This document provides an overview of visual field basics and interpretation. It defines key terms like visual field, isopter, scotoma and perimetry. It describes the normal limits and locations of visual field defects. Different visual field testing methods are outlined, including manual Goldmann perimetry and automated static perimetry tools like Humphrey and Octopus. Factors affecting visual field tests and how to interpret results, including global indices, are also summarized.

1. Visual Field Basics &
Interpretation
Dr Salman Sohail
FCPS Resident - I

2. VISUAL FIELD
• THE VISUAL AREA THAT IS PERCEIVED SIMULTANEOUSLY, BY A FIXATED
EYE.

4. Blind Spot
• Optic disc
• Nasal to the fovea (on retina) –
• Seen in temporal VF as a Blind spot
( on visual field )

5. • Right or Left EYE ? L
• Field From the front

6. Normal limits of visual field

7. 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.

8. Isopter
• 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
NONVISIBILITY FOR A
PARTICULAR STIMULUS

9. • 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

10. Location of VF defect
• CENTRAL
5 DEGREES OR LESS FROM THE POINT OF FIXATION
• PARACENTRAL
> 5 DEGRESS – 30 DEGREES
• • PERIPHERAL
• • >30 DEGREES

11. 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

13. VISUAL FIELD TESTING
METHODS/TOOLS
• CENTRAL
AMSLER GRID: 200
TANGENT (BJERRUM SCREEN): 300
GOLDMANN
AUTOMATED (OCTOPUS / HUMPHERY) :300
• PERIPHERAL
CONFRONTATION
GOLDMANN
AUTOMATED 900 PROGRAMME

14. Perimetry
• SYSTEMATIC MEASUREMENT OF VF BY THE USE OF A
PERIMETER

15. PERIMETRY TYPES

16. 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
of VARYING SIZE AND ILLUMINATION

18. Interpretation of perimetry
• 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

19. Whats the Possible Diagnosis?
• RIGHT EYE
• LEFT EYE

20. Bitemporal Hemianopia

21. AUTOMATED PERIMETRY
( STATIC )
• MACHINE CONSTRUCTED ALONG THE BASIC LINES OF A GOLDMAN
PERIMETER WITH ADDITION OF SOPHISTICATED SOFTWARE
PROGRAMS.

22. 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

23. • Humphrey
• Octopus

24. 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

25. 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

26. Interpretation of Visual Field AP

28. DATA
NAME
AGE DOB
TEST TYPE
30-2
24-2
10-2

29. 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

30. Raw data –
0 is absolute scotoma
32/31.5 Normal
Grey scale –
Pattern or Type of scotoma
Darker means more severe scotoma

31. • Total Deviation plot
- According to AGE avg. sensitivity
to the stimulus given
0 Normal to that age ..
- less the value in minus , more the deviation and
defect
- Probability of TDP
%age of normal of that age group

32. • Total deviation plot affected by media opacities
Commonly are Cataracts
So to minus that
We have PATTERN DEVIATION

33. Global Indices - Humphrey
• MD (total value of VF loss , Normal : 0 to +2 dB) –ve as worsens
• PSD ( Normal value + MD ) Absolute value – threshold and avg seen at
each point
• VFI (1 - 100 % of normal VF)
• GHT

34. 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)

37. Take Home Message
• Very much patient and technician dependent
• Check reliability markers after DATA AGE
• Clinical correlation always
• Repeat if in doubt

38. THANKYOU
LEFT TEMPORAL HEMIANOPIA