This document discusses perimetry and visual field testing. It defines visual field as the area that can be seen at a given moment. There are various methods of visual field testing including kinetic and static perimetry. Automated static perimetry tests like Humphrey and Octopus are now commonly used and test the threshold light intensity that can be detected at different points in the visual field. The results are analyzed based on total deviation plots, pattern deviation plots and global indices to detect and monitor glaucomatous visual field defects. Common patterns of visual field defects seen in different conditions are also described.

3. PERIMETRY
&
HUMPHREY VISUAL FIELD ASSAY
Lt Col A.K.M. Rashed-Ul-Hasan
Long Term Fellow
Trainee(Glaucoma)
CMH Dhaka

4. VISUAL FIELD
Visual field is an island hill of vision surrounded
by a sea of blindness – Traquair
Visual field is all the space that one eye can see at
any given instant ---Tate & Lynn

5. 60
50 50
90 90
70 70
Fixation
X X
= Physiological Blind spot
X
NORMAL VISUAL FIELD
LIMITS

6. Visual Field Testing Methods
Central Field
Amslar Grid- 20°
Tangent (Bjerrum) Screen- 30°
Goldmann
Automated (Octopus/Humphrey)- 30°
Peripheral Field
Confrontation
Goldmann
Automated 90° program

7. Location of Visual Field Defects
Peripheral
> 30º
Central
5º or less from the point of fixation
Paracentral
>5º – 30º
Ceacal
Paraceacal
Periceacal
Centroceacal

8. Perimetry is defined simply as the study of the
visual field .
PERIMETRY & PERIMETER
Perimeter is an instrument designed for
perimetry.

9. Kinetic
Stimulus moves
 Confrontation
 Lister
 Tangent screen
 Goldman
Type of Perimetry
Static
Stimulus does not moves
 HVFA
 OCTOPUS

10. VFD detect earlier with 40% defect
Intensity fixed but stimulus moves
from non-seeing to seeing area
 2D
Not Computarized
Non Threshold type
More error
Good for neurological, periphery
of field & adv glaucoma
Static Kinetic
VFD detect earlier with 20%
defect
Area fixed but stimulus varies
in intensity
 3D
Computarized
Threshold type
Less error
Both glaucoma and
neurological

11. Role of Perimetry
1.To diagnose clinical conditions.
A) Ocular- Glaucoma, Optic nerve disorders.
B) CNS conditions- Optic nerve pathway disorders.
CNS Tumors.
Occipital lobe disorders.
2. To manage glaucoma.
To set target IOP
Follow up.

12. Different types of Automated Perimetry

13. THRESHOLD
If a particular intensity of light is shown 100 times and
if it is appreciated 50 times then that particular intensity of light is
termed as threshold.

14. Determination of threshold

15. APOSTILB (Asb)
Absolute units of light intensity / brightness
 Humphrey : 1 - 10,000 asb
 Goldman & Octopus : 1 - 1000 asb

16. DECIBEL (dB)
Tenth of logarithm unit ( 1 dB = 0.1 log unit )
Relative units of light intensity
Higher the dB lower intensity of light stimulus
high retinal sensitivity.

17. 0 dB = 10,000 asb
10 dB = 1,000 asb
20 dB = 100 asb
30 dB = 10 asb
40 dB = 1 asb
0 dB = Brightest light = low retinal sensitivity.
40 dB = Dimmest light = high retinal sensitivity.

18. Humphrey visual field test
Threshold test
Central Test
a. Central 30-2 ( 76 )
b. Central 24-2 (54)
c. Central 10-2 (68)
d. Macular progm (16)
Peripheral Test
a. Peripheral 60-4
b. Nasal Step
c. Temporal crescent
Speciality test
a. Neurological 20
b. Neurological 30
Strategy
Standerd threshold
strategy
a. Full Threshold Strategy
b. Fast Pac
Newer threshold strategy
a, SITA Standerd
b. SITA fast
Screening or
suprathreshold test
NB: Central 30º represent : 66% of ganglion cell & 83% visual cortex

19. Interpretation

20. Zone 1 Patient data & test data
Zone 2 Foveal Threshold & Reliable
indices
Zone 3 Gray Scale
Zone 4 Total Deviation
Zone 5 Pattern Deviation
Zone 6 Global Indices
Zone 7 Glaucoma Hemi-field Test
Zone 8 Raw Data

22. 0.2 second duration
The effect of size of pupil:
 Pupil should be 3-4 mm
 Constricted pupil
 Diffuse visual field depression
 Edge scotoma
 Very important in follow up test

23. RELIABILITY INDICES

25.  Central :
Yellow light at centre of bowl.
 Small diamond :
Below the central target
Macular degeneration
 Large diamond :
When central fixation lost
Central scotoma
 Bottom LED:
Superior field test
Fixation of target

26. Fixation loss
 Indicates steadiness of gaze during the
test
 >20% is unreliable
 5% Stimulus is presented over blind spot

27. False positive
>15% is unreliable (SITA Standard)
>33% is unreliable (Full threshold)
 Trigger Happy
Abnormally
pale

28. False Negative
>15% is unreliable (SITA Standard)
>33% is unreliable (Full threshold)
 Fatigue, inattention, malingering
Clover leaf pattern

29. Gaze Tracker
Upward spikes : indicating eye movements
Downward spikes : indicating blinking during stimulus presentation.

30. Total Deviation plots
1. Numeric value in upper plot
Diff. in dB between the patients test results and
the age corrected normal values at each tested point
in the visual Field.
Value is abnormal : if >5 dB less than normal .
1. Gray scale symbols in lower plot
Translates values of upper plot,
Darker the symbols, more the depth of defect
1. Generalized depression:
A. Media opacities
B. Refractive error
C. Miosis

31. Pattern Deviation
It is derived from total
deviation values and
adjusted to demonstrates
the localized defect.

32. P Value

33. Global Indices
It’s the summary values that represent distilled statistical
information.
Used to monitor progression of glaucomatous damage
Consists :
1. VFI: Patient’s overall VF function.
2. MD: Overall sensitivity of the field.
3. PSD: Focal loss within the field.

34. Glaucoma Hemifield Test
Compare 5 zone of upper field with mirror image of lower
field to see asymmetric field loss in glaucoma.
1. Outside normal limit
2. Borderline
3. General reduction of sensitivity
4. Abnormal high sensitivity
5. With in normal limit

35. Localized Field defect
The TDPP and PDPP looks
similar.
Causes-
 Early glaucomatous ON
damage
 AION
 ON pathway defect
 Occipital lobe infarcts

36. Generalized field defect in
TDPP.
Localized defect in PDPP.
 Found in advance stage of
glaucoma.
 Cataract associated with glaucoma
Irregular Generalized Field
defect

37. Generalized defect in TDPP.
Normal PDPP.
Causes
 Media opacities.
 Advanced and end stage glaucoma.
 Optic neuritis.
Uniform Generalized Field
defect

38. PRACTICE

39. Nasal Step Pattern

40. Arcuate pattern

41. Advanced case of
glaucoma

42. Enlargement of
blind spot

43. Left Sided Homonymous Haemianopia

44. Bi-nasal
hemianopia

45. Bi-temporal hemianopia

46. AION

47. Upper Haemiretinal Vein Occlusion

48. Tubular field
defect due to RP

49. Toxoplasma
choroidoretinitis

50. Glaucomatous Field Defect

51. Progression of field defects in POAG
 Initially observed in Bjerrum’s area ( 10 ˚ -25 ˚ from fixation)
Generalised contraction of field
Baring of blind spot : exclusion of the blind spot from the central
field due to inward curve of the outer boundary of 30° central field
(Fig A)
Small wing-shaped paracentral scotoma (Fig B)
Seidel’s scotoma : paracental scotoma joins the blind spot (Fig C)
Arcuate or Bjerrum’s scotoma: by the extension of Seidel’s
scotoma in an area either above or below the fixation point to
reach the horizontal line (Fig D)
Ring or double arcuate scotoma & Roenne's central nasal
step : when the two arcuate scotomas join (Fig E)
Advanced glaucomatous field defects : Tubulur vision