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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
What concentration is fluorescence detected in?
0.1% - 0.0000001% (6 0s after decimal)
26
what color is NaFl in concentrated or powdered form?
orange-red.
27
what is the normal adult dosage for NaFl?
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
28
what is the pediatric dosage of NaFl ?
35mg per 10lbs of body weight. Know how this would be in a calculation because I think she will form a qs like that.
29
What would be the amount of fluorescence given to an 70 lb kid?
``` 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%) ```
30
what filter is used to selectively photograph the retinal and choroidal circulation?
a barrier filter ( blue and yellow green filters)
31
what prevents the staining of the retinal substrate?
inner and outer blood-retinal barriers
32
what is the difference between healthy retinal vessels and healthy choriocapillary vessels
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)
33
what does a healthy macula look like in FAN?
dark because dense RPE and xanthophyll mask choroidal flush
34
Which veins separate choroidal circulation and retinal circulation?
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)
35
what is the prearterial phase of FAN
a very quick phase where choroidal circulation is filled but no dye has reached the retinal arteries (0-10secs after injection)
36
what is the arterial phase of FAN?
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
37
what is the capillary phase in FAN?
complete filling of arteries and capillaries this is especially visible around ONH 13sec
38
Early venous phase of the FAN also called lamellar stage
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
39
Mid venous phase of FAN.
veins nearly filled 16-17sec
40
late venous phase of FAN
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
41
What are all the stages of FAN administration? How long does each stage last?
``` 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) ```
42
Within the vessels where si blood flow faster?
at the center than in the walls, this is is why we see laminar flow (center is dark but walls are bright)
43
What are some contraindications of this dye?
kidney failure - can't remove the dye
44
what can an arterial stage delay of 2-30 secs indicate?
cardiac disease, cardiac output, blood viscosity issues and vessel caliber
45
what can choroidal flush delay indicate?
diseases such as decreased cardiac output, congestive heart failure, hypertension, giant cell arteritis
46
what does a patchy choroidal flush / filling indicate?
giant cell arteritis
47
What is autofluorescence or pseudo-fluorescence?
something that makes the structures look bright before the injection Ex: drusens we can tell the difference by using the different filters
48
What are some signs of temporal arteritis in elderly pts?
headache, sudden onset VA loss, jaw pain or anorexia
49
what is FAZ ?
Foveal avascular zone- looks dark (along with macula) because there are no capillaries here.
50
What are causes of HYPERfluorescence?
1) transmission 2) pooling 3) leakage 4) staining
51
what are transmission hyperflourescence?
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
what is pooling hyperfluorescence?
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
What is leakage hyperfluorescence?
caused by abnormal retinal vessels, CNV, breakdown of INNER blood retinal barrier EX: IRMA, NVD, NVE, microaneurysms, vein occlusions, tumor feeder vessels
54
What is staining hyperfluorescence?
prolonged NaFl retention | ex: exposed retina, fibrous tissue, drusens, sclera, ONH, vascular occlusion, malignant melanoma (slide 42)
55
What causes hypofluorescence?
optical obstruction or inadquate perfusion
56
what can cause inadequate perfusion that leads to hypofluorescence/
blockage of retinal fluorescence, blockage of background choroidal fluorescence or filling defects
57
what are optical barriers that lead to hypofluorescence?
pigment or blood
58
what are some examples of filling defects for hypofluorescence?
capillary closure and retinal vascular occlusions.
59
what causes blocked fluorescence?
most commonly because of blood but also lipid exudate, lipofuscin, xanthophyll pigment or melanin pigment EX: pre retinal lesions (blood),
60
What does a pre-retinal heme do?
blocks visibility of both choroidal and retinal vasculature. EX: diabetic retinopathy
61
where does a sub-retinal heme occur?
under retina and only obscures choroidal circulation
62
what are some deep retinal lesions that could lead to inadequate perfusion
intraretinal heme, and hard exudates
63
How is loss of vascular bed occur?
severe myopic degeneration --> can lead to filling defects (hypo)
64
how is oral fluorescein angioscopy done?
1gm of fluorescein solution mixed with 200 ml of liquid. concentration peaks in 30 min.
65
what is the purpose of oral FAN?
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
what are the side effects of IV FAN
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
what are adverse side effects of FA?
``` extravasation and skin necrosis syncope hypotension cardiac arrythmia signs and symptoms of hypersensitivity basilar artery ischemia thrombophlebitis cardiac arrest death: 1/250000 ```
68
what are some more contraindications of FA?
``` hypersensitivity to dye, iodine or shellfish keep epipen in office just incase. kidney impairment unstable angina 1st trimester pregnancy ```
69
What is indocyanine green?
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
who is indocyanine green used for?
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
contraindications of ICG
allergic to iodine or shellfish. ICG is exerted by the liver so a patient with liver disease.
72
what does ICG bound to?
albumin protein 98% so there is very little leakage from choriocapillaries
73
what is the technique to ICG?
similar to FA but image can be taken up to 45 mins.
74
why is ICG better for patients with melanin pigment or media opacities?
ICG absorbs and emits IR range. Infra red is scattered less and allows better penetration of opacities
75
how far is the Central field?
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
peripheral field
specialized in detection of motion signals | ex: driving, enables safe navigation around our environment
77
what is the flow of blood from heart to eye?
aorta --> common carotid --> internal carotid --> ophthalmic artery --> central retinal and short posterior
78
what is a papillomacular bundle?
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
what is the visual pathway?
Retinal nerve fibers --> optic nerve --> optic chiasm --> optic tract --> lateral geniculate body --> optic radiations --> occipital cortex
80
what is a neurilemma
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
how thick is the NF?
``` 2-10um and 50 mm long intraocular= 1mm intraorbital = 30 mm intracanalicular = 6-9 mm intracranial = 10mm ```
82
where does CRA enter nerve?
10 mm behind eyeball
83
what separates the sphenoid and posterior ethmoidal sinus from ONH?
papyricea
84
what is different about the dura mater on the intraorbital nerve and intracranial nerve?
intraorbital covered by all 3 layers, intra cranial only covered by pia mater
85
what supplies the optic chiasma
Intercranial artery that runs below and lateral
86
what does the chiasma lie over?
diaphragma sella
87
what percent of fibers cross at the chiasm?
55% of nasal FIBERS (temporal visual fields )
88
what is the anterior wall of the third ventricle?
the chiasm
89
what are the anatomical variations of the chiasm?
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
how are the macular fibers arranged in the optic chiasma?
some are crossed and some are uncrossed (temporal) nasal half go central superior and posterior
91
how are superior fibers located in the optic tract?
superior nasal (crossed) and superior temporal (uncrossed) run medially
92
how much of the LGB does the macular fibers occupy?
2/3 posteriorly ( dorsal)
93
how id the LGB divided?
6 layers of neurons alternating with white matter
94
what layers of LGB is magno cellular (temporal)
1-2
95
what layers are parvocellular?
3-6
96
where do the fibers from ipsilateral temporal retina end in the LGB?
2,3,5
97
where do fibers from the contralateral nasal retina end in the LGB?
1,4,6
98
in the optic radiations where do the superior fibers go through?
directly through the parietal lobe( these serve inferior field)
99
where do the inferior fibers of the optic radiations go through?
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
what happens if there is an issue with meyer's loop?
contralateral superior quadrantanopsia (pie in the sky)
101
what happens if there is a defect on the parietal lobe?
inferior quadrantopsia (pie on the floor)
102
what if there is a more posterior defect of the optic radiations?
same in both eyes defect of VF.
103
what divides the primary visual cortical area?
calcarine fissure
104
where is the visuosensory area located?
striate area 17
105
where is the visuopsychic area located
18 and 19
106
on the VF island where is the blind spot located?
15 degrees temporal and 1.5 degrees below central fixation point
107
what are the different sorts of scotomas?
central hemianopic peripheral and pareacentral
108
what happens in a lesion of the optic nerve?
near pupillary reflex still present NO direct or consensual has APD
109
How far away does the tangent screen have to be placed?
! m away with target at eye level, if there is a VF defect, move back 1 m
110
what is a medication that causes central VF loss?
Plaquenil
111
what is the standard VF exam?
humphrey

PCO3 (3 decks)

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