2. Situations demanding Field Test
Glaucoma Diagnostic
Triad with IOP and
Disc changes.
IOP > 21mm Hg.
Significant Cupping
with/without high IOP
Strong Family History,
Myopia, Diabetes
Narrow Angles/Int.
IOP
Normal “Other” Eye of
the glaucoma patient
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3. What are we testing?
Actual visual field Tested visual field
60°
Fixation Blind The central 30° field
spot represents 66% of the
ganglion cells and 83% of the
visual cortex
Nearly all pathologies can be
60° 30° 90°
associated with loss of retinal
sensitivity in the 30° visual
field
Nasal field Temporal
field If in doubt, it is recommended
70° to repeat the central field
rather than test the periphery
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4. What are we looking for?
Is the visual field reliable?
Pattern of defects
Significance of defects
Normal or Glaucoma
Clinical correlation
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5. Reading the chart
Patient and
examination data
Measured values
and greyscale
GHT
Defect Curve
Comparison values
VF Indices
Probability plots
Eye fixation
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6. Patient and examination data
Program and strategy Pupil size
Date of birth
Questions, repetitions and catch
Refraction trials
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9. Reliability check by catch
trials
Positive Catch Trials
With the positive catch trials, the perimeter
produces a stimulus sound although NO
light is projected - the patient should not
respond.
With many positive mistakes, the patient is
a “happy trigger” patient.
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10. Reliability check by
catch trials
Negative Catch Trials
With the negative catch trials, the
perimeter projects its brightest spot where
a less intense stimulus was seen before -
the patient must respond!
With severely depressed fields, the patient
usually makes more mistakes. This is
normal.
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11. Reliability check by catch
trials
Evaluation
The Reliability Factor is the number in
percent of the positive and negative catch
trial mistakes.
Whenever this factor exceeds 15-20% the
results must be evaluated with caution.
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12. Value table and VA grey-scale
The measured values are the The VA grey-scale presents a
base for all further calculations comprehensive summary of
and graphics the visual field
Foveal Threshold
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14. Basic perimeter parameters
Parameter OCTOPUS 101 OCTOPUS 300 HFA
Bowl type Spherical bowl Direct projection A-spherical bowl
42.5 cm 18-30 cm
Background
- Luminance 4 asb 31.4 asb 31.5 asb
(1.27 cd/m²) (10 cd/m²) (10 cd/m²)
Stimulus
- Size Goldmann I - V Goldmann III, V Goldmann I - V
- Duration 100 ms 100 ms 200 ms
- Luminance 1’000 asb 4’800 asb 10’000 asb
for 0 dB
Measuring range 0 - 40 dB 0 - 40 dB 0 - 40 dB
Test strategies 4-2-1 dB bracketing 4-2-1 dB bracketing 4-2 dB bracketing
Dynamic strategy Dynamic strategy SITA Normal
TOP TOP SITA Fast
Normal values Age correction per year of age
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15. Comparison table and CO grey-scale:(difference (comparison) between
the age-corrected normal data and the actual measured
results)
Actual Value table Age matched comparison
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16. Corrected comparisons table: depicts local defects
relative to the mean diffuse depression
In the “corrected” comparisons table the deviation value is taken
into account to highlight pathological changes without the effect
of any preretinal interferences(mean diffuse depression of 8db)
This table displays
comparisons minus
deviation
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17. The cumulative defect (Bebie) curve
The CO values are sorted in size and displayed in order (ranking) from the
smallest to the largest defect
CO values
Ranking
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18. Typical defect curves
Suspect field:
• incorrect date of birth
Normal visual field or trial lens
• small pupil
• cataract
• early glaucoma
Focal defect e.g. Early glaucoma
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20. Visual field indices
For a quick assessment of the visual field it is helpful to
average all values in a few (global) indices
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21. Index - mean sensitivity
(MS)
Normal values
Mean sensitivity MS
Average of all
measured values
Measured values
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22. Mean defect (MD)
Normal values
Mean sensitivity MS
Mean defect (MD) difference
between
average normal and MS
Measured values
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23. Normal range of MD = -2 to +2 dB
The Mean Defect MD represents the average
defect of the entire visual field
MD reacts strongly on diffuse (homogeneous)
depression
Localized (topical) defects have practically no
influence on MD
MD is the index for uniform loss of sensitivity
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24. Loss variance (LV)
Normal values
MS
MD
Loss variance (LV)
Spread of measured
Measured values values from MS
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25. Normal range of LV = 0 to 6 dB2
The index Loss variance (LV) is sensitive to
the irregularity of the visual field
Normal visual fields have an LV of 0 .. 6 dB2
LV (or sLV) = standard deviation (sd)
Normal visual fields have an sLV of 0 .. 2.5 dB
An elevated LV (or sLV) is an indication that
the field has localized defects exceeding the
normal local variability
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26. Probability of defects
Probability plots helpful to
signal the significance of a
local defect
P<0.5 means that less
than 0.5% of the
normal population
shows a defect of this
size at this location –
Therefore this defect
is a significant defect
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27. What are we looking at?
Established glaucomatous damage
Nasal and upper hemifield defects
Classic arcuate Bjerrum scotoma
Nasal Step respecting the horizontal raphe
Differentiate between generalized or diffuse
against localized deep defects.
Increased fluctuations in retinal sensitivity in
those specific areas.
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28. Diagnostic field defects in glaucoma
The visual field below demonstrates a cecocentral
Locations on chart scotoma and superior nasal step and inferior nasal step
with some extension into the acruate bundle.
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29. Criteria for glaucomatous loss
Early Stage
MD > 3 < 6dB
Fewer than 15 points affected with p < 5%
and fewer than 8 points below p < 1%
level
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30. Criteria for glaucomatous loss
Moderate Stage
MD > 6 < 12dB
Fewer than 30 points affected with p < 5%
and fewer than 15 points below p < 1%
level
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31. Criteria for glaucomatous loss
Advanced Stage
MD > 12dB
More than 30 points affected with p < 5%
and more than 15 points below p < 1%
level
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32. Early Field Loss
Same Patient comparison
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34. Severe Field Loss
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35. Pearls
Check field for reliability
Look for glaucoma specific
losses/neurological
Correlate with disc cupping, NFL loss and
IOP, complete fundus examination.
Repeat fields : 1. If in doubt
2. Follow-up
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36. Thank You
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37. 55 yr Male, LE DV post op 6 months
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38. Field RE
LE
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