Interpretation of Humphrey

8/13/2019 Interpretation of Humphrey

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Traquair difined the visual field as the “island of vision

surrounded by the sea of darkness”

• Axis X, Y(parallel to the

sea level)

• Axis Z

(perpendicular

to the sea level)



•

The visualfield is

measured in

two ways• Kinetic and

Static

perimetry



The visual field is plotted as the

patient sees it



Units of light intensity

• The light intensity expressed in

apostilb (asb) or decibel (dB) units• Retinal sensitivity expressed in

decibel

• As the dB value is decreasing,the light intensity is increasing



As the dB value is decreasing,

the light intensity is increasing

In Humphrey Field Analyzer

• 0 dB no attenuation =10.000 asb

• 10 dB is 1/10 x 10.000 = 1.000 asb

• 20 dB is 1/102 x 10.000 = 100 asb

•

30 dB is 1/10

3

x 10.000 = 10 asb• 40 dB is 1/104 x 10.000 = 1 asb







Definition of threshold

•

Threshold sensitivity is defined as thestimulus intensity at which the patient

respond 50% of the time



2

24

4

Humphrey Visual Field Analyzer





ANALYSIS OF VISUAL FIELD DATA

To understand and interpret the single

field printout it is divided in 8 zones

• Zone 1 : Patient and test data

•

Zone 2 : Reliability indices and foveal treshold• Zone 3 : Raw data

• Zone 4 : Gray scale

• Zone 5 : Total deviation plot

• Zone 6 : Pattern deviation plot• Zone 7 : Global indices

• Zone 8 : Glaucoma hemi field test (GHT)(Gupta AK,et al,2007)



Zone 1 : Patient and Test Data



Zone 1 : Patient and Test Data

•

Patient name and identity number• Age and date of birth

– Wrong patients’ age can alter results of field test

•

Eye tested• Visual acuity and refractive correction used

• Pupillary size

– Pupillary size should remain constant in follow upfields



The test data has the following information

• Test pattern and strategy performed.

• Fixation monitor (Blind spot) *

• Stimulus size : Goldmann size III• Background illumination : It is a constant at 31.5

asb. *

•Color of the stimulus : White *

• Fixation target



Zone 2 : Reliability parameter and foveal threshold

Reliability parameter

Unreliable ….XX

Patient Fixation………… > 20%

False Positive errors… > 33%

False negative errors… > 33%



Zone 2 : Reliability parameter and foveal threshold

False positive > 33%gray scale : white scotomaGHT : abnormaly high sensitivity

False negative >33%lack of attentive, fatique, advance damage

Low patient reliability does not necessarilymean lack useful information

It is just that such field are not included in thedatabase, such field must be interpreted withmore caution.



Zone 3: Raw data

• Actual threshold value

• Even if all zones are

normal, but the

clinical picture are

very suspicious,

inspect zone 8.

•

One may pick up ascotoma



Zone 4: Gray scale

• Conversion of the raw datato gray tone symbols

• Do not make any diagnosis

on the basis of gray scale

• It give an impression anddraw attention to an area

• Useful to explain thecondition to the patient



Useful when there areGross False positive (white scotoma)

False negative error (clover leaf)

Explain the seriousness of the condition to the patient

Zone 4: Gray scale



Paracentral

Scotoma

Arcuate

Scotoma

Nasal StepTemporal

Wedge



Zone 5: Total deviation plot

numeric values

probability plot

symbols that indicate thestatistical significance of

each measured deviation



Zone 6: Pattern deviation plot

• Provided as numerical

and probability plot

• To expose localized

defect

• It adjust for any overall

sinking of hill of vision



Normal “Hill of vision”

Zone 4: normal no depressed point

Zone 5: normal no depressed point

(courtesy of Prof. Ravi Thomas)



Generalized depression (cataract)

Zone 4: many depressed point

Zone 5: normal

No localized defect




Localized scotoma

There are depressed point in zone 4 that persist in zone 5




Zone 7: Global indices

• Each global index summarized andcharacterizes one aspect of the test as asingle value



Zone 7: Global indices

• MD (mean deviation)shows how much, on average, the whole field depart fromnormal

• PSD (Pattern Standard Deviation)reflects irregularities in the field caused by localizeddefects

• SF (Short term Fluctuation)is index of intra test variationSF is removed from PSD to produced CPSD (CorrectedPattern Standard Deviation)



Hoddap Classification

Early Glaucomatous Loss

a. MD > -6 dB

b. Fewer than 18 points depressed below

the 5% probability level and fewer than

10 points below the p<1% level

c. No point in the central 5 degrees with

a sensitivity of less than 15 dB



Moderate Glaucomatous Loss

a. -6>MD > -12 dB

b. Fewer than 37 points depressed below the5% probability level and fewer than 20points below the p<1% level

c. No absolute deficit (0 dB) in the 5 central

degreesd. Only one hemifield with sensitivity of < 15

dB in the 5 central degrees




Advanced Glaucomatous Loss

a. MD < -12 dB

b. More than 37 points depressed below the5% probability level or more than 20points below the p<1% level

c. Absolute deficity (0 dB) in the 5 central

degreesd. Sensitivity < 15 dB in the 5 central degrees

in both hemifields




Zone 8: Glaucoma Hemifield Test

Five possible message of GHT

• Outside normal limit

•

Borderline• General reduction of sensitivity

• Abnormally high sensitivity

• Within normal limits



Zone 8: Glaucoma Hemifield Test

Five zones in the

upper field arecompared its

mirror-image in

the lower field



Early glaucoma:

1.Pattern deviationprobability plot shows a

cluster of > 3 non-edgepoints with p< 5% andone points has p<1%.

2.PSD or CPSD with p< 5%

3.GHT outside normal limits





FIGURE 1 :

HFA 30-2CONSTRICTED

FIELD



FIGURE 2 :HFA 30-2 of the

same patient as

in figure 1 withthe field

repeated with

an appropriatecontact lens



TRY TO INTERPRET THIS PRINTOUT...

CASE 1 Zone 1: entered correctly

Zone 2 : reliable field

false neg NA

Zone 3 : central islandZone 4 : all depressed point

Zone 5 : better than deviationplot

Zone 6 : MD and PSD flag asabnormal

GHT : outside normal limit

Advance field loss

Order for 10-2 and macula

program



The result of 10-2

CASE 1



CASE 2

Zone 1 and 2: OkZone 3 : arcuate defectZone 4 : depressed pointsuperiorlyZone 5 : arcuate scotomaZone 6: MD and PSDabnormalZone 7: GHT outside normallimits

It is consistent with typicalglaucomatous defect

Then correlate with fundusfinding



Inferiorretinochoroidcoloboma

Neverinterpret thefield alone!!

CASE 2



Case 3

Zone 1: 30-2 program

Zone 2: reliable field

Zone 4: many depressed pointp<0.5%

Zone 5 : many depressed point

persist with p< 0.5% in arcuatearea

Zone 6 :MD and PSD flag asabnormal

Zone 7: GHT outside normal limit

This is a Juvenile OAG, posttrabeculectomy, IOP 12 mmHg,

cd 0.7



THANK YOU

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Interpretation of Humphrey