Ophthalmologic Anesthesia

Question 1

What is the difference between a retrobulbar block and a peribulbar block?

Answer 1

retrobulbar injection is within the muscle cone of the eye, peribulbar injection is outside the muscle cone of the eye (slower onset)

Question 2

What are the complications of a retrobulbar block?

Answer 2

1. bradycardia (occulocardiac reflex)
2. retrobulbar hemmorhage
3. apnea due to spinal anesthesia through dura of optic nerve

Question 3

What drug is contraindicated prior to injection of sulfur hexafluoride during vitrectomy for retinal detachment?

Answer 3

nitrous oxide - will diffuse into detachment cavity and expand it

Question 4

What is normal intra-occular pressure?

Answer 4

12-20 mmHg

Question 5

What causes the greatest increase in intra-occular pressure?

Answer 5

increased venous pressure

Question 6

How much does succinylcholine increased intra-occular pressure?

Answer 6

5-10 mmHg

Question 7

What is the afferent pathway of the occulocardic reflex?

Answer 7

ciliary nerves travel to the ciliary ganglion, the impulse then travels along the ophthalmic division of cranial nerve V through the trigeminal (Gasserian) ganglion

Question 8

How do echothiophate eye drops taken for glaucoma affect induction of general anesthesia?

Answer 8

Succinylcholine should be avoided due to potential irreversible inhibition of cholinesterases (including pseudocholinesterase)

Question 9

What are the risk factors for post-op blindness caused by ischemic optic neuropathy?

Answer 9

prone or head down positioning

long duration of surgery

intraoperative hypotension

intraoperative anemia

diabetes, smoking, CAD