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Disease/glaucoma Dr. Davey 2016 > Lecture 5 Imaging technology > Flashcards

Lecture 5 Imaging technology Flashcards

1
Q
  • What is the gold standard of imaging?
    a) simultaneous stereo photography
    b) HRT
    c) GDX
    d) OCT
A

a) simultaneous stereo photography

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2
Q

(T/F) Detectable NFL changes in a glaucoma pt can still be asymptomatic

A

True

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3
Q

(T/F) NFL thickness increases with age

A

False, it decreases

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4
Q

Which imaging device takes 2 images of the optic nerve at slightly different angles in order to view them in 3-D?

a) simultaneous stereo photography
b) HRT
c) GDX
d) OCT

A

a) simultaneous stereo photography

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5
Q

Which imaging device uses a confocal laser and takes 3 images of the optic nerve from anterior to posterior to create a 3-D image?

a) simultaneous stereo photography
b) HRT
c) GDX
d) OCT

A

b) HRT (the 3 images are taken from the vitreous interface to deep within the nerve)

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6
Q

Which imaging device uses a confocal laser with a polarized light filter which takes advantage of the birefringent properties of the eye?

a) simultaneous stereo photography
b) HRT
c) GDX
d) OCT

A

c) GDX (GDX is basically the HRT but with the added polarized light filter)

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7
Q

What is the difference between the GDX and GDX-Pro?

A

The GDX-Pro has an enhanced corneal compensator and improved signal to noise ratio

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8
Q

Which imaging device is similar to an ultrasound but instead of using sound to echo the structure of the optic nerve, it uses light waves that bounce back?

a) simultaneous stereo photography
b) HRT
c) GDX
d) OCT

A

d) OCT

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9
Q

Which imaging device creates a series of A-scans to form a b-scan?

a) simultaneous stereo photography
b) HRT
c) GDX
d) OCT

A

d) OCT

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10
Q

Which imaging device was the first?

a) simultaneous stereo photography
b) HRT
c) GDX
d) OCT

A

b) HRT

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11
Q

Why is there a discrepancy between the Dr’s observation of the C/D ratio and the C/D ratio measured by the HRT?

A

because the standard reference plane of the HRT is set 50 microns below the temporal disc edge

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12
Q

What is the main difference between the HRT-2 and HRT-3?

A

The HRT-2 has info for one eye on one side of the page and info for the other eye on the back side of the page. HRT-3 has both eye’s info on one page for easy comparison.

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13
Q

What are the 4 sections of the HRT-3 printout?

A

1) Patient demographics and quality checks
2) Optic disc cup (cup analysis)
3) Retinal Nerve Fiber layer (RNFL) (RNFL analysis)
4) Neuroretinal rim (rim analysis)

(If all else fails: remember the acronym it makes lol)

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14
Q

Which imaging device is the only one that compares patients with others in their ethnicity group?

a) simultaneous stereo photography
b) HRT
c) GDX
d) OCT

A

b) HRT

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15
Q
  • Which imaging device uses MRA (Moorefields regression analysis) as the BEST parameter to diagnose glaucoma?
    a) simultaneous stereo photography
    b) HRT
    c) GDX
    d) OCT
A

b) HRT (*MRA is also the parameter to predict future damage on OHT pt’s)

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16
Q
  • Which imaging device uses the NFL as the BEST indicator of diagnosing glaucoma?
    a) simultaneous stereo photography
    b) HRT
    c) GDX
    d) OCT
A

c) GDX

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17
Q
  • Which imaging device uses the inferior average as the BEST parameter in identifying glaucoma?
    a) simultaneous stereo photography
    b) HRT
    c) GDX
    d) OCT
A

d) OCT

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18
Q

In regard to the quality checks on the HRT: Match the following:

1) excellent
2) very good
3) good
4) acceptable
5) poor
6) very poor

a) >50
b) 41-50
c) 31-40
d) 21-30
e) 11-20
f) less than 10

A

1) excellent is less than 10
2) very good 11-20
3) good 21-30
4) acceptable 31-40
5) poor 41-50
6) very poor greater than 50

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19
Q

In regards to the HRT: what are the probability indices ranges?

A

1) p greater than 0.05 is a 95% chance that it is normal
2) p less than 0.05 and greater than 0.001 is borderline
3) 0.001 is high chance of being abnormal (low chance of being normal)

20
Q

In regards to the HRT: what are the optic disc size ranges?

A

1) small is less than 1.6 mm2
2) avg is 1.6-2.5 mm2
3) large is greater than 2.5 mm2

21
Q

In regards to the HRT: which one of the following is not information given for cup analysis?

a) cup topography
b) cup asymmetry
c) cup deviation
d) cup parameters (C/D ratio and cup shape)

A

c) cup deviation (i just made that up)

22
Q

In regards to the HRT: which one of the following is not information given for rim analysis?

a) Moorfields regression analysis
b) inferior average
c) rim parameters (area and volume)
d) rim asymmetry

A

b) inferior average. (remember this is given on OCT)

23
Q

In regards to the HRT: which one of the following is not information given for RNFL analysis?

a) RNFL deviation
b) RNFL profile graph
c) RNFL asymmetry
d) RNFL parameters (thickness and height)

A

a) RNFL deviation (i made that up, dont worry, its not a thing =)

24
Q

Asymmetry is simply…..

A

OD minus OS (If the C/D ratio of the OD is 0.66 and the OS is 0.64 then the asymmetry is 0.02.)

25
Q

Which of the following imaging devices utilizes Moorfields regression analysis?

a) simultaneous stereo photography
b) HRT
c) GDX
d) OCT

A

b) HRT is the only one

26
Q

*(T/F) the larger the nerve head, the larger the rim

A

True

27
Q

Which imaging device give you probability indices for the rim, divided in 6 sections, using a check mark, and exclamation mark, and an “X”?

a) simultaneous stereo photography
b) HRT
c) GDX
d) OCT

A

b) HRT

28
Q

Which one of the following is NOT true regarding GPS (glaucoma probability score) found on the latest edition HRT?

a) it is a sophisticated new analysis based on the 3-D shape of the optic disc and peripapillary RNFL
b) It has no contour line or reference line
c) it employs a new form of artificial intelligence, the relevence vector machine (RVM).
d) All of the above are correct

A

d) All of the above are correct

29
Q

The GPS is broken down into 3 parts: the model, the analysis RVM, and the classification. What 5 parameters make up the model?

A

3 parameters describe the optic disc and 2 parameters describe the RNFL.

1) optic disc: rim steepness, cup size, cup depth
2) RNFL: Horizontal RNFL curvature, Vertical RNFL curvature

30
Q

What is the purpose of using the polarized filter on the GDX?

A

It is able to remove corneal and lens birefringent properties from the RNFL data. It takes those out of the calculation. Total birefringence=lens+cornea+RNFL (GDX is only used for glaucoma)

31
Q

(T/F) In regards to the GDX, it only uses red laser as the light source, not white light, therefore it is not a true fundus photo and should not substituted for one.

A

True

32
Q

Which one of the following statements regarding the GDX thickness map is NOT true?

a) blue means thick
b) red/orange and yellow is thick
c) blue is thin
d) absence of red is glaucomatous damage

A

a) blue means thick

33
Q

*In regards to the GDX Nerve Fiber Indicator (NFI) what does a value of 50 mean?

A

A value over 50 means high likelihood of glaucoma

1) Low likelihood of glaucoma is less than 30
2) suspect is between 30 and 50
3) High likelihood of glaucoma is over 50

34
Q

In regards to GDx, Which is at higher risk for glaucoma, a high standard deviation or low standard deviation?

A

A low standard deviation is at higher risk for glaucoma (remember the standard deviation is the average of the peaks and valleys of the NFL thickness)

35
Q

Which one of the following is false regarding atypical birefringence pattern?

a) It is a poor signal to noise ratio
b) it affects 10-15% of eyes or as high as 40% in certain populations
c) these eyes are not suitable for SLP imaging
d) occurs when there is less choroidal pigment or cataracts or high myopia
e) all of the above are correct

A

e) all of the above are correct

36
Q

What are the main 2 types of OCT?

A

Time domain (older version) and Fourier domain (newer version)

37
Q

Why did the Time domain OCT take longer than the Fourier domain OCT?

A

because the mirror had to move back and forth (that was the rate limiting step). If the protocol required 512 A-scans, the mirror had to move 512 times. The Fourier domain has a fixed mirror, allowing it perform much fatser.

38
Q

Why was the 1st series of the Time domain OCT not good at measuring cup/disc ratio?

A

because it measured 150 microns under the rim edge

39
Q
  • In regards to the 2 main types of OCT’s: Match the following:
    1) Time domain
    2) Fourier domain

a) slower than eye movements
b) faster than eye movements
c) up to 40,000 A-scans per second
d) 400 A-scans per second
e) 1024 pixels per A-scan
f) 2048 pixels per A-scan
g) 1024 A-scans in 0.04 seconds
h) 512 A-scans in 1.28 seconds
I) sequential
j) simultaneous

A

a) slower than eye movements–>time
b) faster than eye movements–>fourier
c) up to 40,000 A-scans per second–>fourier
d) 400 A-scans per second–>time
e) 1024 pixels per A-scan–>time
f) 2048 pixels per A-scan–>fourier–>fourier
g) 1024 A-scans in 0.04 seconds–>fourier
h) 512 A-scans in 1.28 seconds–>time
I) sequential–>time
j) simultaneous–> fourier

Take home message: Fourier is faster, has more pixels per scan

40
Q

The optic nerve head isn’t the only place for glaucomatous damage. What else can you look at and get data from using the OCT?

A

The macula

41
Q

What 3 components make up the ganglion cell complex in the Optovue (choose 3)?

a) Outer plexiform layer
b) nerve fiber layer
c) ganglion cell layer
d) inner plexiform layer
e) inner nuclear layer

A

b) nerve fiber layer
c) ganglion cell layer
d) inner plexiform layer

42
Q

What 2 components make up the ganglion cell analysis in the Zeiss (choose 2)?

a) Outer plexiform layer
b) nerve fiber layer
c) ganglion cell layer
d) inner plexiform layer
e) inner nuclear layer

A

c) ganglion cell layer

d) inner plexiform layer

43
Q

(T/F) The Fourier domain OCT has a 5 micron accuracy, whereas all other imaging devices have a 10 micron accuracy.

A

True. Ideally this should not cause false negatives and false positives should be low.

44
Q

The SD OCT image should be placed in the:

a) top 1/3rd
b) middle
c) bottom 1/3rd

A

a) top 1/3rd (the bottom portion is a “deeper Z depth” and image quality decreases at deeper Z depths.

45
Q

In regards to the OCT: in order for the result to be reliable which 6 image acceptance criteria need to met?

A

1) Image quality score (due to dirty lens, improper head/chin position, improper focus, reduced tear film)
2) eye blinks (shows missing data)
3) eye movement (shows chopped vessels, ok if in far periphery but not close to ONH)
4) clipping ( not in top 1/3rd, must repeat)
5) fixation/centration (ONH needs to be centered, a shadow may be the edge of the pupil)
6) localized weak signal (sometime as floater creates a shadow)

46
Q

Which one of the following is NOT one of the 3 parts of the interpretation report?

a) clinical findings
b) comparison
c) billing
d) plan

A

c) billing (there is 2 components to billing tho: doing the test and creating the interpretation report

Disease/glaucoma Dr. Davey 2016 (13 decks)

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