Dr. Shreeji Shrestha provides an overview of perimetry, beginning with an introduction to the visual field and its importance in mapping disorders of the optic nerve and visual pathway. The document then discusses different types of perimetry, including kinetic, static, bedside, and formal perimetry. Key terms used in perimetry are defined, such as threshold, isopter, and decibel. Factors that can affect sensitivity are reviewed. Common visual field defects seen in conditions like glaucoma and their progression are described. Emerging techniques like short wavelength automated perimetry and frequency doubling technology are also summarized.

1. PERIMETRY
Dr SHREEJI
SHRESTHA

2. Presentation layout
Introduction of visual field
Perimetry - types
Important terms
bedside perimetry
Formal perimetry
Defects
Short wavelength automated perimetry
Frequency doubling technology

3. Introduction of visual field
• environment wherein a steadily fixating eye
can detect visual stimulus.
•BASIS - presence of Photoreceptors with its
visual pathways upto the periphery of retina
away from point of fixation i.e fovea.
•IMPORTANCE – mapping extend - disorder or
optic nerve and visual pathway

4. Extend

5. contour

6. Blind spot
•Corresponding to optic nerve
head
•no photoreceptors
•10-15 deg temporal to point of
fixation
•Span – 5 deg horizontal
-- 7 deg vertical
•2 portion- absolute scotoma
- relative scotoma

7. Definition of Perimetry
■ Measurement of visual functions of the
eye at topographically defined loci in the
visual field1
■ Measures differential light sensitivity, or the
ability of a subject to distinguish a stimulus
light from background illumination2

8. Factors affecting
sensitivityPupil size - miosis
Refractive error - myopia - posterior staphyloma -
refraction scotoma. (glaucomatous field defect)
Hypermetropia - alter threshold
sensitivity
Age- 20years
Sensitivity dec - age (10yrs - 0.5-1 db)
Clarity of ocular media
Fatigue

9. types of perimetry
According to the principal:
• Kinetic
• Static
Clinically
• Automated static perimetry
• Manual kinetic and static perimetry using a
Goldmann type bowl perimeter

10. Kinetic perimetry:
• outer visual field is determined by moving objects from the
non-seeing area to the center.
• Uses a moving object of a fixed size and intensity.
Advantages:
• Allows large areas to be traversed in a fairly short period.
• less expensive and durable.
• Perimetrist is constantly communicating with the patient so
it is more comfortable.
Disadvantage:
• Reproducibility and reliability is not constant in the manual
kinetic perimetry.

11. Static perimetry:
• The outer boundary of the island of vision determined by
measuring the retinal sensitivity at each point.
• The test location is fixed while the intensity of the test
object of known size is varied.
• Octopus and Humphrey perimeters.
Advantage:
• Reliability and reproducibility
Disadvantage:
• Manual static perimetry is tedious.

12. Riddoch phenomenon
Only moving object are seen and static
object not seen
Lesion in occipital lobe

13. Terms in perimetry
Threshold:
• differential light sensitivity at which a stimulus of a given size and
duration of presentation is seen 50%
• dimmest spot detected during testing.
Suprathreshold:
• 95% of the projected times.
• stimulus - made suprathreshold - increasing size or duration.
Infrathreshold:
• Low intensity stimulus - 5%

14. Isopter: a line on a visual field representation – connecting
points with the same threshold.
Depression: a decrease in retinal sensitivity
scotoma: an area of decreased retinal sensitivity within the visual
field surrounded by an area of greater sensitivity.
Decibel (dB):
• Its value depends on the maximum illumination of the
perimeter.
• log units of attenuation of the maximum light intensity
available in the perimeter being used.
• OdB is maximum stimulus intensity

15. variables
Patient:
• attentiveness and fatigue
Perimetrist:
• manual perimetry
Fixation:
• fixation is off centered
• It is especially true in automated static tests.
Background luminace:
• luminace of the surface on which stimulus is projected
• background luminance of 4-31.5 apostilbs.
sensitivity is greatest at fixation
Stimulus luminance
• greater size, duration, brighter- stimulus- visible

16. Size of stimulus:
Standard stimulus - 0= 1/16mm2, 1= 1/14 mm2, 11 =
1mm2, 111 = 4mm2, 1v = 16mm2, v= 24mm2
Presentation time: longer time, the more visible a given
stimulus(0.2)
Speed of stimulus movement:
• if a kinetic target = quickly, by the time the patient
responds, the target may have gone beyond its location
• The time period between visualization and response is
termed the latency period or visual reaction time.

17. Bedside perimetry
PR
hand motion
finger counting
Hand identification
Testing with neurological pin
red desaturation

18. Amsler grid
• For Central 10 deg ( static )
• Other eye occluded
• Near correction given
• Chart at held 28-30 cm – each small square subtends angle of 1 deg
• Patient fixates at central dot – tells whether all corners are seen simultaneously and
about lines- parallel, distorted, missing
• Can be used for mapping blind spot – patient fixates at edge of grid
• Macular scarring- lines bow outward
• macular edema - lines appear closer

19. Perimetry

21. HFA

22. Zone 1-Parameters
Teststrategy
Fullthreshold- eachpointstimulated 5times,longduration
SITA-standard-90%pointtested- remaining10%nottested
SITAfast-80%pointtested
SITArelies onmodelofVF
Region/pattern used
➢30-2 (test points = 76points) , 24-2(54) ,
10-2(68points)
Patientdetails
➢dateof birth,dateof VF,pupil size,
test time, VA,correction, eye tested

24. Zone 1- Reliability
• Fixation monitor
• Fixation target – central, small diamond
• Test duration
• Reliability indices
Fixation losses <20 %
False positives < 33%
False negatives < 33 %
Foveal threshold

25. Fixation loss
Stimulus flashed in blind spot
Limited value in patient with large defect surrounding
blind spot
sees stimulus
Patient is not fixating at center and moving eye

26. Patient response to patient fail to
respond audible click when he isn't seeing
False positive/trigger happy False negative

27. Compare total & pattern deviation
3.Age Corrected plots
HumphreyTM
Zero in on the probability plots

28. HumphreyTM
Compare total & pattern
deviation
actual local defect
Media opacity

29. Zone 4: global indices
single numbers to denote whole field
• MEAN DEVIATION : average loss of sensitivity from normal age
matched population along with probability
calculated from total deviation plot
• PATTERN STANDARD DEVIATION : range over which change of
sensitivity at all the points has occurred, along with probability
compensates for effect of generalized depression or elevation
of field on mean deviation value
local defects affect PSD > MD

30. Mean deviation
Pattern
standard
deviation
Visual field
Normal Normal Normal
Abnormal Normal Generalized depression
normal Abnormal
Localized defect in one
location

31. 4.Glaucoma hemifield
test

32. Outside normal limits
All cluster pairs differ @ p < 1% OR
1 cluster pair differs @ p < 0.5%
Borderline
Hemifields differ @ p < 3%
General reduction of sensitivity
Overall field depressed @ p < 0.5%
Abnormal high sensitivity
Overall field elevated( best 15 % points) @ p < 0.5 %
Within normal limits

33. Octopus HFA
Bowl Spherical Aspherical
stimulus
size
Goldman 111 v 1-v
Duration 100ms 200ms
Luminance
for 0dB
4800asb 10,000asb
test strategy 4-2-1 bracketing
4-2
bracketing
Fixation
loss
Automatically
discount
Present

35. Early Glaucoma Defect
• 18 pts)below 5% and (10 pts)below 1%

36. Moderate Glaucoma Defect
• <50% (37 pts) <5% level and <25% (20pts) <1 % level
• Only 1 hemi field has point with sensitivity <15dB in the central 5 degree

37. Severe Glaucoma Defect
• On PD plot
> 50% of pts < 5%level
> 25% of pts < 1%level
• Both hemi-fields w/ pt(s) w/ sensitivity< 15 dB w/in th central 50

38. visual field defect
•Generalized depression
(both peripheral and central contraction)
e g cataract
•Peripheral Contraction – retinitis pigmentosa
•Temporal contraction - age
•Hemifield defect - hemianopia
•Altitudinal defect - glaucoma, OD drusen, AION

42. Progression in glaucoma
Development of new defect
Deepening or enlargement of preexisting defect
Diffuse loss of sensitivity
for follow up, 6 visual field examination in first 2 years
for consistent baseline and RO aggressive disease
then reduced to once/twice yearly

46. clover leaf artifact

47. Parietal lobe/pie in
floor/BAUM loop
Temporal lobe/ Meyer loop
Sup
Sup
inf

49. Short wavelength automated
perimetryBlue stimulus
Yellow light- background - reduces sensitivity of RED
and GREEN cones.
Detect glaucomatous field defect early

50. Frequency doubling
technologyBased on frequency doubling illusion
stimulus - series of black and white bands flickering at
25Hz
Mediated by large ganglian cells (M ganglion cells) -
magnocellular visual pathway
M cells - sensitive to motion and contrast -
glaucomatous damage
Portable, inexpensive
Also advocated for use in
children
Screening

51. Visual field easy app

52. Reference
Jakobiec principle and practice of ophthalmology - 3rd
edition - neuroophthalmology
Shields textbook of glaucoma- assessment of visual
field
Ophthalmology investigation and examination
technique-bruce James , Larry Benjamin
AAO - glaucoma - section 10-
pearls of glaucoma management- giaconi, law