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APA3 levi 2019 S.Horvath > eyeballs > Flashcards

eyeballs Flashcards

1
Q

uveal tract: sympathetic stim causes dilation or constriction of the pupil? what muscle?

A

contraction of iris dilator muscle leading to DILATION or mydriasis

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2
Q

mydriasis is constriction or dilatation?

A

dilatation

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3
Q

miosis is constriction or dilatation?

A

constriction

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4
Q

uveal tract: parasympathetic stim causes dilation or constriction of the pupil? what muscle?

A

contraction of iris sphincter muscle causing CONSTRICTION or miosis

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5
Q

what is a major cause of vision loss that has to do with the innermost layer of the retina?

A

there are no capillaries, so the choroid layer provides oxygen. detachment from the choroid compromises blood supply and is the major cause of vision loss.

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6
Q

how does the OCR reflex manifest cardiac

A

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

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7
Q

OCR can occur with any stimulation of orbital contents including lid and periosteum, but it is seen especially with ___ ____ ____

A

medial rectus traction

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8
Q

The OCR reflex is ___ in nature

A

trigeminovagal

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9
Q

OCR Reflex: where do afferent impulses originate?

A 
orbital contents (via long and short ciliary nerves)
[cn V trigeminal]
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10
Q

OCR Reflex: what is the efferent limb

A

vagus nerve to the heart

[cn X]

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11
Q

T/F OCR is seen during topical and general anesthesia, more during retrobulbar blocks

A

FALSE. it is seen less during retrobulbar blocks, although orbital injections can stimulate reflex.

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12
Q

OCR response is worsened by what two things

A

hypoxemia and hypercarbia

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13
Q

OCR: can pre-treat with what two drugs? consider in patients with conduction block or on BB rx

A

glyco or atropine

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14
Q

what is the formula for intraocular perfusion pressure?

A

MAP - IOP

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15
Q

If IOP is ___, blood supply and optic nerve function will be impaired

A

high

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16
Q

Once the globe is open, what can factors increasing IOP cause?

A

prolapse and loss of IO contents, with perm vision loss.

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17
Q

T/F The globe is relatively non-compliant and volume is relatively fixed except for aqueous fluid and choroid blood volume.

A

TRUE.

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18
Q

the quantity of ___ and ____ volume regulates IOP

A

aqueous and blood volume

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19
Q

what is normal IOP

A

10-22

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20
Q

IOP > ? is pathological?

A

25

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21
Q

What is the production of aqueous humor facilitated by

A

carbonic anhydrase

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22
Q

what does decreased IOP lead to?

A

fluid accumulation in the eye

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23
Q

T/F sudden increases in BP increases IOP and this has a lasting effect

A

FALSE. soon dissipates d/t drainage system

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24
Q

sudden decreases in BP<90 will drop IOP, why?

A

d/t loss of auto regulation.

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25
Q

how does 60 systolic affect IOP?

A

causes a 3-4 torr decrease in IOP from decreased blood flow in nl eye

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26
Q

what increases IOP more… increase in CVP or increase in BP?

A

increase in CVP

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27
Q

coughing, straining, breatholding, and vomiting increases IOP by _____ of drainage. IOP may increase up to ___ with coughing

A

obstruction. 40.

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28
Q

how does posture effect IOP?

A

same way it effects BP. sit up and it goes down.

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29
Q

what two factors related to the prone position have been indicated in post op vision loss?

A

direct pressure on the eye from compression in the prone position and lower systolic BP

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30
Q

decreased paco2 results in a fast drop in IOP. why?

A

choroidal vasoconstriction

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31
Q

Increase in PaCO2 results in a slow ____ in IOP

A

increase

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32
Q

a fast RR may increase IOP. why?

A

insufficient venous drainage

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33
Q

metabolic acidosis ___ IOP, while metabolic alkalosis ____ IOP

A

acidosis decreases the choroid vessel volume and therefore IOP.

alkalosis increases choroid vessel volume and therefore IOP

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34
Q

how do inhaled agents affect IOP?

A

decrease - because they lower BP thereby decreasing choroidal volume, relax extra ocular muscles and lower wall tension, and pupil constriction enables aqueous outflow

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35
Q

what is ketamines affect on IOP?

A

increase as it usually raises BP and doesnt relax extra ocular muscles

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36
Q

which induction agent is associated with myoclonus (10-60%) and may not be appropriate with an open globe?

A

etomidate

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37
Q

opioids generally ___ IOP

A

decrease

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38
Q

T/F Tracheal intubation will increase IOP if depth of anesthesia is inadequate regardless of NMR used.

A

TRUE

39
Q

T/F non depolarizing NMR do not alter IOP.

A

true

curare is an exception which decreases it.

40
Q

how does succs affect IOP

A

increases.

41
Q

succs inc in IOP starts within ___ minute, increases ___ for ___ min due to prolonged contracture of extra ocular muscle

A

1min, 5-10,

42
Q

T/F Glaucoma patient has an exaggerated response to succs

A

FALSE. not exaggerated or prolonged

43
Q

how does acetazolamide work?

A

it is a carbonic anhydrase inhibitor, decreases aqueous production by inhibiting Na pump responsible for secretion of aqueous humor, decreasing IOP.

44
Q

how does carbonic anhydrase chronic use effect lytes?

A

it depletes Na, K and bicarb, leading to metabolic acidosis

45
Q

mannitol is an osmotic diuretic that is used IV intraop to drop IOP. max effect is ____min, returns to baseline after ____h

A

30-45. 5-6

46
Q

hemorrhage is serious in which two surgeries?

A

orbital and oculoplastic

47
Q

hemorrhage is intermediate in which three surgeries?

A

vitreoretinal, glaucoma, corneal transplant

48
Q

T/F most providers agree it’s safe to do a cataract with patient on warfarin

A

TRUE

49
Q

what is the most common complication of retrobulbar block

A

retrobulbar hemorrhage

50
Q

topical applied eye drugs are absorbed at a rate ____ between subcutaneous and IV injection

A

intermediate

51
Q

what is echothipate used for?

A

it is a topical anticholinesterase drug, maintains miosis to rx glaucoma

52
Q

what happens with systemic absorption of echothipate

A

it leads to total inhibition of plasma cholinesterase. so you have prolonged muscle paralysis after succs

53
Q

phenylephrine is used for what?

A

to dilate pupil. 2.5% causes less htn then 10%, but will aggravate BP in some

54
Q

____ and ____ are cholinergic drugs used to constrict pupil. bradycardia and acute bronchospasm have been reported

A

pilocarpine and acetylcholine

55
Q

what is timolol used for and what does systemic absorption cause?

A

used for glaucoma. systemic absorption can cause bradycardia, bronchospasm, and CHF exacerbation

56
Q

flomax has selective alpha ____ properties. it binds to the iris dilator muscles, affecting iris dilation and complicates cataract surgery. Iris remains floppy even after ____ off therapy

A

antagonistic.

7-28days

57
Q

if a patient has stage 3 htn (sys>180 or dias >110), reschedule until _____ of antihypertensive rx

A

two weeks

58
Q

critical result of urea nitrogen is > ____

A

104

59
Q

which block is utilized when complete akinesis of eyelids is desired

A

facial nerve block

60
Q

what muscle does the facial nerve block block?

A

orbicular oculi

61
Q

____ ____ blocks entire trunk of facial nerve , so you can expect what?

A

nadbath rehman
expect lower facial droop post for several hours.
injection is close to vagus and glossopharyngeal nerve.. associated with vocal cord paralysis, laryngospasm, dysphagia, and resp distress

62
Q

which block is associated with proptosis and subconjunctival ecchymosis? downward displacement

A

RBB

63
Q

arterial injection of ___ leads to high brain levels via retrograde flow in internal carotid artery. CNS excitation and seizure possibility, usually transient d/t redistribution

A

RBB

64
Q

RBB complications: injection into optic nerve sheath leads to ____ amaurosis

A

contralateral (complete lack of vision)

65
Q

RBB complications: injection into optic nerve sheath will manifest how neurologically ?

A

obtundation

66
Q

RBB complications: injection into optic nerve sheath leads to resp arrest that occurs within ___ min and resolves within ____

A

20, hour

67
Q

which block can cause a total spinal

A

RBB into optic nerve sheath - vascular collapse from depressant effect on the medulla

68
Q

which block can cause post=op strabismus from anesthetic myotoxicitiy?

A

RBB

69
Q

how does post-op strabismus from anesthetic myotoxicitiy present?

A

vertical double vision the day after surgery, worsening over 2mo.

70
Q

post-op strabismus is characterized by tight ___ ___muscle

A

inferior rectus

71
Q

how does peribulbar blockade compare to RBB

A
  • safer
  • multiple injections made around eye without entering the muscular cone
  • longer onset time (9-12 min)
  • less complete akinesia
  • globe perf have been reported
  • increased likelihood of ecchymosis
72
Q

for a ruptured globe, ____ anesthesia is the only choice!!

A

GETA

73
Q

vitroeretinal procedures — air bubble injected into the eye to tamponade the detached retina into the globe —- N20 should be d/c’d ___min before placement of sulfur hexafluoride and avoided for __ to __ days after

A

15min, avoid 7-10days.

74
Q

____ persists for weeks so avoid n20 for one month after instillation of this agent

A

perfluoropropane (C3F6)

75
Q

strabismus surgery is done to resection (____) and recession (____) opposite muscle

A

shorten, lengthen

76
Q

what surgery is associated with mh

A

strabismus

77
Q

should you use succs for a strabismus surgery?

A

no. 16% of these patients have a muscle disorder - dystrophic myotonia or myotonia atrophic inherited muscle wasting disease…. also associated with MH

78
Q

what surgeries are associated with diabetic retinopathy, high myopia, complicated intracapsular lens extraction?

A

retinal detachment

79
Q

what kind of anesthetic can be used for retinal detachment and virteal surgery?

A

RBB or general, oett(rae), or LMA

80
Q

which anatomic structure is responsible for formation of aqueous humor?

A

ciliary body

81
Q

deep inhalation and IV anesthesia ____ IOP

A

decrease

82
Q

ketamine and hypercarbia ___ IOP

A

increase

83
Q

what agent is used for the tx of glaucoma?

A

echothiophate

84
Q

aqueous humor is produced by ____ and reabsorbed by ____

A

produced by ciliary process (posterior chamber) and reabsorbed by canal of schlemm (ant chamber)

85
Q

brady with OCR is ___ likely to occur with repeated stim

A

less

86
Q

traction of the ____ ____ muscle is associated with OCR

A

medial rectus

87
Q

which 3 things are part of the middle layers of eye

A

choroid - ciliary - iris. (NOT sclera!)

88
Q

orbital muscle cranial nerve VI?

A

lateral rectus

89
Q

eye adduction muscle and CN?

A

medial rectus CN III

90
Q

OCR afferent CN ___ which is ___, and efferent CN ___ which is ____

A

afferent CN V which is trigeminal, and efferent CN X which is vagus

91
Q

which two drugs decrease aqueous humor production

A

acetazolamide and timolol

92
Q

which drug promotes aqueous humor drainage

A

echo

*remember this drug prolongs succs and ester LA

93
Q

superior rectus, inferior rectus, medial rectus, inferior oblique are CN __, lateral rectus is CN ___, and superior rectus is CN___

A

superior rectus, inferior rectus, medial rectus, inferior oblique are CN 3 (oculomotor)
lateral rectus is CN VI (abducens)
and superior rectus is CN IV (trochlear)

APA3 levi 2019 S.Horvath (16 decks)

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