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OHP II > Threshold Packet 1&2, MT1 Material > Flashcards

Threshold Packet 1&2, MT1 Material Flashcards

1
Q

humphrey field analyzer (HFA 24-2) has how many test points?

A

54

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2
Q

HFA 30-2 has how many test points?

A

76

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3
Q

Octopus G test has how many test poins?

A

59

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4
Q

quantitative perimetry CPT code is:

A

92083

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5
Q

what is an important trend of fluctuation

A

fluctuation (fatigue, boredom, attention) can increase in the earliest stages of VF loss that will later become definite VF defects

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6
Q

if VF loss is getting deeper is it a higher or lower dB value

A

lower dB value

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7
Q

what should have the highest sensitivity in the VF?

A

fovea

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8
Q

how much does the perifoveal sensitivity drop off?

A

drops 2-4 dB at the first ring of points outside of the fovea

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9
Q

what is defined as central VF? how does sensitivity drop off?

A

central 30 degrees radius around fixation

-sensitivity declines about 3dB/10 degrees (more rapid decline in superior VF beyond 15/20 degrees)

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10
Q

type of fluctuation that occurs during a threshold test, impacts whether there appears to be a VF defect or not

A

short-term fluctuation (STF)

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11
Q

type of fluctuation that is typically about 2dB on average across all points in the VF

A

short-term fluctuation (STF)

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12
Q

type of fluctuation that increases with the distance from fixation

A

short-term fluctuation (STF)

-significantly greater in the peripheral VF and superiorly beyond 15/20 degrees

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13
Q

type of fluctuation that is between threshold tests

A

long term fluctuation

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14
Q

type of fluctuation that impacts whether the VF or VF defect appears to be changing/progressing or stable

A

long term fluctuation

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15
Q

what type of perimetry is a “white stimulus on a white background” like HFA, Octopus, and several other instruments

A

standard automated perimetry (SAP)

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16
Q

what type of perimetry has less variability/fluctuation, therefore you can recognize true VF loss more confidently and can recognize true progression/change more confidently

A

standard automated perimetry (SAP)

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17
Q

what type of perimetry is most commonly used type of perimetry for following glaucoma

A

standard automated perimetry (SAP)

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18
Q

what is alternative perimetry

A

uses a stimulus other than a white stimulus white background, usually one that stimulates a small subset of retinal ganglion cells (m-cells)

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19
Q

SWAP=

A

short wavelength automated perimetry

-blue stimulus on yellow background

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20
Q

pros/cons of alternative perimetry

A
  • designed to detect VF loss earlier than SAP but tends to have more variability/fluctuation
  • increased fluctuation/variability
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21
Q

why use SAP rather than alternative perimetry?

A
  • less variability/fluctuation
  • best progressive software to detect change/progression
  • most sensitive to early glaucomatous VF loss than white-on-white screening VF
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22
Q

false field defects are very common in threshold perimetry, and the specificity is not good, at best ___- ___%

A

60-70 %

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23
Q

explain why interpretation is often much more difficult in threshold vs. screening

A

because you are interpreting dB value sensitivities (not misses vs. hits) and this causes reduced specificity

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24
Q

indications for threshold perimetry

A
  • central VF defect that may change with tim e
  • glaucoma suspects
  • glaucoma patients
  • macular disease
  • neuro-ophthalmic disorders
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25
Q

the small pupil effect can cause what on the VF?

A

generalized depression

more likely if cataract is present as well

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26
Q

most common causes of no BS:

A
  • neither eye is patched
  • wrong eye is patched
  • poor fixation and perimetrist is not monitoring
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27
Q

do you need trial lenses for the octopus VF on QTC patients?

A

no lenses needed

-lenses are not needed for peripheral VF

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28
Q

if patient is dilated, what trial lens do you use

A

assume patient is completely cyclopleged so we give +3.25 add (over distance Rx)

29
Q

if the lensholder is much too far from the eye, what will it cause?

A

a major lens/lensholder artifact at 10 or 15 degrees from fixation

30
Q

the most common artifact from lensholder is

A

temporal to blindspot

which is extremely unlikely location for early glaucomatous VF loss

31
Q

why is having the foveal threshold response on good?

A

it helps the perimetrist to recognize FP responses during the test and to prevent it

32
Q

patient ed on gaze tracker is:

A

look in the middle at the orange/yellow light. blink your eyes 3 or 4 times and now hold your eyes wide open and don’t blink or move your eyes

33
Q

sensitivities higher than the fovea suggest:

A

false positive responses

34
Q

what is a true fixation loss

A

patient not looking at the central (orange) light, preterits should be able to see this

35
Q

what causes poor BS localization?

A

very often due to false positive responses or false negatives as the instrument tries to localize the BS at the beginning go the test

36
Q

central field test point pattern is:

A

6 degree grid pattern with points straddling the midline

37
Q

why do we use SITA strategies?

A

faster, less variability/fluctuation, more reliable, more repeatable results
-can more confidently recognize VF loss and progression of VF loss

38
Q

when evaluating the reliability of the results, you look at what indices?

A
  • fixation losses
  • false positive trials
  • false negative trials
  • fixation losses
39
Q

significance of FP responses?

A
  • can cause a VF defect to be missed
  • VFI and MD will likely be higher than they should be
  • can destroy the reliability of the test
40
Q

what % of FP is flagged on HFA printout?

A

33

41
Q

what are some clues to FP responses during the test

A
  • sensitivity values that are higher than expected

- fixation loss index shows several fixation losses but the patient’s fixation was very steady on the video eye monitor

42
Q

causes of false negative responses

A
  • large or deep VF loss

- can be due to fatigue, lack of attention

43
Q

do high FNs always indicate reduced test reliability?

A

they do not necessarily indicate reduced test reliability, they very often indicate much VF loss such as in advanced glaucoma

44
Q

what are some ways to detect increased FNs?

A
  • increased FN index (>33%)
  • can be due to fatigue, lack of attention
  • several seconds of no responses during the test, usually late in test
  • slow or late responses
45
Q

why should you not use greytone alone to interpret the VF?

A
  • lower sensitivities are colored darker therefore more peripheral areas will normally be darker
  • not adjusted for age, on an absolute scale
  • can miss VF defects
46
Q

what does the “numeric total deviation map” represent?

A

the difference between the pt’s sensitivities of pts in the normal database of the same age

47
Q

what does a minus number on the numeric total deviation map represent?

A

lower than “normal” sensitivities, possible VF loss

48
Q

what does a plus number on the numeric total deviation map represent?

A

higher than normal sensitivities due to a pt’s sensitivities being higher than the average. can be caused by FP response or wrong birthdate entered

49
Q

what is done to pattern deviation maps to minimize the chance that localized defects hide within deep generalized depression?

A

plots are “corrected” for any generalized loss of sensitivity or generalized higher than normal sensitivity

50
Q

common causes of generalized depression

A
  • blur (wrong trial lens)
  • small pupil (< 3mm)
  • media opacity (cataract)
  • fatigue
  • 1st threshold VF test
  • glaucoma (but often hard to isolate as the cause)
51
Q

what does it mean if the total and pattern deviation maps look very similar

A

there is little or no generalized depression

52
Q

what does it mean if there are:

  • many significantly depressed points on the total deviation maps
  • none or very few depressed points on the pattern deviation maps
A

generalized depression, often cataract

53
Q

what does it mean is there are:

  • many significantly depressed points on the pattern deviation maps
  • none or very few depressed points on the total deviation maps
A

probably “trigger happy” patient who gave many FP responses

54
Q

the cause of localized VF loss should almost always be evident in the eye if the loss is:

A

anterior to the lateral geniculate

55
Q

GHT=

A

glaucoma hemifield test

56
Q

what is the GHT?

A

an analysis of HFA 30-2 or 24-2 results which compares groups of test points in the superior hemifield to the mirror image groups in the inferior hemifield

57
Q

what is important about the groups tested in the GHT?

A

the groups follow the pathway of the arcuate nerve fiber bundles which are very often damaged in early glaucoma

58
Q

GHT is very useful for identifying:

A

glaucomatous VF loss

59
Q

what does GHT not give you though?

A

does not give info on the location or pattern of the VF defect(s)

60
Q

what are the 2 global indices

A 
MD= mean deviation on HFA
PSD= pattern standard deviation
61
Q

what is the mean deviation indices (MD)

A

the difference in average sensitivity of the patient and same-age normal patient in the normal/reference database

62
Q

MD is most affected by what two factors:

A
  • number of defective points (size of VF defect)

- depth of VF loss at defective points

63
Q

what type of defects most increase MD?

A

large, deep VF defects most increase MD (in minus direction)

64
Q

what is PSD?

A

index of localized irregularity of the surface of the patient’s hill of vision

65
Q

what type of defects most increase PSD?

A

most by deep, localized VF defects

66
Q

as VF ____ in size, the PSD starts decreasing

A

increase

67
Q

increased MD and normal PSD=

A

probable gen depression

68
Q

increased MD and increased PSD=

A

probable large and/or very deep localized defects

69
Q

normal MD and increased PSD=

A

localized VF defects

OHP II (6 decks)

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