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PCO3 > Test 3 > Flashcards

Test 3 Flashcards

1
Q

When and who introduced intravenous applications?

A

Novorty and Alvis in 1961.

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2
Q

What is FAN and what is it used for?

A

Fluorescein Angiography and it is used to assess choroid, RPE, Retina ONH and vascular abnormalities. Also assesses the anterior segment blood flow and aqueous flow.

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3
Q

How is FAN performed?

A

requires injection of Sodium fluorescein (NaFl) and uses fundus photos to assess NaFl flow.

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4
Q

REVIEW: What do retinal capillary beds do?

A

Supplies the inner 2/3 of retina. it has tight junctions, therefor no leaking that leads to an inner blood- retina barrier.

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5
Q

What do choriocapillaries do?

A

the supply outer 1/3 of the retina. these are fenestrated and thus NaFl permeates into extracellular spaces.

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6
Q

where are choriocapillaries located?

A

beneath the RPE.

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7
Q

What blocks the entrance of blood or NaFl entrance into retina? THE OUTER blood-retinal barrier

A

Burch’s membrane, Zonula adherens and RPE.

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8
Q

What is special about the RPE that it wont show the fluorescein?

A

it has melanin that does not show the choroidal flush underneath. This is the same for choroidal nevus.

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9
Q

How is the circulation time for NaFl

A

it is very fast and it reaches the choriocapillaries before it reaches the Central retinal artery. This means there will be a choroidal flush before a bright CRA, if this is delayed we must see why.

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10
Q

what is the route of input of blood in the retina?

A

CRA–> arterioles –> capillaries –> venules –> CRV. none of these are supposed to leak!

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11
Q

what is a disease that might cause fluorescein to leak out?

A

CRAO (central retinal arterial occlusion) this causes fluorescein to leak out and the ONH will appear less bright.

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12
Q

What is the output route in retina?

A

vortex veins and CRV –> superior/ inferior ophthalmic veins –> cavernous sinus –> venous plexus –> facial vein –> jugular

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13
Q

what is the inner- blood retina barrier?

A

retinal capillary beds that have tight junctions of endothelial cells, (minor roles from basement membranes and pericytes)

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14
Q

Are the major choroidal vessels permeable to NaFl?

A

NO because they do not have fenestrations. It is the chorioCAPILLARIES that are permeable to NaFl.

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15
Q

What is the order of membranes from choriocapillaries to the outer limiting membrane of retina?

A

fenestrated capillaries –> burch’s membrane –> basal infoldings –> melanin granules with in RPE –> tight junctions –> outer segment –> inner segment –> outer limiting membrane.

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16
Q

What are some of the diseases FAN can diagnose?

A

macular lesions, central serous choroidopathy, diabetic retinopathy etc.

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17
Q

where is NaFl injected into in the arm?

A

it is injected into an antecubital vein (a superficial vein in the arm ) and this circulates to the eye. The NaFl then binds to albumin and RBC (70-85% binds) Slide 19 of FAN 1 ppt has pictures)

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18
Q

At what wavelength is NaFl excited?

A

465nm ( IMPORTANT: excited by shorter wavelength )

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19
Q

what wavelength does fluorescein (NaFl) emit?

A

525 nm (IMPORTANT: excited by shorter wavelength and emits longer wavelength)

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20
Q

what is NaFl metabolized to?

A

a weak fluorescent conjugate that binds to plasma proteins less.

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21
Q

How long does it take for the dye to appear in the CRA? (transition time)

A

10-15 secs. Remember: the choroidal flush occurs 1 sec before CRA appearance.

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22
Q

What sort of light does NaFl absorb?

A

blue light between 456-490 nm so we have to put blue filter on retinal camera

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23
Q

what color does NaFl appear to be on a broad spectrum illumination?

A

bright yellow-green (broad spectrum means white light I believe) and when you use blue light the bright yellow-green color intensifies dramatically

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24
Q

How does pH affect the intensity of fluorescence?

A

It affects the intensity. The maximum intensity occurs at pH 7.4 (the same as our tears, this is why we use saline solution for TBUT). FAN needs a higher pH for stability so it is adjusted to 8- 9.8

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25
Q

What concentration is fluorescence detected in?

A

0.1% - 0.0000001% (6 0s after decimal)

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26
Q

what color is NaFl in concentrated or powdered form?

A

orange-red.

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27
Q

what is the normal adult dosage for NaFl?

A

500 mg packed in either 5ml of 10% or 2 ml of 25% (1000 x 0.10(%) = 100 x 5(ml) = 500 (mg) OR 1000x .25 (%) = 250 x2 (ml)= 500 mg

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28
Q

what is the pediatric dosage of NaFl ?

A

35mg per 10lbs of body weight. Know how this would be in a calculation because I think she will form a qs like that.

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29
Q

What would be the amount of fluorescence given to an 70 lb kid?

A 
70/10 =  7 x 35mg  = 245 mg 
what would this be in ml? 
(1000 x .10 = 100 
245/100 = 2.45ml of 10%  OR 1000 x .25 = 250
245/ 250= 0.98ml of 25%)
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30
Q

what filter is used to selectively photograph the retinal and choroidal circulation?

A

a barrier filter ( blue and yellow green filters)

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31
Q

what prevents the staining of the retinal substrate?

A

inner and outer blood-retinal barriers

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32
Q

what is the difference between healthy retinal vessels and healthy choriocapillary vessels

A

retinal vessels do not leak because they are not fenestrated and choriocapillaries are so they do leak and cause a flush (look at different pictures and know the difference)

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33
Q

what does a healthy macula look like in FAN?

A

dark because dense RPE and xanthophyll mask choroidal flush

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34
Q

Which veins separate choroidal circulation and retinal circulation?

A

dye enters the eye through the ophthalmic artery, then goes to choroidal circulation through the short posterior ciliary artery (SPCA) and retinal circulation through the central retinal artery (CRA)

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35
Q

what is the prearterial phase of FAN

A

a very quick phase where choroidal circulation is filled but no dye has reached the retinal arteries (0-10secs after injection)

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36
Q

what is the arterial phase of FAN?

A

1 sec after prearterial phase. lasts from first appearance of dye in arteries till whole artery is filled 10-12 secs ( so CRA is white but CRV is black) picture in lect. 1 slide 21

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37
Q

what is the capillary phase in FAN?

A

complete filling of arteries and capillaries this is especially visible around ONH 13sec

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38
Q

Early venous phase of the FAN also called lamellar stage

A

arteries, capillaries are filled and lamellar flow in veins where the central lumen (middle of vein) is dark but walls have fluorescence so is bright 14-15sec

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39
Q

Mid venous phase of FAN.

A

veins nearly filled 16-17sec

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40
Q

late venous phase of FAN

A

veins completely filled and arteries begin to empty 18-20secs this is when dye starts to be removed by the kidneys and arteries start to get re-perfused with blood

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41
Q

What are all the stages of FAN administration? How long does each stage last?

A 
Pre-arterial (0-10secs)
posterior ciliary arteries fill at 9.5 secs
choroidal flush at 10secs
arterial (10-12secs) 
capillary (13secs) 
Early-venous ( 14-15secs) 
Mid venous (16-17secs) 
late venous (18-20secs) 
retrofluoresece / late fluorescence (5min)
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42
Q

Within the vessels where si blood flow faster?

A

at the center than in the walls, this is is why we see laminar flow (center is dark but walls are bright)

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43
Q

What are some contraindications of this dye?

A

kidney failure - can’t remove the dye

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44
Q

what can an arterial stage delay of 2-30 secs indicate?

A

cardiac disease, cardiac output, blood viscosity issues and vessel caliber

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45
Q

what can choroidal flush delay indicate?

A

diseases such as decreased cardiac output, congestive heart failure, hypertension, giant cell arteritis

46
Q

what does a patchy choroidal flush / filling indicate?

A

giant cell arteritis

47
Q

What is autofluorescence or pseudo-fluorescence?

A

something that makes the structures look bright before the injection Ex: drusens we can tell the difference by using the different filters

48
Q

What are some signs of temporal arteritis in elderly pts?

A

headache, sudden onset VA loss, jaw pain or anorexia

49
Q

what is FAZ ?

A

Foveal avascular zone- looks dark (along with macula) because there are no capillaries here.

50
Q

What are causes of HYPERfluorescence?

A

1) transmission
2) pooling
3) leakage
4) staining

51
Q

what are transmission hyperflourescence?

A

window defects and atrophy or absence of RPE. there will eb eary hyperfluorescence that increases in intensity and then suddenly fades without change in size or intensity
EX: dry end stage ARMD

52
Q

what is pooling hyperfluorescence?

A

hapens due to the breakdown of OUTER blood retinal barrier (RPE, Burch’s membrane, Zonula occludens). A bright mushroom bomb shaped spot that inc. in size and intensity in the subretinal space (CSR)
EX: serous detachment of RPE or Retina (slide 40 -41)

53
Q

What is leakage hyperfluorescence?

A

caused by abnormal retinal vessels, CNV, breakdown of INNER blood retinal barrier
EX: IRMA, NVD, NVE, microaneurysms, vein occlusions, tumor feeder vessels

54
Q

What is staining hyperfluorescence?

A

prolonged NaFl retention

ex: exposed retina, fibrous tissue, drusens, sclera, ONH, vascular occlusion, malignant melanoma (slide 42)

55
Q

What causes hypofluorescence?

A

optical obstruction or inadquate perfusion

56
Q

what can cause inadequate perfusion that leads to hypofluorescence/

A

blockage of retinal fluorescence, blockage of background choroidal fluorescence or filling defects

57
Q

what are optical barriers that lead to hypofluorescence?

A

pigment or blood

58
Q

what are some examples of filling defects for hypofluorescence?

A

capillary closure and retinal vascular occlusions.

59
Q

what causes blocked fluorescence?

A

most commonly because of blood but also lipid exudate, lipofuscin, xanthophyll pigment or melanin pigment
EX: pre retinal lesions (blood),

60
Q

What does a pre-retinal heme do?

A

blocks visibility of both choroidal and retinal vasculature. EX: diabetic retinopathy

61
Q

where does a sub-retinal heme occur?

A

under retina and only obscures choroidal circulation

62
Q

what are some deep retinal lesions that could lead to inadequate perfusion

A

intraretinal heme, and hard exudates

63
Q

How is loss of vascular bed occur?

A

severe myopic degeneration –> can lead to filling defects (hypo)

64
Q

how is oral fluorescein angioscopy done?

A

1gm of fluorescein solution mixed with 200 ml of liquid. concentration peaks in 30 min.

65
Q

what is the purpose of oral FAN?

A

to study disorders characterized by late leakage of dye eg: cystoid macular edema.
to document disorders characterized by late leakage EX: RPE detachment, cental serous choroidopathy, optic disc edema
If you cannot outline critical vascular details needed for photocoagulation.
Side effects are rare

66
Q

what are the side effects of IV FAN

A

10% of pts. have adverse reactions. most common is nausea and sometimes vomiting
post injection nausea may be related to NaFl concentration and speed of injection (slower and lower is better)
50 mg promethazine (Phenergan) c PO 1 hr before FA decreases nausea incidence
laryngeal edema, urticaria pruritus
bronchospasms (less common)
temporary urine and skin discoloration
headache
GI distress and vomiting

67
Q

what are adverse side effects of FA?

A 
extravasation and skin necrosis 
syncope
hypotension
cardiac arrythmia
signs and symptoms of hypersensitivity 
basilar artery ischemia 
thrombophlebitis
cardiac arrest 
death: 1/250000
68
Q

what are some more contraindications of FA?

A 
hypersensitivity to dye, iodine or shellfish 
  keep epipen in office just incase. 
kidney impairment
unstable angina
1st trimester pregnancy
69
Q

What is indocyanine green?

A

dye that is no toxic to living ENDOTHELIAL cells. stains diseased or dead endothelial cells. used for evaluation of donor cornea viability
ICG angiography to observe vasculature of the human choroid.

70
Q

who is indocyanine green used for?

A

molecule absorbs and emits light into IR spectrum better for Pts. with medical opacities or a lot of pigment. good for enhancing tissue in the choroid like CNVM (Choroidal neovascular membranes)

71
Q

contraindications of ICG

A

allergic to iodine or shellfish. ICG is exerted by the liver so a patient with liver disease.

72
Q

what does ICG bound to?

A

albumin protein 98% so there is very little leakage from choriocapillaries

73
Q

what is the technique to ICG?

A

similar to FA but image can be taken up to 45 mins.

74
Q

why is ICG better for patients with melanin pigment or media opacities?

A

ICG absorbs and emits IR range. Infra red is scattered less and allows better penetration of opacities

75
Q

how far is the Central field?

A

30degrees
it is a highly developed area of the retina responsible for detailed vision 60-70% of fiber optics are here EX: reading, color vision, details, recognizing faces

76
Q

peripheral field

A

specialized in detection of motion signals

ex: driving, enables safe navigation around our environment

77
Q

what is the flow of blood from heart to eye?

A

aorta –> common carotid –> internal carotid –> ophthalmic artery –> central retinal and short posterior

78
Q

what is a papillomacular bundle?

A

collection of retinal ganglion cells that carry the information from the macula (the central retina) to the optic nerve and on to the brain. defcts can cause central vision defects

79
Q

what is the visual pathway?

A

Retinal nerve fibers –> optic nerve –> optic chiasm –> optic tract –> lateral geniculate body –> optic radiations –> occipital cortex

80
Q

what is a neurilemma

A

schwann sheath that surrounds axons of the neuron to protect. NF may regenerate if the prikaryon is not damaged and neurolemma is still intact.

81
Q

how thick is the NF?

A 
2-10um and 50 mm long 
intraocular= 1mm 
intraorbital = 30 mm 
intracanalicular = 6-9 mm 
intracranial = 10mm
82
Q

where does CRA enter nerve?

A

10 mm behind eyeball

83
Q

what separates the sphenoid and posterior ethmoidal sinus from ONH?

A

papyricea

84
Q

what is different about the dura mater on the intraorbital nerve and intracranial nerve?

A

intraorbital covered by all 3 layers, intra cranial only covered by pia mater

85
Q

what supplies the optic chiasma

A

Intercranial artery that runs below and lateral

86
Q

what does the chiasma lie over?

A

diaphragma sella

87
Q

what percent of fibers cross at the chiasm?

A

55% of nasal FIBERS (temporal visual fields )

88
Q

what is the anterior wall of the third ventricle?

A

the chiasm

89
Q

what are the anatomical variations of the chiasm?

A

central 80% - lies directly over sella turica and tumors involve chiasm first.
prefixed - 10% lies more anteriorly and affects optic tract
post-fixed- 10% lies more posteriorly and will affect optic nerve

90
Q

how are the macular fibers arranged in the optic chiasma?

A

some are crossed and some are uncrossed (temporal) nasal half go central superior and posterior

91
Q

how are superior fibers located in the optic tract?

A

superior nasal (crossed) and superior temporal (uncrossed) run medially

92
Q

how much of the LGB does the macular fibers occupy?

A

2/3 posteriorly ( dorsal)

93
Q

how id the LGB divided?

A

6 layers of neurons alternating with white matter

94
Q

what layers of LGB is magno cellular (temporal)

A

1-2

95
Q

what layers are parvocellular?

A

3-6

96
Q

where do the fibers from ipsilateral temporal retina end in the LGB?

A

2,3,5

97
Q

where do fibers from the contralateral nasal retina end in the LGB?

A

1,4,6

98
Q

in the optic radiations where do the superior fibers go through?

A

directly through the parietal lobe( these serve inferior field)

99
Q

where do the inferior fibers of the optic radiations go through?

A

Meyer’s loop that is around the anterior tip of temporal horn of lateral ventricle and then into the temporal lobe.. THIS SERVES the superior field

100
Q

what happens if there is an issue with meyer’s loop?

A

contralateral superior quadrantanopsia (pie in the sky)

101
Q

what happens if there is a defect on the parietal lobe?

A

inferior quadrantopsia (pie on the floor)

102
Q

what if there is a more posterior defect of the optic radiations?

A

same in both eyes defect of VF.

103
Q

what divides the primary visual cortical area?

A

calcarine fissure

104
Q

where is the visuosensory area located?

A

striate area 17

105
Q

where is the visuopsychic area located

A

18 and 19

106
Q

on the VF island where is the blind spot located?

A

15 degrees temporal and 1.5 degrees below central fixation point

107
Q

what are the different sorts of scotomas?

A

central
hemianopic
peripheral and pareacentral

108
Q

what happens in a lesion of the optic nerve?

A

near pupillary reflex still present NO direct or consensual has APD

109
Q

How far away does the tangent screen have to be placed?

A

! m away with target at eye level, if there is a VF defect, move back 1 m

110
Q

what is a medication that causes central VF loss?

A

Plaquenil

111
Q

what is the standard VF exam?

A

humphrey

PCO3 (3 decks)

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