Ophthalmology Flashcards
what is the oculocardiac reflex
- pressure is put on the globe of the eye/traction on the extraocular muscles 2. causes bradycardia and dysrhythmias (via trigeminal [afferent] and vagus [efferent] nerves)
under which type of anesthesia can the oculocardiac reflex be induced?
- local 2. regional 3. general
what is the anticipated outcome of the oculocardiac reflex with continued stimuli?
the reflex arc will fatuge
which anesthetic technique can induce the oculocardiac reflex, but can also be protective from future stimuli
regional (blocks)
anesthetic management of the oculocardiac reflex
- release pressure/stop eye manipulation 2. atropine 10 mcg/kg (could also use glycopyrrolate)
oculocardiac reflex with complete vagal block, up to ___________ mg of atropine could be given
3-Feb
T/F: you can prevent oculocardiac reflex with opthalamic surgery when pre-treat with atropine and/or retrobulbar block
false; pre-tx with atropine and/or retrobulbar block is not helpful
if oculocardiac reflex is eliciting refractory bradycardia, how can you tx it?
infiltrate the rectus muscle with local anesthetic
what is normal intraocular pressure
10-20 mmHg
what are the most important determinants of intraocular pressure?
balance between (1) production, (2) drainage, (3) and reabsorption of the aqueous humor
what are the determinants of intraocular pressure
- aqueous humor dynamics 2. changes in choroidal blood volume 3. central venous pressure 4. extraocular muscle tone
which anesthetic agents decrease IOP?
- volatile inhalation agents 2. N2O 3. propofol 4. Benzodiazepines 5. opioids 6. Rocuronium
which anesthetic agents increase IOP?
- succinylcholine 2. ketamine
what is the most common form of glaucoma
open angle
_________________ is d/t a gradual blockage of outflow of the aqueous humor d/t sclerosis of the trabecular tissue
open angle glaucoma
what are the medication goals in tx open angle glaucoma
- enhanced drainage of aqueous humor 2. reduced production of aqueous humor
cholinergics and sympatholytics are used to tx ________________ glaucoma
open angle
outflow of open angle glaucoma is improved with medications that cause the pupil to _________________
constrict (miosis)
atropine drops –> mydriasis is contrindacted in which type of glaucoma
closed angle
which glaucoma type can appear suddenly and is often painful, often an ocular emergency
closed angle glaucoma
____________________ glaucoma is d/t obstruction from the posterior chamber to the anterior chamber
closed angle
_______________ angle glaucoma worsens with mydriasis
closed angle
T/F: you can use drugs like neostigmine to reverse NMB in pts with closed angle glaucoma
true, normally you would avoid drugs that cause mydriasis, but IV NMB reversals are okay
beta 2 stimulation on aqueous humor production?
B2 stimulation increases aqueous humor production
Muscarinc stimulation on aqueous humor production
improves the outflow of aqueous humor
how can the anesthesia provider prevent corneal abrasion from occurring while under anesthesia
- ensuring the eyelids are closed and secured with tape 2. muscle relaxant use with ocular surgery 3. ensure padding and periodic checks of the eye if the patient is in the prone position
when would you expect a patient to get an intraocular injection of perfluropropane or sulfur hexafluoride?
retinal detachment procedures
anesthetic considerations for a patient who has had an intraocular injection of perfluropropane or sulfur hexafluoride
- N20 must be stopped at least 15 min prior to injection 2. avoid N2O for 10 days after sulfur hexafluoride 3. N2O must be avoided for 30 days after perfluoropropane injection
why would a scleral buckling procedure be performed?
retinal detachment
how is a scleral buckling procedure performed?
- silicone band sewn around the sclera, creates a dimple on the eye wall 2. buckle is secured under conjunctiva, moving wall of eye closer to the detached retina 3. laser therapy creates permanent adhesion
the __________________ score is used to evaluate criteria for discharging patient from ambulatory center to home
aldrete
what are the components of the aldrete score?
- activity (ability to move extremities voluntarily/follow commands) 2. respiration (can they breathe deeply and cough freely?) 3. circulation (BP +/- % of preanesthetic level) 4. level of consciousness 5. oxygenation
the “muscle cone” of the eye is formed by __________ extraocular muscles
6
what are the 3 layers of (eye) globe wall?
- sclera (outermost) 2. uveal tract 3. retina
what is the fx of the sclera
maintains the shape of hte eye
what is found within the middle layer of the globe wall, (aka uveal tract)
- choroid 2. iris 3. ciliary body
________________ is the part of the eye that produces aqueous humor
ciliary body
____________ is within the uveal tract of the eye, where the vessels and capillaries are found
choroid
dilation of the iris is via _____________ stimulation, and constriction is via _____________
SNS; PNS
_________________ is part of the eye where photoreceptors are stimulated by light, and signals the optic nerve
retina
__________________ is the artery that provides most of the blood flow to the eye
ophthalamic
T/F: veins in the eye are valveless
TRUE
the optic nerve (CN II), is technically an outgrowth of the brain covered by meninges. This creates an ___________________ space, which injections can accidently go into
orbital epidural
if an injection into the optic nerve goes into the orbital epidural space, this can go directly to the ____________ via CSF causing ______________ and/or ___________
midbrain; CNS depression; respiratory arrest
if you suspect an optic nerve injection went into the epidural space, you should check the ________________ pupil
contralateral (will be dilated)
which nerve is the primary motor nerve for extraocular motion
oculomotor (CN III)
fx of oculomotor nerve at the eye
- extraocular motor movement 2. PNS innervation of iris –> constx
the oculomotor nerve controls all extraocular muscle movement, except for _________________ & ______________
lateral rectus; superior oblique
which nerve controls motor function of the lateral rectus muscle
abducens (CN VI)
which nerve controls the motor function of the superior oblique muscle
Trochlear nerve (CN IV)
which nerve is the primary sensory nerve of the eye
trigeminal (CN V)
the trigeminal nerve (CN V) controls sensation to?
- cornea 2. ciliary body 3. iris 4. lacrimal gland 5. conjunctiva 6. eye lid 7. eyebrow 8. forehead 9. nose 10. nasal mucosa
which nerve controls motor eye lid contraction?
facial (VII)
what effect does hypoventilation, causing hypercarbia have on IOP?
increases IOP
hypoxia will _____________ IOP
increase
coughing, straining, vomiting, and/or intubation can increase IOP to ______________, which have serious implication with ______________ injury
30-40 mmHg; open globe
anesthetic goals for pt with glaucoma
- avoid venous congestion/fluid overload 2. avoid hypotension
what are the different types of procedures that can be done for glaucoma
- trabulectomy 2. ahmed shunt device 3. laser to trabecular meshwork
what is the anesthetic choice for the glaucoma procedures? (trabulectomy, ahmed shunt, laser to trabecular network)
MAC
ahmed shunt device will function to do what?
drain aqueous humor under the conjunctiva
what is the purpose of a trabulectomy?
excision of trabecula to increase drainage of aqueous humor
which ocular medications function to decrease aqueous humor production?
- beta blockers (timolol) 2. Alpha-2 agonists (brimonidine) 3. carbonic anhydrase inhibitors (acetazolamide)
which ocular medications function to increase the outflow of aqueous humor?
- acetylcholine (Miochol-E) 2. anticholinesterases (physostigmine & echothiophate) 3. prostaglandins (lanoprost and bimatoprost)
what are some regional anesthetic techniques used in opthalmologic surgery?
- peribulbar block (extraconal) 2. retrobulbar block (intraconal) 3. sub-tenon block
what is the recommended LA used for regional anesthetic in opthalmologic surgeries?
lidocaine 2% and Bupivicaine 0.5%
what are complications with regional anesthesia techniques for opthalmologic surgies?
- intravascular injeciton –> seizures 2. globe puncture 3. optic nerve injury 4. superficial hemorrhage 5. retrobulbar hemorrhage 6. retinal vascular events 7. muscle palsy 8. loss of vision 9. respiratory arrest from CSF infiltration via optic nerve 10. oculocardiac reflex 11. central retinal artery occlusion 12. inadvertent brainstem anesthesia
what is the pro of using succinylcholine with open globe injury procedure
faster onset than with NDMR
what is the con of using succinylcholine with open globe injury procedure
increases IOP 5-10 mmhg for 5-10 minutes
pros of using NDMR with open globe injury procedure
- satisfactory for induction 2. decreases IOP 3. now have suggamadex to reverse quickly
cons of using NDMR with open globe injury procedure
- slower onset 2. slower to metabolize/wear off
ophthalmic drop medications are absorbed at a rate that is slower than ____________, but faster than __________
IV; subQ
what are some techniques to increase absorption of ophthalmic medication and decrease lacrimal drainage?
- close eyes for 60 seconds 2. hold external pressure on medial canthus 3. no blinking
considerations with MAC technique for ophthalmic surgery
- pt must be cooperative 2. must be able to lie flat 3. may not be best choice if pt: snores, OSA, claustrophobic, anxious
which regional anesthetic block for ophthalmic surgery has the highest risk of retrobulbar hemorrhage
retrobulbar block
regional anesthetic techniques for ophthalmic surgery, which is injected intraconal?
retrobulbar
what are the advantages of a retrobulbar block, compared to peribulbar
- smaller volume needed (3-5 mL) 2. more rapid onset (~ 2min) 3. lower risk of block failure
what are the cons with retrobulbar block compared to peribulbar
increased risk of retrobulbar hemorrhage
what depth does should the needle not exceed when doing a retrobulbar block in order to avoid the deeop orbital structures
1 “
what are the cons of a peribulbar block compared to retrobulbar
- requires larger vol (4-6 mL but up to 8-10 mL) 2. higher risk of block failure 3. longer onset (10 min) 4. 2 injections (upper and lower)
what are the pros of a peribulbar block compared to retrobulbar
lower risk of retrobulbar hemorrhage
______________ globe injury, the IOP is atmospheric
open
which which type of globe injury is it important to preven the extrusion of contents
open
which globe injury is it vital to prevent increases in IOP
closed globe
when pressure is put on the globe of the eye and traction on the extraocular muscle it triggers the oculocardiac reflex, the afferent nerve in this process is _________________, and the efferent is _____________________.
trigeminal; vagus
