How to Interpret Humprey Perimetry Printout

1. How to Interpret
Humphrey Visual Field
Dr. Mohammad Mohiey

2. Visual Field
“ An Island of Vision Surrounded by A Sea of Darkness”
“Measurement of Hill of Vision, in Terms of Establishing
Patient’s Differential Light Sensitivity across Visual Field ”
Perimetry

3. Hill of Visiono Hill of Increasing
Sensitivity/Visual Acuity
o Maximum Height at
Fixation
Fovea.
o Blind Spot 10-20 °
Temporal to Fixation
Optic Nerve Head
o Decreases Towards
Periphery
Steeply Nasally
Gradually Temporally

4. Field Extensions
• Superiorly
60 °
• Nasally
60 °
• Inferiorly
70-75 °
• Temporally
90-100 °

5. Types of Perimetry
Static Perimetry:
 Examples: Henson, Octopus, Humphrey.
 Provide 3D Measure of Vertical Boundaries of Visual Field.
 Stimulus of Variable Luminance and Size at Different Locations of Field.
 Automated Computerized Standardized , Uses Machine with Preset Programs.
 Test Analysis in Quantitive Manner (Available Normative Data and Statistical Analysis).
Kinetic Perimetry:
 Examples: Simple Confrontation, Bjerrrum Screen, Lister or Goldmann Perimeter.
 Provide 2D Measure of Boundary of Hill of Vision.
 Stimulus of Known Fixed Size and Brightness. Slowly Moved from Periphery Toward Center.
 The Points at which Stimulus Perceived, Plotted on Chart, Joined by Line to Form Isoptres.
 Test Analysis in Qualitative Manner (NO Available Normative Data & Statistical Analysis).

6. Stimulus Series of White-on-White Light Stimuli
 Variable Intensities (0-51 decibel) & Brightness (0.08-10000 apostilb)
Minimum Intensity (0 dB) = Maximum Brightness (10.000 asb)
Maximum Intensity (51 Db) = Maximum Dimness (0.08 asb)
 Variable Sizes (I to V), Ranging from 0.25 mm² to 64 mm² (0.1° to 1.72°)
 Uniform Background Illumination of 31.5 asb. (10 Cd/m2) [Standardized]
This Adaptation Level = Minimum Brightness for Photopic Vision
That depends upon Retinal Cone function rather than on Rods.
 Fixed Duration of (200 milli-seconds) [Standardized]
Long Enough for Visibility.
Shorter than Latency for Voluntary Eye Movements (No Time to See Then Look Towards)
 Various Locations at Visual FieldAccurate Mapping of Presentation of Stimuli on Retina.
 Fixation Monitoring by Gaze Tracker with Precision of 1°, Recoded with Each Stimulus.

7. o All Test Targets much Smaller than Blind Spot
Which measures 5° horizontally by 7° vertically.
o In Standardized Test, Used Stimulus; Size III White
Which measures 4 mm² (0.43° diameter ofVisualAngle)
o Size V is sometimes employed in Advanced Field Loss.
o Dimmest stimulus that can be seen
By young, well-trained observer is <40 Db
o Size V is sometimes employed in Advanced Field Loss.

8.  Peripheral
• Rarely Used, Rule Out Retinal Detachment.
 Central 30-2
• Tests 76 Points.
• In Central 30° of Fixation.
• Long and Laborious.
 Central 24-2
• Tests 54 Points.
• In Central 24° of Fixation.
• Gold Standard.
 Central 10-2
• Tests 68 Points.
• In Central 10° of Fixation.
• Used in Advanced Glaucoma, Valuable in Evaluating VF Loss in Macular Disease.
Test Patterns

9. Testing Types
Threshold Test:
 Quantifies Sensitivity (measure differential sensitivity at each tested location).
 Used for Diagnosis, Detects Earliest Changes of Visual Field.
 Standard of Care for Following-Up of Patients with Established Field Loss.
 Increase Stimulus Intensity to 4 dB then Re-Checked by Decreasing to 2 dB.
Supra-Threshold Test:
 Establish Visual Function/Sensitivity, Whether or NOT is Abnormal.
 Mainly Used for Screening (120-Point of Light at Luminance Level 2-6 dB).
 +ve Test = Total 17 Missed Points or 8 Missed Points in any One Quadrant.
 NO Quantitive Data / NOT Sensitive to Early Visual Field Loss as Threshold.

10. Testing Strategies
 Offers High Accuracy & Sensitivity with Time Saving (of 3-7 Minutes/Eye).
 Uses Computerized Algorithms based on Normative Age-Matched Database.
 Utilizes Threshold Values of Tested and Adjacent Points to Determine Starting Points, so Saving Time by
Reducing Number of Presentations.
Full Threshold
 Testing at a Single Location in Each Quadrant of the visual field
 If a stimulus is seen, Subsequent Stimuli at that location are Dimmed in steps until no longer seen.
 If Initial stimulus is NOT Seen, Subsequent presentations are made brighter in steps until been seen.
SITA Fast vs. SITA Standard
Shorter Duration (of 2-5 Minutes/Eye), But May be Less Reliability & Sensitivity
TOP Tendency Oriented Perimetry Octopus
SITA Swedish Interactive Threshold Algorithm Humphrey

11.  Known as Blue-Yellow Perimetry.
 Stimulus: Blue Goldmann Size V.
to Preferentially Stimulate Short-Wave Sensitive Pathway (Blue-Cone System)
 Background: Yellow High Luminance (100 Cd/m2).
to Saturate Both Medium and Long Wave-Length Sensitive Pathways.
and Simultaneously Suppress Rod, Red and Green Cone System.
 Theory: Blue Visual Pathways have Less Redundancy.
and are Preferentially Damaged in Glaucoma.
 So Detection of Loss of Blue Pathway Nerve Fibers in Visual Field Defects
Allows Earlier Detection of Glaucomatous Visual Field Loss.
 It is Sensitive But Less Specific, Greater Fluctuations, Longer Time.
SWAP Short Wavelength Automated Perimetry

12. Choosing A Test ?
24-2
Size III
White
SITA
Standard
Little Diagnostic information is Lost.
Considerable Testing Time is Saved.
Fewer Artifacts also Seen.
Computerized Static Perimetry has established the
Goldmann white, Size III stimulus as Standard.
Twice as Fast as the older strategies they replaced.
More Precise, Tolerable. Reliable.

13. Humphrey
©Zeiss
SAP Standard Automated Perimetry
 Static Computerized Threshold Perimetry
 With White-on-White Stimulus
Most Frequently Used Analyzer in Egypt and UK.
Consists of Hemispherical Bowl onto which
Target is Projected.
Patient Presses a Button when Target Seen.

14. Testing Procedure

15. When Is Perimetry Called For?
GLAUCOMA
o Repeated Perimetric Tests that Reproducibly Demonstrate Visual Field Loss.
The Most Conclusive Contributor to Glaucoma Diagnosis.
The Most Precise Method for Quantifying Glaucomatous Progression.
NEUROLOGICAL Disease:
 NOT as Crucial Technique as in Glaucoma; Neuroimaging often replace it..
 May Sometimes provide an In-Expensive and Non-Invasive Alternate.
 A Way of Documenting Changes in Visual Function.
RETINAL Disease:
 One of Ancillary Tests; Fundus Observation & Imaging usually are of greater value.
 Peripheral Visual Field Testing may play Larger role than in Glaucoma or Neurological.

16. What Are We Looking for?
GLAUCOMATOUS Visual Field Defects:
 Early Defects most often take form of Localized Relative Scotomas.
 Defects in Nasal Field are particularly Common.
 Only Small % occur in Peripheral Field Alone, Testing Central 24°–30° Field is Preferred.
NEUROLOGICAL Visual Field Defects:
 Most Neurological Defects are Hemianopic,
 Tend to Affect Either Right or Left Half and to Respect Vertical Meridian.
 Mostly Start in Central Visual Field, So Testing Central 30 ° Field is Preferred.
RETINAL Visual Field Defects:
 Such Defects are Often Deep, with Steep Borders.
 May occur in Any Part of Visual Field.

17. Zones of Printout
1. Patient Data
2. Test Data
3. Reliability Indices
4. Threshold Values
5. Grayscale Map
6. Total Deviation Maps
(Numerical & Probability)
7. Pattern Deviation Maps
(Numerical & Probability)
8. Glaucoma Hemifield Test
9. Global Indices
10. Gaze Tracking Record

18.  False Positive Response Errors
• Should Not Exceeding 15%
• Measures Tendency to Press Response Button Even When NO Stimulus Actually Seen.
• Identify so-called Trigger-Happy Patients.
 False Negative Response Errors
• Assess Patient Inattention, Identify patients who Failed to Respond to Stimuli Should have been Seen.
• Measured by Presenting Bright stimuli at Test Points where Threshold Sensitivity Already Found Normal.
• FN Rates are Elevated in Glaucomatous Visual Fields, So it is of Limited Utility in Glaucoma.
 Fixation Loss Rate:
• Should Not Exceeding 20%. (Prefer to Turn Off FL Catch Trials and Rely on Full-Time Gaze Tracker)
• Estimated by Periodically Presenting Stimuli at Presumed Location of Patient’s Blind Spot (Heijl-Krakau method).
• Seen Artifactually, when Blind Spot Not Been Properly Located, (in Trigger-Happy patients, Head Tilting)
Reliability
Indices

19. Gaze
Tracker Fixation Stability, No Gaze Errors of Any Significance Magnitude
Mostly Consistent Fixation, Except for a period of instability. Field showed a well-defined area of abnormality
that was Consistent with Follow-up Tests and the Result was considered to be of Good Reliability.
Frequent loss of tracking signal caused by Blinks or Other Interference by Lids or Lashes is indicated by the
many downward deflections in the trace, and may have been caused by Ptosis.
Unreliable Fixation. Numerous maximal gaze errors are combined with loss of tracking signal late in the test.
Occasional Gaze Track Rrrors. This represents Good Fixation Stability.

20.  Simple Threshold Sensitivities measured at Each Test Point
are presented both in Numerical and Grayscale form.
 Sensitivities are indicated in decibels (dB):
• 0 dB indicates a test point location where only the maximum
available stimulus brightness (10,000 asb) was seen.
• 10 dB indicates a stimulus 1/10 as bright (1,000 asb).
• 20 dB 1/100 of maximum brightness (100 asb), and so on.
• A 40 dB (1 asb) stimulus is slightly fainter than the foveal
threshold sensitivity of most young perimetrically experienced
subjects.
Numeric and Grayscale

21.  Identify Test Locations that are Outside Normal Limits.
 Threshold Sensitivity is Compared with Age-Corrected Normal Values at each test
point to produce Total Deviation Numerical Map.
• Negative (ve) Values Indicates Lower than Normal Sensitivity.
• Postive (+ve) Values Indicates Higher than Normal Sensitivity.
• Zero (0) Values Indicates NO Changes.
 Statistical Significances of these Deviations and are indicated in the Associated
Total Deviation Probability Plot.
• Deviations are Highlighted when they are Worse than those found in Key at bottom
[5%, 2%, 1%, 0.5%] of Sensitivities in Normal subjects of Same Age as Patient.
• eg. 2% Symbol = 98% of Normal Same Aged have Higher Sensitivity than Recorded.
 Range of Sensitivity among healthy subjects is larger in Periphery than Center.
• So deviation of Same Value (5 dB) are Statistically Significant at Center of Field,
But is Totally Within Normal Range of Sensitivity in Periphery..
Total Deviation Maps

22.  The Single Most useful Analysis on printout is Pattern Deviation probability plot
 Shows Sensitivity Losses After an Adjustment
to Remove Any Generalized Depression or Elevation of Overall Hill of Vision.
 Uses Same Symbols as Total Deviation Plots to Identify Deviating by Statistically
Significant amounts from the range of values typically found in healthy subjects.
 Cataract causes Generalized Suppression, which complicate detection of localized
early glaucomatous defects.
• By removing the generalized component of field change, PD analysis can highlight
subtle localized loss while largely ignoring cataract effects.
 Strength of the probability maps is that:
• Ignore results that are within normal variability.
• Highlight subtle, but Statistically Significant Variations that might otherwise
Escape Notice.
• De-Emphasize common artifactual patterns, such as eyelid-induced Superior
depressions
Pattern Deviation Maps

23. Comparing Total and Pattern Deviation Maps
A typical cataract pattern with a considerably greater number of significantly depressed test point
locations in the Total Deviation probability map than in the Pattern Deviation probability map

24. Mixed Glaucoma and Cataract

25. Lid ArtifactsTrial Lens Artifacts

26. Trigger Happy PatientCover-Leaf Field
Tired Patient

27.  (GHT) Provides Plain Language Classification of 30-2 and 24-2 Test Results
Based upon Patterns of Loss commonly seen in glaucoma.
• Pattern Deviation scores in each of Five Zones in Upper Hemifield are
Compared to Findings in Mirror-Image Zones in Inferior Hemifield.
• Scoring Differences between Mirror Image Zones are compared to Normative
Significance Limits Specific to Each Zone Pair.
 GHT findings are divided into the following categories:
• “Outside Normal Limits” is displayed whenever at least ONE Zone Pair differs
by an amount found in fewer than 1% of normal subjects.
• Fields not classified as Outside Normal Limits are labeled as “Borderline”
whenever at least one zone pair differs by an amount found in fewer than 3%
but more than 1% of normal subjects.
• “General Depression” or “Abnormally High Sensitivity” messages are presented
whenever even the best test point locations are either so low or so high as to
be at levels seen in fewer than 0.5% percent of normal subjects.
• “Within Normal Limits” is presented whenever None of Above Conditions Met.
Glaucoma Hemifield Test

28. Global Indices
 VFI Visual Field Index
• Recently Developed Staging Index, Designed to be Less Affected by Cataract
• Provide Improved Correspondence to Ganglion Cell Loss compared to MD
• VFI is approximately 100% in Normal fields, Approaches 0% in Perimetrically Blind fields.
 MD Mean Deviation
• Shows how much on average Whole field departs from Age-Normal.
• Center-Weighted Average of decibel deviations shown in Total Deviation plot.
• Primarily used to stage visual field loss and as a metric for rate of change over time.
• MD is approximately 0 dB in normal fields and –30 dB to –35 dB in extreme visual field loss.
 PSD Pattern Standard Deviation
• Reflects Irregularities in the Field, such as those caused by localized field defects.
• PSD is small, close to Zero, Both in Normality and Blindness., Peaks at Moderate levels of Localized field loss.
• Because of this Non-Linear Behavior, PSD should NOT be Used as a Staging or Progression index.

29. Summary Report
Guided Progression Analysis (GPA)
 Baseline Tests
 VFI Graph
 GPA Alert
• European Glaucoma Society practice guidelines
recommend collection of 3 fields/year -including baseline
tests- in the first 2 years after initial diagnosis.
• But if that cannot be done, 2 per year during the first 3
years after diagnosis is very much better than just one
test per year.

30. System Of Reading Visual Field Printout
We Can Follow The Letters of Word
WANDER
 W for What was Done.
 A for Accuracy of what was Done.
 N for Normality or Abnormality.
 D for Defect Pattern Present.
 E for Evaluation of Compatible Disease that produce such pattern.
 R for Review the literature regarding possible and differential diagnosis.