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COT > Ophthalmic Imaging 7% > Flashcards

Ophthalmic Imaging 7% Flashcards

1
Q

What does the corneal topography do?

A

Makes a colored map of the corneal curvature. Provides a greater detail of the surface of the cornea, including peaks and valleys. Uses color code to indicate the areas of steepness and flatness

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2
Q

Test that uses placido disk that is projected onto the cornea and the computer software creates a series of data points to create a map with colors which represents varied elevations.

A

Corneal topography

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3
Q

Corneal topography measures 1000’s of points from ___to ___of the K

A

limbus to limbus

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4
Q

What is the corneal topography information used for?

A

CL fitting, Diagnosing and managing corneal pathology like KCN, and post corneal refractive sx evaluations

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5
Q

The warm colors(red, orange, yellow) on corneal topography shows the ___areas of the K

A

steeper

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6
Q

The cool colors(green and blue) on corneal topography represents the ___areas of the K

A

flatter

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7
Q

On corneal topography ____=steeper K
____=flatter K

A

Warm colors(red, orange, and yellow)
Cool colors (green, blue)

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8
Q

Corneal topography is ____detailed than the standard keratometer

A

more

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9
Q

Peaks and valleys of the K are areas that are impacted by ___

A

CL

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10
Q

The computer on the corneal topography interprets the ____of the placido discs on the K to create a map

A

reflection

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11
Q

The scale on the corneal topography is adjustable so that if a pt has a very steep or a very flat cornea you can adjust the scale and it will still show…..

A

the relative areas of flatness or steepness

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12
Q

________makes cross sectional images of different structures in the eye to the sub mircometer

A

OCT (Optical Coherence Tomography)

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13
Q

What does the term tomography mean?

A

cross sectional imaging

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14
Q

OCT uses an ____technique similar to contact and emersion Ascan but it uses _____technology not sound.

A

echo
laser light

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15
Q

What cause a weak signal in the OCT?

A

dry eye or K scars

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16
Q

What does the OCT image?

A

AC, Retina, ON

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17
Q

The OCT is much better tolerated and much lower risk than an _____

A

angiogram

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18
Q

______can prevent you from getting a quality scan with OCT

A

very dense media
(dense CAT or K opacification)

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19
Q

OCT measures a standard deviation which will tell you the _____

A

quality of the scan

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20
Q

OCT uses a technology called ____ which is the ability to reproduce precise skin placement in subsequent scan so that they can be realigned to directly compare with the baseline exam.

A

Registration

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21
Q

Registration technology will lock on to certain _____in the base line exam then in the f/u exams it will look for those same ones and lock onto them. It will pivot subsequent scans to that they align precisely with the baseline exam so that they can do a direct comparison to them.

A

anatomical features

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22
Q

Nerve fiber analyzers such as HRT and GDX are ____lasers

A

scanning

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23
Q

Nerve fiber analyzers make multiple sequential scans to create at ____image of different ocular structures and it also uses registration technology to align them with the baseline for comparative purposes.

A

3D

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24
Q

HRT and GDX starts above the _____, captures ______images at increasing depths

A

retinal surfaces
parallel

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25
Q

To obtain and accurate scan with HRT and GDX you must….

A

-correct refractive error including cyl of >1D
-have a good tear film
-may need to dilate pt

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26
Q

HRT and GDX(nerver fiber analyzers) use traffic light signal for quality; ____=good and ____=bad scan

A

Green
Red

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27
Q

HRT and GDX images…..

A

ON and macula

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28
Q

HRT and GDX software compares the pts data to …..

A

population at large
progress analysis

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29
Q

Fluorescein angiography documents……

A

Retinal circulation

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30
Q

Fluorescein angiography exploits the fact that ….

A

light has a range of wavelengths

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31
Q

Fluorescein angiography uses ___to filter out certain wavelengths of light that will appear on the film.

A

different interference filters

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32
Q

The visible spectrum of the human eye is between____

A

400-700nm

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33
Q

What type of dye is used in the fluorescein angiography?

A

fluorescein sodum dye injected into the pts arm or hand

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34
Q

____is a property of certain transparent substances.

A

Fluorescein

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35
Q

When a substance is exposed to light of a shorter wavelength ____is absorbed by it and its molecules become excited which raises electrons to a higher energy level.

A

energy

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36
Q

As molecules return to their original state the substance emits light of a ____wavelength

A

longer

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37
Q

Fluorescein Sodium is a ___soluble dye

A

water

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38
Q

Light absorption peak is _______.
______ filter in FA’s uses wavelength within this range.

A

465-490nm
Blue exciter

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39
Q

Light emission peak is at a wavelength between _______

A

520-530nm

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40
Q

What are the different interference filters used in FA’s?

A

Exciter (Blue) and Barrier (yellow-green)

41
Q

In FA’s the ________ filter excites the fluorescein molecules to a higher state of activity.

A

Exciter(Blue)

42
Q

Exciter (blue) filter emits a ______light of a higher wavelength.

A

greenish yellow

43
Q

The______filter is positioned in the light path between the eye and the film or digital image which filters out the ___light and only allows the fluorescence to be recorded on the film

A

Barrier (yellow-green)
(Also known as “red free”)

Blue light

44
Q

With infra red phase of FA’s there is such a thing as _____illumination

A

too much

45
Q

In FA’s turn up the illumination until ……..

A

you just see the fundus (even illumination)

46
Q

_____images are taken as a control prior to injecting the fluorescein dye. This records the pts natural ______

A

Red free

auto fluorescence

47
Q

FA performs ___images per minute

A

60

48
Q

In order to get quality images in FA you must have

A

Even illumination (may need to increase when pupil small)
Minimal artifacts
Center of the macula, unless other wise indicated.
Always better to take more images than less.
Take one image per second for the first 1 minute (60 images per minute)
Make sure pt is relaxed and cooperation is key

49
Q

How do you adjust intensity in FA

A

by adjusting the sensitivity knob

50
Q

Describe the path of Fluorescing dye.

A

It enters through central retinal arteries, then enters the arteries, then the capillaries, then the veins then finally through the central retinal vein.

51
Q

In FA explain mnemonic CACVC

A

path of fluorescein:
Centeral retinal arteries
Arteries
Capillaries
Veins
Central retinal veins

52
Q

The _______phase of FA occurs 8-10 seconds after injection.

A

Choroidal (pre-arterial)

53
Q

In the____ phase of FA the choroid is illuminated with fluorescein but non of the fluorescein has filled any of the retinal vessels yet.

A

choroidal (pre-arterial)

54
Q

___phase in FA occurs about 10-12 sec after injection (about 1 sec after choroidal phase)

A

Arterial phase

55
Q

In the ___phase of FA the dye has entered the central retinal artery and fans out to the superior and inferior arcades. However, the veins have not received any dye yet.

A

arterial phase

56
Q

The ____phase of FA occurs about 3 seconds after the choroidal flush

A

Capillary

57
Q

Choroidal flush or background fluorescence is int the _____phase

A

choroidal phase

58
Q

In the ____phase of FA the fine capillaries around the fovea fill and in the periphery

A

Capillary

59
Q

The _____phase of the FA occurs 5 seconds after choroidal filling(flush), evidenced by ____

A

Eary venous phase
Laminar flow

60
Q

What is laminar flow in early venous phase of FA?

A

White stripping of outer walls of veins

61
Q

Why are the veins striped in laminar flow?

A

Because the fluorescein dye enters the vein and fills on the periphery first and then gradually fills towards the center of the vein.

62
Q

___phase in FA is 10 seconds after choroidal filling (flush)

A

Full Venous Phase

63
Q

_____phase of FA is where the laminar filling is complete and the dye is filled to the center of the veins.

A

Full venous phase

64
Q

Once all the phases of FA is reached you have ____

A

Complete fill of the arteries and veins

65
Q

The ____phase of FA occurs 3-5 minutes after injection

A

Recirculation phase

66
Q

In ___phase of FA the veins and arteries remain roughly equal in brightness and the intensity of fluorescence diminish slowly during this phase.

A

Recirculation phase

67
Q

Early leakage and staining can occur during the ___phase of FA

A

Recirculation phase

68
Q

In FA, Photos are typically captured ____minutes after injection

A

7-15 minutes

69
Q

Late phase (Elimination Phase) occurs _____minutes after injection

A

30-60

70
Q

In FA, _____spaces fill slowly, about 20-30 minutes after the dye has pooled

A

cystic

71
Q

____phase demonstrates the gradual elimination dye from retinal and choroidal vasculature

A

Late phase

72
Q

FA: Late staining of the optic disc is a ___finding

A

normal

73
Q

In FA , in the ____phase and in the normal eye, the dye has mixed with blood to a point where it is almost invisible with the camer

A

Late phase

74
Q

____uses a radiating wave of ultrasound to help detect tumors and to image different intraocular and periocular structures.

A

B Scan

75
Q

B Scan is a ___dimensional scan

A

2

76
Q

An a wave in an A scan travel a ____line, a beam of light (a linear wave)

A

single straight

77
Q

A B scan extends below and above the _____and sweeps the contents of the entire globe

A

horizontal

78
Q

The “B” in B scan stands for …

A

brightness

79
Q

The scan that uses ultrasound..
(A scan or B scan)

A

B scan

80
Q

In Bscan the sound waves _____ different tissue of varied densities at varied speeds and are ____by other tissue.

A

pass through
reflected

81
Q

The speed that a sound wave travels at through tissue during a B scan depends on …..

A

the density of the tissue

82
Q

In B scan the sound waves are converted into images by the ______

A

Transducer

83
Q

Why is it useful for the transducer in the Bscan to convert soundwaves to images especially if pt had dense media opacities?

A

Because sound travels through dense media just fine and light technology does not.

84
Q

Most setting on B scan are _____

A

left constant

85
Q

What can you adjust on
B scan to enhance the view of anatomical structures, tumors, and foreign bodies?

A

Sound intensity adjustment

86
Q

What does the marker at then end of the Bscan probe indicate?

A

top of oscilloscope display
(what’s at the top of your display)

87
Q

If marker on Bscan probe is pointed up this means….

A

the top part of the pts eye is at the top of our display

88
Q

If marker on the Bscan probe is aimed nasally then…

A

the nasal aspect of they eye is at the top of the display

89
Q

For vertical scans on B scan you orient the probe ____
for horizontal scans ____

A

superiorly
nasally

90
Q

When placing the Bscan probe on the eyelid or eye itself you want to place it _____to the structures that you want to image so that the sound waves travel back to the transducer rather than bouncing off of them in another direction, allows you to get a higher quality image.

A

perpendicular

91
Q

Explaing how to perform a Bscan.

A

First locate the ON (acts as a landmark), typically you’ll place the probe medially, temporally, superiorly, and inferior to limbus.

92
Q

If you find pathology when performing Bscan, place the probe…..

A

place the probe opposite to clock hour to where the pathology is.

93
Q

B scan: You are always imaging the _____clock hour to the eye to where your probe is oriented.

A

opposite

94
Q

_____is used to image endothelial cells.

A

Specular Biomicroscopy

95
Q

_____photographs K endothelial cells and can be contact or non contact

A

Specular Biomicroscopy

96
Q

Endo cells do not _____

A

regenerate

97
Q

What caused endothelial cells to diminish?

A

age, cataract distraction (intraocular sx)

98
Q

When performing contact endothelial cell count….

A

-Do not press on K
-Patient must be stabilized with forehead rest
-Topical anesthetic uses
-Take a photo of the endo cells and then place a graph over top rotate grid and count the number of cells in that grid, you then use a formula used to figure endo cell count
-Appropriately clean and disinfect probe

COT (28 decks)

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