Useful for Optometry Students and Optometrist involved in Clinical Practice

1. Visual Field
Testing and Interpretation
Raman P Shah
Optometrist
B. P. Koirala Lions Center for Ophthalmic Studies

2. References and recommended readings
• Walsh TJ. Visual fields Examination and
Interpretation, Ophthalmology monographs, AAO
• J Boyd Eskridge. Clinical procedures in Optometry.
Mosby
• Automated Perimetry; Visual Field Digest: 5th
edition
• David O. Harrington, Michael V. Drake. The visual
fields .7th
edition

3. Presentation layout
• Introduction on Visual field
• Normal limits of Visual field
• Short overview on history of VF
• Terminologies related to VF
• Visual field testing methods
– Kinetic, static
• Interpretation of VF reports

4. Introduction
Visual Field
• The visual area that is
perceived simultaneously by
a fixating eye.

5. Retina Vs Visual Field
Optic disc
Nasal to the fovea – Seen in
temporal VF as a Blind spot

6. Traquairs field of vision

7. Hill of Vision

8. Normal limits of visual field

9. Short History of Visual Field
• In B.C 150, Ptolemy: used some form of
perimetric device to measure extend of VF
• First clinical investigation of VF defect –
Hippocrates in 5th
century, hemianopic field
defect
• Finally in 1604 Kepler explained the principle of
sight in term of an inverted retinal image –
– an stage for modern investigation of VF

10. History….
• In 1666, Mariotte discovered
physiological blind spot
• In 1801, Young stated the normal
extend of VF of an eye
• Von Graefe mapped out blind spot,
central scotomas, construction of
isopter.
– Introduced VF in clinical medicine
for the first time
• Until 1869, Foerester invented arc
perimeter, till then VF plotted on
flat surface
Thomas
Young
Von
Graefe

11. History……
• In 1880, Bjerrum
developed Tangent screen
• In 1940, Marc Amsler
introduced Amsler grid
• In 1939 Sloan described
static perimetry
• In 1945 Goldman
Perimeter
• In 1960 Tubinger- manual
testing of both static and JannikPetersonBjerrum
HenningRønne
Dr.HansGoldman

12. Few Terminologies
• Threshold: The weakest test stimulus that is just
visible in a particular location under the specific
testing condition.
– Varies across the visual field.
• Sensitivity: most subtle characteristics of a
stimulus that is visible at a specific point in space.
• Fixation: that part of visual field corresponding
to fovea centralis.

13. Terminologies…
• Isopter:
– Line connecting all points in the visual field with the same
threshold ( for a given test spot)
– Boundary between area of visibility to the area of non-
visibility for a particular stimulus

14. Terminologies…
• Scotoma: Localized defectsdepressions surrounded by
normal visual field.
– Absolute: defect that persists when the maximum stimulus is
used e. g blind spot.
– Relative : defect that is present to weaker stimulus but
disappears with brighter stimulus.

15. Location of Visual field defects
• Central
– 5 degrees or less from the point of fixation
• Paracentral
– >5 degress – 30 degrees
– Ceacal, paraceacal, periceacal
– Centrocecal
• Peripheral
– >30 degrees

17. Descriptive components of VF
defects
• Monocular descriptions
– Density
• Absolute (no visual sensation) or relative (depressed visual sensation)
– Area
• General or local
– Shape
• Sectorial (hemianopic) or non-sectorial (regular or
irregular)
– Extent
• Total or Partial
– Position
• Rt. Or Lt. . Temporal, nasal, superior, inferior

18. Descriptive components of VF
defects
•Binocular description
• Laterality
•Unilateral or bilateral (homonymous/heteronymous)
•Equalness
•Congruous or incongruous
•Additional description
•Awareness
•Positive (defect perceived) or negative (defect not perceived)

20. Significance of Visual field testing
• Find out the extent of VF
• To diagnose and detect diseases as well as
extent of damage caused in VF by the disease
• To locate possible lesion in neurological
disorder
• To find out the progression of diseases

21. Visual field testing methods/tools
• Central
– Amsler Grid: 200
– Tangent (Bjerrum screen): 300
– Goldmann
– Automated (Octopus / Humphery) :300
• Peripheral
– Confrontation
– Goldmann
– Automated 900
programme

22. Perimetry
• Systematic measurement of VF by the use of a
perimeter
• Modern Perimeter
– Consist of a bowl positioned at a fixed distance
from the eye,
• enable the controlled presentation of stimuli with in the
bowl
• Enables assessment of the visual function through out
the visual field
• Detection & quantification of damage to the visual
field
• Monitoring the change over a time

23. Perimetry types
Kinetic Static
• measures extent of visual field
by plotting isopters ( locus of
retinal points having same
sensitivity)
•Stimulus moves from non-
seeing to seeing area.
•Result depends upon the
experience of the operator.
• e.g, Goldman perimetry,
confrontation, Tangent screen,
Arc perimetry
• measures the sensitivity of
each retinal points.
•The stimulus is stationary but
increases in luminance.
• Mostly automatic, very little
role of the operator.
•e. g, Automated perimetry,
Goldman perimetry

24. Goldman Perimetry
• The most widely used instrument for manual
perimetry.
• Has a calibrated bowl projection instrument
– with a background intensity of 31.5 apostilbs (asb),
• Test Targets: dots
– Varying size and illumination

25. Perimetry Bowl
• Background luminance
31.5 asb
Radius of the bowl
30 cm Patient side

26. Goldmann Targets
• The stimuli (Dot) used to plot an isopter
denoted by
– Roman numeral, a number, and a letter.
• Roman Numerals = 0 to V (Size)
• Number = 1 to 5 (Luminance) use of Filter
• Alphabet = a to e ( ‘’) use of filter
V4e , I4e, IV3e

27. Goldmann Perimetry: Roman numeral
• Sizes of Stimuli [0...V scale]
• Each size increment equals
• a twofold increase in diameter and a fourfold
increase in area.
Diameter (mm) Area (mm2
)
0 0.28 1/16
I 0.56 ¼
II 1.13 1
III 2.26 4
IV 4.51 16
V 9.03 64

28. Target illumination
• Luminance settings
• Expressed in units called Apostilbs
(candela/m2
)
• 2 sets of filters – 5 each
– 10 steps
• Standard Vs Fine settings
• (1...5 and a...e scales)
• 1, 2, 3, 4 settings represent 0.5 log
unit changes = 5 db
• a, b, c, d and e settings represent 0.1
log unit changes = 1db

29. Target Range in Goldmann
• More than 100 combinations of size and intensity
of test targets are Possible
– but only a few isopter are needed to define the visual
field.
• Size “0” generally is omitted
– because results of the plots are inconsistent.
• The fine-intensity filter is usually set to the letter “e”
– which eliminates the small-increment light filters.
– Test target : Denoted by – Size + (Std. + fine)
Luminance
• Eg: V4e, I4e, II3e

30. Some interesting facts
• A change of one number of intensity
– is roughly equivalent to a change of one Roman
numeral of size i.e. III4e = IV3e
• Isopter plotted with Targets of equal Sum of
– Roman Numerals (size) & Number (Intensity)
• are considered equivalent.
– For example,
• the I4e isopter is roughly equivalent to the II3e isopter.
• I + 4 = 5, II + 3 = 5

31. Standard VF plot of RE

32. Required Equipment for VF mapping
• Goldmann bowl perimeter
• Lens holder
• Recording paper
• Colored markers
• Patch for monocular testing

33. Goldmann Perimeter
Pantoscopic handle
Horizontal cut
Patient Side (Bowl)

34. Goldmann Perimeter
Patient Side (Bowl)
Fixation target
Chin rest
Head rest
Len Holder

35. Guideline to Plot
• First demonstrate the procedure
to patient
– by statically presenting large test
General rules for plotting
“Isopters”
– An isopter is mapped for the
particular stimulus size and
intensity
• move from NON-SEEING TO
SEEING while presenting stimulus
• move at a rate of 5 degrees per second
inside
• present kinetically every 15 degrees
interval

36. Guidelines for plotting
• Begin in the far periphery and kinetic plot isopter in
all meridians
–Use a V4e, I-3e , I-2e or target (depending
upon age
–Plot the Blindspot
• only 4 meridians are required( more if irregular or
Large)
– Use the I-4e for the blind spot
• within isopter of I-2e or I-3e

37. Guidelines
• Central static test with I-2e
– Explore for any scotomas
• Kinetic plot with I-3e stimulus only in suspected defect
area
• Static test between I-3e and I-2e isopters with the
I-3e stimulus (scotoma search)

38. Guidelines
• Special case plots
– Glaucoma suspects
– Plot more points along the nasal edge of the isopter
– Plot approximately
• every 3-5 degrees,
• 15 degrees above and below the horizontal raphe
Repeat for central, intermediate and peripheral plots
• Suspected neurological lesions
– Plot more points on either side of the vertical meridian
– Repeat for central, intermediate and peripheral plots

39. Recording
• All recording should be done on
the Goldmann recording paper
– Patient name,
– Date,
– Rx used,
– Pupil size,
– Eye tested and
– Patient cooperation / Fixation
– Indicate the target sizes used in
the bottom right hand block (color
marker)

40. Color coding of Isopters
• I-2e Blue
• I-3e Orange
• I-4e Red
• II-4e Green
• III-4e Purple
• IV-4e Brown
• V-4e Black

41. Expected findings for normal Isopters
• Patients under 50 years of age
i. Peripheral I-4e (size=same, brighter luminance)
ii. Intermediate I-3e
iii. Central I-2e (size=same, dimmer luminance)

42. Expected findings for normal
Isopters
• Patients 50 years or older
i. Peripheral II-4e (size=larger, brighter luminance)
ii. Intermediate I-4e
iii. Central I-2e or I-3e (size=smaller, dimmer luminance)

43. Interpretation
• The visual field is considered abnormal if:
– the threshold values are significantly brighter
(0.5 log units or more) than the expected values
AND / OR
– Scotomas or depressions are present

44. Some Visual field defects

45. Some Visual field defects

46. Bitemporal hemianopia
Right eye Left eye

47. Automated Perimetry ( Static)
• Machine constructed along the basic lines of
a Goldman perimeter + sophisticated software
programs.
• Key reason for increased interest in automated
perimetry has been due to the standardization
automated perimetry allows.

48. Automated Perimetry
• Visual threshold is measured at a series of
fixed points in the visual field.
• The brightness of the test spot is varied, but
not its location.
• Threshold is usually plotted relative to normal
fields, to reveal defects

49. Automated Perimetry

50. Automated Perimetry
• Humphrey:
• Octopus:

51. Threshold determination
Frequency of seeing curve

52. Threshold determination
28dB
24 dB
32 dB
30 dB
29 dB
0 dB brightest stimulus

53. Threshold determination
• Age matched normal data are used to compare
patient’s data
• Normal range determined by
– Sensitivity of each retinal points 10,000
individuals
– Upper 95% as normal
– Lower 5% as abnormal

54. Testing strategies
• Octopus
– Normal
– Dynamic
– TOP ( Tendency oriented perimetry)
• Humphrey
– SITA (Swedish Interactive threshold algorithm)
– SITA fast
– Full threshold

55. Difference between Octopus and Humphrey (test
parameters)

56. Factors affecting Automated
Perimetry
• Background luminance
• Stimulus size
• Fixation control
• Refractive errors
• Cataracts and other media opacities
• Miosis
• Facial structure
• Fatigue
• Experience of a perimeter

57. Validity of the test
• False positive response
– > 20% unreliable
• False negative
– >20% unreliable
• Short term fluctuation
– 1-3 dB normal fluctuation
• Fixation loss
– >33% unreliable

58. Choosing an appropriate program
Examination procedure
Test program(G1, G2, 32, M2)
+
Test strategy (Normal, dynamic, top)
+
Perimetry method( W/W, flicker, B/Y, kinetic)

59. Programs
G1/G2
• Central 30 degree
• Glaucoma screening
• 59 points
• Locations more closely with topography of
retina (in areas of concern of glaucoma)
• 2.8 deg spacing

60. Programs
32 ( general examination)= 30-2 in Humphrey
• introduced with early automated perimetry
• 76 test locations
• Wide spacing (6 degrees) ( not appropriate for
glaucoma)

61. Programs
Macula program(M2)
• Central and paracentral visual defects in
neurological and macular problems
• Central 10 deg
• 56 test locations
• spacing 2 degrees
• 0.7deg spacing in the macula

62. Programs
LVC (central low vision)
• To test how much sensitivity is remained in
the central foveal area.
• 77 locations
• 30 degrees
• End stage glaucoma

63. Strategies
• Normal strategy
– Standard
– 4-2-1 bracketing procedure
– 10-15 min
– Early and shallow defects
– Younger patients ( good condition in answering
the question till the end of a long program)

64. Strategies
• Dynamic strategy
– One threshold crossing
– Small steps in regions with Normal sensitivity and
large towards depressed field
– Test duration reduced by two
– Especially when focal defects are expected

65. Strategies
• TOP ( tendency oriented perimetry)
– Light sensitivity of the retinal is interrelated rather
than having an individual value
– 2 minutes
– For patients with depressed fields, for children,
elderly ones who are not capable of finishing a
longer examination

66. Interpretation of results

68. Different zones

69. Greyscale

70. Value table

71. Comparison /corrected comparison(Total and pattern
deviation)

73. Probability plots

74. Cumulative defect curve

76. Glaucoma Hemifield test
• 5 sectors in the upper field are compared to
five mirror images in the lower
• If value in two sectors differ to an extent that
found in
– <0.5% of the normal population ( highly sensitive)
– <1% of normal population (outside normal limit)
– <3% of the normal population (Boderline)
– <5% of the normal population ( can be a normal
plot)

78. Global indices
Octopus
• Mean sensitivity (MS)
• Mean deviation (MD) (–
2dB to +2dB)
• Loss variance (LV) (0-
6dB)
• CLV(0-4dB)
• SF (1.5dB- 2.5dB)
• RF < 15%
Humphrey
• GHT
• Mean deviation
• PSD
• CPSD
• SF

79. Octopus criteria for visual field defect§

80. HFA criteria for VF loss
• Pattern deviation plot

82. Recent advances in automated
perimetry
• Goldman kinetic module
• High-pass resolution perimetry - Uses thin rings instead of
spots
• Short wavelength sensitive perimetry - Blue on Yellow for S
cones
• Flicker Perimetry - Flickering targets instead of static flashes
• Aulhorn's Snow field campimetry - Uses TV “snow” and
pointing
• Motion perimetry - Detect moving targets instead of flashed
ones
• Rarebit perimetry- uses very small, bright spots
• Pupil Perimetry - measures pupil responses instead of subject
reports
• Multifocal VEP - measures cortical evoked potentials instead of
subject reports

83. Summary
• Principle of kinetic and automated perimetry
• Appropriate selection of visual field testing for
a particular patient
• Accurate interpretation of VF reports