Visual field testing is an important diagnostic consideration in the evaluation of patients with many different types of pathologies. Most commonly, it is used for conditions affecting the optic nerve and other forms of neurological disease; but it’s also helpful for retinal conditions and instances when visual field function needs to be measured.
At the end of the lecture optometrists will have a better understanding of testing and interpreting visual field results.
1. Interpreting Visual Fields
Andrew White
BMedSc(Hons), MBBS, PhD, FRANZCO
Glaucoma consultant, Westmead Hospital
Clinical Senior Lecturer, University of Sydney
Chair, Expert Advisory Panel, Glaucoma Australia
Board Member, World Glaucoma Association
Gosford Eye Surgery
3. FDT: Frequency Doubling Technology
Relies on detection of a
flickering grating
Attempt to make it
perimetry but never
originally designed for that
– physiologically
impossible1.
Cheap, desk mounted and
sensitive
No reliable progression
analysis
1: White et al. Invest Ophthalmol Vis Sci.
2002;43:3590–3599
4. Humphrey Visual Field
• 24-2 White on White is the
standard
• Can be full threshold, SITA
standard or SITA Fast.
– Biggest difference between
them is time
• SWAP and 30-2 less useful
• 10-2 For advanced Glaucoma
• Not directly comparable with
Octopus or Medmont
(different algorithms)!
• FDT not comparable at all.
• If you start with a paradigm,
you should keep the same to
make it meaningful.
7. If The Field Is Not Normal....
How long did it take? (a well trained alert person
will take 3-5mins SITA Fast)
What was fixation loss?
What was false +v and false -ve (gave up or trigger
happy?)
Clover leafing?
Were they asleep? (a flat eye tracker reading)
Were they properly refracted?
Do they have a ptosis/heavy brow?
11. Visual Fields are Inherently Noisy
X X X
X
X
The one bad VF
VisualFieldIndex
20
40
60
80
100
0
X X X
X
One Bad VF -probably
VisualFieldIndex
20
40
60
80
100
0
XX
X
X X X
X
X
Progression
X
X
VisualFieldIndex
20
40
60
80
100
0
12. Rates of Visual Decay
• Glaucomatous
progression is almost 10
times faster than the
normal rate of decay of
visual function with age.
• Structural change
usually preceeds
functional loss but not
always
• We are most concerned
with progression in the
order of 1.5-2dB per
year
Common RoP
(0.6 dB/year)
in a clinical
population with
glaucoma
Mean RoP for
normal visual
decay
(0.07 dB/year)
Mean RoP (1.1
dB/year)
in untreated
glaucoma
Heijl et al. Arch Ophthalmol 1987;105:1544–9.
Haas et al. Am J Ophthalmol 1986;101:199–203.
Heijl et al. Ophthalmology 2009;116:2271–6.
13. Guidelines for VF Testing
• Ideally need 3 visual
fields/yr to determine
progression1
• Medicare allows 2 per year
• Young (<80) stable
patients and suspects
monitored 6 monthly
• Older and very stable
patients yearly
• High risk patients may
need 3-4 fields/year
• Often combined with optic
disc imaging
1: Chuhan et al. Br J Ophthalmol. 2008 92(4): 569–573
14. Neurological Causes of Field Loss
Refractive
Stroke
Optic neuritis/
neuropathy
Chiasmal tumours
Raised intracranial
pressure
15. Is Something Else Causing The Field
Loss?
Tilted discs
Myopia
Disc Drusen
Retinal Disease
16. Take Home Messages
• Not every visual field defect is
glaucoma!
• Structural change often
proceeds functional change
• Progression on visual fields
over time important.
• Many need several tests to
differentiate from noise in the
data
• Need to compare the same
test each time to be
meaningful
• 24-2 HVF the Gold Standard
17. Q1
• What is the gold standard visual field?
• 1. 24-2 White on White Humphrey
• 2. FDT
• 3. 30-2 White on White Humphrey
• 4. Medmont Perimetry
18. Q2
• Does FDT have validated progression
analysis?
• 1.yes
• 2.no
19. Q3
• What is the rate of progression of visual
field loss in treated glaucoma?
• 1: 1.5 dB yr
• 2: 0.07dB yr
• 3: 1.0 dB yr
• 4. 0.6 dB yr
20. Q4
• What rate of glaucoma progression means
an increase in treatment is warranted?
• 1: 0.5 dB yr
• 2: 1.5-2 dB yr
• 3: 1-1.5dB yr
• 4: Any progression
