vf in glau (basic course)

Visual Fields in Glaucoma

Cesar A. Perez Jr MD DPBO Philippine Glaucoma Society

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)

Extent of the Visual Field

Anderson RA. Automated Static Perimetry

Temporal fieldNasal field

60°

90°

70°

60° 30°

Blind spot

Why only the central 30 degrees?

Visual Field vs Anatomy

Anderson RA. Automated Static Perimetry

Traquair’s Island of Vision

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

Clinical Perimetry■ Two major perimetry types

➢ Manual kinetic

➢ Automated static (gold standard)

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

static achromatic stimulus (Gold Standard)

Clinical PerimetryStimulus size

Size V

Size III (standard)Blind spot

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

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

Clinical Perimetry“Bracketing” reveals the threshold

Infrathreshold (can’t be seen)

Suprathreshold (seen)

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)

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

Interconnecting cells ▪ Bipolar ▪ Horizontal ▪ Amacrine cells

Visual Physiology of the Retina

Light

photoreceptors

RPE

Transmitting cells ▪ Ganglion cellsG G

Humphrey & Octopus practical reading system

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

34 5

12 HumphreyTM

• 5 Zones • Counter-clockwise

1) Parameters 2) Reliability 3) Age Corrected 4) Tests 5) Indices 6) Correlate

clinically 7) Evaluate

1

23

4

5

OctopusTM

• 5 Zones • Clockwise



▪ 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

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)

Full threshold

HumphreyTM

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

HumphreyTM

SITA - Standard

■ 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

• 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

HumphreyTM

advanced glaucoma 30-2

HumphreyTM

12

HumphreyTM

1) Parameters 2) Reliability

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

3

12 HumphreyTM

1) Parameters 2) Reliability 3) Age Corrected

Compare total & pattern deviation

3.Age Corrected plots HumphreyTM

Zero in on the probability plots

Compare total deviation (TD) & pattern deviation (PD) probability plots HumphreyTM

▪ If defect in TD & PD plots look similar ➢ Focal field defect

▪ Depressed TD w/ a normal PD ➢ Diffuse or generalized field defect

Focal defect

Compare total & pattern deviation HumphreyTM

HumphreyTM

Generalized defect

Compare total & pattern deviation

34

12 HumphreyTM

1) Parameters 2) Reliability 3) Age Corrected 4) Tests

■ Outside normal limits ➢if sensitivities in > 1 of the

5 zones in upper half of the field are different (p<0.01) from those in the corresponding lower half zones

4.Tests: glaucoma hemifield test (GHT) HumphreyTM

34 5

12 HumphreyTM

1) Parameters 2) Reliability 3) Age Corrected 4) Tests 5) Indices

5.Indices (global)

▪ MD: mean deviation ▪ PSD: pattern standard deviation ▪ SF: short-term fluctuation ▪ CPSD: corrected PSD

HumphreyTM

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

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

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

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

▪ 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)

34 5

12 HumphreyTM


clinically 6

34 5

12 HumphreyTM


clinically 7) Evaluate 67

11) Parameters

OctopusTM

▪ 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

▪ Points positioned in areas of concern in glaucoma ➢Accentuates nasal

step ➢Higher resolution in

paracentral area

G1 program

OS

OctopusTM

1.Parameters - pattern

“Full Threshold”

Normal Strategy

OctopusTM

OctopusTM

➢excellent correlation w/ normal strategy

▪ Dynamic ▪ TOP

Shorter strategies:

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)

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)

G1 vs 32 pattern

OctopusTM

▪ For detection and/or f/up of defects in the central 100

➢ Neurological ➢ Macular ➢ Peri-macular

M2 program

00 100

OctopusTM

1.Parameters - pattern

M2 program (central 100)

OctopusTM

▪ 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

LVC program

OctopusTM

2. Reliability Factor

▪ Ideally < 15 ▪ Lower the better

OctopusTM

1

23

OctopusTM

1) Parameters 2) Reliability 3) Age Corrected

Zero in on the probability plots

OctopusTM

Compare C & CC probability plots

3.Age Corrected plots

OctopusTM

4.Tests: Bebie curve

▪ 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


Diffuse defect: curve below & parallel to normal curve

OctopusTM


Focal defect: steep fall-offs

4.Tests: Bebie curve OctopusTM

OctopusTM

5. Indices (global)

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)

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 )

1

23

4

56

OctopusTM


clinically

1

23

4

567

OctopusTM



Is the field defect glaucomatous?

• Is the defect focal?

• Is the defect diffuse?

STEP 1

Glaucoma defects are Focal in nature

Diffuse Focal

What kind of a defect is this? diffuse or focal?

combined diffuse & focal defect

If the defect is Focal

STEP 2:

Is the focal defect glaucomatous?

Glaucomatous Visual Field Defects (Seagig Glaucoma Guidelines ‘08)

▪ Asymmetrical across horizontal meridian* ▪ Are located in mid-periphery* (5–250

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

Localized patterns of glaucoma VF defects

▪ Nasal step (earliest)

▪ Paracentral scotoma

▪ Arcuate (Bjerrum) scotoma ➢ Later becoming altitudinal

▪Temporal island

▪ Central island

Superior nasal step

Inferior paracentral scotoma

Arcuate (Bjerrum) scotoma

Superior altitudinal w/ inferior arcuate scotoma

Reproducibilty■ A visual field defect must be real. To be real, it

must be confirmed on repeated exams

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

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

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

Criteria for glaucoma defects (3)

Abnormal GHT

Anderson DR, Patella VM. Automated Static Perimetry. 2nd Ed. St Louis: Mosby 1999

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

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

Early Glaucoma Defect

▪ 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


Criteria for Moderate Glaucoma Defect

Moderate Glaucoma Defect

▪ 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


Criteria for Severe Glaucoma Defect

Severe Glaucoma Defect

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)

■ 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


Octopus

▪ Series Program ➢3 examinations arranged in one

printout ▪ PeriTrend® Statistical Software ▪ EyeSuite®


Octopus: Series Program


▪ Calculates regression curves of MD (mean defect) and LV (loss variance)

▪ Color-coded curves to show changes: ➢red – depressed ➢green – improved ➢blue – trend isn’t significant/stable

Octopus: PeriTrend®Detecting Progression

Octopus: PeriTrend®


Humphrey

■ Overview print-out

■ Glaucoma Progression Analysis® (GPA®) software


Humphrey: Overview print-out


Humphrey: GPA® software


Structure-Function Correlation

■ Combined w/ other examinations

■ No isolated interpretations

■ Disc features must match visual field defects (clinical picture takes precedence)

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

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

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

▪ 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

Although sometimes it is not as easy as it seems

Thank You!

Perimetry Exercises

…1 year after

…1 year after

Early defects may show up in probability plots and not in the grayscale

…1 year after

… 6 mos. after

… 6 mos. after

progressing cataract

• 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

both a focal and a diffuse defect

….a year after

post cataract surgery

double arcuate scotomas

superior paracentral scotoma

inferior nasal step extending to blind spot

…1 month after

…1 month after

withdrawal of miotic TX

Are the VF defects artifacts?

▪ “Learning effect” ?

▪ Rim effect ?

▪ Ptosis, prominent brows ?

▪ Lack of instructions or supervision ?

▪ Anxiety/fatigue/drowsiness ?

▪ Malingering ?

Learning effect

▪ Depressed sensitivity in mid-periphery 20-300

▪ Less common in shorter algorithms ▪ 10-20% of normal patients don’t

produce normal VF’s on their first test

Rim effect

Lid effect seen on grayscale but not seen on probability plots

Ptosis effect seen on probability plots

same patient after taping upper lid

“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

• The first visual field IS NOT THE BASELINE.

• “LEARNING CURVE”

vf in glau (basic course)

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