Anesthetics & Dyes Flashcards

1
Q

1 dye in clinic

A

Fluorescein sodium

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2
Q

Fluorescein sodium absorbs __ and emits ____.

A

Absorbs blue (493nm) and emits green (520nm)

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3
Q

Clinical uses of fluorescein sodium

A

Topical & oral & intravenous

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4
Q

Fluorescein sodium is used topically for

A

Evaluating ocular surface integrity, tear film visualization and analysis, CL fitting, lacrimal drainage evaluation , and Goldmann

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5
Q

Optics of fluorescein angiography

A

Only blue light is allowed through the excitation filter

Only green light is allowed to pass through the barrier filter

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6
Q

Fluorescein injection have rare cases of death due to

A

Anaphylaxis

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7
Q

Fluorescein can be consumed orally to perform

A

Angiography

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8
Q

Factors affecting intensity of fluorescence

A
  • concentration
  • pH
  • wavelength of the exciting light
  • thickness of the layer of fluorescein
  • presence of substances that suppress fluorescence (quenching)
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9
Q

Decreased fluorescence at high concentrations is due to

A

Quenching

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10
Q

Intensity of fluorescein sodium increases with (concentration)

A

Increasing concentration up to 0.001% , above which it diminishes

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11
Q

Intensity of fluorescein sodium increases with (pH)

A

Rising pH until pH 8 after which there is a decrease

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12
Q

Intensity of fluorescein sodium increases with (wavelength)

A

Peak emission from fluorescein is achieved with exciting light of 493 nm

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13
Q

Intensity of fluorescein sodium increases with (thickness of the layer)

A

Increases linearly up to a point with the thickness of the fluorescein solution

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14
Q

Intensity of fluorescein sodium is suppressed by

A

Topical anesthetics and other drugs

Other fluorescein molecules when at high concentration (self quenching)

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15
Q

How does hyper fluorescence happen on the ocular surface

A
  • fluorescein pooling
  • ingress around cells
  • uptake by damaged cells
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16
Q

Ingress of fluorescein sodium around cells is caused by

A

Disruption of tight junctions at the epithelial surface

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17
Q

Higher pH of intraepithelial environment may contribute to

A

Greater fluorescence

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18
Q

Fluorescein may enter and become concentrate within damaged epithelial cells, but it

A

Does not stain/bind

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19
Q

Increased concentration of fluorescence within damaged cells my contribute to

A

Greater fluoresce

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20
Q

Fluorescein can enter the epithelium only where

A

There is interrupted continuity of the epithelial surface / damaged epithelium

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21
Q

Fluorescein penetrates

A

Intercellular spaces and concentrates inside damaged cells

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22
Q

What does fluorescein bind to during staining

A

NOTHING

Staining is transient

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23
Q

What is the dye of choice for evaluation of corneal surface integrity

A

Fluorescein sodium

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24
Q

Filter used to excite fluorescein sodium dye

A

Cobalt blue filter making lesions appear vivid green

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25
Q

Filter for fluorescein sodium enhances visualization of stained areas

A

Yellow barrier filter

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26
Q

What to do if fluorescein doesn’t stain after the 1st instillation

A

Apply every 3-5 min over a 30 min interval for a total of 6-10 instillations

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27
Q

Clinical significance of fluorescein reveal after sequential instillation

A

Associated with cl intolerance

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28
Q

Seidel sign

A

Flow of aqueous through a defect in the globe visualized with the use of fluorescein

Aqueous could come from anterior chamber

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29
Q

Fluorescein no wetting /negative staying

A

Absence of tears on the corneal surface appear as dark regions of non fluorescence

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30
Q

How is fluorescein sodium used for CL fitting

A

Rigid lens alignment with corneal surface

Hypofluorescence in areas of greater contact

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31
Q

High molecular weight fluorescein maybe be used in conjunction with

A

Soft contact lenses to prevent penetration of the dye into the lens matrix

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32
Q

Fluorescein sodium used in lacrimal system evaluation

A

TBUT

Jones test

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33
Q

TBUT with fluorescein sodium

A

The time interval between the last complete blink and the first randomly distributes dark spot (nonwetting) in the tear film

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34
Q

TBUT indication of dry eye

A

Decreased break up time

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35
Q

Jones test with fluorescein sodium measures

A

Patency of the lacrimal drainage system

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36
Q

How is jones test performed

A

Evaluated by instilling NaFl into the eye and then observing for its presence in the nose

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37
Q

Jones test is useful in evaluating symptoms of

A

Wet eye

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38
Q

Norm for TBUT

A

10 seconds

6-10 is moderate

5 is severe

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39
Q

Applanation Tonometry

A

Fluorescein permits visualization of the applanated area

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40
Q

What if applanation Tonometry is done with out fluorescein?

A

It will underestimate IOP because of decreased visibility of the apex of the tear meniscus

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41
Q

Topical adverse reactions of fluorescein sodium

A

Mild transient stinging

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42
Q

Systemic adverse reaction of fluorescein sodium

A

Rare cases of anaphylaxis that may be fatal

43
Q

Fluorescein sodium is highly susceptible to

A

Bacterial contamination

Especially pseudomonas aeruginosa

44
Q

An iodine derivative of fluorescein

A

Rose bengal

45
Q

Rose Bengal binds to/ stains

A
  • mucus in the tear film
  • epithelium with disturbed glycocalyx
  • devitalized (dead tissue)
46
Q

Is Rose bengal a vital dye?

A

No

47
Q

Rose bengal is photoreactive and generates

A

Singlet oxygen when exposed to light which is highly toxic got cells

48
Q

Rose bengal will instantly kill and stain

A

Unprotected cells exposed to it

49
Q

A cotton candy like structure that the epithelial surface binds mucin onto the ocular surface

A

Glycocalyx

50
Q

Toxicity of rose bengal can be blocked by an

A

Intact glycocalyx

51
Q

What’s a vital dye?

A

A non toxic dye that satins devitalized tissue

Used to determine live/dead cell ratio

52
Q

Why is rose bengal not a vital dye?

A

It’s toxic and will kill live healthy cells if there is a compromised glycocalyx

53
Q

Rose bengal is best performed by

A

Using 1% sol.

Waiting a few min. before examination with both white and red free light

54
Q

If you instill rose bengal and then fluorescein

A

Subtle areas will be highlighted by surrounding flourescein and use of blue light

55
Q

Dye of choice for assessment of conjunctival staining

A

Rose bengal

56
Q

Temporal conjunctival rose bengal staining differentiates

A

Sjorgren syndrome from KCS

57
Q

Clinical uses of rose bengal (3)

A
  • dry eye syndrome
  • H. Simplex dendritic ulcers
  • H. Zoster pseudodendrites
58
Q

Swollen epithelial cells that stain minimally with fluorescein and vividly with rose bengal

A

H zoster pseudodendrites

59
Q

Stains with flourescein along length of lesion, but the raised edges stain negatively

A

H simplex dendritic ulcers

60
Q

Rose bengal is taken up by the swollen epithelial cells at the ulcers border and terminal bulbs

A

H. Simplex dendritic ulcers

61
Q

Contraindication of rose bengal

A

Toxic to H. Simplex

Don’t use prior to culturing suspected hermetic lesions

62
Q

Side effects to rose bengal;

A

Stains skin/clothes

Burns

63
Q

Stains in an identical fashion to rose bengal

A

Lisasmine green

64
Q

Is lissamine green a vital dye ?

A

Yes

Stains membrane damages or devitalized cells

65
Q

Topical anesthetic MOA

A

Prevents generation and conduction of nerve impulses

66
Q

Efficacy of topical anesthetics is determined by

A

Their ability to suppress corneal sensitivity

67
Q

What happens if you combine two or more topical anesthetics

A

Does NOT produce an additive effect, but does increase the risk of side effects

68
Q

All topical anesthetics are

A

Esters

69
Q

Amide anesthetics are

A

Less toxic

70
Q

Ocular toxicity of topical anesthetics

A

Desquamation of corneal epithelium
Retards epithelial mitosis and migration

Inhibits epithelial mitosis and migration
Mild stinging

71
Q

Diffuse SPK may occur following a single drop of topical anesthetic due to

A

Corneal toxicity

72
Q

Local hypersensitivity reactions of topical anesthetics

A
  • Allergy can develop die to repeat exposure (glaucoma pts)
  • mild blepharoconjunctivitis
  • little cross reactivity among topical anesthetics
73
Q

How to treat blepharoconjunctivitis

A

Cold compresses and topical decongestants

74
Q

Systemic hypersensitivity reactions to topical anesthetics

A

No life threatening reactions reported

75
Q

Self administration of topical anesthetics

A
  • adverse effects due to corneal toxicity
  • permanent vision loss due to corneal scarring
  • health care workers have access to them
76
Q

Dispensing of topical anesthetics to patients

A

NEVER DISPENSE

77
Q

When to consider topical anesthetic abuse

A

Differential diagnosis of unexplained chronic persistent corneal erosions

78
Q

Clinical features of anesthetic abuse

A
  • intense pain, severe tearing, photophobia
  • There is a vicious cycle of pain, leading to more frequent use of drops, causing motor damage and pain
  • epithelial defect
  • ring shape opacification
  • stroma infiltrate
  • hypopyon
  • contact dermatitis
79
Q

Most of the patients abusing anesthetics had

A

Epithelial defects

80
Q

Topical anesthetics use for short term under close supervision is highly controversial

A

Alternative methods are equally effective, less toxic and less prone to abuse

81
Q

Pregnancy contraindications of topical anesthetics

A

All are pregnancy category C

82
Q

Cross sensitivity between topical anesthetics

A

Substitute different topical anesthetics because there is little cross sensitivity

83
Q

topical anesthetics for dry eye testing

A

Do not instill a topical anesthetic prior to checking for ocular surface disease

Epithelial toxicity can confuse clinical picture

84
Q

Instillation of a topical anesthetic prior to obtaining a culture specimen may

A

Decrease yield because anesthetics are toxic to microorganisms

85
Q

Which topical anesthetic is the least toxic

A

Proparacaine

86
Q

Topical anesthetics precaution during pachymetry

A

May cause transient corneal swelling

Wait 5 min after instillation prior to performing pachymetry for accurate measurements

87
Q

Topical anesthetics could cause perforating injuries

A

Endothelial toxicity if anesthetic enters AC

88
Q

Commonly used anesthetics

A

Proparacaine
Tetracaoine
Benoxinate

89
Q

Potency among the topical anesthetics proparacaine tetracaine and benoxinate

A

No significant difference in potency

90
Q

Benoxinate is only availed

A

As 0.4% soln combined with flourescein for Tonometry

91
Q

Benoxinate contraindications

A

Same as all topical anesthetics

92
Q

Benoxinate side effects

A

Mild stinging
Epithelial desquamation (less than proparacaine)
Little cross sensitivity with tetracaine or proparacaine

93
Q

Advantage of benoxinate

A

Less desquamation

94
Q

Benoxinate during applanation Tonometry

A

Rapid onset and brief duration

Minimal quenching of fluorescein

Good comfort

95
Q

Quenching

A

Process that to a reduction in fluorescence

96
Q

Proparacaine is commercially available in

A

0.5% solution

97
Q

What if proparacaine looks a faint yellow ?

A

Don’t use

It should be stored tightly, opaque and refrigerated container or retard degradation

98
Q

Proparacaine has extremely low systemic toxicity

A

Poor penetration of the conjunctiva and cornea

99
Q

Least bacteriocidal of the topical anesthetics and should be used prior to obtaining cultures

A

Proparacaine

100
Q

Least painful anesthetic

A

Proparacaine

101
Q

Proparacaine quenching of fluorescein

A

Greater than benoxinate

102
Q

Corneal toxicity of proparacaine

A

Low

Greater than benoxinate less than tetracaine

103
Q

Contraindication of proparacaine

A

Same as all anesthetics

104
Q

Typical allergic reaction of proparacaine

A

Contact beloharoconjunctivitis, consisting of conjunctival hypermedia, swelling of the eyelids, lacrimation and itching