Visual Field Progression: Differences Between Normal-Tension and Exfoliative High-Tension Glaucoma

1
Visual Field Progression Differences Between
Normal-Tension and Exfoliative High-Tension
Glaucoma

• KG Ahrlich,1,3 CGV De Moraes,2 CC Teng,2 TS
  Prata,2 R Ritch,2 JM Liebmann1,2

1New York University School of Medicine, New
York, NY 2Einhorn Clinical Research Center, New
York Eye Ear Infirmary, New York, NY
3Manhattan Eye, Ear, and Throat Hospital, New
York, NY
Supported by the ASCRS Foundation and the Ephraim
and Catherine Gildor Research Fund of the New
York Glaucoma Research Institute.
The authors have no financial interest in the
subject matter of this poster.
2
Introduction

• The relative importance of IOP-dependent and
  IOP-independent risk factors varies among
  individuals and forms of glaucoma.
• Exfoliative glaucoma (XFG) is characteristically
  associated with elevated IOP (exfoliative high
  tension glaucoma, XHTG), and IOP-dependent
  factors are thought to play a central role in
  disease onset and progression.
• Glaucomatous eyes with an IOP in the
  statistically normal range (normal-tension
  glaucoma, NTG) are less dependent on IOP for
  disease onset and progression.
• It remains unclear whether the same pattern and
  rates of glaucomatous visual field deterioration
  are present in both NTG and XHTG.1-8

3
Purpose

• To compare the pattern, location, and rate of
  visual field (VF) loss in NTG and XHTG.

4
Methods

• The Glaucoma Progression Study (GAPS) consists of
  43,660 consecutive subjects (132,512 VF tests)
  evaluated in a glaucoma referral practice from
  January 1999 to December 2008.
• Subjects with glaucomatous optic neuropathy,
  repeatable VF loss, 5 SITA-Standard VF
  examinations, and NTG or HTG, were enrolled. If
  both eyes were eligible, one was selected
  randomly.
• NTG was defined as glaucomatous VF loss and all
  known IOP measurements 21 mmHg.
• HTG was limited to exfoliative glaucoma (XFG),
  defined as glaucomatous VF loss, untreated IOP
  gt21 mmHg, and the presence of exfoliation
  material on the pupillary margin and/or on the
  anterior lens capsule.

5
Methods

• VISUAL FIELD ANALYSIS
• Automated pointwise linear regression (PLR)
  analysis was performed using Progressor (Version
  3.3, Medisoft, Inc., London, UK), providing
  slopes (decibels dB/year) of progression
  globally and locally for each point based on
  threshold maps, as well as significance
  (p-values).
• The number and location of the significantly
  progressing points was compared with the division
  of VF sectors described by Garway-Heath et al.9
  This information was used to establish the most
  common location of progressing points in each
  group.

6
Methods

• CLINICAL DATA
• Baseline central VF loss was defined by the
  presence of at least one point with plt0.01 within
  the four central-most points of the pattern
  deviation graph in the two consecutive baseline
  tests.
• Progression was defined as the presence of a
  test point with a slope of sensitivity over time
  gt1 dB loss/year, with plt0.01. For edge points, a
  stricter slope criterion of gt2 dB loss/year (also
  with plt0.01) was used.
• Paracentral progression was defined as
  progression of any of the points adjacent to the
  four central-most points of the VF (i.e., within
  the 12 central-most points).

7
Results
Table 1. Baseline characteristics of the studied
population.
NTG (n139) XHTG (n154) P-value
Age (years) 62.7 12.8 72.6 9.4 lt0.01
Gender (women) 92 (66.1) 88 (57.1) 0.14
Ethnicity (European ancestry) 106 (76.2) 144 (93.5) lt0.01
Migraine/Raynauds/Hypotension 53 (38) 6 (4) lt0.01
Cardiovascular diseases 59 (42) 86 (56) 0.02
Mean number of VF 8.2 3.5 8.1 2.9 0.78
Mean follow-up time (years) 5.2 2.0 5.6 1.8 0.07
Baseline mean deviation (dB) -6.5 5.4 -6.7 7.0 0.78
Central defect at baseline VF 82 (58.9) 49 (31.8) lt0.01
CCT (µm) 533.9 35.9 544.0 35.7 0.01
Mean follow-up IOP (mm Hg) 13.3 2.0 16.5 3.2 lt0.01
VFvisual field, NTGnormal-tension glaucoma,
XHTGexfoliative high-tension glaucoma,
CCTcentral corneal thickness, IOPintraocular
pressure. Includes hypertension, coronary
ischemia, stroke.
8
Results
Table 2. Intercurrent characteristics of the
studied population.
NTG (n139) XHTG (n154) P-value
Endpoint of progression 64 (46) 75 (48.7) 0.73
Mean follow-up time of progressing eyes (days) 2102 590 2087 587 0.88
Progression at or adjacent to central VF 48/64 (75) 43/75 (57.3) 0.04
Global rate of change1 (dB loss/year) -0.46 0.6 -0.58 0.7 0.20
Localized rate of change1 (progressing points) (dB loss/year) -2.0 2.2 -2.8 2.1 0.08
Mean number of progressing points in the VF 3.7 8.3 5.5 8.1 0.35
VFvisual field, NTGnormal-tension glaucoma,
XHTGexfoliative high-tension glaucoma,
CCTcentral corneal thickness, IOPintraocular
pressure. 1Values are adjusted for differences
in age, CCT, and mean IOP between groups.
9
Results
Figure. Mapping of the location of significant
visual progression in glaucomatous eyes that
reached a progression endpoint (modified from
Garway-Heath et al.9 Significant progression was
defined by any test point with a slope gt1.0 dB
loss/year with plt0.01 (or gt2.0 db loss/year for
edge points). A, NTG B, XHTG.
10
Discussion

• We optimized the evaluation of the velocity and
  pattern of VF progression associated with IOP by
  comparing a group of patients with
  non-IOP-dependent factors (NTG) and one in which
  IOP is believed to play a predominant role
  (XHTG).
• XHTG and NTG eyes progress at a similar global
  rate after adjustment for differences in CCT,
  IOP, and age. However, NTG eyes progress more
  often in the central field, independent of other
  factors.
• The most important factor associated with
  paracentral progression among eyes that reached a
  progression endpoint was the diagnosis of NTG.
• The results of our analysis of VF progression
  correlate well with previous studies of NTG and
  XHTG, despite our use of trend analysis by
  PLR.10,11
• Our map (figure) shows that in eyes with
  statistically elevated IOP, superior and inferior
  arcuate areas progress faster, whereas the
  central field may be more influenced by
  IOP-independent factors. This requires further
  clarification.

11
Conclusion

• NTG eyes tended to show a faster progression rate
  in the central field, but rates of global VF loss
  are similar between treated NTG and XHTG
  patients.
• Greater surveillance of the central field in NTG
  may be warranted, with more widespread use of
  alternative methods to follow NTG patients,
  including
• visual field strategies assessing the central ten
  degrees
• multifocal visual evoked potential techniques
• microperimetry

12
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