Ophthalmic part 2

Question 1

Local anesthetics for eye surgery are

Answer 1

most often placed by surgeon

toxicity is rare but may occur

Question 2

Topical agents used for eye surgery include

Answer 2

tetracaine (most common)
proparacaine
bupivacaine
lidocaine
cocaine

Question 3

Topical eye medications enter bloodstream through

Answer 3

outer eye membrane & lacrimal apparatus

Question 4

Measures to reduce the amount of topical eye medication that enters the bloodstream include:

Answer 4

close eyes for 60 seconds after drops instilled to encourage absorption by eye
avoid blinking
block tear outflow canal (place index finger over medial canthus)

Question 5

The most frequently performed intraocular procedures include

Answer 5

cataract & vitreoretinal surgeries

Question 6

______ for cataract is effective in providing adequate analgesia

Answer 6

topical anesthesia

Question 7

Ocular regional anesthesia is the most common and effective way to consistently

Answer 7

produce analgesia & akinesia of the eye and eyelids

Question 8

Ocular local anesthesia includes

Answer 8

peribulbar block & retrobulbar block

Question 9

To provide ocular regional anesthesia, one may block ______ outside of the eye

Answer 9

anesthetize multiple cranial nerves (III, IV, V, VI, or VII)
orbital epidural space
facial nerve block

Question 10

A peribulbar block is injection of local anesthesia

Answer 10

outside** the muscle cone

Question 11

Peribulbar block provides

Answer 11

analgesia & akinesia of the eye

relatively low complication rate

Question 12

Disadvantages of peribulbar block includes:

Answer 12

large volumes injected (6-8 mL)
may increase IOP
slower onset of action (5-10 minutes)
-possible perforation of globe
-vertical diplopia (myotoxicity from local anesthesia)

Question 13

To perform the peribulbar block,

Answer 13

have the patient look straight ahead- avoid vasculature & optic nerve
use dull, short-beveled 25-27 gauge, 22 mm needle
insert needle in lateral aspect of the inferotemporal quadrant & superiornasal
do not insert beyond 25 mm or pierce muscle cone
ASPIRATE before slowly injection
6 mL of LA
lidocaine + bupivacaine

Question 14

A retrobulbar block is injection of local anesthesia

Answer 14

INSIDE** the muscle cone

provides analgesia & akinesia of the eye

Question 15

The ______ block has a higher complication rate

Answer 15

retrobulbar block

Question 16

Describe how to perform the retrobulbar block.

Answer 16

insert 25 gauge needle through lower lid at the junction of the lateral third & medial 2/3 of the inferior orbital edge
advance 25-35 mm toward apex of orbit (19-31 mm safest)
ASPIRATE and inject 2-5 mL LA
lidocaine & bupivacaine most common

Question 17

Complications of the retrobulbar block include

Answer 17

complications occur in 1:500 blocks
trauma to optic nerve
vision loss
retrobulbar hemorrhage
globe perforation
oculocardiac reflex
brainstem anesthesia (injection into optic nerve sheath)
intravenous or intra-arterial injection
seizure
respiratory or cardiac arrest

Question 18

Complications of the retrobulbar block usually occur within

Answer 18

15 minutes after block

standard monitors, emergency equipment, & vigilance

Question 19

Contraindications to the retrobulbar block include:

Answer 19

bleeding disorders, anticoagulation, extreme myopia, open eye injury

Question 20

A sub-Tenon’s (Episcleral) block is local anesthetic placed into

Answer 20

potential space between Tenon’s capsule & the sclera

inferonasal conjunctival fornix is most commonly used

Question 21

Describe how to perform Sub-Tenon’s block.

Answer 21

direct needle posteriorly following curve of globe
superficial injection allows LA to spread circularly around scleral portion of globe (3-5 mL)
larger volume (8-11 mL) allows spread to extraocular muscle sheaths
Deep injection- posterior intra & extraconal spaces is most common

Question 22

A facial nerve block may be performed to

Answer 22

prevent excessive blinking during eye surgery

periocular branches of the facial nerve

Question 23

30% of eye injury claims are due to

Answer 23

patient movement during ophthalmic surgery- blindness was the outcome in all cases

Question 24

Describe pediatric considerations for ophthalmic surgery

Answer 24

assess for congenital, metabolic, MSK, and malignant hyperthermia

Question 25

Describe the elderly considerations for ophthalmic surgery.

Answer 25

HTN, DM, CHF, pulmonary disease, mental status, arthritis, polypharmacy, cardiac disease

Question 26

Most eye operations can be performed under

Answer 26

regional anesthesia & sedation -same standard of care NPO status is even more important

Question 27

Unique preoperative considerations include:

Answer 27

can patient lie flat, lie still, claustrophobia, etc.? make sure patient knows what to expect for anesthetic considerations for GETA general anesthesia for infants and young children temperature, fluids, & foley

Question 28

Indications for general anesthesia include:

Answer 28

pediatric patient, patient's lack of cooperation, severe claustrophobia, inability to communicate, inability to lie flat, open-eye injuries, procedures with durations greater than 2 hours

Question 29

Disadvantages of general anesthesia for eye surgeries include

Answer 29

N/V, retching/bucking, increased intraocular pressure, aspiration, complications secondary to other medical problems, time & expense

Question 30

For sedation for blocks consider use of

Answer 30

short-acting agents to provide amnesia, analgesia, & immobility -prevent cardiac or respiratory side effects

Question 31

Intraoperative medications for eye procedures include

Answer 31

fentanyl, alfentanil, remifentanil, midazolam, propofol, dexmedetomidine -consider synergistic effects, dosing for elderly/pediatrics, circulation time

Question 32

Describe intraoperative management for eye procedures:

Answer 32

``` unnecessary to maintain sedation if block is adequate OR table turned 90 or 180 degrees standard monitors oculocardiac reflex temperature fluids "Light" GA for little stimulation hypotension oxygen & cautery risk of corneal abrasion, retinal artery occlusion ```

Question 33

Describe postoperative management for eye procedures:

Answer 33

PONV postop eye pain is unusual- corneal abrasion & acute intraocular HTN (treat with mannitol/acetazolamide) elderly patients with history of MI are at increased risk for ischemic events even under LA- consider preop beta-blockers

Question 34

Common eye procedures include

Answer 34

strabismus repair, foreign body removal, conjunctival flap, corneal transplant, trabeculectomy, penetrating eye injuries, cataract, ptosis surgery, eyelid reconstruction, blepharoplasty, retinal detachment repair (scleral buckling), vitrectomy, ophthalmic oncology

Question 35

Strabismus is an

Answer 35

ocular misalignment | most common ophthalmic condition requiring surgical repair in children

Question 36

Intervention for strabismus should occur before

Answer 36

4 months to allow normal stereoscopic visual development

Question 37

Strabismus surgery

Answer 37

lengthens/shortens ocular muscles to straighten eyes & allow binocular vision

Question 38

Strabismus is performed under

Answer 38

GA minimal EBL table turned

Question 39

With strabismus concerns include

Answer 39

oculocardiac reflex, increased risk of MH, PONV

Question 40

Describe the oculocardiac reflex with strabismus

Answer 40

increased PaCO2 shown to decrease OCR during strabismus | stop stimulation, administer anticholinergics, LA infiltration

Question 41

Describe increased risk of MH with strabismus.

Answer 41

associated with underlying myopathy- higher risk of MH avoid triggers monitor: temp, EKG, EtCo2, muscle rigidity ABG: low PaO2, high PaCO2, hyperkalemia, acidosis Dantrolene 2.5 mg/kg IV up to 10 mg/kg

Question 42

PONV with strabismus is due to the

Answer 42

ocular-emetic reflex - possible disruption of surgical repair prevention: hydration, minimize opioids, avoid N2O, propofol, La infiltration near extraocular muscle, antiemetics

Question 43

Penetrating eye injury concerns include:

Answer 43

full stomach precautions aspiration risk prevent increase in IOP- succinylcholine (increases within 1 minute, peaks with 9 mmHg), coughing open globe- succinylcholine risk vs. benefit; laryngoscopy & intubation increases IOP, consider non-depolarizing NMB for RSI

Question 44

Open globe with a full stomach is an

Answer 44

EMERGENCY SURGERY WITH GA****

Question 45

The do's and don'ts to prevent aspiration with open globe include:

Answer 45

do NOT attempt to evacuate contents using NGT preop DO administer metoclopramide IV, H2 antagonists (ranitidine), non-particulate antacid prior to induction -Do NOT attempt regional anesthesia (LA injection will increase IOP) -DO attempt RSI using cricoid pressure avoiding PPV -DO extubate awake, spontaneously breathing, head turned to side

Question 46

Preventing increase in IOP with open globe includes:

Answer 46

``` avoid direct pressure on eye avoid Trendelenburg position avoid regional anesthesia avoid increases in CVP avoid drugs that increase IOP avoid agitation in young children ```

Question 47

Anesthesia complications for eye surgeries include

Answer 47

``` retrobulbar hemorrhage globe puncture optic nerve sheath trauma intravascular injection ocular ischemia extraocular muscle palsy & ptosis facial nerve blocks oculocardiac reflex corneal abrasion central retinal artery occlusion (prolonged pressure) ```

Question 48

Retrobulbar hemorrhage results from

Answer 48

trauma to an orbital vessel | moves eyeball forward

Question 49

Venous hemorrhages have

Answer 49

slow onset, while arterial hemorrhage has rapid onset & pronounced proptosis

Question 50

Lateral canthotomy may be indicated if the hemorrhage is

Answer 50

not resolved by digital pressure - increase orbital space by cutting the lateral canthus - reduces orbital pressure that results from hemorrhage - place hemostat in temporal direction along lateral canthus 4-6 mm and clamp hemostat - use scissors to incise the crush marks left by hemostat - control local bleeding

Question 51

Globe puncture can be due to

Answer 51

sharp and dull needles both reported to have penetrated the eye during injections globe can burst apart from IOP caused by injection

Question 52

Risks for globe puncture include

Answer 52

myopic eye, scleral thinning, scleral buckling, bulging of sclera

Question 53

Prevention of globe puncture includes

Answer 53

avoid supranasal position of gaze direct needle away from axis of globe during insertion insert needle slowly with bevel towards globe never forcefully inject LA use modified techniques

Question 54

Symptoms of globe puncture include:

Answer 54

increased resistance to injection dilation/paralysis of pupil increased IOP hemorrhage

Question 55

The optic nerve sheath surrounds

Answer 55

the optic nerve

Question 56

The optic nerve sheath is composed of

Answer 56

meninges of brain - outer sheath contains dura mater - inner sheath consists of arachnoid & pia mater - subarachnoid space contains CSF and is continuous with optic chiasm - dura splits into two layers at optic foramen

Question 57

When evaluating for optic nerve sheath trauma,

Answer 57

observe contralateral pupil before block if contralateral pupil constricted--> dilated after block--> assume subarachnoid/subdural injection and prepare for respiratory arrest

Question 58

_______ has been reported after ocular blocks.

Answer 58

retinal vascular occlusion or thrombosis

Question 59

Ocular ischemia may be a result of

Answer 59

decreased pulsatile ocular blood flow after blocks | optic nerve atrophy reported after regional block or GA

Question 60

Transient symptoms of optic nerve injury include

Answer 60

contralateral amaurosis or respiratory arrest; or vascular occlusion/thrombosis which may lead to loss of vision

Question 61

______ may occur secondary to direct nerve trauma.

Answer 61

Bell's palsy

Question 62

Prevention of facial nerve block paralysis includes:

Answer 62

avoid large volume LA, avoid Nadbath technique in certain patients, seated/lateral position to protect airway, intubate if airway concerns

Question 63

With paresis of the vagus, glossopharyngeal, and spinal accessory nerves,

Answer 63

dysphagia, hoarseness, coughing, and respiratory distress may be seen - nerves exit skull 10 mm medial to CN VII - LA injected for CN VII block can reach these nerves - Unilateral vocal cord paralysis

Question 64

Extraocular muscle palsy is a result of

Answer 64

inferior muscle palsy reported after retrobulbar anesthesia

Question 65

Symptoms of extraocular muscle palsy include

Answer 65

persistent vertical diplopia | surgical intervention may be indicated

Question 66

Prevention of extraocular muscle palsy includes

Answer 66

avoid needle contact with extraocular muscles, avoid deep orbital penetration, avoid angling needle toward visual axis of globe

Question 67

Myotoxicity of LA may cause postoperative

Answer 67

diplopia and/or ptosis