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TESTING OF FIELD OF 
VISION 
By 
SRIDEVI RAJEEVE 
2008 BATCH
VISUAL FIELD 
Visual field 
3 dimensional area of a subjects surrounding that can be seen at any 
one time around an objec...
VISUAL FIELD 
1.Central field includes an area from fixation point 
to a circle 30* away. 
Contains the Physiological Blin...
Methods of estimating Visual fields 
(1) Perimetry . 
It is the procedure for estimating extent of the visual fields. 
It ...
. 
b. Static perimetry. 
 . 
This involves presenting a 
stimulus at a predetermined position for preset 
duration with v...
Extent of normal visual field
Peripheral versus central field charting 
 Peripheral field charting 
 Central field charting 
Confrontation method 
Per...
Manual perimetry & Automated perimetry 
A. Manual perimetry 
1. Confrontation method (central field): Assuming the examine...
Lister’s perimeter
2. Lister’s Perimeter 
 Extent of peripheral field 
 Metallic semicircular arc, graded with degrees 
& white dot in cent...
3. Campimetry (Scotometry) 
To evaluate the central and paracentral area (30*) of the 
visual field. 
 . 
The Bjerrum’s s...
. 
Initially physiological blind spot (15* temporal 
to fixation pt) is charted which corresponds 
to optic nerve head. 
...
BJERRUM’S SCREEN 
.
4. Goldmann’s perimeter
Goldmann’s perimeter 
 Hemispherical dome 
 Test condition & intensity of target are always same 
 Permits greater repr...
.B. AUTOMATED PERIMETRY 
Automated perimeters are computer assisted and test 
visual fields by a static method. 
The auto...
. 
Advantages over manual perimetry 
Automated computerized perimetry offers an unprecedented flexibility, a 
level of pre...
Humphrey field analyser
INTERPRETATION OF AUTOMATED PERIMETRY PRINT 
OUT FIELD CHARTS 
 Automated perimeter variables 
 Testing strategies and p...
A. AUTOMATED PERIMETER VARIABLES 
1. Background illumination 
2. Stimulus intensity 
3. Stimulus size 
4. Stimulus duratio...
. 
 1. BACKGROUND ILLUMINATION 
HFA Uses 31.5 apostilb[asb] background illumination. 
Apostilb [asb] = Unit of brightness...
3.STIMULUS SIZE 
 HFA offers 5 sizes of stimuli corresponding to Goldmann’s 
perimeter stimuli 1 through v 
 Standard ta...
Stimulus intensity scales comparison
Testing strategies and programmes 
 Visual threshold - physiological ability to detect a stimulus under 
defined testing ...
TESTING STRATEGIES 
&PROGRAMMES 
Basic strategies 
 Supra threshold testing 
 Threshold testing 
1. Full threshold testi...
. 
SUPRA THRESHOLD TESTING 
Target obove brightness a patient should be able to see 
Screening procedure for gross defects...
1. FULL THRESHOLD TESTING 
 Determines threshold value at each pt. By bracketing tech 
 4-2 on HFA 
 4-2-1 on OCTOPUS 
...
2. FAST PAC 
 More rapid 
 Threshold once cross strategy not applicable 
3. SITA 
 Swedish interactive threshold algori...
TEST PROGRAMMES 
A. Central field tests 
central 30-2 test 
central 24-2 test 
central 10-2 test 
macular grid test 
B. Pe...
Central 30-2 test 
 Most comprehensive form of visual field assessment of central 30 
degrees 
 Consists of 76 points, 6...
Central 24-2test 
 54 points examined 
 Near similar to 30-2 test except - 
2 peripheral nasal points at 30* on either s...
Central 10-2 test 
 Most pt.s in arcuate region b/w 10* & 30* - 
marked depression 
 Assess and follow 68 pt.s 2 degrees...
Macular grid test 
 Used when field is limited to central 5 degrees 
 Test examines 10 points spaced on 29 degree 
squar...
Arbitraty division of Humphry Single Field printout(Statpac 
printout) with central 30-2 test in sparts (zones)
EVALUATION OF HFA SINGLE FIELD 
PRINT OUT 
Software used - Statpac printout. Divided into 8 zones viz; 
I. Patient data & ...
. 
II. Reliability Indices (RI) 
Shows Reliability indices & Test duration 
Visual field examination = Unreliable - if thr...
. 
III. Gray scale stimulation 
 Depicted in Zone 3. 
 The darker the print out the worse is the field. 
 Provides fiel...
. 
 IV. Total deviation plots 
 Provides deviation of patients threshold values from that of 
age corrected normal data....
. 
Probability plot 
 In the lower part of zone IV of the printout, the total 
deviation plot is represented graphically....
. 
VI. Global indices 
 Depicted in zone VI of printout. 
 Are calculations made by Statpac to provide overall 
guidelin...
. 
2. Pattern std deviation (PSD) -Measure 
of variability within the field. It measures the diff 
between a given point &...
.. 
 4.Corrected pattern std deviation (CPSD)- PSD 
corrected for SF. 
 Indicates the variability between adjacent point...
. 
1. Outside normal limits 
Denotes that either the values in upper & lower clusters differ to 
an extent found in less t...
. 
VIII. Actual threshold values 
 Inspected for any pattern or Scotoma when 
clinical features are suspeciant and even i...
. 
THANK YOU!
Testing of Field of Vision
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Testing of Field of Vision

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Testing of Field of Vision

  1. 1. TESTING OF FIELD OF VISION By SRIDEVI RAJEEVE 2008 BATCH
  2. 2. VISUAL FIELD Visual field 3 dimensional area of a subjects surrounding that can be seen at any one time around an object of fixation Extent of normal field Superiorly 50* Nasally 60* Inferiorly 70* temporally 90*
  3. 3. VISUAL FIELD 1.Central field includes an area from fixation point to a circle 30* away. Contains the Physiological Blind Spot on its temporal side. 2. Peripheral field refers to rest of the area beyond 30* to outer extent of field of vision
  4. 4. Methods of estimating Visual fields (1) Perimetry . It is the procedure for estimating extent of the visual fields. It can be classified as below: a. Kinetic perimetry: In this the stimulus of known luminance is moved from periphery towards the centre to establish isopters. Various methods of kinetic perimetry are; Confrontation method Lister’s perimetery Tangent screen scotometry Goldmann’s perimetry
  5. 5. . b. Static perimetry.  . This involves presenting a stimulus at a predetermined position for preset duration with varying luminance. Various methods of static perimetry adopted are; Goldmann perimetry Friedmann perimetry Automated perimetry.
  6. 6. Extent of normal visual field
  7. 7. Peripheral versus central field charting  Peripheral field charting  Central field charting Confrontation method Perimetry: Lister’s, Goldmann’s & Automated Campimetry or scotometry Goldmann’s perimetry Automated field analysis
  8. 8. Manual perimetry & Automated perimetry A. Manual perimetry 1. Confrontation method (central field): Assuming the examiner’s field to be within the normal range, they are compared with patient’s visual fields Rough, rapid & extremely simple method MoE: The patient is seated facing the examiner at a distance of 1 metre. While testing the left eye, thepatient covers his right eye and looks into the examiner’s right eye. The examiner occludes his left eye and moves his hands in from the periphery keeping it midway between the patient and himself. The patient and the examiner ought to see the hand simultaneously, for the patient’s field to be considered normal. The hand is moved similarly from above, below and from right and left.
  9. 9. Lister’s perimeter
  10. 10. 2. Lister’s Perimeter  Extent of peripheral field  Metallic semicircular arc, graded with degrees & white dot in centre for fixation.  Arc can be rotated in different meridians  MoE: Patient seated facing arc. One eye occluded, fixates on the central white dot. Test object (white, 3-5mm) moved along the arc from periphery towards centre.  Point which is 1st seen is registered on chart  Arc moved 30* each time & 12 readings noted.  Perimeter extent of Peripheral field is noted
  11. 11. 3. Campimetry (Scotometry) To evaluate the central and paracentral area (30*) of the visual field.  . The Bjerrum’s screen is used and can be of size 1 metre or 2 metres square. MoE: Pt seated at 1m or 2m. Screen has white object for fixation in centre around which concentric circles from 5* to 30* are marked. Pt fixates on the central dot with one eye occluded. A White target (1-10mm) moved from periphery towards centre in various meridians
  12. 12. . Initially physiological blind spot (15* temporal to fixation pt) is charted which corresponds to optic nerve head.  Blind spot dimensions: Horizontally 7-8* Vertically 10-11*  Central & paracentral scotoma - Found in - Optic neuritis Open angle glaucoma
  13. 13. BJERRUM’S SCREEN .
  14. 14. 4. Goldmann’s perimeter
  15. 15. Goldmann’s perimeter  Hemispherical dome  Test condition & intensity of target are always same  Permits greater reproducibility
  16. 16. .B. AUTOMATED PERIMETRY Automated perimeters are computer assisted and test visual fields by a static method. The automated perimeters automatically test supra-threshold and threshold stimuli and quantify depth of field defect. Commonly used automated perimeters are; Octopus Field Master Humphrey field analyser
  17. 17. . Advantages over manual perimetry Automated computerized perimetry offers an unprecedented flexibility, a level of precision and consistency of test method that are not generally possible with manual perimetry. Other advantages; Data storage capability Ease of operation Well controlled fixation Menu driven software Online assistance making them easy to learn and use. Facility to compare results statistically with normal individuals of the same age group and with previous tests of the same individual.
  18. 18. Humphrey field analyser
  19. 19. INTERPRETATION OF AUTOMATED PERIMETRY PRINT OUT FIELD CHARTS  Automated perimeter variables  Testing strategies and programme Following discussion is based on the HFA.
  20. 20. A. AUTOMATED PERIMETER VARIABLES 1. Background illumination 2. Stimulus intensity 3. Stimulus size 4. Stimulus duration
  21. 21. .  1. BACKGROUND ILLUMINATION HFA Uses 31.5 apostilb[asb] background illumination. Apostilb [asb] = Unit of brightness per unit area (1/35 candela/sq.m)  2. STIMULUS INTENSITY HFA uses projected stimuli  Intensity varied more than 5%log units (51 decibel) b/w 0.08 & 10,000 asb. In db notation, value refers to retinal sensitivity.  Higher no. Indicate logarithmic reduction in test object brightness & greater sensitivity of vision
  22. 22. 3.STIMULUS SIZE  HFA offers 5 sizes of stimuli corresponding to Goldmann’s perimeter stimuli 1 through v  Standard target size equivalent to Goldmann size III (4 sq.mm) 4. STIMULUS DURATION Shorter than latency time for voluntary eye movements (about 0.25 sec) HFA - 0.2sec OCTOPUS - 0.1sec
  23. 23. Stimulus intensity scales comparison
  24. 24. Testing strategies and programmes  Visual threshold - physiological ability to detect a stimulus under defined testing conditions.  Normal threshold = Mean threshold in normal peoplein a given age goup at a given location in the visual field.  Machine compares patient sensitivity against these values.  Threshold: 0-50 db  50 db – dimmest target  0 db - brightest illumination perimeter can project  50 db - high sensitivity  0 db low sensitivity
  25. 25. TESTING STRATEGIES &PROGRAMMES Basic strategies  Supra threshold testing  Threshold testing 1. Full threshold testing 2. Fast Pac 3. SITA (Swedish Interactive Threshold Algorithm)
  26. 26. . SUPRA THRESHOLD TESTING Target obove brightness a patient should be able to see Screening procedure for gross defects THRESHOLD TESTING Precise Clinician preferred More time consuming Expensive
  27. 27. 1. FULL THRESHOLD TESTING  Determines threshold value at each pt. By bracketing tech  4-2 on HFA  4-2-1 on OCTOPUS  Stimulus test pt. 0.2 sec  Machine wait y/n  If stimulus not seen-intensity of stimulus increased 4db steps  Once threshold crosses stimulus intensity is decreased 2db steps till stimulus not seen
  28. 28. 2. FAST PAC  More rapid  Threshold once cross strategy not applicable 3. SITA  Swedish interactive threshold algorithm  Reduces test time  Fast SITA  Standard SITA
  29. 29. TEST PROGRAMMES A. Central field tests central 30-2 test central 24-2 test central 10-2 test macular grid test B. Peripheral field tests peripheral 30/60-1 peripheral 30/60-2 nasal step temporal cresent C. Speciality tests Neurological-20 Neurological-50 Central 10-12 Macular test D. Custom tests
  30. 30. Central 30-2 test  Most comprehensive form of visual field assessment of central 30 degrees  Consists of 76 points, 6 degrees apart on either sides of vertical & horizontal axis  Inner most points are 3* from fixation point.
  31. 31. Central 24-2test  54 points examined  Near similar to 30-2 test except - 2 peripheral nasal points at 30* on either side of horizontal axis are not included (while testing central 24*)
  32. 32. Central 10-2 test  Most pt.s in arcuate region b/w 10* & 30* - marked depression  Assess and follow 68 pt.s 2 degrees apart in central 10 degrees
  33. 33. Macular grid test  Used when field is limited to central 5 degrees  Test examines 10 points spaced on 29 degree square grid centered on point of fixation
  34. 34. Arbitraty division of Humphry Single Field printout(Statpac printout) with central 30-2 test in sparts (zones)
  35. 35. EVALUATION OF HFA SINGLE FIELD PRINT OUT Software used - Statpac printout. Divided into 8 zones viz; I. Patient data & test parameters 1. Patient data: Name Date of birth Eye (right/left) Pupil size Visual acuity 2. Test parameters: Test name Strategy Stimulus used Background
  36. 36. . II. Reliability Indices (RI) Shows Reliability indices & Test duration Visual field examination = Unreliable - if three or more of the following reliability indices have below mentioned values;  Fixation losses >= 20%  False positive error >= 33%  False negative error >= 33%  Short term fluctuations >= 4.0dB  Total questions >= 400
  37. 37. . III. Gray scale stimulation  Depicted in Zone 3.  The darker the print out the worse is the field.  Provides field defects at a glance.  We do not make a diagnosis based on this. Nb: Main emphasis on statistical help shows in zone IV to VIII of the printout.
  38. 38. .  IV. Total deviation plots  Provides deviation of patients threshold values from that of age corrected normal data. 1.Numerical value plot 2.Probablity plot (grey scale symbol plot) Numerical value plot  Represents the differences in decibels .  Zero value-expected threshold for that age.  Positive numbers –points that are more sensitive than average for that age.  Negative numbers-reflect points that are depressed compared with the average.
  39. 39. . Probability plot  In the lower part of zone IV of the printout, the total deviation plot is represented graphically.  Darker the representation,the more significant it is. V.Pattern deviation plots  1. Numeric PDP  2. Probability PDP  Shown in zone V  Similar to the total deviation plots except that here Statpac software has corrected the results for the changes caused by cataract, small pupil etc.
  40. 40. . VI. Global indices  Depicted in zone VI of printout.  Are calculations made by Statpac to provide overall guidelines to help the practitioner assess the field results as a whole.  Used to monitor progression of glaucomatous damage than initial diagnosis. 1. Mean deviation - Mean difference between the normative data for that age compared with that of collected data.  Indicator of general depression of field.  Worse than normal value is indicated by a negative value.
  41. 41. . 2. Pattern std deviation (PSD) -Measure of variability within the field. It measures the diff between a given point & adjacent points.  Points out localized field loss & is most useful in identifying early defects. 3. Short term fluctuation (SF) - Measure of the variability between two different evaluations of the same 10 points in the field.  Not available with SITA strategy.  High SF means either decreased reliability or an early finding indicative of Glaucoma.
  42. 42. ..  4.Corrected pattern std deviation (CPSD)- PSD corrected for SF.  Indicates the variability between adjacent points that may be due to disease than intra-test variability. VII. Glaucoma hemifield test (GHT)  Compares the 5 clusters of points in the upper field with the 5 mirror images in the lower field.  Clusters developed based on anatomical distribution of nerve fibres  Specific for detection of Glaucoma.  Depending on differences between upper and lower clusters of points, five inferences can be made;
  43. 43. . 1. Outside normal limits Denotes that either the values in upper & lower clusters differ to an extent found in less than 1% of population or any one air of clusters is depressed to the extent that would be expected in less than 0.5% of population. 2. Borderline  Difference between any one of the upper & lower mirror clusters is what might be expected in less than 3% of population. 3. General reduction in sensitivity  Best part of visual field is depressed to an extent expected in less than 0.5% of the population. 4. Abnormally high sensitivity  Best part of visual field is such as would be found in less than 0.5% of population . 5. Within normal limits  When none of above criteria is met.
  44. 44. . VIII. Actual threshold values  Inspected for any pattern or Scotoma when clinical features are suspeciant and even if all the seven other parts of printout are normal.  A Scotoma is the depressed part of field as compared to surroundings (not w.r.t normal).  When actual test threshold values are below 15dB – sensitivity of the test is lost.
  45. 45. . THANK YOU!

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