about kinetic and static visual field

1. KINETIC VS STATIC PERIMETRY,
AUTOMATED PERIMETRY
SURAJ CHHETRI
B.OPTOMETRY
16th batch

2. Presentation layout
 Introduction to perimetry and visual field
 Various terminologies
 Kinetic vs static perimetry
 Automated perimetry
 Difference between octopus and Humphrey
 Humphrey field analyzer
o The hardware
o Threshold testing strategies
o Field locations for Humphrey
o Single field analysis and interpretation
o Learning effect and artifact in AVF
o Point pattern of HFA

3. Is the subjective examination method for
estimating the extent of visual field.
Enables the assessment of:
 Visual function throughout the visual field
 Detection and quantification of damage to the visual field.
 Monitoring the change over a time.
Perimetry

4. Standard clinical perimetry tests the distribution of
light difference sensitivity in the visual field.
Sensitivity reflects the capability of the eye to
perceive a brightness difference between target and
its background.
DLS=L1/L2-L1, where L1 is the background luminance and L2
is target luminance.

5. 5
The field of vision is defined as the area that is perceived
simultaneously by a fixating eye
Ref:Becker- Shaffer’s Diagnosis and Management of Glaucoma, 8th edition.
VISUAL FIELD

6. 6/21/2016
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7.  Traquair defined visual field as island of vision in the sea of
darkness.
 Hill of vision is a 3D representation of the retinal light sensitivity
 Sea represents the areas of no light perception
• Under photopic condition, the shape
of hill of vision is closely related to
the packing density of the cones and
receptive field size.
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8. VARIOUS TERMINOLOGIES
 Luminance: It is the intensity or
‘brightness’ of a light stimulus,
measured in apostilbs (asb)
( inverse of sensitivity)
 Isopter: All the locations where the
stimulus is first seen have equal
sensitivity, these locations can be
connected to form a ring shaped locus
of points
6/21/2016
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9. Continue…..
Threshold: : The minimum light energy necessary to evoke a
visual response with a probability of 0.5, i.e. the observer can
detect the stimulus 50% of the time it is presented
 Sensitivity which is reciprocal of threshold. Sensitivity is
presented in decibel(dB)
Higher db = lower intensity = high retinal sensitivity
Lower db= higher intensity = lower retinal sensitivity

10. Continue….
 Anopia / anopsia : defect in visual field. e.g hemianopia
 Absolute Scotoma : It is an area of total (‘absolute’) loss of
vision which is surrounded by a seeing area
Relative scotoma: It is an area of reduced (‘relative’) loss of
vision which is surrounded by a seeing area.

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Kinetic vs. static perimetry

12. A stimulus of
 same size and intensity
 moved from a non seeing area of the visual field a seeing area
 along a set meridian to determine the extent of VF or VF defects.
 The procedure is repeated with the use of the same
stimulus along other meridians, usually spaced every
15°: to plot an Isopter.
The hill of vision is found by approaching it
horizontally.
Eg. Goldmann, Arc perimetry
Kinetic perimetry

14. The size and location of the test target remain
constant and measure the threshold of the retinal
points
The threshold is determined exactly by increasing
the luminance of an infrathreshold target as well
as by decreasing the luminance of a
suprathreshold targets, until the threshold has
been determined.
Eg: Goldmann , Automated Perimetry
Static perimetry

16.  Principle difference is the way of detecting the differential
light sensitivity.
 The kinetic examination with moving test objects allows us to
detect steep gradients or circumscribed scotomas especially
well.
 The static perimetry where the test target is stationary is a
method especially suited to detect field defects with a flat
gradient. e.gCircumscribed flat scotomas or a generalised
depression of d. l. sensitivity
Comparison between kinetic and
static perimetry

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Eccentricity
E
d.Lsensitivity
d.Lsensitivity
Eccentricity

18. Continue….
 If we find a steep slope in the visual field the kinetic principle
with horizontal motion toward the hill of vision or toward the
margins of the scotoma will provide a much sharper and well
delineated threshold than the vertical approach.
 If the slope is flat and if there is only a slightly inclined nearly
horizontal gradient, the static method with vertical approach
will be superior to the kinetic method

19. Continue……
 The physiologic distribution of differential light sensitivity with
a relatively flat slope in the paracentral area and in the mid
periphery make the static principle for central VF the method
of choice.
 Similarly, the steep gradients of the peripheral VF make the
kinetic principle superior to the static one.

20. Kinetic perimetry Static perimetry
Measures the extent of visual
field by plotting the isopters
Measures the sensitivity of each
retinal points
Stimulus moves from non seeing
to seeing area
Stimulus is stationary but
increases in luminance until seen
Stimulus size can be varied Constant
2D measurement of hill of vision 3D assessment of height of
predetermined areas of hill of
vision 6/21/2016
20

21. Kinetic perimetry Static perimetry
Results depend upon the experience
of the operators
Though it depends but has very little
role of the operator
Can rapidly evaluate the peripheral
VF, plot deep defects.
Can accurately plot steep bordered
defects and useful for localization,
characterization of neurological
defects
It has ability to detect scotomas,
particularly small, shallow, or
fluctuating scotomas but cannot
correctly outline the border of the
defect
Eg. Confrontation perimeter, tangent
perimeter, Arc perimeter, Goldmann
perimeter
Eg. Automated perimeter, Goldmann
perimeter
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22.  A moving stimulus will be detected more readily in the
periphery than a static stimulus because of successive lateral
spatial summation.
 As the stimulus moves across the visual field, spatial
summation of receptive fields adjacent to the receptive field
over which the stimulus is placed occurs.
 Thus, the detection of the stimulus will be influenced by
normal areas of visual field, in addition to any damaged areas,
which could lead to shallow focal loss in the visual field being
missed.
6/21/2016
22
Continue…

23. Automated perimetry
 Is merely a computer assisted examination (and not a fully
automatic test) since the results depend on the patient’s
collaboration and the accuracy of the answers.
 Field testing strategy mainly static field testing
 Test target is placed at a preselected field position, and
intensity gradually raised until the patient detects it.
e.g Humphrey ,octopus , dicon ,Topcon perimeters
23

24. OCTOPUS 300 HUMPHREY 700
BOWL TYPE Direct projection A spherical bowl (1/3m)
Background
luminance
31.4 asb 31.5 asb
Stimulus size Goldmann III and V Goldmann I-V
Duration 100ms 200ms
Luminance for 0 dB 4800asb 10000asb
Measuring range 0 – 40 dB 0-40dB
Test strategies 4-2-1dB bracketting
Dynamic strategy
TOP
4-2dB bracketting
SITA Normal
SITA Fast
Normal values Age correction per yr of age
24

25. HUMPHREY FIELD ANALYZER
 The hardware: consist of following parts
 The bowl : HFA|| aspherical or bullet shaped surface
 Distance from eye to center of bowl is 30 cm
 Bowl surface is textured perfectly matte finish known as
Lambertian surface
 The optical system: stimuli presented by aiming a particular
location to be tested
1. The bowl or projection system
2. The optical system
3. Central processor
4. The patient interface

26. Continue…..
 The central processor : it fulfills many functions
commonly seen in desktop computers
 must control optical system
 Split second strategy adjustment based upon the each
patient response
 The patient interface : consists of
 Chin rest, forehead rest , trial lens holder,table and chair
 Trial lens holder use to hold 37mm ophthalmic trial lens
which is never used for testing outside 30 degrees
because lens and holder will produce an area of deep
artifact

27. THRESHOLD TESTING STRATEGIES
 1) Old threshold strategy
 Suprathreshold strategy
 Full threshold strategy
 2) newer threshold strategies
 Fast PAC
 SITA standard
 SITA fast

28. Time saving strategy
Screen for the presence of a defect, and roughly
localize it (SCREENING STRATEGY)
Two type:
Single intensity static suprathreshold strategy/ One-
level suprathreshold strategy
Gradient- adapted threshold strategy/Two level
suprathreshold test
Suprathreshold strategy

29. Continue…
A stimulus that is 2 to 6 db
brighter (suprathreshold) than
the expected hill of vision is
used to test multiple locations
in the visual field
Stimulus luminance is automatically
modified to be brighter at more
peripheral locations and dimmer
centrally, thus suprathreshold level
will take into account the normal
shape of hill of vision.

30.  DLS determined by use of 4-2 bracketing strategy (Staircase
method )
 Computer determines threshold first at one primary point per
quadrant. (9 degree away from vertical meridian and horizontal
meridian for 30-2 program)
 Staircase consist of 4db decrements in light intensity until the
patient fail to respond(first reversal), then 2db increment until
the patient sees the light again(second reversal). This final level
is the sensitivity recorded
Full threshold/Normal strategy

31.  Uses 3 db step size.
 Staircase terminates when it has crossed the threshold once
 Threshold is recorded as the last seen stimulus
 Time saving – 1/3rd of time of standard full threshold.
 Drawback: short term fluctuation more and increased
threshold error, thus reducing the reproducibility.
FASTPAC

32. Comparison between standard full threshold
and FASTPAC

33.  Ideal threshold algorithm
 Estimate threshold with high precision within minimum time
 Also uses the staircase method to determine threshold like the
standard threshod.
 But, it compares the threshold of patient with the recorded
normal and abnormal values and make sophisticated statistical
analysis and give probability plotting.
SITA(Swedish Interactive Threshold
Algorithm)

34.  Unlike, other threshold algorithms used in perimeters, SITA
adapts the stimulus presentation speed to the reaction times
of the patient, which in most cases reduces test time.
 Available in two forms :SITA Standard and SITA Fast
 The difference between the two is the chosen level of
accuracy for the threshold estimation.
 That is SITA Fast more faster with less accuracy than the SITA
Standard.

35. Accuracy
 SITA Standard is equivalent with full/ standard threshold
consuming less time.
 SITA Fast is equivalent with FASTPAC consuming less time.
Comparison of SITA algorithm with other
threshold strategy

36. TIME TAKEN BY STRATEGIES
30-2 SITA fast takes 5.5 min to estimate threshold

37. Examination programs
OCTOPUS 300
G1/G2
PROGRAM 32
M1/M2
HUMPHREY 700
CENTRAL ZONE
PERIPHERAL ZONE
FULL FIELD
SPECIAL DESIGNS
37

38. Field location options for Humphrey
ZONE SCREENING THRESHOLD TEST AREA OF
FIELD
COVERED
CENTRAL FIELD
ONLY
Central 40 pt or
Central 80pt
Central 76pt or
Central 166pt
Macula
Central 10-2
Central 24-1
Central 24-2
Central 30-1
Central 30-2
0-4°
0-10°
0-24°
0-24°
0-30°
0-30°
PERIPHERAL
FIELD ONLY
Peripheral 68 pt Peripheral 30/60-1
Peripheral 30/60-2
30-60°
30-60°

39. `
ZONE SCREENING TEST AREA OF FIELD COVERED
FULL FIELD Full field 120 pt
Full field 246 pt
0-60°
0-60°
 -1 version start their point on the horizontal and vertical
meridians whereas -2 version place test locations
flanking the meridians
 - 2 better for detemining nasal and hemianopic steps.1
1 field of vision: a manual and atlas of perimetry by Barton and Banetar

40.  Statistical analysis of patient’s result is done and the this
package available in Humphrey is called STATPAC.
 Greatly simplifies VF interpretation
 by differentiating between normal and abnormal VFs
 by identifying significant change in the series of visual
fields.
 Also determines whether the patient VF results fall
within the range normal for his/her age.
Printing results

41. The analysis of the data acquired, is presented in following
formats
 Single field analysis
 Change analysis
 Overview glaucoma change printout
 Single field analysis is devoted to analysis of a single field
 Change analysis and overview are used to interpret multiple
fields obtained at different times.

42. Single Field Analysis and Interpretation
 VF Printout consists of following regions:
 1. Patient data/ Test data/Demographic data
 2. Reliability indices/foveal threshold
 3. Raw data
 4. Grey scale
 5. Total Deviation Numerical Plot (TDNP)
 6. Total Deviation Probability Plot (TDPP)
 7. Pattern Deviation Numerical Plot (PDNP)
 8. Pattern Deviation Probability Plot (PDPP)
 9. Global indices (MD, PSD, CPSD, SF)
 10. Glaucoma Hemi-field test (GHT)

43.  1: demographic data
 Name, age/gender
 Birth date
 Pupil size (at least 2.5 to 3 mm)
 Visual acuity
 Refractive error
 Test performed ( strategy)
 Stimulus size and color
 Fixation target

44.  2:Foveal threshold Reliablity parameters
 Fixation loss
 False positive error
 False negative error
 Test duration
 Foveal sensitivity

45. Monitered by three methods
Observation of perimetrist(manual): perimeter has video
system to project an image of the eye on monitor and
perimetrist has to detect fixation shifts and faulty head
positioning.
Automatic fixation: either signals the perimetrist when
fixation wanders or repeat the stimulus presentation.
Fixation loss

46. Heijl Krakau method:
Blindspot is localised though not necessarily plotted,
early in the testing process.
Stimuli is then periodically presented in the
presumed blind spot.
Light seen by patient in this area means fixation loss.
Fixation loss >20% are considered unreliable test.
Continue…

47.  In case of HFA, there is gaze tracking/monitor at the bottom of
the single field analysis printout.
 Here, the distance between a corneal light reflex and the center
of the pupil is measured. Thus eye rotations can be judged.
 Errors are indicated by upward deflections from the baseline. i.e
upward deflections indicate deviations due to eye movement.
 Downward deflections indicate that the patient blinked when a
stimulus was present.
Continue…

48.  This is a positive response by the patient even in
absence of stimulus
 Also called positive catch trials
 In case of SITA algorithm, the number of anticipatory
response made too soon to light stimulus than expected
are labelled as false positive.
 False positive up to 20% is acceptable.
False positive error

49.  A fairly bright suprathreshold target is flashed in a region
previously tested with fainter targets. If the patient fails to
indicate its presence, this is recorded with false negative.
 Called as negative catch trial.
 High false negative implies inattention or fatigueness of
patient.
 Acceptable upto 20%.
 High false negative value is indicated by XX beside the
abberant value and a printed statement of low patient
reliability in upper left corner.
False negative

50. 3: Raw data
 It is exact retinal sensitivity expressed in db units
 Raw data used by different strategies differs so always use
same strategy for follow ups
 Normally (<) sign is seen only in front of zero(0). But if (<1)
then, maximum intensity of light projected by field analyzer is
not 10,000 asb units but 9500 asb.
 So, (<) sign in any digit other than zero ‘0’ indicate that the
light is becoming dim and it’s time to replace bulb or it requires
calibration)
Visual field threshold decline with age about 0.5 to 1 db per decade

51. 4:Gray scale/half tone/color scale
 Numerical values from raw data are presented graphically according
to a grey scale form,
 Grey scale doesn’t give definitive diagnosis .it only help doctors to
explain status of visual field to patients
• Areas of high sensitivity are denoted by lighter shades and area of low
sensitivity are denoted by darker shades
 Never ever use gray scale solely for diagnosis
( we examine 76/54 points but gray scale form by upto 2000 points
)

52.  The numeric value of threshold ( raw data) is compared
with the age matched normative data and the difference
in value at each points is printed in numbers.
 Lower than normal value is printed with minus sign
whereas points higher than normal value is printed
without any sign.
 Draws attention towards overall sinking of hill of vision
(media opacities like cataracts, refractive errors, corneal
opacities and miosis)
5: Total deviation plot

53.  Depicted by two plots: Total deviationnumerical plot ( TDNP) and
Total deviation probability plot(TDPP)
 Numeric plot: has numeric value showing point to point difference
in the patient ‘s threshold from those expected in age corrected
normal
 Probability plot: gives the probability of each deviation being normal
or abnormal.
 All dots are considered as normal, whereas all other symbols,
denotes the different p-value.
 Darker the symbol, more chances of being abnormal.
Continue…

54. Probability/ P- value
 P- value doesn’t say if loss of sensitivity is normal or abnormal but
only say percentage that on how many people the defect is seen.
 STATPAC only calculates P-value where there loss of sensitivity but
not for the points where retinal sensitivity is better than normal.
 If no P value is given beside a global index, it can be considered
normal.

55.  Gives the total deviation plot after correcting it for the
generalized field defect which may be due to cataract ,
vitreous haemorrage , miosis of pupil, uncorrected refractive
error and optic atrophy
 The localized defect will be more prominent in this plot.
 Probability plot of pattern deviation plot: depicts the
probability of pattern deviation plot being abnormal.
6: Pattern deviation

56. continue
 Depicted by two plots: pattern deviation numeric plot (PDNP)
and pattern deviation probability plot (PDPP)
 Pattern deviation plot is created to now the pattern and
extent of the deep sootomas, masked by generalized
depression in the Total Deviation Probability Plots.
 Pattern Deviation Probability Plots never shows generalized
depression. ( as generalized depression is removed)

58. 7: Global indices:
 Provide grand summary that captures something about the field
in a single number.
 All are printed as sensitivity measures in db, along with p-value
 Are useful in sequential follow up.
 Consist of
 Mean Deviation(MD)
 Pattern Standard Deviation(PSD)
 Short-term fluctuation(SF)
 Corrected pattern standard deviation(CPSD)

59. Mean deviation(MD)
 Mean Deviation index signifies the average of oveall severity of field
loss i.e average of all numbers of TDNP except two points in area of
blind spot.
 Difference of MD index between both eyes should be taken as a
serious clue in confirming the diagnosis of glaucoma.
 1 db MD difference means , 52 db difference in 2 eyes in 24-2 point
pattern.( 54 points in 24-2)
 It is the most important index to asses field defect progression (
expected change in MD per yaer is 0.08 db
 MD can be increased due to reasons that cause generalized field
defect.

60. continue
 Negative value- represent depressed field and positive value
represent elevated field.
 MD between +/- 2 db is normal
mild defect if MD -2 to -6 db
moderate defect if MD -6 to -12 db
sever defect if MD greater than -12 db
 Loss of sensitivity is distributed equally to all the points
If depression of field is not significant, MD will be a simple
number without P-value.

61. Pattern standard deviation
 Expresses dissimilar deviation values in the Total Deviation Numerical
Plot whether it is smooth or rough.
 The roughness of hill of vision can be either due to the loss of
sensitivity or due to the measured sensitivity being better than
normal values.
 PSD doesn’t carry either “+” or “-“ sign in front of it. It will just be a
simple number.
 If roughness of slope is not significant, PSD will be a simple number
without P-value.
 If the deviation of slope is significant it will be represented by P-value.
So, PSD with significant P-value indicates the numbers in TDNP are
not similar to each other.

62. Continue…
 PSD is higher in localized or irregular generalized field
defect but lower in uniform generalized field defect.
 PSD pick up localized scotoma. So, useful in early glaucoma
but once glaucoma is diagnosed PSD have very minimal role
in management of glaucoma.
 PSD less than 6 consider as normal

63. Short term fluctuation (SF)
 SF is an index of intra test variation
 The result of 1st series of the test will be calculated with second
series of threshold values at these points .
 Difference between them is calculated and expressed as a Root Mea
Square (RMS) of the standard deviations estimated at these locations.
 SF is usually < 3db i.e between 1 to 2.5 db, value higher than this
shows an index of unreliability or pathology.
 Short term fluctuation and corrected Pattern Standard Deviation will
be calculated by full threshold or FAST PAC strategies. (SITA strategies
do not calculate SF and CPSD)

64. Corrected pattern standard deviation(CPSD)
 PSD corrected for SF.
 Since moment to moment variability(SF) may cause a
patient to fail to respond sensitively in a particular region,
generating a local depression adversely affecting PSD. Thus,
CPSD adjust for SF and separate real deviations from
deviations due to variability.
 Normally CPSD should be less than 4

65. 8: Glaucoma Hemifield Test
Five sectors in upper field are compared with five sectors
in lower field which are mirror images. 6/21/2016
65

66. Continue……
 There can be five result of GHT
 1. Outside Normal Limit
Indicates that one of two conditions has been met
 a) When the scores in upper zones are compared with those of
lower zones, at least one sector pairs’ sore difference must
exceed that found in 99 % of normal population.
 b) The individual zone scores in both members of any zone pair
exceed that found in 99.5 % of normal population.
 2.Borderline
 In comparing the upper zone with lower zones, at least one
zone pair difference exceeds that found in 97% of normal
individuals.

67. Continue…..
 3.General Reduction in sensitivity
- This message appears only if neither of conditions for “outside
normal limit” message is met, but general height calculation shows
the best part of field to be depressed to a degree that occurs in
fewer than 0.5% of normal population.
 4. Abnormally high sensitivity
 The general height calculation shows the overall sensitivity in the
best part of the field to be higher than that found in others.
 In phase of abnormally high sensitivity, the comparison of upper
zones with lower zones is not made.

68. Continue….
 Within normal limits
 This message appears if none of above four conditions are
met.
 30-2 outer sets are not included in GHT test except the two
outer points on nasal side)

69. Visual field index (VFI)
 Is a single number that summarizes each patient’s visual field
status as a percentage of the normal age-corrected sensitivity.
 Originally designed to approximately reflect the rate of ganglion
cell loss.
 It is derived from PD and is centre weighted, considering the
high density of the retinal ganglion cells in the central retina.

70. Anderson and patella’s criteria diagnostic
of glaucoma field
1.Cluster of 3 or more points on pattern deviation plot abnormal at P < 5%
level, at least one at the P < 1% level in an expected area of the visual field
2.Pattern standard deviation abnormal at P < 5% level.
3.GHT outside normal limits.
If any one of the above criteria is met, glaucoma should be suspected
provided that the visual field defect is repeatable on a second visual field
test in a similar location and is not attributable to other pathologic findings
such as nonglaucomatous optic neuropathy or chorioretinal disease.

71. Glaucoma progression
 We compare the baseline visual field with the follow up
visual field.
 Proper baseline visual fields should be done usually 2-3
(more if required).
71

72. Changes detected by:
 Change Analysis-box plot
 Overview programme
 Glaucoma progression analysis
72

73. Overview programme
 Sequential series of fields for
the same patient over a period
of time.
 Has all the single field
information including total and
pattern deviation plots
 Tells us at a glance what is
happening and allows us to
deduce why it is happening
73

74. Glaucoma Progression Analysis
 GPA is now in clinical use
 Change is based on the pattern deviation plot
 It compares the current visual field with a baseline
composed of 2 separate visual field tests.
 The operator must choose the 2 baseline visual fields.
 As a result, if progression occurs, a new baseline must be
established for future analysis.
74

75. 75
Each of the 3 visual fields shown demonstrates progressive loss compared
with the same baseline.
The black triangles designate points with a probability (P < .05) that the
value is worse than the baseline value.
Progression of glaucomatous damage

76. Progression
The following are reasonable guidelines:
 Deepening of an existing scotoma is suggested by the
reproducible depression of a point in an existing scotoma by
>or=7 dB.
 Enlargement of an existing scotoma is suggested by the
reproducible depression of a point adjacent to an existing
scotoma by > or =9 dB.
 Development of a new scotoma is suggested by the
reproducible depression of a previously normal point in the
visual field by > or=11 dB, or of 2 adjacent,previously normal
points by > or =5dB
76

77. Learning effects and artefacts in
automated perimetry

78. Learning effects
 Patients performance improves with learning and
experience , this phenomenon is termed as ‘ learning
effect’
 learning effect greater for peripheral rather than for
central stimulus locations.
 To minimize learning effects, it is advisable to conduct a
practice test procedure in “demonstration”

79.  PUPIL SIZE: Testing with a pupil of size less than 2.5mm in diameter
can produce artifact.
 Size of pupil should be kept constant from test to test.
 Pupil size can affect retinal illumination and influence visual field
sensitivity
 constricted pupil dims both the intensity of the stimulus and that of
the background.
 Mydriasis has less influence on the visual field and it may only
reduce peripheral threshold sensitivity.
Miosed pupil

80. Media opacities
 Opacity of ocular media reduces the brightness of test stimuli
and background equally, so overall depression of retinal
sensitivity
 This is reflected in changes to the total deviation plot and
global indices
 E.g corneal opacity , cataract , vitreous hemorrhage

81. Fatigue effect
 Difficulty in maintaining attention. This becomes more
pronounced as the examination time increases
 ‘clover leaf pattern’ in which the patient performs well at the
beginning of the test but becomes inattentive with time and
fails to respond to the stimuli
 It may also be associated with a high false negative rate.
 Patient fatigue usually begins approx after 3 min. Longer the
duration of examination more the sensitivity decreases.

82.  usually located between 25
and 3o degree.
 So lens should not be used
in measuring VF larger than
30 degrees
 Lens should place as close
as possible to eye without
touching eyelashes
Lens Rim Artifact:

83. Uncorrected Refrative error
 Uncorrected error defocus the target thus reduces the
luminance of the stimulus on the retina.

84. Continue…….
 High myopic errors can create areas of retinal blur that appear
as a vertical wedge–type defect and may be confused with
glaucomatous field loss
 A rule of thumb would be to correct refractive error even as
low as 1.00D.
 significant cylindrical defocus being induced when astigmatism
is greater than 1.00D.
 In case of presbyopia Humphrey visual field analyzer uses age-
matched data to aid in determining the appropriate correction.

85. Eyelid and facial features
 Superior lid ptosis –
superior VF defect
 Large nose can mimic
defect as inferior nasal
steps
 Overhanging brow and
deep set eyes can lead to
superior peripheral
artefactual field defects

86. Head position
 The head must also be placed against the headrest, in order to
prevent an artefactual altitudinal defect from forming (as a
result of the patient not being able to see stimuli presented in
the inferior visual field).
 If the head is turned temporally, the nose may present a
considerable obstacle, even to a central 30° plot
 If the head is tilted, the blind spot may be elevated

87. Trigger happy field
 Some patients, particularly if they are anxious, will be eager to
see most or even all of the stimuli during a test.
 will press the response button as often as possible, resulting in
large numbers of false positive errors.
 “trigger-happy” field is characterized by patches of abnormally
light white areas in the greyscale plot due to abnormally high
thresholds.

88. Hysterical visual field loss and malingering
 Hysteria and malingering are examples of ‘functional visual field
loss’
 Such visual fields plots are best assessed using kinetic techniques
(e.g. Goldmann bowl perimeter)
 Typically yield a constricted visual field or spiral defects

89. Point pattern of Humphrey field analyzer
 Two most commonly used pattern in management of glaucoma
 Group 1: used in suspected and established glaucoma
 30-2 point pattern
 24-2 pont pattern
 Nasal step
 Group 2: used in advanced cases in glaucoma
 10-2 point pattern
 Macular programming point pattern
 Custom test

90. Group 1: used in suspected and established
glaucoma
 To reduce the number of points, a bare area of 3⁰ around fixation
point is planned in 30-2 and 24-2 point patterns as macula will be
affected last.
 30-2 point pattern
 VF extent = 30⁰ radius
 There are no points on both the horizontal and vertical axis.
 Distance between two points: 6⁰
 76 points measured
 3⁰ bare area
 24-2 point pattern
 - Similar to 30-2 except VF extent is 24⁰ and points measures is 54 points

91. Continue……
 In 24 -2 point pattern extra 2 points above and below horizontal
on nasal side is taken making it 27⁰ at nasal field
 Thus 24-2 pattern is not circular and extra points indicates area
where there is high possibility of VF loss
 Nasal step pattern
 It is peripheral test pattern that explores from 30⁰ to 50⁰.
 The nasal step test points provide 2 points above and 2 points
below the horizontal axis of 30⁰,40⁰ and 50⁰ as well as 2
eccentric central points.

92. Group 2: used in advanced cases in
glaucoma
 10-2 point pattern
 VF tested= 10⁰
 No points in horizontal and vertical axis
 Distance between points=2⁰
 68 points tested
 Bare area= 1⁰( extra 12 points are checked inside 3⁰ )
 Macular point pattern
 3 ⁰ VF tested in 10-2 pattern
 No points in vertical and horizontal axis
 Distance between points= 2⁰
 16 points are checked in 3⁰ area

93. Continue…
 Custom test 6-2 point pattern
 Subset of 10-2 program
 VF extent= 6⁰
 Distance between points= 2⁰
 24 points measured
 Bare area= 1⁰
 In advanced glaucoma, use 10-2 pattern, but, if sensitivity loss
is from 10-25 db then normal we should go for macular
program.

94. why24-2 point pattern is test choice than 30-2?
 The outer set of 30-2 are not considered while selecting the 7th
best sensitivity point of TDNP ( Total Deviation Numerical Plot)
 The outer set of 30-2 are not included in five zones of GHT
(Glaucoma Hemi-field Test)
 The outer set of 30-2 are not considered in the Anderson’s
criteria to pick up early field defects due to glaucoma.
 The outer set of points of 30-2 are tested last. The patient may be
fatigued and there is chance to get high fixation losses, high false
–ve errors.
 The average normative data value of peripheral points have a
wide range.

95. Conclusion
 It is important to correlate changes in the visual field with
those of the optic disc.
 If such correlation is lacking, other causes of visual loss
should be considered, such as ischemic optic neuropathy,
demyelinating or other neurologic disease, pituitary tumor,
and so forth.
95

96. This consideration is especially important in the
following situations:
 The patient's optic disc seems less cupped than would be
expected for the degree of visual field loss.
 The pallor of the disc is more impressive than the cupping.
 The progression of the visual field loss seems excessive.
 The pattern of visual field loss is uncharacteristic for
glaucoma- for example, it respects the vertical midline.
 The location of the cupping or thinning of the neural rim
does not correspond to the proper location of the visual
field defect.
96

97. DIAGNOSIS IS MADE ONLY IF THE DEFECTS ARE REPEATABLE AND
CORRELATE WITH DISC AND CLINICAL FINDINGS.
97

98. INFERIOR NOTCHING OF NRR WITH SUPERIOR VF
DEFECT

99. References