This case presentation discusses a patient with normal tension glaucoma. Key details include a past ocular history of high myopia and elevated intraocular pressure in both eyes. Visual field testing over several years using Humphrey 24-2 and 24-2C grids showed progressive visual field loss. The presenter reviews visual field test patterns, parameters, and how to integrate visual field tests with ganglion cell complex scans. A journal article is summarized that compares the 24-2 and 24-2C grids' ability to detect central visual field defects and evaluate structure-function concordance in glaucoma.

1. CASE PRESENTATION
PRESENTER： Clerk 楊 憶
SUPERVISOR： VS 陳瑛瑛 主任
R4 楊子萱 醫師

2. PRESENTATION OUTLINE
¡ Case
¡ Topic review
¡ Journal review
¡ Case-based discussion

3. ▶ Patient profile
吳O翰, 38 y/o male (Chart No. 11388957)
▶ Chief complaint
Elevated IOP OU
▶ Past history
HTN(-), DM(-), Asthma(-), CAD(-), Renal dx(-),
Cold extremities(-), Migraine(-), Herb(-), Steroids(-)
* Family hx: Father has glaucoma OU s/p OP
▶ Ocular history
Trauma(-), OP(-)

4. ▶ Ocular examination (2012.07.06)
OD OS
VA 1.2 (-5.75 -0.25×120) 1.2 (-4.50 -1.00×175)
IOP 22 mmHg 20 mmHg
Conjunctiva Mild congestion Mild congestion
Cornea Pannus Pannus
A/C Deep/clear Deep/clear
Iris/Pupil RIC, LR(+) RIC, LR(+)
Lens Clear Clear
Fundus C/D: 0.4*0.4
C/D: 0.5*0.5
temporal thinning

5. ▶ Fundus photo

6. AXL ACD Lens thickness CCT(𝝁m)
OD 27.29 mm 3.69 mm 4.27 mm 622 𝝁m
OS 27.03 mm 3.79 mm 4.12 mm 636 𝝁m
▶ Gonioscopy

7. ▶ GCC

8. ▶ VF Humphrey Matrix: 30-2
OD
OS

9. ▶ Impression
1. Normal tension glaucoma OS
2. High myopia OU
▶ Plan
1. Xalatan HS OS

10. ▶ VF and GCC
2012.11.09
2013.05.10
Humphrey Matrix: 30-2
82.05
80.85

11. ▶ VF and GCC
2014.01.15
2014.08.28
Humphrey Matrix: 30-2
80.44

12. ▶ VF and GCC
2015.02.12
2015.08.12
Humphrey Matrix: 30-2
30-2
77.08

13. ▶ VF and GCC
2016.06.16
2016.03.17
Humphrey Matrix: 30-2
30-2
79.35

14. ▶ VF and GCC
24-2
2019.07.04
2019.12.19 24-2
75
85
72
83

15. ▶ VF
24-2
2020.06.18
2020.09.10
24-2C

16. ▶ IOP and Rx

17. TOPIC REVIEW
¡ Visual field test patterns and parameters
Humphrey® Field Analyzer 3

18. VISUAL FIELD TEST PATTERN AND PARAMETER
HUMPHREY® FIELD ANALYZER 3
• Threshold Test Patterns
Ref: Humphrey® Field Analyzer 3 (HFA3) Instructions for Use

19. VISUAL FIELD TEST PATTERN AND PARAMETER
HUMPHREY® FIELD ANALYZER 3

20. 24-2C incorporates 10 additional test points within the central 10 degrees from
fixation, five in each hemifield. The locations of the test points were purportedly
derived from test locations commonly affected in glaucoma
VISUAL FIELD TEST PATTERN AND PARAMETER

21. How to integrate visual field test with GCC scan??

22. • GCC(Ganglion cell complex) scan mode measures the inner macular retinal
layer thickness from the internal limiting membrane to the inner plexiform
layer, centered around the fovea and covering the central macula and is used in
detection of early glaucoma.
• The GCC map yields a 6-mm map of the macular area, the center of the GCC
scan is shifted approximately 1 mm temporal to the fovea so as to improve the
sampling of temporal peripheral nerve fibers(10 degrees in the superior and
inferior directions, 7 degrees in the nasal direction, and 13 degrees in the
temporal direction), so the macular VF was projected slightly nasally on the
Humphrey 24-2 SITA map.

23. Ganglion cell displacement
10-2
24-2C

24. • Test parameter setting
(Swedish Interactive Threshold Algorithm (SITA) )
Ref: Humphrey® Field Analyzer 3 (HFA3) Instructions for Use
VISUAL FIELD TEST PATTERN AND PARAMETER

25. JOURNAL REVIEW
¡ Ability of 24-2C and 24-2 grids in identifying central
visual field defects and structure- function
concordance in glaucoma and suspects
Jack Phu, Michael Kalloniatis

26. ▶ Introduction
• Using the 24-2 in isolation has been challenged by the literature
reporting on the prevalence of central visual field defects not
typically detected by the 24-2 test grid.
• Recently, the 24-2C has become available for clinical use on the
Humphrey Field Analyzer, but the usefulness of the additional
points have yet to be tested.
• 3 aims to this study:
The comparison of
1. Conventional visual field indices
2. Test duration
3. Colocalized structural and functional central defects

27. ▶ Methods
• Prospective, cross-sectional study
• Study was conducted at Centre for Eye Health,
based within the University of New South Wales

28. ▶ Methods
• Inclusion criteria
ü Glaucoma:
1. Glaucomatous structural anomalies
(increased cup-to-disc ratio, cup-to-disc asymmetry, and
neuroretinal rim thinning or notching)
2. +/- corresponding visual field loss
(defined using the 24-2 SITA-Standard result: a pattern
standard deviation result at p< 0.05, GHT outside normal
limits or a “fail” on the cluster criterion)
3. +/- IOP ↑
ü Glaucoma suspects:
1. One or more of the above signs were present, but
the signs were insufficient for a diagnosis of glaucoma
requiring therapeutic intervention.

29. ▶ Methods
• Other inclusion criteria
ü ≥18 y/o
ü No other ocular, systemic or neurological comorbidities that
would confound the visual field test result
ü No hx of ocular surgery aside from uncomplicated selective
laser trabeculoplasty, laser peripheral iridotomy or cataract
surgery and intraocular lens implantation
ü No hx of ocular trauma
ü Spherical equivalent refractive error between ±8.00 diopters
ü The ability to complete a perimetric test

30. ▶ Methods
• VF testing and data extraction
ü The 24-2 test grid was examined first, followed by the 24-2C grid
ü A random eye was chosen for testing
ü Two cohorts:
1. 24-2 SITA-Standard, then 24-2C SITA-Faster
2. 24-2 SITA-Faster, then 24-2C SITA-Faster
ü Reliability criteria for inclusion
1. False positive rate <15%
2. No seeding point errors
3. Gaze tracker deviation exceeded 6 degrees <20%
4. Absence of other technician-related errors
* False negative rates and fixation losses were not used as measures of low test reliability

31. ▶ Methods
• Total sample of patients: 100
ü SITA-Standard 24-2 and SITA-Faster 24-2C: 40
ü SITA-Faster 24-2 and 24-2C: 60

32. ▶ Methods
• Aim 1: Comparison of conventional visual field indices
ü Mean deviation
ü Pattern standard deviation
ü Glaucoma Hemifield Test
ü Central mean sensitivity (central 10°)
ü The “cluster” criterion (5%, 5%, 1%)
1. Pass (did not meet)/ Fail (met)
2. Whether the 24-2C was additive to the pass/fail
outcome
3. Central clusters

33. ▶ Methods
• Aim 2: Comparison of test duration
ü The final test duration = total test time

34. ▶ Methods
• Aim 3: Comparison of colocalized structural and
functional central defects
ü The 4 centrally located points within the 24-2
vs. the 10 points exclusive to the 24-2C
ü The 24-2, the 24-2 component extracted from the 24-2C,
and the 24-2C only (within 10°)
Boundary of the Ganglion Cell Analysis deviation map

35. ▶ Results
• Demographic and clinical characteristics of cohorts
ü Overall no differences

36. ▶ Results
• Aim 1: Conventional visual field indices
ü MD:
1. Worse using the 24-2C for the SITA-Standard cohort
(median difference: -0.73 dB; p = 0.0038)
2. No significant difference for the SITA-Faster cohort
(p = 0.9715)
ü PSD and GHT: not significantly different between test grids
ü Central mean sensitivity:
1. Worse for the 24-2C in the SITA-Standard cohort
(median difference: -0.35 dB; p = 0.0226)
2. Not significantly different between the SITA-Faster
cohort (p = 0.2769)

37. ▶ Results
• Aim 1: Conventional visual field indices
ü The cluster criterion:
1. No significant differences between 24-2 only, 24-2C
(all) and 24-2C (24-2 component only) for both SITA-
Standard and SITA-Faster cohorts
* In the SITA-Faster cohort, there were 2 cases (3.1%) where the
24-2C grid found a statistically significant cluster of defects not
identified using the 24-2 grid only
2. Central clusters: Although there was a tendency for
more clusters being identified by the 24-2C compared to
the 24-2 only, there were no significant differences
between the 24-2C and 24-2 in identifying central
clusters

38. ▶ Results
• Aim 2: Test duration
ü SITA-Standard 24-2 (314s) > SITA-Faster 24-2C (155s)
→ median difference: 153.5s (p<0.0001)
ü SITA-Faster 24-2C (154.5s) > SITA-Faster 24-2 (125.5s)
→ median difference: 26s (p<0.0001)

39. ▶ Results
• Aim 3: Colocalized structural and functional central defects
ü The ability for each test grid to identify structural defects
1. SITA-Standard cohort: No significant difference in performance
between the 24-2 or 24-2C
2. SITA-Faster cohort: The 24-2C test grid identified more significant
defects at regions with structural loss compared to the 24-2 grids
3. A similar tendency was found at p< 0.01 level

40. ▶ Results
ü Relative frequency of functional defects identified at each test location
1. The frequency of defects identified across all locations when considering a
criterion where any functional deficit was present for the 24-2 locations
were not significantly different.

41. ▶ Results
2. For 24-2C test locations, the frequency of functional defects identified
across locations in the SITA-Standard cohort were not significantly
different, but there were significant differences in distribution in the
SITA-Faster cohort

42. ▶ Results
ü Relative frequency of structural defect occurred at each test location
1. Significant differences in the frequency of defect occurrence for all
conditions (p< 0.0001)

43. ▶ Results
2. There were also locations at which no structural defects were seen,
specifically at anatomical locations annotated 4, 5, 7, 9, 10
3. These locations fall outside of the Ganglion Cell Analysis scan circle after
accounting for ganglion cell displacement

44. ▶ Results
2. There were also locations at which no structural defects were seen,
specifically at anatomical locations annotated 4, 5, 7, 9, 10
3. These locations fall outside of the Ganglion Cell Analysis scan circle after
accounting for ganglion cell displacement

45. ▶ Discussion
• Frequency of central test location sensitivity reduction
1. There was a tendency for the 24-2C to identify clusters of
sensitivity reduction within the 10° compared to the 24-2 test
grid alone.
2. Although this was not found to be statistically significant, this
highlights the potential role for an increased index of suspicion
for central field loss for the examining clinician.

46. ▶ Discussion
• Derivation of useful points for testing the central visual field
1. Half of 24-2C test locations had no colocalized structural and
functional defects, as the points fell outside of the area
examined in the Ganglion Cell Analysis used for structural
correlations.
2. Previous studies comparing 10-2 test locations with the
Ganglion Cell Analysis or a similarly small scan zone have also
shown that the more peripherally located points do not fall
within the scan area, once ganglion cell displacement had been
accounted for.

47. ▶ Discussion
• Derivation of useful points for testing the central visual field
3. Bespoke test grids using retinal structural information can
potentially improve structure-function concordance by
specifically sampling regions where functional losses are
predicted.
* This may preclude cases of glaucoma where functional deficits
occur prior to structural loss detectable using OCT

48. ▶ Discussion
• Clinical impact of 24-2C exclusive test locations
1. The present results do not clearly support an increased clinical
utility of the 24-2C exclusive test points if considering
significant changes to the management plan achieved using
global indices.
2. Central defects are often used for identifying advanced
glaucoma, and the importance of this distinction is for the
purposes of treatment titration.
* Lack of consensus on the significance of central visual field loss, such
as how many locations are required to qualify for advanced glaucoma.
3. The value of the 24-2C grid in changing clinical management
appears questionable.

49. ▶ Discussion
• Limitations
1. Did not specifically target patients with central visual field loss
2. The entirety of our patient cohort did not represent those
predicted to have structurally and functionally concordant
defects
3. Sample sizes for the cohorts were not large enough
4. 24-2C after the 24-2 test: fatigue effect ?
5. Cirrus OCT: limited elliptical scan area

50. ▶ Conclusion
• 24-2C returns global results similar to 24-2;
use in glaucoma staging is unclear
• 24-2C may be used in a targeted approach where central
defects are suspected
• 24-2C is not ideal for comparing loss using the Ganglion
Cell Analysis in glaucoma; need to integrate a wider scan
protocol

51. BACK TO OUR CASE
§ Although the use of the 24-2C test grid in glaucoma staging
is unclear, it may have a potential advantage for flagging to
the clinician the presence of central visual field loss.
OS OD