This document provides an overview of visual field examination and interpretation of automated perimetry results. It discusses the different types of perimetry testing including kinetic, static, and automated threshold testing. Important testing parameters like reliability indices, total deviation plots, and glaucoma hemifield tests are explained. Common visual field defects seen in conditions like glaucoma are demonstrated. The summary emphasizes that visual field defects must be reproducible to confirm abnormalities and clinical correlation is important when interpreting results.

1. VISUAL FIELD EXAMINATION
AND
INTERPRETATION OF AUTOMATED
PERIMETRY
PRESENTER: Dr DIVYA KESARWANI
MODERATOR: Dr VAIBHAV JAIN
DEPARTMENT OF OPHTHALMOLOGY, SGPGIMS, LUCKNOW
29/04/2019

2. EXAMINATION METHODOLOGY

3. KINETIC
 Test object of particular size and intensity is passed from
non seeing area to seeing area along a particular meridian
at the rate of 3 – 5 deg per sec
 Repeated every 15 – 30 deg

4. STATIC
 The location, size and duration of stimulus is kept constant and the
luminance is gradually increased until seen
 Actual estimation of sensitivity ( THRESHOLD ) of each point is
made out
 SUPRA THRESHOLD stimulus used for screening
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IMPORTANT :
 One eye is tested at a time, other is occluded.
 Fixation of the patient has to be steady and is monitored
throughout the test
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5. EQUIPMENTS

6. PERIMETRY VS CAMPIMETRY
o Perimetry – measurement of visual field by projecting
targets onto a curved surface.
o Campimetry – measurement of visual field by
projecting targets onto a flat surface.

7. BJERRUM’S SCREEN ( CAMPIMETRY)
 Patient sits at 1 or 2 m from flat screen
 Kinetic and static
 For central 30 deg only
 Done under subdued lighting

8. GOLDMANN’S PERIMETER
 Bowl type
 Standardization
 Both kinetic and static
 Peripheral as well as central

9. AUTOMATED PERIMETRY
HUMPHREY FIELD ANALYZER
OCTOPUS
 STATIC perimetry
 Measurement of threshold values
 STATPAC (HFA)- Comparison to normative data
 Inbuilt program for analysis – diagnosis and progression

11. AUTOMATED PERIMETRY
 Automated threshold static perimetry quantifies the sensitivity
of a patient’s central vision using efficient and standardized
testing algorithms.

13. PROGRAMS / PATTERNS
o 30-2 – gold standard
o 24-2
o 10-2
o MACULAR
o Nasal step program – additional 12 locations upto 50 deg nasal
peripheral 60 and 60-4 prog
o Estermann test – for binocular 120 deg field

14. MACULA PROGRAM :16 locations
within the central 5° with 2° spacing.
Each location is tested three times

15. TERMINOLOGIES
 Isopter
 Line on a visual field representation connecting points with
same visible threshold.

16.  Scotoma
 It is an area of reduced(‘relative’) or total(‘absolute’)loss of vision that
is surrounded by a field of normal or a relatively well-preserved
vision.
 Blind spot
 Physiological scotoma corresponding to optic nerve head
 b/w 10-20 ˚ .It is located temporally and slightly inferiorly.
 Threshold :
 Physiological capacity to detect a stimulus at a given location, that
stimulus intensity that has a 50%probability of being seen.

18. SWEDISH INTERACTIVE TESTING ALGORITHM (SITA)
1. SITA STANDARD ( Bracketing strategy based)
2. SITA FAST ( FASTPAC based)
o Analyzes patients response and responds accordingly
o Decreases overall no of stimuli presented, hence test duration
o Doesn’t estimate Short term Fluctuations

19. THRESHOLD
BRACKETING STRATEGY( staircase)
– GOLD STANDARD

20. –It is useful to measure the foveal threshold at the very beginning of the
test .
 If the patient is not properly focused on the bowl ,foveal sensitivity will
be reduced along with the remainder of the field.
 Visual Acuity-BCVA should be 6/36 or better for the visual field to be
tested.

21.  Apostilbs:
 Absolute units of light intensity.
 Luminance of test target.
 1 asb=.3183 candela/m2
 Decibels:
 Relative scale, created by manufacturers.
 Attenuation of light by neutral density filters.
 1dB=1/10 log units of attenuation of max. stimulus.
 Measures sensitivity at each point.0to40dB.

25.  Background intensity = 31.6 asb
 Higher intensity stimulus has higher asb value, this is
inverse of retinal sensitivity.
 Stimulus  Maximum intensity = 0 dB
Minimum intensity = 40 dB

26.  Selection of adequate test
 Proper environment
 Comfortable sitting position
 Adequate size of pupil >3mm
 Adequate Near correction
 Proper explanation – running of demonstration
 Reassurance – not all points will be seen
- test can be paused by keeping the response button
pressed

27. INTERPRETATION OF
VISUAL FIELD PRINTOUT.

30. Patient data
 Name, DOB, eye
 Vision, refraction,
 Pupil diameter
Test data
 Date and time
 Program and strategy
 Background illumination
 Test size, color, duration,
interval
ZONE 1 : REPRODUCIBILITY

31. REFRACTIVE ERROR-
o Refractive blur reduces visual sensitivity to perimetric stimuli.
o One dioptre of refractive blur in undilated patient will produce a
little more than 1dB of depression of field of vision when testing
with Goldmann Size III stimulus.
o Hence near vision must be properly corrected , otherwise the visual
field will show a generalized depression .

32. Constricted field d/t miosis
Pupil Diameter: 1.0mm

33. Repeat Perimetry with
Pupil Diameter: 2.5 mm

34. ZONE 2 : RELIABILITY
 Fixation monitor
 Fixation target
 Reliability indices
Fixation losses < 20%
Gaze tracking
False positives < 15%
(trigger happy)
False negatives < 15%
Foveal threshold

35.  Fixation monitor may be chosen as blind spot and/or gaze.
 Fixation target may be central or large diamond, the latter being
chosen in patients with central visual loss.
 Fixation losses: The fixation can be tested in different machines using
blind spot monitoring with Heijl Krakau method, gaze monitoring
with gaze tracker or manually by observation of eye monitor.
 When the fixation monitoring test parameter is set to blind spot
(Heijl-Krakau) mode, proper fixation is checked by projecting 5% of
stimuli at the presumed location of the physiological blind spot.
 If fixation losses exceed 20%, “XX” will be printed after the score.

37. •False positive response-
- FP >15% is strongly
associated with
compromised test.
-With a high FP score grey
scale appears abnormally pale.

38. High false positive responses :
 Seen in patients who are anxious about not seeing all test points and
might be trigger happy.
 Such a field would show in addition to false positives, numeric
sensitivities above 40 dB, white areas on grayscale, a pattern
deviation plot worse than total deviation, positive mean deviation
and abnormally high sensitivity on GHT.

39.  False negative response-
- In general >15% of FN is
considered abnormal
-Grey scale pattern in high FN
cases tends to have a clover-
leaf pattern.

40. High values occur if:
 The patient is fatigued and falling asleep
 Has changed personal criteria for response,
 There is presence of true visual field loss where sensitivities are
variable.
 May be normally present in cases with advanced defect as the
visibility may be highly variable in glaucomatous visual fields

41. While false negative errors and fixation loss scores may not make a
field invalid, high false positive errors may warrant rejection of the
test results.

42. RAW DATA AND GRAYSCALE
 Simple threshold sensitivities are measured in decibels and given in
the numeric plot.
 Values above 40 dB are generally not expected and may be indicative
of a trigger happy field.
 The actual numeric values may not be concentrated upon for day to
day interpretation of field but only with specific purposes.
 Grayscale is an artists interpolation of the raw data and we do not base
our diagnosis on it.

43.  The raw data is the exact retinal sensitivity in dB units of the selected
points calculated by field analyser.
 In raw data 0 dB = absolute scotoma.
 40 dB is the highest retinal sensitivity.
 In same patient the raw data calculated by different strategies is not
exactly similar .

44. ZONE 4 : GREY SCALE
 Based on actual threshold values at each location
 General identification
 Patient information

45.  It can though typically highlight certain artifactual fields
 Lid artifact –showing defect in superior part due to a droopy eyelid
 Rim artifact- showing concentric constriction due to rim of trial
lens which is either decentered or placed away from the eye
 Clover leaf-typical pattern of initial response around four primary
points in each quadrant followed by depressed or no response as seen
in a new and poorly instructed patient.
 Trigger happy fields-patches of white tones in grayscale seen in
overanxious patient with high false positive responses.

47. ZONE 5&6 :TOTAL DEVIATION PLOT
 Numerical plot – indicates by how much decibels
is each point depressed compared to mean value
in normal population of similar age.
 Probability plot- grey scale indicates the
probability of occurrence of the deviation in
normal population.
Generalized depression due to media opacities,
refractive error, miosis may hamper appearance
of a pattern

48.  P<5% indicates the retinal sensitivity of that
point is seen in < 5% of normal population.
 Darker the symbol, the greater the probability
of abnormality as indicated by P value.
 Higher the P value lesser the chances of field
being abnormal

49. ZONE 7&8 : PATTERN DEVIATION
PLOT
 Numerical - calculated by adjustment for
generalized depression or elevation of visual
field

50. COMPARISON OF TOTAL AND PATTERN
DEVIATION PLOTS
 Uniformly depressed total deviation plot and normal looking pattern
deviation plot: cataract or any generalized depression of fi eld
 Both plots look more or less the same: little or no generalized loss
 Normal total deviation and abnormal looking pattern deviation:
trigger happy patient

52. ZONE-9 GLOBAL INDICES
 The global indices summarise the field.
 The indices available in SITA strategies are:
 Mean Deviation: how much the total field departs from normal
 Pattern Standard Deviation: irregularities in the field.
 Visual Field Index: visual field status as a percent of a normal field.
 Short term fluctuation (SF)
 Corrected pattern standard deviation(CPSD)

53. • MD gives an indication of the
overall sensitivity of the field.
• The positive value  better
overall retinal sensitivity than
normal observer.
• Negative value  worse than
normal.

54.  Negative value would be increased in presence of:
 Generalized depression of entire field
 Multiple localized depressions
 Deep localized depression
 Positive mean deviation is seen in:
 Hypersensitive or trigger happy patient
 Normal patients having sensitivity values higher than those in normative
database.

55. • Measure of focal loss or variability
within the field taking into account any
generalized depression in the hill of
vision.
 More specific indicator of
glaucomatous damage than MD.

56.  Measures irregularity by summing the absolute value of the difference between
the threshold value for each point and the average visual field sensitivity at
each point (equal to the normal value for each point + the MD).
 Low PSD indicates:
 Smooth hill of vision
 Near normal field
 Severely depressed field
 High PSD indicates:
 Variability in field response
 Irregular field due to localized deep defects

57. KEY NOTE POINTS
 The diagnosis of glaucoma should not be based on global indices.
 Probability plots and GHT are more useful for diagnosis while indices may
help in staging disease and follow up.
 So in follow up of a patient if a worsening MD is accompanied by a stable
PSD it could be due to increasing generalized loss like in cataract.
 On the other hand a nearly stable or slightly lowering MD accompanied by
a worsening PSD could be indicative of worsening localized loss as in
glaucoma

58. VISUAL FIELD INDEX
 New index which expresses the visual field status as a percent of a
normal age-adjusted visual field.
 This PSD based index was devised mainly to detect progression of
glaucomatous defect.
 Greater weight is given to points closer to fi xation to adjust for
gangion cell density and visual function.
 The index may also be less sensitive to cataract and media changes.

59. ZONE 10 : GLAUCOMA HEMIFIELD TEST
 Comparison of 5 clusters of points in superior
hemifield with mirror images in inferior hemifield

60. POSSIBLE OUTCOMES ARE:
 Outside normal limits. The GHT is described as “outside normal limits” when
matched pairs of zones differ by an amount greater than that seen in 99%
normal subjects, or when both members of a pair of zones are more abnormal
than 99.5% of the individuals with the normative population.
 Borderline. When matched pairs of zones differ by an amount greater than
that seen in 97% normal subjects but not reaching the level of outside normal
limits
 General reduction of sensitivity. When the best region of the VF is depressed
to a level seen in only 0.5% of the normative database but both conditions for
“outside normal limits” are not met
 Abnormally high sensitivity. When the best region of the VF is elevated to a
level seen in only 0.5% of the normative database.
 Within normal limits. When none of the above conditions are met.

61. ARTEFACTS
 OBSTRUCTION
RIM ARTEFACTS
PTOSIS
MEDIA OPACITIES
 MIOSIS
 REFRACTION ARTEFACTS
 High power plus and minus lenses

65. ANDERSON & PATELLA CRITERIA
 3 or more congrous ‘non edge points’ in typical arcuate area on 30-2
program
depressed @ p< 5 % with at least one point @ p<1 %
PSD / CPSD @ p< 5%
GHT – outside normal limits
 Must be demonstrated on 2 field tests

67. Nasal step
scotoma

68. ARCUATE
SCOTOMA

69. SEVERE DEFECT

71. RECOGNITION OF PROGRESSIVE DAMAGE
 Compare baseline field to each individual field
 Study the entire series.

72. OVERVIEW

73. READING A SAMPLE PRINTOUT

74. TAKE HOME MESSAGE
 The field defect must be reproducible as is confirmed by repeat
field examination of the same patient
 Clinical correlation is of prime importance .
 Interpreting a single analysis may not be difficult if we go in a
stepwise manner.
 Important thing to remember is that presence of field defect does
not always mean presence of disease.

75. THANK YOU