Ophthalmology Modified Flashcards
1
Q
Where are ophthalmic procedures common?
A
ambulatory surgery centers (98.5%)
2
Q
What are the common procedures of the eye?
A
lens and cataract (70%)
intraocular (10%)
eyelids, cornea, conjunctiva (10%)
3
Q
Sclera
A
outer, fibrinous protective layer, white and opaque and lies just posterior to the cornea
4
Q
Cornea
A
the outer, fibrinous protective layer located anteriorly, and it is transparent and colorless
5
Q
Choroid
A
middle, vascular layer
6
Q
Retina
A
the inner layer of the posterior half of the eye
7
Q
Conjunctiva
A
a thin, transparent mucous membrane that covers the posterior surface of the eyelids and the anterior surface of the sclera
8
Q
Anterior chamber
A
b/w cornea and iris
9
Q
posterior chamber
A
b/w iris and lens
10
Q
orbits
A
two symmetrical bony enclosures in the front of the skull
11
Q
what is the visual axis
A
an imaginary line from the midpoint of cornea to midpoint of retina or macula
12
Q
What is suspended in the anterosuperior part of the orbit
A
the globe
13
Q
What are the three layers of the eyeball
A
large posterior segment (vitreous humor, retina, macula and root of optic nerve)
Small convex anterior segment (two chambers)
Anterior chamber: immediately behind cornea filled with aqueous humor that is produced by ciliary body
posterior chamber: contains the lens
14
Q
How many muscles is the eye surrounded by?
A
6 extraocular muscles
15
Q
Superior rectus muscle
A
moves the eye upward
supraduction
CN 3
16
Q
inferior rectus muscle
A
moves the eye downward
infraduction
CN3
17
Q
Medial retcus muscle
A
move the eyeball nasally (adducts)
adduction
CN3
18
Q
Lateral recuts muscle
A
moves the eyeball laterally (abducts)
abduction CN6
19
Q
Superior oblique muscle
A
rotates the eyeball horizontally towards nose and down
intorsion, depression CN 4
20
Q
Inferior oblique muscle
A
rotates the eyeball horizontally towards temple and up
extorsion, elevation CN 3
21
Q
What CNs supply the motor innervation to the eye?
A
CN 3, 4, 6
22
Q
What does the optic nerve extend through?
A
optic canal
23
Q
What does the optic nerve meet intracranially?
A
optic chiasm
24
Q
What is the optic nerve covered by?
A
meninges, the fibrous wrappings of the arachnoid, dura, pia mater, which envelop the central nervous system, and surround by CSF
25
How does a total spinal occur from regional to the eye?
any anesthetic agent injected into the optic nerve sheath can find its way back to the midbrain through the CSF
26
Cranial Nerve 2
optic nerve
outgrowth of the brain
part of CNS
27
Cranial nerve 3
oculomotor nerve
| primary motor nerve to the extraocular muscles
28
Cranial nerve 4
trochelar nerve
| only orbital cranial nerve that enters the orbit from outside the muscle cone
29
Cranial nerve 5
trigeminal nerve
| afferent pathway for oculocardiac reflex-> bradycardia and dysrrhythmias
30
what are the branches of CN5?
ophthalmic, maxillary and mandibular branches
| sensory and motor
31
Ophthalmic branch provides
sensation of pain, touch, and temperature to the cornea, ciliary body, iris, lacrimal gland, conjunctiva, nasal mucosa, eyelid, eyebrow, forehead and nose
32
MAxillary branch
sensation of pain, touch and temperature to upper lip, nasal mucosa, scalp muscles
33
CN 6
abducens
| motor function to lateral rectus muscle
34
CN7
facial nerve
upper branch further divides into the temporal and zygomatic branches, which innervate the orbicular muscles of the eye, the superficial facial muscles and scalp muscles
35
CN 10
vagus nerve
| afferent pathway for the oculocardiac reflex-> bradycardia and dysrrhythmias
36
What muscles raise the upper eyelids?
levator muscles
| orbicular muscle contracts the eyelid
37
What is normal intraocular pressure?
10-22mmHg
38
What is the most important determinant of IOP?
balance between production and elimination of aqueous humor, maintaining an average volume of 250ml
39
What decreases IOP?
IV and inhalation anesthetics
hyperventilation
hypothermia
hypotension
40
What increases IOP?
```
blinking, squinting
succinylcholine (transient 5-10mmHg)
ketamine (nystagmus)
nitrous oxide
atropine/scopolamine (acute angle closure glaucoma in susceptible patients)
valsalva, pressure on eyeball, coughing, vomiting
laryngoscopy/tracheal intubation
hypercapnia, hypoxemia, hypertension
```
41
What is aqueous humor?
thin watery fluid that fills the space in the anterior chamber between cornea and iris
continually produced by ciliary body
drains out eye via trabecular meshwork into the aqueous veins and eventually into the veins of the orbit
42
What is the prupose of the aqueous humor?
nourishes the cornea and lens
| gives the front of the eye its form and shape
43
What are common adult ophthalmic procedures?
```
cataract extraction
occuloplastics (ptosis repair)
cornea transplants or grafting
trabeculectomy (for glaucoma)
vitrectomy and retinal buckling
trauma (enucleation or orbital fracture repair)
LASIX
```
44
What is the leading cause of blindness in adults 20-74?
diabetes
45
What is the leading cause of blindness in children?
vitamin A deficiency
46
What are common pediatric eye cases?
```
strabismus
exam under anesthesia
retinoblastoma
glaucoma
cataracts
retinal detachments
```
47
Strabismus
muscular surgery to fix ocular misalignment
Of the six muscles that innervate the eye, misalignment is present
can effect vision
48
Strabismus Anesthesia implications
```
it hurts!
N/V
multiple rounds for pediatrics
emergence delirium
oculocardiac reflex
```
49
What are common medications seen in strabismus surgery?
acetaminophen (15mg/kg)
ketorlac (0.5mg/kg)
fentanyl (as needed)
50
What is the oculocardiac reflex?
traction on the extraocular muscles of the eye, manipulation of the globe and pressure on the eyeball (increased IOP) cause bradycardia, sinus arrest, v fib, AV block, ventricular ectopy and negative inotropy
51
What is the physiology behind the oculocardiac reflex?
5th cranial nerve (afferent) to brainstem
| 10CN vagus efferent to cardioinhibitory center
52
What is the corneal reflex?
CN V (corneal touch) and CN VII (blink, orbicularis oculi)
53
What is the dose of atropine to help correct oculocardiac reflex bradycardia?
10mg/kg
54
Dark Adaptation and ERGs (electroretinograms)
Prior to EUA to assess the actual cones and rods and their functionality
55
Retinoblastoma
ocular cancer of retina primarily affecting kids under age 4
| most curable, but increased risk of other cancers later in life
56
LMA will work for what procedures
radiation and procedures for retinoblastoma and strabismus
glaucoma
cataracts
Nasolacrimal duct probing
57
Amblyopia
Lazy eye
eye doesn't work correctly in kids, message between teh eye and brain make it such that the worse eye kind of shuts off while the good eye does all the seeing
58
What happens if a lazy eye isn't corrected?
when the brain focuses on the message coming from the good eye this can become permenant even if the weak eye is fixed
59
Who does amblyopia affect?
kids from birth to 7 years of age
60
How do you initially treat amblyopia?
eye patches or dilation drops on the stronger eye to force the weaker eye to work
61
Chalazion procedures
sty won't go away and needs removal
| zit on top of eyelid that wont go away
62
Nasolacrimal duct probing is
used to clear clogged tear ducts
63
Will you see stage 2 in eye surgery patients?
no
64
What should you travel to PACU with?
emergency drugs and a peds mask (propofol)
65
What are emergency eye cases?
open globes
corneal transplants melts causing open globes
canaliculi repairs
endopthalmitis
66
What is an open globe?
full thickness defect in the cornea (transplant outer covering) or sclera (white outer covering)
67
When should open globes go to surgery?
within 12-24 hours of surgery
68
Anesthetic considerations for globes
Dehydrated
GETA (succ can raise IOP, neccessity depends on NPO status, viable eye vs difficult airway)
Oral RAE tube
Antibiotics needed
69
What is a corneal transplant melts?
corneal transplant has rejected or the suture to the eye has come undone, leaving an opening to the eye
70
Anesthesia for a corneal transplant melt?
GETA
| LMA vs ETT will depend on severity of melt
71
Anesthesia considerations for canaliculi repairs
younger children from dog bites/stratches
can be inner or outre
assuming NPO and patient appropraite can be LMA
fairly quick procedures
72
Endopthalmitis
infection of the tissues or fluids inside the eyeball
| infection in the vitreous
73
Surgical considerations for endopthalmitis
vitrectomy to remove some of the infected vitreous gel and inject antibiotics
discuss anesthesia with surgeon, possible with peribulbar block but may not if infection too bad
74
Ophthalmology and General anesthesia
retina cases
| consider oral rae tube
75
MAC/PBB/RBB cases?
anesthesia provides sedation, surgeon places block in OR to prep
76
MAC/Cutdown
used on patients on anticoagulants and unsafe to use PBB/RBB
Done like a cataract from our standpoint. Use sedation and tetracaine gtts and once the surgeon drapes they will inject local by cutting the conjunctiva and placing local in back of eye. A little different than a peri-bulbar block but achieves same idea of localization.
We do these if patient's are on anticoagulants to reduce risk of bleeding. Also some surgeons just prefer them because of less risk associated with them
77
Topical Anesthesia
tetracaine drops only with sedation PRN
78
Take away for eye cases
```
Use oral RAE tube for ETT
N/V common
paralysis rarely required
Smooth induction
smooth emergence
```
79
Anesthesia tips for emergency eye cases
if patient awake, ensure comfortable
no airway
Local in helpful
80
What should be placed if doing an extensive open globe case?
foley up front
81
Ocular regional anesthesia is effective for
analgesia and akinesia of the eye and eyelids
82
What nerves does Ocular regional anesthesia effect?
CN 3,4, 5,6, 7
83
What is the anesthetic used for Ocular regional anesthesia?
versed and fentanyl +/- small propofol doses to get patient through actual block
84
Retrobulbar block
Needle inserted through the skin in the infratemporal area, just above the inferior orbital rim and advanced toward the orbital apex deep into the muscle cone (retrobulbar space)
2-4ml of LA
better akinesia
85
Complications of RRB
trauma to optic nerve, blood vessels, globe
retrobulbar hemorrhage b/c anesthetic is put inside the orbital epidural space
spread of LA to CSF causing hemodynamic instability and respiratory depression within 5 minutes
seizures if intravascular
86
Peribulbar Block
may require an injection above or below the orbit (although most of our surgeons just do one below)
8-12ml
anesthetic is injected, creating positive extraconal pressure that spreads the agent inside the muscle cone to anesthesize the cranial nerves (avoids muscle cone and vital structures)
87
What is a safer choice block and why?
PBB b/c of less risk of hemorrhage and central spinal
88
What is the max dose of tetracaine?
3mg/kg
89
How do you administered tetracaine?
2-6 drops (divided doses 1-2 minutes apart) in the eye prior to prep
90
Sub-tenon Block
greater analgesia than motor block
block performed between rectus muscles of the globe
conjunctiva incised-> tenon tissue is elevated and incised-> a short cannula is inserted into the sub-tenon space
3-4 ml to achieve analgesia
larger doses may give akinesia
91
What is tennon tissue?
tissue that encapsulates the globe posteriorly and fuses with the conjunctiva anteriorly
92
What is the objective of the sub-tenon block LA placement?
to get posterior spread of the agent
93
What are ophthalmic medications that cause dilation?
atropine/scopolamine
epinephrine
phenylephrine
cyclopentolate
94
What class is atropine/scopolamine?
anticholinergic
95
What are adverse effects of atropine/scopolamine?
central cholinergic syndrome
| scopolamine can cause disorientation in some patients
96
What is epinephrine?
sympathetic agonist
97
What are side effects of epi?
tachycardia, arrhythmias, HTN, headache
98
What is phenylephrine
alpha agonist
99
What are side effects of phenylephrine?
HTN, arrhythmias, headache, reflex bradycardia
100
What is cyclopentolate?
synthetic anticholinergic
101
What are side effects for cyclopentolate?
disorientation, psychosis, seizures
102
What ocular medications cause miosis?
pilocarpine
carboachol
physostigmine
echothiopate
103
What is pilocarpine? Side effects?
muscarinic alkaloid
| redness of sclera, irritation
104
What is carboachol? Side effects?
synthetic carbamyl ester of choline
| used if not responsive to pilocarpine
105
What is physostigmine? side effects
indirect acting anticholinesterase
| miosis
106
What is echothiopate? side effects?
indirect acting organophosphorus cholinesterase inhibitor
increases drainage of intraocular fluid and used to treat glaucoma
irreversibly binds to cholinesterase (effects will last for weeks)-- will prolong succinycholine
107
What are ophthalmic glaucoma medications?
```
timolol
acetazolamide
echothiopate
iatanoprost
brimonidine
```
108
What is timolol? side effects?
potent non-selective beta blocker
| bradycardia, asthma, CHF
109
What is acetazolamide? Side effects?
carbonic anhydrase inhibitor
mild diuretic, hypokalemia, acidosis, hematuria, paresthesia, gastric disease, flaccid paralysis, seizures
avoid with hepatic renal disease
110
What is iatanoprost?
prostaglandin
111
What is brimonidine?
alpha 2 agonist
112
How does acetazolamide (diamox) work?
used to lower the pressure in the eye by lowering the amount of aqeous humor production in front of the eye
113
What is the dose of acetazolamide?
250-500mg mixed with normal saline
114
What is special about acetazolamide?
incompatible with IV and other medications (precipates with zofran)
115
Who can not have acetazolamide?
pateints with a sulfa allergy
116
How do topical eye medications enter the bloodstream?
through the outer eye membrane and lacrimal apparatus
117
How can you reduce the amount of topical medications that enter the bloodstream?
patient closes eyes for 60 seconds
avoid blinking
block the tear outflow canal by placing the index finger over the medial canthus after the eye is closed
118
What are ophthalmic complications?
```
retrobulbar hemorrhage
intravascular LA injection
globe puncture
optic nerve sheath trauma
ocular ischemia
extraocular muscle palsy and ptosis
facial nerve block
oculocardiac reflex
corneal abrasion
central retinal artery occulsion
```
119
Preoperative considerations for ophthalmology
can the patient lie supine for a long time?
evaluate claustrophobia, chronic pain, COPD, tremors, mental status (anxiety, inability to cooperate)
postnasal drip, vasoconstrictive nose drops
120
What is the cause of sudden onset of nausea at home after procedure?
increased intra-ocular pressure than anesthetic medications
121
What is intraocular gas?
retinal procedures may utilize sulfur hexafluoride
| is not removed will dissipate in 10-14 days
122
What needs to be discontinued 15 minutes prior to gas injection?
nitrous oxide
123
Cautions of intraocular gas
can not fly or go to high altitudes
if needing general anesthesia within 14 days no N2O
may be required to lie face down during recovery
