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Vf in glau (basic course)
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Transcript of Vf in glau (basic course)
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Visual Fields in Glaucoma
Cesar A. Perez Jr MD DPBO Philippine Glaucoma Society
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Definition of Visual Field
The visual field is that portion of the external environment of the observer wherein the steadily fixating eye can detect visual stimuli
International Perimetric Society (1978)
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Extent of the Visual Field
Anderson RA. Automated Static Perimetry
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Temporal fieldNasal field
60
90
70
60 30
Blind spot
Why only the central 30 degrees?
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Visual Field vs Anatomy
Anderson RA. Automated Static Perimetry
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Traquairs Island of Vision
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Definition of Perimetry
Measurement of visual functions of the eye at topographically defined loci in the visual field1
Measures differential light sensitivity, or the ability of a subject to distinguish a stimulus light from background illumination2
1. International Perimetric Society (1978) 2. American Academy of Ophthalmology
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Clinical Perimetry Two major perimetry types Manual kinetic
Automated static (gold standard)
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Automated Static Threshold Perimetry Measures the retina's sensitivity to
light at predetermined locations in the visual field
While the patient focuses on the point of fixation, stimuli are presented in random order at each of the predetermined locations w/in the visual field
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static achromatic stimulus (Gold Standard)
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Clinical PerimetryStimulus size
Size V
Size III (standard)Blind spot
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Apostilbs (Asb) (luminance)
Humphrey Decibels (dB) (sensitivity)
Octopus Decibels (dB)
0.1 50 40
1 40 30
1000 10 0
10,000 0 -
Clinical Perimetry
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Clinical Perimetry
Stimulus intensity is varied but w/ fixed size & duration Determines the minimum intensity at w/c
patient responds to 50% of the time (threshold)
Determined by bracketing - stimulus intensities moved above & below the threshold
Threshold strategy
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Clinical PerimetryBracketing reveals the threshold
Infrathreshold (cant be seen)
Suprathreshold (seen)
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Why test the Visual Field?
Defines state of optic nerve function Defines visual impairment1 To detect eye diseases (glaucoma,
retinal, neuro-ophtha, etc) To monitor an eye disease/visual
impairment
1. Asia Pacific Glaucoma Guidelines (2003-2004)
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What is being tested in Perimetry? Light sensitivity is measured in
different retinal areas Foveal/central areas more sensitive than
peripheral areas
Light sensitivity compared to a normative database derived from multicenter studies
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Interconnecting cells Bipolar Horizontal Amacrine cells
Visual Physiology of the Retina
Light
photoreceptors
RPE
Transmitting cells Ganglion cellsG G
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Humphrey & Octopus practical reading system
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Parameters Reliability Age Corrected plots Tests (GHT/Bebie curve) Indices Correlate clinically Evaluate
7 Steps 5 zones (PRACTICE) HumphreyTM OctopusTM
1) P 2) R 3) AC 4) T 5) I 6) C 7) E
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34 5
12 HumphreyTM 5 Zones Counter-clockwise
1) Parameters 2) Reliability 3) Age Corrected 4) Tests 5) Indices 6) Correlate
clinically 7) Evaluate
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1
23
4
5
OctopusTM
5 Zones Clockwise
1) Parameters 2) Reliability 3) Age Corrected 4) Tests 5) Indices 6) Correlate
clinically 7) Evaluate
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Test strategy Full threshold, SITA-standard, SITA fast
Region/pattern used 30-2, 24-2, 10-2
Patient details date of birth, date of VF, pupil size, test time, VA, correction, eye tested
1.Parameters HumphreyTM
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Perimetry Programs Full Threshold 30-2
Standard 18-20 minutes per eye 4-2-1 staircase with double crossover for
Octopus; 4-2 staircase for Humphrey Light stimulus size is standard (Goldmann
Size III)
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Full threshold
HumphreyTM
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SITA Standard Diagnostic sensitivity similar to full
threshold (both 95%)1 Sensitivity, specificity, characterization, &
reliability of determining VF properties > vs other threshold tests2-4
50% reduction in testing times 4 minutes for a normal field 8 minutes for a glaucoma field
1. Delgado, et al, Ophthalmology Dec 2002 2. Bengtsson B, et al. Acta Ophthalmol Scand. 1998 3. Bengtsson, B, Heijl. A. Acta Ophthalmol Scand. 1998 4. Budenz DL, et al. Ophthalmology. 2002
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HumphreyTM
SITA - Standard
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2-6 minutes 3 minutes normal field 5.5 minutes glaucoma field
93% sensitivity vs 95% for SITA standard1 For patients : Younger Restless Learning
1. Delgado, et al, Ophthalmology Dec 2002
SITA Fast
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24-2 tests 54 points 30-2 tests 76 points
24-2 or 30-2? HumphreyTM
10-2? For advanced
glaucoma Tests 68 points
in the central 10 degrees
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HumphreyTM
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advanced glaucoma 30-2
HumphreyTM
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12
HumphreyTM
1) Parameters 2) Reliability
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Is the field reliable? false (+): pressing button even w/o
visual stimulus
false (-): failure to respond to a threshold stimulus previously seen at the same point
if > 33% FP or FN, then unreliable if > 20% fixation losses then unreliable
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3
12 HumphreyTM1) Parameters 2) Reliability 3) Age Corrected
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Compare total & pattern deviation
3.Age Corrected plots HumphreyTM
Zero in on the probability plots
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Compare total deviation (TD) & pattern deviation (PD) probability plots Humphrey
TM
If defect in TD & PD plots look similar Focal field defect
Depressed TD w/ a normal PD Diffuse or generalized field defect
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Focal defect
Compare total & pattern deviation HumphreyTM
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HumphreyTM
Generalized defect
Compare total & pattern deviation
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34
12 HumphreyTM1) Parameters 2) Reliability 3) Age Corrected 4) Tests
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Outside normal limits if sensitivities in > 1 of the
5 zones in upper half of the field are different (p
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34 5
12 HumphreyTM1) Parameters 2) Reliability 3) Age Corrected 4) Tests 5) Indices
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5.Indices (global)
MD: mean deviation PSD: pattern standard deviation SF: short-term fluctuation CPSD: corrected PSD
HumphreyTM
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Mean deviation (MD)
Average difference between overall sensitivity of patient and age-matched controls
Indication of generalized defects or elevation (+ or - 2 dB normal)
Good measure of diffuse defects
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5.Indices (global) HumphreyTMMean deviation (MD)
40
0
30
20
10
90 60 30 0 30 60 90
Normal hill of vision (age corrected)
dB
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Pattern standard deviation (PSD) shape of VF departs from normal age-
corrected field
Focal / localized defects Single most useful analysis Beginning VF loss appear earlier in
probability plots vs grayscale Normal value : 0 to 6 dB
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Short term fluctuations (SF)
0-2dB normal Average between 2 determinations should be: < 2dB in normal field < 3dB in early damage < 4dB in moderate damage
Increased fluctuation
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Pattern Standard Deviation (PSD) corrected for the SF
Better measure of localized field loss (0-4 dB normal)
Corrected Pattern Standard deviation (CPSD)
HumphreyTM
5. Indices (global)
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34 5
12 HumphreyTM1) Parameters 2) Reliability 3) Age Corrected 4) Tests 5) Indices 6) Correlate
clinically 6
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34 5
12 HumphreyTM1) Parameters 2) Reliability 3) Age Corrected 4) Tests 5) Indices 6) Correlate
clinically 7) Evaluate 67
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11) Parameters
OctopusTM
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Test strategy Normal, Dynamic, TOP
Pattern/region used G1, 32, M2, LVC
Patient details Date of birth, date of VF, pupil size, test time, VA, correction, eye tested
OctopusTM
1.Parameters
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Points positioned in areas of concern in glaucoma Accentuates nasal
step Higher resolution in
paracentral area
G1 program
OS
OctopusTM
1.Parameters - pattern
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Full Threshold
Normal Strategy
OctopusTM
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OctopusTM
excellent correlation w/ normal strategy
Dynamic TOP
Shorter strategies:
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Perimetry Programs Dynamic Program 30-2 (Octopus)
~ 7 minutes per eye Stimulus presentation adapted to
measured threshold value Higher sensitivity ! smaller steps (2 dB) Lower sensitivity ! larger steps (6-10 dB)
Single crossover Light stimulus size is standard (Goldmann
Size III)
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Perimetry Programs Tendency Oriented Perimetry (TOP)
Program 30-2 ~ 2-3 minutes per eye Screening Only 1 test question per location Single answer influences the value of 8
neighboring points Light stimulus size is standard (Goldmann
Size III) Phase 1 only No SF (short term fluctuation)
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G1 vs 32 pattern
OctopusTM
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For detection and/or f/up of defects in the central 100 Neurological Macular Peri-macular
M2 program
00 100
OctopusTM
1.Parameters - pattern
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M2 program (central 100)
OctopusTM
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Tests sensitivity in central foveal area Same grid as 32
program End stage glaucoma Goldmann stimulus V
LVC program
00 300
1.Parameters - pattern OctopusTM
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LVC program
OctopusTM
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2. Reliability Factor
Ideally < 15 Lower the better
OctopusTM
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1
23
OctopusTM
1) Parameters 2) Reliability 3) Age Corrected
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Zero in on the probability plots
OctopusTM
Compare C & CC probability plots
3.Age Corrected plots
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OctopusTM
4.Tests: Bebie curve
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Quickly assesses defect characteristics & depth
Diffuse vs focal defect Diffuse: curve below & parallel to the
normal curve Focal: steep fall-offs on the right side
of the curve
OctopusTM
4.Tests: Bebie curve
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Diffuse defect: curve below & parallel to normal curve
OctopusTM
4.Tests: Bebie curve
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Focal defect: steep fall-offs
4.Tests: Bebie curve OctopusTM
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OctopusTM
5. Indices (global)
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mean sensitivity (MS)mean deviation (MD) mean defect (MD)pattern std deviation (PSD) loss variance (LV)short term fluctuations (SF)
short term fluctuations (SF)
corrected pattern standard deviation (CPSD)
corrected loss variance (CLV)
OctopusTM HumphreyTM
5.Indices (global)
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Visual Field Indices Normal Values
Mean Defect ( -2.0 to +2.0 db )
Loss Variance ( 0 to 6.0 db )
Short-term Fluctuation ( 0 to 2.0 db )
Corrected Loss Variance ( 0 to 4.0 db )
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1
23
4
56
OctopusTM
1) Parameters 2) Reliability 3) Age Corrected 4) Tests 5) Indices 6) Correlate
clinically
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1
23
4
567
OctopusTM
1) Parameters 2) Reliability 3) Age Corrected 4) Tests 5) Indices 6) Correlate
clinically 7) Evaluate
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Is the field defect glaucomatous?
Is the defect focal?
Is the defect diffuse?
STEP 1
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Glaucoma defects are Focal in nature
Diffuse Focal
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What kind of a defect is this? diffuse or focal?
combined diffuse & focal defect
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If the defect is Focal
STEP 2:
Is the focal defect glaucomatous?
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Glaucomatous Visual Field Defects (Seagig Glaucoma Guidelines 08)
Asymmetrical across horizontal meridian* Are located in mid-periphery* (5250
from fixation) Reproducible Not attributable to other pathology Clustered in neighboring test pts (localised) Correlate with optic disc and RNFL
* Applicable to early/moderate cases
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Localized patterns of glaucoma VF defects
Nasal step (earliest)
Paracentral scotoma
Arcuate (Bjerrum) scotoma Later becoming altitudinal
Temporal island
Central island
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Superior nasal step
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Inferior paracentral scotoma
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Arcuate (Bjerrum) scotoma
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Superior altitudinal w/ inferior arcuate scotoma
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Reproducibilty A visual field defect must be real. To be real, it
must be confirmed on repeated exams
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1. Anderson DR, Patella VM. Automated Static Perimetry. 2nd Ed. St Louis: Mosby 1999
2. Hodapp E, Parrish RK, Anderson DR. Clinical decisions in glaucoma. St Louis: Mosby
What is the minimum criteria for a defect to be possibly glaucoma?1
When do you classify a glaucoma defects as:2 Early? Moderate? Severe?
Identification & Classification of a glaucoma defect
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Minimum Criteria for glaucoma defects (1)
3 non-edge points w/ p< 5%
One point w/ p< 1% Cluster in arcuate area
Anderson DR, Patella VM. Automated Static Perimetry. 2nd Ed. St Louis: Mosby 1999
Pattern deviation plot
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Criteria for glaucoma defects (2)
CPSD or PSD depressed, with p < 5%
Anderson DR, Patella VM. Automated Static Perimetry. 2nd Ed. St Louis: Mosby,1999
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Criteria for glaucoma defects (3)
Abnormal GHT
Anderson DR, Patella VM. Automated Static Perimetry. 2nd Ed. St Louis: Mosby 1999
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3 minimum criteria for glaucoma defects
2) CPSD or PSD depressed w/ p < 5%
3) Abnormal GHTAnderson DR, Patella VM. Automated Static Perimetry. 2nd Ed. St Louis: Mosby 1999
1) PD plot a) 3 non-edge points w/
p< 5% b) 1 point w/ p < 1% c) Cluster in arcuate area
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Hodapp E, Parrish RK, Anderson DR. Clinical decisions in glaucoma. St Louis: Mosby
Criteria for Early Glaucoma Defect
MD < -6 dB
On PD plot, < 25% (18 pts) below 5% level and < 15% (10 pts) below 1% level
No pt w/in central 50 : sensitivity < 15 dB
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Early Glaucoma Defect
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MD > -6 dB but < -12 dB
PD plot, < 50% (37 pts) < 5% level and < 25% (20 pts) < 1% level
No absolute deficit (0 dB) in the central 50
Only 1 hemi-field has point w/ sensitivity < 15 dB in the central 50
Hodapp E, Parrish RK, Anderson DR. Clinical decisions in glaucoma. St Louis: Mosby
Criteria for Moderate Glaucoma Defect
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Moderate Glaucoma Defect
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MD > -12 dB
On PD plot > 50% of pts < 5% level > 25% of pts < 1% level
Absolute deficit (0 dB) in the central 50
Both hemi-fields w/ pt(s) w/ sensitivity < 15 dB w/in th central 50
Hodapp E, Parrish RK, Anderson DR. Clinical decisions in glaucoma. St Louis: Mosby
Criteria for Severe Glaucoma Defect
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Severe Glaucoma Defect
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Detecting Progression
Widening or deepening of an existing scotoma
Development of a new glaucomatous scotoma
Occasionally generalized field depression (although usually caused by media opacity or miosis)
Asia Pacific Glaucoma Guidelines (2003-2004)
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Requires a series of at least 3 or 4 fields
Basing judgements on only 1 progressed field is very risky unless the changes encountered are Very large and/or Confirmed by other clinical findings, such as
changes in optic disc configuration
Detecting Progression
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Octopus
Series Program 3 examinations arranged in one
printout PeriTrend Statistical Software EyeSuite
Detecting Progression
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Octopus: Series Program
Detecting Progression
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Calculates regression curves of MD (mean defect) and LV (loss variance)
Color-coded curves to show changes: red depressed green improved blue trend isnt significant/stable
Octopus: PeriTrendDetecting Progression
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Octopus: PeriTrend
Detecting Progression
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Humphrey
Overview print-out
Glaucoma Progression Analysis (GPA) software
Detecting Progression
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Humphrey: Overview print-out
Detecting Progression
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Humphrey: GPA software
Detecting Progression
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Structure-Function Correlation
Combined w/ other examinations
No isolated interpretations
Disc features must match visual field defects (clinical picture takes precedence)
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New Perimetry Technologies Short Wavelength Automated
Perimetry (SWAP)
Blue light stimulus on yellow background (blue on yellow)
Detects VF loss 3-5 yrs before white on white perimetry1
Utilizes the K ganglion cells
1. Racette L et al. Ophthalmol Clin North Am. 2003: 16: 227-236
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Goldmann size V 440 nm, 1.80
> 500 nm yellow background
Except for these differences, SWAP is still a basic threshold perimetry test, in w/c std Goldmann stimuli are presented in the conventional way
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New Perimetry Technologies
Frequency Doubling Technology (FDT) perimeter
Motion/flicker perimetry FDT can detect VF loss 4 yrs before
SAP1 Utilizes the M ganglion cells/
Magnocellular pathway
1. Johnson CA et al. J Vision. 2002; 2:100a
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Functional testing essential: SAP Know retinal anatomy & its relation to
visual function Know programs/parameters Stick to a single one for ff-up
Glaucoma defects are focal Progression is a hallmark of
Glaucoma CLINICAL CORRELATION
Summary
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Although sometimes it is not as easy as it seems
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Thank You!
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Perimetry Exercises
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1 year after
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1 year after
Early defects may show up in probability plots and not in the grayscale
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1 year after
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6 mos. after
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6 mos. after
progressing cataract
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elevated false + score GHF abnormally high sensitivity white scotoma on grayscale larger defects on the pattern
deviation plots than in the total deviation probability plots
highly positive mean deviation (MD)
Trigger happy field
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both a focal and a diffuse defect
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.a year after
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post cataract surgery
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double arcuate scotomas
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superior paracentral scotoma
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inferior nasal step extending to blind spot
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1 month after
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1 month after
withdrawal of miotic TX
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Are the VF defects artifacts?
Learning effect ? Rim effect ? Ptosis, prominent brows ? Lack of instructions or supervision ? Anxiety/fatigue/drowsiness ? Malingering ?
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Learning effect
Depressed sensitivity in mid-periphery 20-300
Less common in shorter algorithms 10-20% of normal patients dont
produce normal VFs on their first test
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Rim effect
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Lid effect seen on grayscale but not seen on probability plots
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Ptosis effect seen on probability plots
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same patient after taping upper lid
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Cloverleaf pattern
Initial good responses ..then poor Test begins centered around 4 primary points
patient misunderstanding, lack of motivation, and/or fatigue
poor instruction/supervision by technician
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The first visual field IS NOT THE BASELINE.
LEARNING CURVE