This document discusses static automated perimetry, which determines the threshold of the retina at fixed points to assess the visual field. It describes the retinal area that can be perceived, variables that affect perimetry tests, different test patterns used, classification of Humphrey field tests, strategies for presenting stimuli, analyzing results, and classifying visual field defects seen in glaucoma. Key points are that static perimetry determines the differential light sensitivity across the retina and compares results to age-normalized databases to detect losses.

1. STATIC
AUTOMATED
PERIMETRY
DR.PUSKAR GHOSH
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2.  Area perceived simultaneously by a fixing
eye.
Extension-
• Superior- 50°
• Inferior-75°
• Nasal-60°
• Temporal-100°-110°
Differential Light Sensitivity- ability to
detect a spot of light against a uniformly
illuminated background at a given point of
the Retina. Central Vision Bjerrum’s area
Isopter

7. STATIC
PERIMETRY
• It is a form of visual field
assessment where threshold of
retina is determined in various
fixed points.

8. Perimeter Variables-
• Stimulus size- Goldman size III (4mm²)
• Background Illumination- Constant (31.5 Asb)
• Exposure Time- 200ms
• Stimulus intensity-
Patient's Variables-
• Pupil size
• Age
• Media clarity
• Refractive error
• Fatigue

9. STIMULUS
 Threshold stimulus- 50% probability of being seen.
Measurement-
• Apostilbs-light intensity
(35ˉˡcandela/m²)
• Converted to Decible (db)-
measurement of retinal
sensitivity
• Db values are relative units of
light attenuation
• 40 dB – maximal foveal
threshold in HVF printouts

10. CLASSIFICATION
of Humphrey Field
Test
• Central Tests- 30-2,24-2,10-2,
macular program
• Peripheral Tests- Nasal step,
Temporal Cresent
Threshold Test
• Supra threshold stimulus
Screening Tests

11. Strategy- Method of presenting stimuli to the patient
to attain the desired information

13. Test Pattern Point density Number of test
point
Remarks
24-2 6° 54 Routine monitoring
30-2 6° 76 1st field in Glaucoma suspects &
established cases
10-2
2° 68 Established/suspects where
macular involvement is to be
ruled out
Macular point
pattern
2° 16 Definite macular involvement
Nasal step 14 To screen for peripheral nasal
step defect

14. • Full threshold- bracketing or
staircase
• Newer threshold strategy
FASTPAC
Sweidish Interactive
threshold algorithm (SITA)
SITA- Fast

15. Glaucoma suspect/established
24-2 point pattern
Absolute scotoma
10-2 pattern
Advanced Glaucoma
Sensitivity <10-15db
Macular split
Size V stimulus
No Macular split- Sx good Macular split present-Sx bad

16. STATPAC
In built software in Humphrey field analyzer
Compare measured retinal sensitivity with mean standard sensitivity at all points.
Calculate various statistical methods (ie total & patterned numerical & probability data) for raw
data.
Glaucoma Hemifield Test- detects glaucoma suspects in more focused manner.
Help to analyze glaucoma progression.
No role in deriving grey scale from raw data.

17. ZONES OF FIELD
ANALYSIS
PRINTOUT

18. Patient Data-
• Name-
• Age (DOB)-
• Pupil Diameter- 3-4mm
• Visual Acuity
• Ref error correction-
Test Data-
• Fixation Monitor- blind spot
• Fixation Target- Central
• Colour of stimulus- white
• Background illumination- 31.5 Asb
• Stimulus size- Goldman III

19. Foveal threshold
Fixation loss- >20% unreliable
False positive error- >15% unreliable
False Negative error- >20% unreliable
Suspected Glaucoma- FN,FP &FL should be 0
Established Glaucoma- up to 20% acceptable

20. • Exact retinal sensitivity in db
units
• ‘0’ – Absolute scotoma
• ‘40’- maximum retinal sensitivity
• Strategy specific

22. RAW DATA expressed in terms of deviation
from normal values
Measured sensitivity – Standard retinal
sensitivity
+ : Measured sens. > standard sens.
- : Measured sens. < standard sens.
0 : Measured sens. = Standard sens.

23. Expression of loss in terms of P values
Numerical values expressed in
symbolic forms of P value
Lesser P value – higher chance of
abnormalities
STATPAC calculate P, ONLY when there
is loss of sensitivity.
To know the pattern and extent of
defect.

24. Generalised field defect
is removed by elevating
each point sensitivity by
certain db
Extent & pattern of
deep scotomas masked
by generalised
depression

25. PDNP is converted to PDPP
by calculating P values at
each point
Representing them with
probability symbols

26. Mean Deviation Index
• average deviation of sensitivity from normative data (average of all numbers in TDNP)
• Indicate generalised loss
• Express height of hill of vision
Pattern Standard Deviation (PSD)
• Express the dissimilar deviation in TDNP
• Contour of hill of vision
• Significant P value- TDNP numbers are markedly dissimilar
Short Term Fluctuation (SF)
• `Intra test variation
• Should be <3db
•Corrected Pattern Standard Deviation(CPSD)
• PSD after removing SF

28. • Pick up dissimilarity of sensitivities of corresponding points on either side of horizontal axis
GHT Result CRITERIA
Outside Normal Limits a) Score diff in one zone pair>99%
population
b) Individual zone score in both member of
any pair>99% population
Borderline One zone pair score diff>97% population
Generalised Reduction of
sensitivity
a)Neither of above criteria
b)Ht of best part of visual field<0.5%
population
Abnormally High
Sensitivity
Ht of best part of visual sensitivity>99.5%
population
Within Normal Limits None of the above

29. Without Statistical assisteance-
OVERVIEW PRINTOUT
With Statistical assistance
• From normative data-
CHANGE ANALYSIS
• Previous data from stable glaucoma pt.-
GLAUCOMA PROGRESSION
ANALYSIS

30. • Hodapp,Parrish and Anderson classification
SEVERITY MD VALUE Point depressed p<5% Point depressed, p<1% Central 5° points
Early/ Mild > -6 db 18 (<25%) <10 All point >15db
Moderate > -12 db <37 (<50%) <20 One hemifield <15db
No point at 0db
Severe < -12 db >37 (50%) >20 Both hemifield at
<15db
At least 1 point at 0 db

31. ANDERSON CRITERIA
1. 3 Non-edge Adjascent point in
PDPP, of which at least
a) 2 points p<0.5%
b) 1 point p<1%
2. CPSD p< 5%
3. GHT-abnormal

32. Reliability parameters
FL<20%
FP<15%
FN<20%
Programe used
Patient data
Foveal Threshold
TD vs PD
Global Indices
Optic Nerve Head
PDP
• 3 contiguous non edge points
• In Bjerrum’s area
• Pattern of loss

33. Paracentral Nasal Step Siedel’s Scotoma Temporal wedge
Arcuate scotoma Breakthrough to periphery Double Arcuate Central Island of vision

34. Lens rim artifact Clover Leaf defect

35. Abnormally pale Grey scale- high false +ve