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Summer Final: Glaucoma > OCT, HRT, GDx > Flashcards

OCT, HRT, GDx Flashcards

1
Q

Measures the reflection of laser light (similar concept to ultrasound and reflection of sound)

A

OCT

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2
Q

Directly measures the thickness of the NFL

A

OCT

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3
Q

TD-OCT

A

Time domain OCT

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4
Q

SD-OCT

A

Spectral domain OCT

  • most common
  • newer
  • aka HD-OCT

Greater speed in capturing images and higher definitaiton. Also different algorithm than TD-OCT

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5
Q

OCT OU report: key parameters

A

Compared to normative data base, are displayed in table formats

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6
Q

Small disc

A

<1.5mm

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7
Q

Medium disc

A

> 1.5

<2.5

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8
Q

Large disc

A

> 2.5

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9
Q

Colors on OCT data

A

GRY based on comparison to normative database

-only for >18 yo

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10
Q

Gray color on OCT

A

Not compared to normative database

-disc area ranges from normative database

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11
Q

Disc area ranges from normative database

A

1/3 < 1.58mm
1/3 are 1.58-1.88
1/3 >1.88mm

Gray when disc area is <1.3mm OR >2.5mm

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12
Q

What does the table tell you on OCT

A 
Average NFL
RNFL symmetry 
Rim area
Disc area
Average CD ratio 
Vertical CD ratio 
Cup volume
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13
Q

White

A

The thickets 5% of measurements fall here

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14
Q

Green

A

90%

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15
Q

Yellow

A

5%

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16
Q

Red

A

1%

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17
Q

Normative data for different ages

A

Will be differ. Just because someone has the same numbers as someone else, it will be different based on their age

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18
Q

RNFL OCT report

A

Thickness map is a topographical display of RNFL. An hourglass Shaw of yellow and red colors is typical of normal eyes

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19
Q

RNFL deviation map

A

Shows deviation fro normal. OCT en face fundus image shows boundaries of the cup and disc and the RNFL calculation circle

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20
Q

Neurotrophic retinal rim thickness OCT report

A

It is matched to normative data

21
Q

RNFL TSNIT graph

A

Displays patients RNFL measurements along the calculation circle, compared to normative data

22
Q

RNFL quadrants an clock hour

A

Average thickness is matched to normative data

23
Q

When looking at the pie chart on the OCYT report, what are we paying attention to

A

Is there a difference between each eye and between visit to visit
• worry from 7-12 numbers difference in the quads and between visit to visit

24
Q

Horizontal and vertical B scans

A

Extracted from the data cube through the center of the disc. RPE layer and disc boundaries shown in black. ILM and cup boundaries are shown in red

25
Q

RNFL calculation circle

A

Is automatically centered on the optic disc and extracted from the data cube

Boundaries of the RNFL layer segmentation is illustrated

26
Q

OCT guided progression analysis report

A

Some machines will compare up to 7 exams to see if there is any changes in the patient between visits

Can choose which exams you compare to each other

Can also chose the baseline to use

27
Q

Why do 2 baselines

A

If someone is glaucoma or suspect, its to make sure its reproducible data

28
Q

RNFL thickness change maps in OCT GPA report

A

Demonstrates change in RNFL thickness. Up to 6 exams are automatically registered to baseline comparison. Areas of statistically significant change are color coded yellow when first noted and then red when the change is sustained over consecutive visuits

29
Q

Average RNFL tivckenss in GPA reports

A

Values are plotted for each exam,. Yellow marker denotes change when it is first noted. Red marker denotes change sustained over consecutive visits. Rate and significance of change is shown in Text

30
Q

RNFL thickness profiles

A

TSNIT values from exams are plotted. Areas of statistically significant change are colro coded yellow where first notes and tried when the change is sustained over consecutive visits

31
Q

RNFL summary GPA report

A

Summarizes GPA analysis and indicates with a check mark if there is possible or likely loss of RNFL

32
Q

RNFL thickness map progression best for

A

Focal change

33
Q

RNFL thickness profiles progression best for

A

Broader focal change

34
Q

Average RNFL thickness progression best for

A

Diffuse change

35
Q

HFA cirrus combines report

A

Some companies will compile the HVF and OCT in one page to compare them together

36
Q

OCT ganglion cell complex

A
  • measures the thickness of the 3 innermost retinal cell layers that are preferentially affected in glaucoma
  • compares the patients two eyes for symmetry
  • asymmetry is an early sign of glaucoma
  • higher correlation between asymmetry and glaucoma in ST and IT regions

Scans macular thickness-evaluating ganglion cell layer. This thins in glaucoma

37
Q

What is involved int he GCC

38
Q

HRT

A
  • laser that produces 3D high resolution image of the ONH

- measure the nerve fibers damage/loss

39
Q

How does HRT work

A

Takes 32 layer by layer pictures from the surface of the optic nerve to form 0.5mm to 4.0mm deep into the ocular structures. The computer then piles the slices together in a reconstructed paper printout that looks like a map drawn to represent the hills ands valleys of a geo area. By color coding areas of elevation and depression, the HRT provides a 2D representation of what the original, 3D, stack looks like

40
Q

Limitations of HRT

A
  • any patient movements (including moving theeye, blinking, or moving the head) will disrupt the lasers path, imparting the quality of the image
  • if patient does not focus on the same location from test to test, the angle of the image will change, and that will affect the measurements greatly
  • the images created by the HRT must be reproducible/identical in order to analyze and compare to the normative database and to monitor for change
41
Q

Image quality and HRT

A

Needs to be very good quality or you cant compare from exam to exam

30 or lower

42
Q

Inter-eye asymmetry on HRT

A

Evaluates the symmetry of the RNFL profiles between the eyes. If the correlation between eyes is good, the value will be close to 0

43
Q

Glaucoma diagnosis nerve fiber analyzer (GDx)

A

Scanning laser polarimter measures nerve fiber layer thickness and 65,536 retinal points

44
Q

Normal NFL on GDx report

A

No statistically significant thinning of the NFL and a nerve fiber indicator (NFI) number less than 30. The NFI ranges from 0 (thick) to 00 (severely thin NFL)

45
Q

Advanced glaucoma in GDx

A

Characterized by statistical significance of nerve fiber layer thinning on GDx scan. Often accompanying by a nerve fiber indicator number of >30 in either eye and poor inter-eye symmetry. Both are seen in this scan of a patient with severe visual field loss secondary to advance glaucoma

46
Q

Symmetry wants a ___ number

47
Q

NFI wants a ___ #

48
Q

Serial analysis of GDx

A

Can compare from visit to visit

Summer Final: Glaucoma (15 decks)

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