anesthesia for eye surgery Flashcards by J C

3 layers of sphere

Sclera
Uveal tract (middle layer)
Retina

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Ocular sphere diameter

24mm

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Sclera is the ________ layer.
Tough, _______, ______ of the eye.
________ most anterior part (most focus power is from curvature of ______)

outermost,
fibrous,
white,
Cornea, Cornea

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3 structures of the middle layer (Uveal tract)

Choroid,
Ciliary body,
Iris,

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layer of blood vessels, located posteriorly

choroid

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behind iris, produces aqueous humor

ciliary

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Pigmented, controls light entry

Iris

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Retina contains _____, no ______, and ____ ____

photoreceptors,
no capillaries,
pars plana

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what provides oxygen to retina if no capillaries?

choroid layer (detachment from choroid compromises blood supply and is major cause of vision loss)

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Area between limbus (edge) of cornea and end of retina

pars plana
(safe entry area for vitrectomy procedures)

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center of eye is filled with _____ gel, attaches to blood vessels and _____ nerve,

vitreous,

optic

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Traction of ______ on _____ causes detachment

vitreous on retina

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Vitrectomy treats

scarring, bleeding, or opacification of vitreous

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responsible for movement of eye upward

superior rectus muscle,

and inferior oblique roates the eyeball on its horizontal axis allowing “rolling eyes”

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responsible for movement of eye downward

inferior rectus

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all ocular muscles originate in the orbital apex around the annulus of ___, except for the ______ ______

Zinn, inferior oblique

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Term used to describe a variety of arrhythmias resulting from manipulation of the eye

Ocular Cardiac Reflex (OCR)

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OCR manifests as

bradycardia, AV block, ventricular ectopy and asystole (rarely)

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T/F: Ocular cardiac reflex can occur with any stimulation of orbital contents including lid and periosteum

True

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OCR is seen especially with ____ _____ traction

medial rectus

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Ocular cardiac reflex is

trigeminovagal

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OCR Afferent impulses originate in ____ contents (via _____ and _____ _____ nerves

orbital

long and short ciliary nerves

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to _____ _____
to _____ division of the _____ nerve
to _____ nucleus of _____ nerve near ______ ventricle,
to ________ motor nuclei of the ______

ciliary ganglion,
opthalmic division of the trigeminal nerve,
to sensory nucleus of trigeminal nerve near fourth ventricle,
to visceral motor nuclei of the vagus

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_____ limb is _____ nerve to the heart

efferent,

vagus

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Ocular cardiac reflex is more frequent in peds or adults?

peds

OCR response worsened by -xemia and -carbia

hypoxemia and hypercarbia

OCR and retrobulbar blocks?

OCR seen less although orbital injections can stimulate

Treatment of Ocular Cardiac Reflex

ask surgeon to stop manipulation, assess adequacy of ventilation, lidocaine localization or deepening anesthetic may help, for persistent bradycardia, treat with atropine, response fatigues with repeated stimulations, pretreatment with glyco or atropine can be effective-consider in patients with conduction block or on BB rx

Calculate intraocular perfusion pressure

MAP less IOP

Normal IOP

10-22mmHg

What regulates IOP?

quantity of aqueous and blood volume

Volume is relatively fixed except for ____ fluid and ______ blood volume

aqueous , | choroid

Anesthetic events that increase BP

laryngoscopy and intubation, | trendelenburg position

IOP may increase up to _____ with coughing

40x

Direct pressure on the eye from compression in the ____ position (coupled with lower SBP) has been indicated in postop vision loss.

prone, | keep MAP above 75 usually

_______PaCO2 results in a fast drop in IOP from ______ vasoconstriction, Although ____ respiratory rate may increase IOP from insufficient _____ drainage

Decreased, choroidial, a fast, venous

Increased PaCO2 results in a ____ increase in IOP

slow

metabolic _____ decreases the choroid vessel volume and therefore IOP

acidosis

metabolic ______ increases the choroid volume and the IOP

alkalosis

most anesthetic drugs and inhalation agents _____ IOP

drop

Ketamine and IOP

may increase as it usually raises BP and doesnt relax extraocular muscles

Etomidate and IOP

associated with myoclonus (10-60%) and may not be appropriate with an open globe

Succs and IOP

starts within 1min and increases 5-10mmHg for 5-10 minutes

Carbonic anhydrase inhibitor: Acetazolamide (Diamox) _____ IOP. Chronic use depletes __, ___, and ____ leading to metabolic ______

decreases, K, Na, and bicarb, metabolic acidosis

Osmotic diuretic used intraop to decrease IOP

Mannitol

Topical anticholinesterase drug maintain miosis to Rx glaucoma

Echothiophate

Systemic absorption of echothiophate leads to

total inhibition of plasma cholinesterase prolonging succs

alpha adrenergic agonist topically used to dilate pupil

phenylepherine

Cholinergic drugs used to constrict pupil

pilocarpine and acetylcholine (bradycardia and acute bronchospasm have been reported)

Topical beta blocker used for glaucoma

Timolol-systemic absoprtion can cause bradycarda, bronchospasm, and CHF exacerbation.

what drug needs held for cataract surgery?

flomax- has selective alphad antagonistic properties. It binds the iris dilator muscles, affecting iris dilation and complicates cataract surgery even after 7-28days off therapy

Most common elderly surgery

Eye surgery

Sustained stage 3 htn SBP>180 or DBP>110 reschedule for cataract?

yes until two weeks of antihtn treatment

Hemorrhage potential serious- intermediate- least-

serious-obrital and oculoplastic surgery intermediate-vitreoretinal, glaucoma, corneal transplant least-cataract surgery (most agree safe to do cataract with pt on warfarin

facial nerve blocks

blocks orbicular oculi muscle (cant squeeze eye, cant squint) Van lint, Atkinson, O'Brien

Blocks entire trunk of facial nerve

Nadbath Rehman

Nadbath Rehman Block expect _____. Close to vagus and glossopharyngeal nerve so associated with

lower facial droop postop for several hours. | vocal cord paralysis, laryngospasm, dysphasia, and resp distress

Injection of local anesthetic within the muscle cone

Retrobulbar Block, produces anesthesia of the globe, akinesia of the extraocular muscle and hypotony

Most common complication of Retrobulbar block

Retrobulbar hemorrhage

Retrobulbar block injection into optic nerve sheath (contiuous with subarachnoid space) leads to

contralateral amaurosis (complete lack of vision), obtundation, resp arrest (occurs w/n 20min resolves w/n an hour), vascular collapse from depressant effect on the medulla (total spinal)

Retrobulbar block ____ nerve damage, ocular ______ w/ ______ detachment and ______ hemorrhage

opitc, perforation, retinal, vitreous

RBB postop Strabismus from anesthetic myotoxicity, | vertical _____ vision day after surgery, worsening over 2 months

double

How can retorbulbar block lead to open eye injury

pressure of fluid behind eye may force intraocular contents out through wound

peribulbar block ___ approach, multiple injections around eye w/o entering muscular _____

safer, cone, increased likelihood of ecchymosis

Block with less complications than retrobulbar block and peribulbar block

Sub-Tenon's Block( Tenon's fascia surrounds globe and extraocular muscles)

Topical avoids complication of block, disadvantages are potential for pt ______

movement

only choice of anesthesia for globe rupture

general ETT

How is the head positioned for eye surgery usually?

away form anesthesia, RAE tube

What can vagal stimulation cause especially after strabismus surgery?

emesis

Severe pain may indicate

IO hypertension, corneal abrasion or other complication

When should N2O be d/c before placement of sulfur hexaflouride and avoided how longer after?

15minutes before and avoided 7 to 10 days after

How long should N2O be avoided after the vitreal air agent, perfluoropropane

for One Month

What anesthetic agent taught not to use for open globe injury?

Succs d/t increase in IOP

Is strabismus surgery intra- or extraocular?

Extraocular

Patients who have strabismus surgery typically have related muscle disorder. Anesthetic consideration?

Malignant hyperthermia, RAE tube, nausea, avoid succs d/t prolonged response

Anesthetic consideration for lacrimal apparatus surgery?

suction pharynx well

What are enucleations done for?

tumor, trauma, CA, painful eye

Why is ketamine usually avoided in eye surgery?

nystagmus

Anesthesia management for retinal detachment and vitreal surgery

Retrobulbar block or general ett(rae or LMA. | Potential for gas buble use