal deposits
digoxin - green vision
ethanbutol - optic nerve damage
steroids -cataracts