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Summer Final: Glaucoma > VF Testing > Flashcards

Flashcards in VF Testing Deck (74):
1

Testing strategies

-automated perimeter
-manual perimeters (tangent screen, Goldman bowl perimeter)
-CVF

2

The systemic measurement of visual function

Perimetry

3

The measurement of hill of vision in terms of establishing the patients differential light sensitivity across the VF

Perimetery

4

Threshold

Location at which detecting threshold is determined

5

How are sensitivity and threshold related

Inversely

6

Standard Humphrey VF: kinetic or static?

Static
-present different targets, but they are not moving targets

7

Tangent screen: kinetic or static?

Kinetic
- physically moving the target

8

0dB sensitivity

Very low

9

Typically range of abnormal vision

0-30dB

10

Normal peripheral sensitivity range

20-40dB

11

Limit of fovea vision

40dB

12

Defined as that area of vision seen with open eyes

Visual field

13

Dimensions of the visual field defined

Defined relative to fixation

14

Basis of VF

Present of pR and corresponding visual pathways up to the periphery or retina away from point of fixation (fovea)

15

Importance of VF

Reflects topographic sensitivity of various foci on retina and corresponding visual apparatus

16

How should you look at VF

OD on the right and OS on the left so you can see differnt heminaopsia correctly

17

Status perimetry

-computer presents stimuli in a random fashion
-speed is also improved with random presentation
-allows for storage of data
-computer assisted stat analysis is available
-most widely used intros meant is the Humphrey VF
-testing methods and stat analysis vary among manufacturers
-static auto perimetry measures retinal sensitivity at predetermined points throughout the VF
-threshold values are determined to discover the shape of the hill of vision

18

How does static perimetry measure threshold

Stimulus at a stationary position is presented by increasing or decreasing the luminance until just noticed by the patients

19

HFA-3

-newest one
-bowl/projection
-optical system
-central processor
-patient interface

20

What is special about the HFA-3

-liquid lens technology allows you to automatically load each pateitns refractive correction form the previous exam

21

SITA faster

About half the time of SITA standard and 70% of SITA fast with the same reproducibility as SITA fast
-may improve patient satisfaction with perimetric testing and reduce patient fatigue

22

What kind of add do you use for presbyopia in HFA-2

3.33
Working distance is 30cm not 40 so cannot use 2.50 as a max

23

HVF: bowl

-aspherical surface where stimuli are projected
-distance from the eye to the center of the bowl is 30cm
-this value dictates the warranted corrective lens wchi should be used dudeitn testing

24

Optical system in HVF

Provides stimuli of known brightness for a known amount of time in aprecise location against a background of known background

25

HVF background lumincation

31.5asb
-dimmer background allow a machine to Preston brighter stimulu to the visua lsystem with respect to background light

26

HVF: stimulus size

-utilizes the same target size as a Goldman perimeter: I, II, III, IV, V
-all size III targets is most often used during testing, however size V stimulus is used on occasions

27

Diamter of the III size in HVF

2.26mm

28

Stimulus intensity of HVF

-0.08asb (51db)-10,000 (0dB)
-brightest target is equivalent to goldmann V4e
-does not switch between target sizes (changes brightness of target only)

29

Stimulus duration of HVF

-around 0.2s
-patient does not have time to see a stimulus in their periphery and look towards

30

Brightest setting on golamdnn

V4e
10,000asb

31

Fixation monitoring in HVF

Includes examiner ability to view the patients eye, an electronic eye motion detector (gaze tracker) and blind spot monitoring

32

Blind spot monitoring

Provides an index of the quality of fixation by presenting a stimuli in the blind spot-positive responses indicate poor fixation

33

Gaze tracker

-measure gaze direction with precision of approx one degree
-these tracking results are shown on the video screen and are printed at the bottom of the print out

34

Calibration of HVF

-done automatically by the instrumentcalibration of background and target

35

Room luminance and HVF

Should be dark without visual or auditory distractions

36

Data entry of HVF

-always enter the date, time, patients name, identification or chart number,and BD
-can also add VA, pupil diameters, and refractive error

37

HVF pateitn set up

-always disinfect surfaces
-one eye is occluded
-chin holder adjusted until the pateitns virwing eye is centered in crosshairs on the screen
-lens holder containing appropriate near spectacle ass is placed as close to the patients eye as possible without touching the lashes

38

Considerations for HVF

-anyone who is aphakic
-anyone who is pseudophakic
-anyone that has been dilated

39

Is it better to be dilated or miotic for VF

Dilated is better, but dont want to be either really

40

Trial lens placement for HVF

-rimless trial frame
-if Plano, put the lens holder down
-ensure the trial lens is as close as possible to the patient without touching the patients lashes
-if performing peripheral VF (outside the central 30), you must remove the trial lens

41

Patients instructions for HVA3

-instructions are extremely impiortnat
-if not given properly, will affect test results
-show the patient the button press and how to operate
-patient should be shown the yellow fixation light in the center of he HVF and instructed to look at it throughout the entire test-must NOT look away
-explain that while the fixate on the central light, the computer will flash small spots of light in their side vision
-they are not to look at the side lights-keep looking straight ahead
-press the button each time they believe they views light off to the side )even if they only thin they’ve seen it)
-ok to blink when needed

42

HVF during the test

-watch for fixation losses
-do not leave the room
-reposition pateitn slightly if necessary during the test
-perform test on other eye
-always save and print results

43

HVF: procedures

-examination strategy
-screening
-standard algorithm (full threshold)
-FASTPAC
-SITA

44

Screening HVF

-single intensity
-threshold related
-three zone

45

Standard algorithm (full trehshold )

-full threshold
-full threshold from prior data
-fast threshold

46

Screening on HVF

-not quantitative
-save time
-reserved for new patients where the suspicions of a defect is low
-if defects are found, examination using a threshold test hsould be performed and used to monitor disease

47

Single intensity on HVF

One value of brightness is presented at all points being tests
-default is 24Db

48

Threshold related: HVF screening

Makes the screening target threshold the same across the entire filed
-me Audrey a central threshold and a peripheral threshold and then creates a normal hill of vision from the two values

49

Three zone: HVA

Takes threshold a step further
-if the suprakthreshold target is missed that spot is retested later with a maximum intensity target of 0DB (10,000 abs)

three zone results:
- normal (Sade suprathershold)
-relative defect (missed Supra, but Saw max)
-abolsute defect )did not see max)

50

Full threshold

Most time sounding, however most accurate and repdoruducle
-threshold is detemeind for one primary point per quadrant. 9 degrees away from horizontal and vertical (30-2)
-this is then used to determine starting point for the staircase at other locations thrghouout the fiel
-these trehshlds then feed into the staircase onset of their neighbors

51

Staircase of full threshold

-consists of 4dB decrement in light intently until the patient fails to repsosne=1st reversal
-then 2Db increments uintl the pateitns faisl to see the light again=2nd reversal. This level is the sensitivity printed
-primary points habe threshold estimated twice

52

If any threshold value deviated by >5dB from expected, then it

Brackets the thriesld once’s more
)parenthesis if more accurate than bracket)

53

FASTPAC

-alternative to full threshold
-changes stimulus instensity by 3db and only crosses the threshold once
-can reduce test trim by as much as 35% however, this comes at an expense to accuracy
-less precise

54

SITA

-uses method of detecting threshold values for 4 ptimayt point in each quadrant
-these are used to generate starting levels of neighboring points
-the result is that threshold determination is reached in a shorter amount of time but with the same accuracy as a fullthreshold
-monitor test point results and utilizes a complex stat technique which assigns a level of confidence for how close each point it to its final value

55

SITA standard vs SITA fast

-main difference is the level of confidence. Standard is more reproducibly
-standard sets a higher level of certainty which requires more trials at a give point this its more accurate
-SITA fast takes less time

56

Which is good for glaucoma tracking

24-2 or 30-1

57

Central 30

-76 test point locations that’s covers the central 30 degrees
Spaced 6 degrees apart

58

Central 24

-54 test point locations
-covers the central 24 degrees, except nasally where it extends 30 degrees
-space locations 6 degrees apart
-can pick up a nasal step in glaucoma where early glaucoma damage starts
-still covers 30 degrees at the nasal margin

59

Central 10

68 test point locations
Spaced 2 degrees apart (instead of 6)

60

Version 1 HVF

-spaces locations 6 degrees apart
-places testing locations on the horizontal and vertical meridians

61

Version -2 of HVF

-spaces locations 6 degrees apart
-places testing locations flanking the horizontal and vertical meridians

Almost never use -1. -2 is the most used

62

Periphal zone

-mapping of the field between 30 and 60 degrees (30/60-1, 30/60-2, 60-4, current test on HFA3)
-meant to supplement a central field exam when a more extensive dield defect is suspected
-seldom used, such defects better evaluated with Goldman

63

Full field

-threshold strategies not available for full field programs
-takes too long to acpcmplosh
-divert to goldmann

64

SWAP

Designed for early detection of glaucoma based on the theroty that glaucoma selectively damages door wavelgnth fibers first
-also known as BY perimetry
-31.5asb background with a yellow background of 100-200
-blue filter is placed int he stimulus projection pathway
-sive V is used
-stimulus duration of 0.2 seconds remain constant

65

Indications of HVF

-suspected VF defect
-retinal disease (RP)
-neuro ophthalmic disease
-glaucoma

66

Quantitivative tsting

-purely quantitative
-performed in order to quantify a suspected VF
-performed in order to establish baseline fueled against which future fields may be compared
-high sensitivity

67

Advantages of VF

-testing administration is more satnadardizable
-minimizes test variability
-improves reliability

68

Disadvantages of HVF

-expensive
-very tedious for certain Patietns=fatigue
-requires a strong knowledge of data interpretation by the examiner

69

Types of screeening

-FDP (frequency doubling perimetry)
-fast trehshold estimation strategy
- HVF screening tests

70

Zeus’s FDT

Includes realizability indices
-fixation losses: 6 trials for threshold mode and 3 trials for screening mode
-both are flagged at 33%
-false positive in both testing modes
-false negatives only in threshold mode

71

Zeus’s FDT: patterns

Suprathreshold C-20 and C-30 screening

C-20-5 full trehshold
-tests the central 20 degrees at 17 locations

N-30-5 full threshold
-tests all the points of C-20 tests, plus two additional nasal locations for a total of 19 locations

72

Advantages for automated perimetry: screening

-portable and compact
-affordable
-no trial lens or eye patch
-high level of sensitivity of specificity
-rapid assessment of the field
-reduced learning curves

73

Disadvantage of automated perimetry: screening

-results limited by cataract and pupils <3mm
-trouble detecting small scotomas due to the fact that the FDT uses larger test targets
-offers fewer testing points (17 or 19) vs a HVF

74

Clover leaf pattern

Tired