Patterns of Damage in Chronic Angle-Closure
Glaucoma Compared to Primary
Open-Angle Glaucoma
KOUROS NOURI-MAHDAVI, CHUTIMA SUPAWAVEJ, ELENA BITRIAN, JOANN A. GIACONI,
SIMON K. LAW, ANNE L. COLEMAN, AND JOSEPH CAPRIOLI
● PURPOSE:
To compare patterns of damage in chronic
angle-closure glaucoma (CACG) to a control group of
patients with primary open-angle glaucoma (POAG).
● DESIGN: Retrospective cross-sectional study.
● METHODS: SETTING: Academic tertiary-care glaucoma
clinic. STUDY POPULATION: Thirty-two eyes of 32 patients
with CACG and good-quality Heidelberg Retina Tomograph (HRT) images (pixel standard deviation <50 ␮m)
and stereoscopic disc photographs within 1 year of a
visual field showing reproducible glaucomatous field loss
(mean deviation >ⴚ15.0 dB) were enrolled. Control
eyes with POAG meeting similar criteria and matched for
severity of field loss (ⴞ1 dB) and race were selected.
OUTCOME MEASURES: Presence of focal rim loss (<1 clock
hour), HRT stereometric parameters, and extent and
location of field loss.
● RESULTS: The average mean deviation was ⴚ5.1 dB in
both groups. Patients with CACG were more hyperopic
(0.6 ⴞ 0.4 vs ⴚ1.4 ⴞ 0.5 D; P < .001) and had higher
IOP at the time of imaging (15.8 ⴞ 0.8 vs 13.9 ⴞ 0.9
mm Hg; P ⴝ .015). Focal disc damage was not less
frequent in PACG eyes (19% vs 24%; P ⴝ .545). Eyes
with PACG had smaller cup area, cup volume, and mean
cup depth and larger rim/disc area ratio (P < .05 for all),
which persisted after adjusting for disc size, age, refractive error, and IOP. The average (ⴞSD) number of
abnormal test locations was similar in the 2 groups (P ⴝ
.709), although CACG eyes were less likely to have
paracentral points involved (47% vs 72%; P ⴝ .04).
● CONCLUSIONS: Patterns of glaucomatous damage seem
to be different in CACG compared with POAG. This
difference in patterns of damage may adversely affect
detection of early disease or its progression in CACG.
(Am J Ophthalmol 2011;152:74 – 80. © 2011 by
Elsevier Inc. All rights reserved.)
Accepted for publication Jan 10, 2011.
From the Glaucoma Division, Jules Stein Eye Institute, David Geffen
School of Medicine, University of California Los Angeles, Los Angeles,
California.
Inquiries to Kouros Nouri-Mahdavi, 100 Stein Plaza, Los Angeles, CA
90095; e-mail: nouri-mahdavi@jsei.ucla.edu
74
©
2011 BY
A
NGLE-CLOSURE GLAUCOMA (ACG) IS BEING STUD-
ied more extensively as the significance of the
disease is better recognized worldwide. Bilateral
blindness from glaucoma is estimated to develop in 3.9
million persons with ACG by 2010, and it is expected to
rise to 5.3 million persons by 2020.1 The focus of most
recent ACG studies has been on imaging of the angle with
newer devices and on better understanding of the pathophysiology of increased intraocular pressure (IOP). While
these are important, there are also unanswered questions
with regard to the natural course and mechanisms of the
optic nerve and visual field damage in this type of
glaucoma. The existing literature about patterns of glaucomatous damage and structure-function relationships in
glaucoma is based mainly on eyes with primary open-angle
glaucoma (POAG). However, ACG is typically a highpressure disease and factors other than the IOP seem less
likely to be involved, at least during earlier stages of the
disease. Therefore, structure-function relationships may
not be the same in ACG.
There is limited evidence in the literature showing that
patterns of optic nerve damage in ACG may be different
from POAG.2–5 A lower prevalence of peripapillary atrophy has been reported in eyes with ACG.2 Thomas and
associates compared the Heidelberg Retina Tomograph
(HRT) stereometric parameters and sensitivity/specificity
of HRT algorithms in 2 groups of East Indian POAG and
primary angle-closure patients.4 The main significant difference between the 2 groups was in the cup shape measure.
However, Boland and associates found that the differences in
HRT’s stereometric parameters such as the cup area, rim area,
and cup-to-disc area ratio would disappear if a Bonferroni
correction were applied.6 We undertook the current study to
explore patterns of glaucomatous damage in chronic ACG
(CACG) and to compare the findings to those in a group of
POAG eyes matched for race and severity of visual field loss.
We hypothesized that patterns of glaucomatous damage in
CACG are different from those in eyes with POAG.
METHODS
THE CLINICAL DATABASE AT THE GLAUCOMA DIVISION,
Jules Stein Eye Institute (Los Angeles, California, USA)
ELSEVIER INC. ALL
RIGHTS RESERVED.
0002-9394/$36.00
doi:10.1016/j.ajo.2011.01.008
TABLE 1. Characteristics of the Enrolled Eyes According to Diagnosis (Chronic AngleClosure Glaucoma vs Primary Open-Angle Glaucoma)
CACG (n ⫽32)
POAG (n ⫽32)
P Value
Age (years, mean ⫾ SD)
68.3 ⫾ 11.6
Gender
Male
15 (46.9%)
Female
17 (53.1%)
Ethnicity
Hispanic
2 (6.2%)
Non-Hispanic
White
23 (71.9%)
African American
3 (9.4%)
Asian
4 (12.5%)
Lens status
Phakic
30 (93.8%)
Pseudophakic
2 (6.2%)
IOP at time of examination (mm Hg, mean ⫾ SD)
15.8 ⫾ 4.5
No. of medications at the time of examination (mean ⫾ SD)
1.4 ⫾ 1.4
LogMAR visual acuity (mean ⫾ SD)
0.13 ⫾ 0.16
Refractive error (diopters, mean ⫾ SD)
0.6 ⫾ 2.0
Visual field MD (dB, mean ⫾ SD)
⫺5.1 ⫾ 2.5
Visual field index (%, median and range)
92 (64–98)
Visual field PSD (dB, mean ⫾ SD)
5.7 ⫾ 3.2
68.4 ⫾ 12.4
.819
14 (43.8%)
18 (56.2%)
.802
2 (6.2%)
N/A
Demographic Variable
23 (71.9%)
3 (9.4%)
4 (12.5%)
20 (62.5%)
12 (37.5%)
13.9 ⫾ 5.2
1.5 ⫾ 1.2
0.14 ⫾ 0.13
⫺1.4 ⫾ 2.7
⫺5.1 ⫾ 2.4
89 (59–96)
5.6 ⫾ 2.8
.002a
.015b
.575
.442
<.001b
.931
.390
.809
CACG ⫽ chronic angle-closure glaucoma; IOP ⫽ intraocular pressure; MD ⫽ mean deviation;
POAG ⫽ primary open-angle glaucoma; PSD ⫽ pattern standard deviation; SD ⫽ standard deviation.
a 2
␹ test.
b
Wilcoxon rank sum test.
Bold font indicates significant P values (less than 0.05).
was retrospectively reviewed to find eyes with a diagnosis
of CACG meeting specified criteria, with at least 1
available HRT image and a set of stereoscopic optic disc
photographs taken within 1 year of visual fields demonstrating reproducible glaucomatous field loss.
Chronic ACG was defined as: presence of visual field
loss consistent with glaucoma along with presence of
peripheral anterior synechiae or occludable angle (“s”
configuration of the iris according to Spaeth’s classification), as determined by the attending ophthalmologist,
along with a history of IOP ⬎21 mm Hg on no medications, or IOP ⬍21 mm Hg on medications or after
glaucoma surgery, including peripheral laser iridotomy.
Eligible patients were required to have at least 1 set of
stereoscopic disc photographs and HRT image available
(with global pixel standard deviation less than 50 ␮m)
within 1 year of the eligible visual field exam. Only optic
disc photographs with adequate quality for making a
judgment with regard to pattern of disc damage were
included.
The eligible eyes were additionally required to have at
least 2 reproducible 24-2 SITA-Standard visual fields
meeting the following criteria: false-positive and falsenegative error rates ⬍25%; and confirmed abnormal pattern standard deviation (PSD) (p ⬍5%) or Glaucoma
Hemifield Test “outside normal limits” and presence of a
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cluster of at least 3 test locations with p ⬍5% and at least
1 location with p ⬍1%.
Fixation loss was not used as a criterion for selecting
reliable fields. All the potentially eligible visual fields were
reviewed by 1 of the authors (C.S.) and eyes with field loss
attributable to lid or lens artifacts were excluded.
Exclusion criteria were as follows: best-corrected visual
acuity ⬍20/100, visual field mean deviation (MD) worse
than ⫺15.0 dB, IOP less than 8 mm Hg on the day of
imaging, presence of neurologic or retinal disease, history
of acute or secondary angle-closure glaucoma, grossly
anomalous disc shape such as disc hypoplasia or tilted disc,
and refractive error ⬎8 diopters (D). In case both eyes of
the same patient were eligible, the eye with the better
visual field mean deviation was selected.
Patients with POAG from the same database were
chosen and matched for severity of visual field loss (mean
deviation within 1 dB) and race. POAG eyes had open
angles and evidence of visual field loss. In case more than
1 matching eye was found, the POAG eye with the closest
mean deviation to the index case was chosen. Two
experienced observers (K.N.M. and J.A.G.), masked to
patient identity, date of exam, and other clinical information, reviewed the optic disc photographs. The observers
graded clarity and stereopsis of the disc photographs on a
0-to-2 scale (0 ⫽ poor, 1 ⫽ fair, 2⫽ good) and checked for
ANGLE-CLOSURE GLAUCOMA
75
TABLE 2. Results of Qualitative Evaluation of Optic Disc Photographs by Reviewers
CACG (Mean ⫾ SD)
POAG (Mean ⫾ SD)
P Value
1.84 ⫾ 0.32
1.75 ⫾ 0.36
0.89 ⫾ 0.34
0.66 ⫾ 0.16
8.0 ⫾ 2.1
6/32 (19%)
0.22 (0-1.25)
1.81 ⫾ 0.35
1.84 ⫾ 0.24
0.76 ⫾ 0.38
0.71 ⫾ 0.1
8.5 ⫾ 1.7
8/32 (25%)
0.24 (0.02-1.78)
.632d
.402d
.364d
.401d
.424d
.545b
.745d
a
Clarity score
Stereoscopic quality scorea
NFL visibility scorea
Average cup-to-disc ratio
Glaucoma certainty scorec
Focal ischemic damage (%)
B-PPA–to-disc-area ratio (median, range)
CACG ⫽ chronic angle-closure glaucoma; NFL ⫽ nerve fiber layer; POAG ⫽ primary open-angle
glaucoma; SD ⫽ standard deviation.
a
0-2 scale: 0 ⫽ poor, 1 ⫽ fair, 2⫽ good.
b 2
␹ test.
c
0-10 scale: 0 ⫽ definitely normal, 10 ⫽ definitely glaucomatous.
d
Wilcoxon rank sum test.
Bold font indicates significant P values (less than 0.05).
TABLE 3. Comparison of Stereometric Parameters From Heidelberg Retina Tomograph in
Eyes With Chronic Angle-Closure and Primary Open-Angle Glaucoma
HRT Variable
CACG
(Mean ⫾ SD)
(n ⫽32)
POAG
(Mean ⫾ SD)
(n ⫽32)
P Value
Disc area (mm2)
Cup area (mm2)
Rim area (mm2)
Cup volume (mm3)
Rim volume (mm3)
Rim-to-disc-area ratio
Cup-to-disc-area ratio
Linear cup-to-disc ratio
Mean cup depth (mm)
Max cup depth (mm)
Cup shape measure
Height variation contour
Mean RNFL thickness (mm)
RNFL cross-sectional area (mm2)
FSM classification
RB discriminant
2.12 ⫾ 0.41
0.92 ⫾ 0.47
1.20 ⫾ 0.44
0.25 ⫾ 0.22
0.27 ⫾ 0.15
0.57 ⫾ 0.19
0.43 ⫾ 0.19
0.62 ⫾ 0.24
0.27 ⫾ 0.14
0.65 ⫾ 0.24
⫺0.11 ⫾ 0.07
0.39 ⫾ 0.16
0.17 ⫾ 0.09
0.90 ⫾ 0.50
⫺0.55 ⫾ 2.34
0.11 ⫾ 0.95
2.18 ⫾ 0.49
1.16 ⫾ 0.46
1.02 ⫾ 0.31
0.36 ⫾ 0.26
0.22 ⫾ 0.09
0.48 ⫾ 0.13
0.52 ⫾ 0.13
0.70 ⫾ 0.10
0.34 ⫾ 0.11
0.76 ⫾ 0.19
⫺0.08 ⫾ 0.07
0.36 ⫾ 0.11
0.19 ⫾ 0.06
0.98 ⫾ 0.35
⫺1.44 ⫾ 1.54
0.05 ⫾ 0.80
.577
.045a
.07
.026b
.079
.03a
.03a
.354
.011b
.044a
.052
.768
.957
.489
.078
.802
CACG ⫽ chronic angle-closure glaucoma; FSM ⫽ FS Mikelberg; HRT ⫽ Heidelberg Retina
Tomograph; POAG ⫽ primary open-angle glaucoma; SD ⫽ standard deviation; RB ⫽ R Bathija;
RNFL ⫽ retinal nerve fiber layer.
a
t test.
b
Wilcoxon rank sum test.
Bold font indicates significant P values (less than 0.05).
presence of focal rim loss (rim thinning ⱕ1 clock hour).
Afterwards, the reviewers scored optic disc photographs for
probability of glaucoma on a 10-level scale (glaucoma
certainty score), with 10 being definitive glaucoma and 0
representing normal findings. The average of scores by the
2 reviewers was used for comparing the 2 groups. The optic
disc photographs were then scanned and digitized as TIFF
images with a resolution of 600 dots per inch with a digital
76
AMERICAN JOURNAL
slide scanner (Nikon LS-5000 ED film scanner, Nikon
Corporation, Tokyo, Japan). One of the authors (K.N.M.)
then sequentially delineated the area of beta-zone peripapillary atrophy (␤-PPA) and the disc using ImageJ software
(National Institutes of Health, Bethesda Maryland, USA).
The ratio of the ␤-PPA area to that of the disc area was
calculated for each eye. Beta-zone peripapillary atrophy
was defined as the crescent of chorioretinal atrophy with
OF
OPHTHALMOLOGY
JULY
2011
FIGURE. Distribution of global (Top row) and sectoral (Middle and Bottom rows) MRA results in chronic angle-closure (CACG)
and primary open-angle glaucoma (POAG) eyes. P values are based on ␹2 tests. WNL ⴝ within normal limits; ONL ⴝ outside
normal limits.
visible sclera and choroidal vessels immediately adjacent to
the scleral ring.
The HRT 3 software (version 1.5.10.0; Heidelberg
Engineering, Heidelberg, Germany) was used to analyze
images. The HRT contour lines were drawn by 1 of the
authors (K.N.M.) after simultaneous review of the optic
disc photographs. Of note, keratometry readings were not
entered into the HRT to correct for image magnification.
The HRT stereometric parameters were exported into a
personal computer using the export function of the machine and disc size and other stereometric parameters were
compared in the 2 groups. Heidelberg Retina Tomograph’s
Moorfields Regression Analysis (MRA) and Glaucoma
Probability Score (GPS) were also compared between the
2 groups.
We compared the number of test locations with p
⬍5% for deviation from normal on pattern deviation
plot in the 2 groups as a measure of extent of field loss.
Also, the proportion of eyes with defects involving 1 of
the 4 paracentral locations on the 24-2 strategy was
determined. The number of test locations demonstrating
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p ⬍0.5% on the pattern deviation plot was also compared between the 2 groups as a measure of glaucomatous defect depth.
Distribution of numerical data was evaluated with the
Wilk-Shapiro test and normal quantile plots. Numerical
data were compared with t test (normal data) and Wilcoxon rank sum test (for data with nongaussian distribution) and proportions were compared with ␹2 test.
Multivariate linear regression models were built adjusting
each of the HRT’s stereometric parameters individually for
confounding factors (age, refractive error, IOP at the time
of imaging, and disc area). In the multivariate models,
each of the stereometric parameters was considered the
dependent variable, with the diagnosis, age, refractive
error, IOP at the time of imaging, and disc area entered
into the model at once as independent variables. If the P
value for diagnosis (reference: POAG group) was ⬍.05,
that particular stereometric parameter was considered significantly different between the 2 groups. A similar multivariate model was used for adjusting the ␤-PPA–to-discarea ratio for diagnosis, age, and refractive error.
ANGLE-CLOSURE GLAUCOMA
77
imaging in multivariate linear regression models (P ⬍ .05
for all).
Eyes with CACG were less likely to have evidence of
global and inferotemporal sectoral rim loss (marked by a
red cross denoting P ⬍ .001) on MRA compared with
POAG eyes (P ⫽ .025 and P ⫽ .003, respectively; ␹2 test;
Figure). No other significant differences were noted between the 2 groups with regard to other MRA sectors (P ⬎
.05), although the P value for the nasal sector almost
reached statistical significance (P ⫽ .051). No difference
in topographic distribution of damage was observed between the 2 groups when global and sectoral GPS results
were compared (P ⬎ .05 for all comparisons). However, a
large proportion of eyes (49-52 eyes out of 64 eyes, or
77%-81% of the eyes) displayed abnormal global or sectoral findings on GPS (marked by a red cross denoting P ⬍
.001).
RESULTS
A TOTAL OF 64 EYES OF 64 PATIENTS (32 EYES IN EACH
group) were enrolled. Forty-two eyes had all the imaging
and visual field examinations performed on the same day.
Twenty-one eyes had the optic disc imaging done within a
year of the eligible visual field. One patient was later found
to have had the disc images performed 20 months after the
eligible visual field but was included in the study.
Table 1 compares the baseline characteristics of the 2
groups. The MD, visual field index, and PSD were similar
in the 2 groups (average MD ⫽ ⫺5.1 dB for both groups).
Eyes with CACG were more likely to be phakic at the time
of the disc imaging (94% vs 63% in POAG eyes, P ⫽ .002,
␹2 test) and had higher IOP at the time of imaging (15.8 ⫾
4.5 vs 13.9 ⫾ 5.2 mm Hg; P ⫽ .015, Wilcoxon rank sum
test). Eyes with CACG were also more hyperopic than
POAG eyes (⫹0.6 ⫾ 0.4 D vs ⫺1.4 ⫾ 0.5 D; P ⬍ .001,
Wilcoxon rank sum test).
● VISUAL FIELD RESULTS: The average (⫾ SD) number
of abnormal test locations (p ⬍5% on pattern deviation
plot) was 17.8 (⫾5.6) in the CACG group and 17.3
(⫾5.2) in POAG eyes (P ⫽ .709; unpaired t test). The
average number of test locations with the most significant
level of loss (p ⬍0.5% on pattern deviation plot) was also
similar in the 2 groups (8.7 ⫾ 6.2 vs 8.6 ⫾ 5.2; P ⫽ .924;
unpaired t test). Eyes with CACG were less likely to have
paracentral areas of the visual field involved (47% vs 72%;
P ⫽ .04; ␹2 test) despite similar levels of visual field loss in
the 2 groups.
● RESULTS OF REVIEW OF OPTIC DISC PHOTOGRAPHS:
Results of optic disc photograph review by clinicians are
presented in Table 2. Overall, quality of the optic disc
photographs was comparable between the 2 groups (P ⬎
.05 for all comparisons, Wilcoxon rank sum test). The
glaucoma certainty scores were similar between the CACG
and POAG eyes (mean ⫾ SD, 8.0 ⫾ 2.1 in CACG vs 8.5 ⫾
1.7 for the POAG group; P ⫽ .424, Wilcoxon rank sum
test). The prevalence of focal rim loss was not significantly
lower in the CACG group (19% vs 25% in the POAG
group; P ⫽ .545, ␹2 test). The ratio of ␤-PPA to disc area
ranged from 0.02 to 1.78 in POAG eyes (median: 0.24)
and from 0 to 1.25 in CACG eyes (median: 0.22; P ⫽ .559,
Wilcoxon rank sum test). After adjusting for age and
refractive error, no significant difference was observed
between the 2 groups with respect to ␤-PPA–to-disc-area
ratio (P ⫽ .745). Increasing age was positively related to
the extent of the ␤-PPA–to-disc-area ratio (P ⫽ .034).
DISCUSSION
THERE IS EVIDENCE IN THE LITERATURE THAT PATTERNS OF
glaucomatous disc or visual field damage may be different
in CACG as compared to POAG. Zhao and associates
compared the optic disc parameters of 20 eyes of 20
normal-tension glaucoma patients to those in 20 ACG
patients.5 They found that the ACG eyes had shallower
cups, lower maximal cup depths and cup volumes, larger
rim areas, smaller vertical cup-to-disc ratios, and more
negative (healthier) cup shape measures. Thomas and
associates looked at the HRT stereometric parameters and
sensitivity/specificity of HRT algorithms in 2 groups of East
Indian POAG and CACG patients.4 The main significant
difference in the subsets of patients with early glaucoma
(average MD of ⫺3.9 and ⫺3.8 dB in POAG and PACG
groups, respectively) was in the cup shape measure, which
tended to be healthier in the early ACG patients (⫺0.14
vs ⫺0.9 for CACG and POAG groups; P ⫽ .016). Boland
and associates found differences between the 2 groups as
measured with HRT.6 The cup area, rim area, rim volume,
cup-to-disc-area ratio, and cup shape measure were significantly different between ACG and POAG eyes. However,
the authors argued that after a Bonferroni correction, the
results were not statistically significant. Given the fact that
● IMAGING RESULTS: The HRT quality according to
global pixel standard deviation was similar in the 2 groups,
with a median (range) of 17.6 (12– 4123) and 17.5
(10 –38) ␮m in CACG and POAG groups, respectively.
Disc area was similar in the 2 groups (P ⫽ .577, unpaired
t test; Table 3). Eyes with CACG had smaller cup area, cup
volume, cup-to-disc-area ratios, and mean and maximum
cup depths and larger rim-to-disc area compared to POAG
eyes (P ⬍ .05 for all; Table 3), whereas cup shape measure
almost reached the cutoff point for significance (mean ⫾
SD: ⫺0.11 ⫾ 0.07 for CACG vs ⫺0.08 ⫾ 0.07 in POAG;
unpaired t test, P ⫽ .052). All significant stereometric
variables except for maximum cup depth (P ⫽ .055)
remained significantly associated with group classification
(CACG vs POAG) when the association was adjusted for
disc area, age, refractive error, and IOP at the time of
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the stereometric HRT parameters are highly correlated, it
is hard to justify using the Bonferroni correction to adjust
P values in this setting. Another interesting finding from
the study by Boland and associates was that ACG eyes had
overall higher retinal nerve fiber layer thickness (as measured with optical coherence tomography) after adjusting
for visual field mean deviation, HRT disc area, and eye
length.
We compared 2 groups of patients with CACG and
POAG matched for severity of glaucoma (MD ⫾1 dB) and
race in this study. Our hypothesis was that POAG eyes are
more likely to have focal disc damage compared to eyes
with CACG, which is typically considered to be a type of
high-tension glaucoma. We also hypothesized that eyes
with CACG may demonstrate less evidence of structural
damage despite a similar level of functional loss based on
preliminary findings in the literature. No significant difference in prevalence of focal rim loss was observed between
the 2 groups on qualitative review of stereoscopic disc
photographs. However, on quantitative analysis with HRT,
eyes with CACG had smaller cup-to-disc-area ratios and
shallower cups. They also had larger rim-to-disc ratios as
well, since the disc size was not significantly different in
the 2 groups. Heidelberg Retina Tomograph MRA results
showed a higher prevalence of localized rim loss in the
inferotemporal sector of the disc. The GPS findings were
similar in the 2 groups of eyes. Most disc sectors were
already out of normal limits (P ⬍ .001) on GPS; hence, it
is hard to draw any conclusions from the GPS results.
Zangwill and associates found GPS to be more sensitive
than MRA and possibly have a higher false-positive rate
compared to MRA.7 The fact that we did not find a higher
prevalence of focal loss on qualitative review of disc
photographs does not necessarily contradict the HRT
findings. Qualitative review of disc photographs is a subjective process and therefore suffers from the shortcomings
of any subjective test.
Many investigators have reported an association between the ␤-PPA and presence of glaucomatous damage in
open-angle glaucoma.8 –10 Presence of a zone of ␤-PPA has
been shown to predict faster progression rates in eyes with
glaucoma.11 However, Uchida and associates reported that
in ACG eyes, both the prevalence and extent of peripapillary atrophy was significantly lower than a matched group
of POAG eyes.2 Lee and associates found that peripapillary
atrophy did not significantly enlarge after an acute episode
of ACG despite an enlargement of the optic cup during a
period of 4 months.12 We did not find a significant
difference between the 2 groups with respect to the
␤-PPA–to-disc-area ratio although the CACG eyes did
have a smaller ␤-PPA–to-disc-area ratio. Increasing myopia and age were associated with increasing ratio of ␤-PPA
to disc area.
There are scant data with regard to patterns of visual
field loss in chronic ACG. Diffuse field depression has been
reported to be more common after episodes of acute
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ACG.13 Gazzard and associates compared visual field
findings in eyes with POAG and ACG enrolled in a
prospective surgical treatment study.14 Overall, eyes with
ACG had a lower PSD, which was interpreted as evidence
for more diffuse field loss in ACG. The investigators also
reported that after dividing the eyes according to glaucoma
severity, POAG eyes were more likely to have evidence of
localized defect in the superior hemifield. This is in
agreement with our finding that inferotemporal rim loss
was more common in POAG eyes. Rhee and associates
reported similar findings in a small group of Korean
patients with POAG and ACG.15
The extent and depth of visual field loss was similar
between CACG and POAG eyes in our study. However,
CACG eyes were less likely to have the paracentral
locations of the visual field involved despite the same level
of glaucoma severity, according to mean deviation and
PSD. This finding, along with results of HRT MRA results,
suggests that mechanisms of glaucoma damage might be
different in the 2 diseases. A higher number of CACG
patients were phakic (94% vs 63%), but the potential
confounding effect of cataract on the visual field could not
be measured given the retrospective nature of our study.
However, the logMAR acuity and the visual field’s PSD
were very similar in the 2 groups, which confirms that the
media opacity influence was likely not significant.
The ramifications of a different pattern of glaucomatous
damage in CACG, if proven in a prospective study, would
be significant. Clinicians are most familiar with patterns of
glaucomatous disc damage in POAG and hence may
underestimate the severity of damage in CACG eyes.
Performance of optic disc imaging devices has also been
most extensively evaluated in eyes with POAG. Parameters best discriminating glaucomatous from normal eyes
may be different in CACG eyes, as reported by Thomas
and associates.4 A set of parameters different from those
applied to RB (R Bathija) or FSM (FS Mikelberg) discriminant functions of HRT may need to be selected to detect
early glaucomatous damage in CACG eyes. If the above
findings are confirmed, they will also have implications for
detection of progression in CACG eyes. If changes in
neuroretinal rim are less obvious given an identical
amount of retinal ganglion cell loss, the current optic
nerve head imaging algorithms may not be sensitive
enough for the timely detection of glaucoma progression in
CACG eyes and clinicians may need to rely more heavily
on nerve fiber layer imaging and visual field findings for
detection of progression. Also, clinicians are accustomed
to seek the earliest evidence of localized glaucomatous
damage in the inferotemporal area of the optic disc. While
this area is the region where the earliest signs of glaucomatous damage becomes manifest in POAG, our findings
suggest that this may not be the case in CACG eyes.
The shortcomings of our study are as follows. The subjects
were recruited from a tertiary-care academic glaucoma clinic
and the number of enrolled eyes was fairly small. It is possible
ANGLE-CLOSURE GLAUCOMA
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that our cohort of CACG eyes may not be representative of
CACG eyes in the general population. Our cohort of patients
was mostly composed of white subjects. It is possible that our
results may not apply to CACG in other ethnicities. Ascertainment of CACG was based on retrospective review of
examination notes recorded by glaucoma specialists. Some of
the CACG eyes may have had an open-angle component
contributing to glaucomatous damage. While this is a possibility, the ensuing confounding effect would have led to an
underestimation of the difference between the 2 groups. We
did not have pretreatment IOPs for most patients and
therefore could not group the POAG eyes according to this
parameter.
In summary, our findings suggest that patterns of optic
nerve damage in eyes with chronic angle-closure glaucoma
may be different in comparison to eyes with primary
open-angle glaucoma. If the findings are confirmed in a
larger prospective study, they may have significant implications with regard to early detection of the disease and its
progression in eyes with chronic angle-closure glaucoma.
PUBLICATION OF THIS ARTICLE WAS SUPPORTED IN PART BY AN UNRESTRICTED GRANT FROM RESEARCH TO PREVENT
Blindness, New York, New York. The authors report the following recent or current financial disclosures: Kouros Nouri-Mahdavi, Allergan Inc
(consulting and lecture fees); Simon K. Law, Allergan Inc (lecture fees); Anne L. Coleman, Allergan Inc and Science Based Health (Advisory
Board/consulting), Allergan Inc (grant support); Joseph Caprioli, Allergan Inc (lecture and consulting fees), and current research grant support from
Pfizer, Allergan, and Alcon. Involved in design (K.N.M., C.S., E.B., S.L.K., A.L.C., J.C.), conduct of the study (C.S., K.N.M., J.A.G.); data collection
(C.S., E.B., K.N.M.); management, analysis, and interpretation of the data (K.N.M., J.A.G., C.S.); and preparation, review, and approval of the
manuscript (K.N.M., C.S., E.B., J.A.G., S.K.L., A.L.C., J.C.). The study was approved by the Institutional Review Board at UCLA and followed the
tenets of the Declaration of Helsinki.
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peripapillary atrophy parameters to differentiate normaltension glaucoma from glaucomalike disk. J Glaucoma 2001;
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Biosketch
Kouros Nouri-Mahdavi, MD MSc, is Assistant Professor of Ophthalmology at the Glaucoma Division, Jules Stein Eye
Institute, University of California Los Angeles. His research interests include role of functional and electrophysiological
tests for detection of glaucoma or its progression, optic disc and retinal nerve fiber layer imaging, and study of treatment
outcomes in glaucoma.
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Biosketch
Chutima Supawavej, MD, graduated from Ramathibodi Hospital, Faculty of Medicine, Mahidol University, Thailand. She
completed her residency in Ophthalmology and a clinical fellowship in glaucoma at Rajavithi Hospital, Thailand. She was
an International Fellow and Adjunct Instructor in the Glaucoma Division at the Jules Stein Eye Institute, University of
California Los Angeles in 2009 –10. Dr. Supawavej is currently a glaucoma specialist at BNH and Samitivej Hospitals,
Bangkok, Thailand. Her special interests include angle-closure glaucoma and management of difficult glaucomas.
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