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Global Prevalence of Glaucoma and
Projections of Glaucoma Burden
through 2040
A Systematic Review and Meta-Analysis
Yih-Chung Tham, BSc Hons,
1,2,
*Xiang Li, BSc,
1,3,
*Tien Y. Wong, FRCS, PhD,
1,2
Harry A. Quigley, MD,
4
Tin Aung, FRCS (Ed), PhD,
1,2
Ching-Yu Cheng, MD, PhD
1,2,5,6
Purpose: Glaucoma is the leading cause of global irreversible blindness. Present estimates of global glau-
coma prevalence are not up-to-date and focused mainly on European ancestry populations. We systematically
examined the global prevalence of primary open-angle glaucoma (POAG) and primary angle-closure glaucoma
(PACG), and projected the number of affected people in 2020 and 2040.
Design: Systematic review and meta-analysis.
Participants: Data from 50 population-based studies (3770 POAG cases among 140 496 examined
individuals and 786 PACG cases among 112 398 examined individuals).
Methods: We searched PubMed, Medline, and Web of Science for population-based studies of glaucoma
prevalence published up to March 25, 2013. Hierarchical Bayesian approach was used to estimate the pooled glau-
coma prevalence of the population aged 40e80 years along with 95% credible intervals (CrIs). Projections of glaucoma
were estimated based on the United Nations World Population Prospects. Bayesian meta-regression models were
performed to assess the association between the prevalence of POAG and the relevant factors.
Main Outcome Measures: Prevalence and projection numbers of glaucoma cases.
Results: The global prevalence of glaucoma for population aged 40e80 years is 3.54% (95% CrI,
2.09e5.82). The prevalence of POAG is highest in Africa (4.20%; 95% CrI, 2.08e7.35), and the prevalence of
PACG is highest in Asia (1.09%; 95% CrI, 0.43e2.32). In 2013, the number of people (aged 40e80 years) with
glaucoma worldwide was estimated to be 64.3 million, increasing to 76.0 million in 2020 and 111.8 million in 2040.
In the Bayesian meta-regression model, men were more likely to have POAG than women (odds ratio [OR], 1.36;
95% CrI, 1.23e1.52), and after adjusting for age, gender, habitation type, response rate, and year of study, people
of African ancestry were more likely to have POAG than people of European ancestry (OR, 2.80; 95% CrI,
1.83e4.06), and people living in urban areas were more likely to have POAG than those in rural areas (OR, 1.58;
95% CrI, 1.19e2.04).
Conclusions: The number of people with glaucoma worldwide will increase to 111.8 million in 2040, dis-
proportionally affecting people residing in Asia and Africa. These estimates are important in guiding the designs of
glaucoma screening, treatment, and related public health strategies. Ophthalmology 2014;-:1e10 ª2014 by the
American Academy of Ophthalmology.
Supplemental material is available at www.aaojournal.org.
Glaucoma is the leading cause of global irreversible
blindness. It has been estimated that 60.5 million people
were affected by primary open-angle glaucoma (POAG)
and primary angle-closure glaucoma (PACG) globally in
2010.
1e3
Because of the rapid increase in aging pop-
ulations worldwide, accurate estimation of the current
glaucoma prevalence and future projections of the number
of people with glaucoma are critical for the formulation of
adequate health policies tailored for the diverse pop-
ulations worldwide.
The risk and subtypes of glaucoma vary among races and
countries. In the United States, blacks have a higher POAG
prevalence than whites.
4,5
While the prevalence of POAG in
East Asian populations is higher than that of PACG,
6e9
Mongolians and Burmese are more affected by PACG than
POAG.
10,11
Nevertheless, the current estimates of glaucoma
prevalence from different population studies have several
limitations that render accurate comparisons among them
challenging. In particular, different studies vary in age group
structures, sample size, geographic regions, ethnicity,
12014 by the American Academy of Ophthalmology
Published by Elsevier Inc.
http://dx.doi.org/10.1016/j.ophtha.2014.05.013
ISSN 0161-6420/14
examination methods, and glaucoma definitions.
12
Therefore,
it is challenging to systematically examine the global trends of
glaucoma.
There have been attempts to pool glaucoma prevalence
estimates from different populations using meta-ana-
lysis.
2,13e15
Most notably, Quigley and Broman
2
reported
worldwide glaucoma prevalence estimates in 2010 and
2020. Nevertheless, these previous estimates were
determined approximately 1 decade ago and may be out
of date. Furthermore, previous reviews focused more on
populations of European ancestry. In recent years, there
has been a rapid emergence of population-based studies in
Asia, providing an opportunity to allow better estimation of
global glaucoma prevalence.
7e11,16e33
Considering Asia
represents approximately 60% of world populations, inclu-
sion of data from contemporary Asian studies may provide a
more up-to-date estimation of global glaucoma prevalence.
In this study, we aimed to estimate the global prevalence
and future projections of glaucoma burden using the Hier-
archical Bayesian (HB) approach. The HB model takes into
account heterogeneity across populations and study char-
acteristics, thus allowing more dissimilar studies to be
included without compromising the validity of the inte-
grated estimates.
34,35
Findings in this study will be useful
for the design of glaucoma screening, treatment, rehabili-
tation, and related public health strategies.
Methods
Systematic Review Process
The review followed the Meta-Analysis of Observational Studies
in Epidemiology guidelines for reporting our systematic reviews
and meta-analyses.
36
We performed a literature search in the
electronic databases of PubMed, Medline, and Web of Science.
We limited our search to English publications and made a final
search on March 25, 2013.
In our literature search, we included a combination of keywords,
such as glaucoma, prevalence, epidemiology, population, and survey,
in the form of title words or medical subject headings (Appendix A,
available at www.aaojournal.org). Two reviewers (Y-C.T., X.L.)
completed the literature search independently. In addition, the 2
reviewers further cross-checked reference lists of all identified arti-
cles to identify other relevant studies. This adopted strategy identified
all articles used in previous reviews.
2,13,14,32
Inclusion and Exclusion Criteria
The criteria for study inclusion were based on the examination
guidelines for glaucoma-related population-based studies reported
previously.
12,37
We included studies that met the following inclu-
sion criteria: (1) population-based study of POAG or PACG from a
defined geographic region, (2) clear definition on random or
clustered sampling procedure, (3) 70% participation rate of the
eligible population participants, (4) optic disc evaluation by oph-
thalmologists using slit-lamp biomicroscopy or fundus photog-
raphy, (5) visual field testing with automated static perimetry was
at least conducted among participants who were glaucoma sus-
pects, (6) anterior chamber angle/depth evaluation determined by
slit-lamp examination or gonioscopy was at least conducted among
participants who were glaucoma suspects, and (7) POAG and
PACG case definitions were based on structural or functional ev-
idence of glaucomatous optic neuropathy evaluated by optic disc
evaluation or visual field testing, respectively, and independent of
intraocular pressure measurement. Thus, our POAG definition
included persons with intraocular pressure at all levels.
However, we excluded studies if they (a) were interview, hos-
pital, or clinic-based; (b) consisted of volunteer participants or
participants with self-reported glaucoma; (c) did not report sam-
pling strategy; (d) were published in languages other than English;
and (e) reported the number of eyes with glaucoma as opposed to
the number of individuals.
Two reviewers (Y-C.T., X.L.) independently selected the
studies for final inclusion on the basis of these criteria. Disagree-
ments between the 2 were resolved and adjudicated by the senior
author (C-Y.C.).
Data Extraction
We extracted the following data from each study: region(s) in
which the study was conducted, age group (only for POAG
analysis), gender, habitation types (urban, rural, or mixed),
ethnicity of study sample, year of study conducted, and partici-
pation response rate. We classified region(s) in which the study
was conducted according to the United Nations’classification of
macro-geographic continental regions, namely, Asia, Africa,
Europe, north America, Latin America and the Caribbean, and
Oceania.
38
Bayesian Pooling of Glaucoma Prevalence
To address the issue of heterogeneity across studies, we used the
HB approach to estimate the global prevalence of POAG, PACG,
and glaucoma (defined as POAG and PACG combined). This
approach allows us to take into account the different age distri-
butions and effects of ethnicity and geographic region across
studies, so that the final prevalence estimates reflect these sources
of variability. Furthermore, the HB approach also takes into ac-
count within-study variability. This modeling approach also has
been adopted and described in previous literature.
14,35,39
Meta-analysis can be naturally described in a hierarchical
structure in an HB model. Briefly, in our analysis, we used the HB
approach to estimate the logit of glaucoma prevalence by modeling
the hierarchical structure of the data extracted, taking into account
the differences in age distribution, ethnicity, and geographic region
across and within studies. We modeled the logit of glaucoma
prevalence as a linear combination of covariates that varies across
studies (i.e., age, ethnicity, geographic region) to account for
between-study variability. We specified the number of people with
glaucoma ðyijÞas binomially distributed: yij wBinomialðnij ;pij Þ,
where nij was the total number of participants and pij was the
prevalence of glaucoma in the ith study for the jth category of the
varying covariate (e.g., some studies may consist of >1 dataset
within the same study, where j>1). For example, when ethnic
group was specified as j, the model would allow us to account for
the variability between various ethnic groups in the same study. In
our Bayesian approach, the prevalence of glaucoma p
ij
was con-
sidered as a random variable that had a probability density function.
Thus, the logit transformation of p
ij
follows a Normal distribution:
logitðpijÞ¼uij and uij wNormalð
m
ij;
s
2Þ, where
s
2¼1
=
s
. Full
details of the model are further specified in Appendix B (available at
www.aaojournal.org).
We fitted the Bayesian model with the Markov chain Monte
Carlo algorithm and obtained the posterior distributions for the logit
of glaucoma prevalence. We then converted these estimations back
to prevalence and represented them as means along with 95%
credible intervals (CrIs), which represent the range of values within
which the true value of an estimate is expected to be within 95%
probability.
Ophthalmology Volume -, Number -, Month 2014
2
Projection Estimates
The World Population Prospects of the United Nations consist of
the latest results of national population consensus and demographic
surveys from countries worldwide and take into account mortality
rate and fertility rate in its projection of world population num-
ber.
40
We incorporated the population projection data from the
World Population Prospects of the United Nations into our age-
and region-adjusted Bayesian model (refer to details in Appendix
B, available at www.aaojournal.org). Specifically, the projected
number of individuals with glaucoma was first given by the
multiplication between the age- and region-specific prevalence
rates and the corresponding population number data. We then
obtained the posterior distributions of the projected number of
individuals with glaucoma for years 2013 to 2040 and derived the
final projection estimates from these posterior distributions. Age
groupespecific prevalence rates were assumed to be constant over
the next 27 years for our global projection to the year 2040.
Bayesian Meta-Regression Modeling
We used the Bayesian meta-regression model to model the logit of
POAG prevalence while adjusting for relevant covariates (refer to
details in Appendix B, available at www.aaojournal.org). We first
performed an age- and gender-adjusted model followed by a
multiple adjusted model, adjusting for age, gender, habitation type,
response rate, and year of study conducted. We did not concur-
rently include ethnicity and world regions in the same model as
covariates because they were strongly collinear to each other. The
coefficients of covariates were all treated as fixed effects. Random
effects were incorporated in the models to account for between-
study variability.
Because of the small numberof PACG cases in most of the studies
conductedin non-Asian regions(particularly in Africa, northAmerica,
and Europe, as shown in Table 1, available at www.aaojournal.org),
age- and gender-specific PACG data were available in only 18
studies from Asia.
8,9,11,16,18,20e23,28e31,41e46
In view of this, age- and
gender-stratified analyses of PACG and glaucoma (defined as POAG
and PACG combined) were not performed.
Results
Figure 1 shows the article selection process for studies included in
the final meta-analyses. In brief, a total of 3035 individual studies
were identified and underwent review, and 2985 studies were
excluded (Fig 1). Ultimately, 50 glaucoma prevalenceerelated
articles were included in the final meta-analysis. In the event
where age group, gender, and ethnic groupespecific data were not
readily available from published articles, we further contacted
respective authors for request of relevant stratified data. For this
reason, we contacted authors from 16 studies, of whom 8 replied
and provided the requested stratified data. A total of 14 studies
consisted of additional data on secondary glaucoma, congenital
glaucoma, and other glaucoma subtypes. However, these data are
not relevant to our main interest of estimating POAG and PACG
prevalence in this review and thus were not included.
Summary of Included Studies
The analyses included data from 50 published articles in 53
population-based samples. We extracted POAG-related data from 48
published articles in 51 population-based samples. In addition, we
extracted PACG-related data from 39 published articles in 40
population-based samples. The included data involved 3770 POAG
cases among a total of 140 496 examined individuals and 786 PACG
cases among 112 398 examined individuals. Table 1 (available at
www.aaojournal.org) summarizes the study population samples
by world regions. In brief, 24 study populations were from
Asia,
6,8e11,16e31,42e50
5 were from Africa,
51e55
12 were from
Europe,
56e67
7 were from north America,
4,5,68e70
2 were from
Latin America and the Caribbean,
71,72
and 3 were from Oceania.
73,74
Of the 48 published articles on POAG prevalence, 37 consisted of
data stratified by both age group and gender. These 37 articles were
used for Bayesian meta-regression modeling for POAG prevalence.
Global Prevalence Estimates of Glaucoma
Table 2 shows the pooled prevalence and number estimates of
glaucoma for the population aged 40 to 80 years. The overall
global prevalence of glaucoma was 3.54% (95% CrI, 2.09e5.82).
The global prevalence of POAG was 3.05% (95% CrI,
1.69e5.27), and the global prevalence of PACG was 0.50% (95%
CrI, 0.11e1.36). Figure 2 (available at www.aaojournal.org)
shows the prevalence estimate for each study.
Variations in Glaucoma Prevalence across Regions
and Ethnicity
The prevalence varied across geographic regions and ethnic groups
(Table 2,Fig 3, and Fig 4, available at www.aaojournal.org). The
prevalence of glaucoma (4.79%; 95% CrI, 2.63e8.03) and POAG
(4.20%; 95% CrI, 2.08e7.35) was highest in Africa, and the
prevalence of PACG was highest in Asia (1.09%; 95% CrI,
0.43e2.32). Across ethnicity, people of African ancestry had the
highest prevalence of glaucoma (6.11%; 95% CrI, 3.83e9.13)
and POAG (5.40%; 95% CrI, 3.17e8.27). Asians had the
highest prevalence of PACG (1.20%; 95% CrI, 0.46e2.55).
For POAG, we performed a Bayesian meta-regression analysis
(Table 3) and found that the odds ratio (OR) of POAG in people
residing in Africa was 2.39 (95% CrI, 1.17e4.53) compared with
those residing in Asia after adjusting for age and gender.
Nevertheless, this relationship became insignificant after further
adjusting for habitation type, response rate, and year of study
conducted. However, after adjusting for age, gender, habitation
type, response rate, and year of study conducted, the OR of POAG
in people of African ancestry was 2.05 (95% CrI, 1.11e3.43, data
not shown) when compared with Asians and 2.80 (95% CrI,
1.83e4.06) when compared with people of European ancestry.
Effect of Age on Primary Open-Angle Glaucoma
Prevalence
The OR of POAG prevalence was 1.73 (95% CrI, 1.63e1.82) with
each decade increase in age (Table 3), after adjusting for gender,
habitation type, response rate, and year of study conducted. We
further examined the effect of age on POAG prevalence,
stratified by geographic regions and ethnic groups (Fig 5). In
general, we found that the trend of POAG prevalence with age
increment differed by region. In this regard, multivariable
adjusted meta-regression analysis (Table 4, available at
www.aaojournal.org) further showed that people residing in
Oceania and north America had greater ORs of POAG per
decade age increment compared with other regions. Across
ethnicity, although the prevalence of POAG was highest in
people of African ancestry at all ages, Hispanics and people of
European ancestry showed a steeper increase in POAG
prevalence with age compared with African ancestry and Asians
(Fig 5). Multivariable meta-regression analysis (Table 4,
available at www.aaojournal.org) consistently showed that
Hispanics and people of European ancestry had evidently greater
ORs of POAG per decade increase in age than people of African
ancestry and Asians.
Tham et al Global Prevalence and Projections of Glaucoma
3
Effect of Gender and Habitation Area on Primary
Open-Angle Glaucoma Prevalence
After adjusting for age, habitation type, response rate, and year of
study conducted, we found that men were more likely to have
POAG than women (OR, 1.36; 95% CrI, 1.23e1.52) (Table 3).
Likewise, after adjusting for age, gender, habitation type,
response rate, and year of study conducted, people living in
urban habitation areas were more likely to have POAG than
those in rural areas (OR, 1.58; 95% CrI, 1.19e2.04) (Table 3).
Number of People with Glaucoma Worldwide from
2013 to 2040
In 2013, the total number of people (aged 40e80 years) with
glaucoma was estimated to be 64.3 million (Table 2). Asia alone
accounted for approximately 60% of the world’s total glaucoma
cases, and Africa had the second highest number of glaucoma
cases with 8.3 million (13%). In addition, Asia also accounts for
53.4% of worldwide POAG cases and 76.7% of worldwide
PACG cases.
We estimated that the number of people (aged 40e80 years)
with glaucoma worldwide will increase by 18.3% to 76 million in
2020 and by 74% to 111.8 million in 2040 compared with 2013
(Table 5 and Table 6, available at www.aaojournal.org). Much of
the increase in the number of glaucoma cases would be
attributable to significant increases in Asia and Africa (Fig 6). In
addition, Asia will still contain the greatest number of people
with POAG and PACG in 2040 with increments of 18.8 million
(79.8%) and 9.0 million (58.4%), respectively, from 2013. Africa
will post an increment in glaucoma cases by 130.8% (10.9
million) from 2013 to 2040. On the contrary, there will be only
Figure 1. Summary of article selection process. PACG ¼primary angle-closure glaucoma; POAG ¼primary open-angle glaucoma.
Table 2. Pooled Prevalence (%) and Number of People (Aged 40e80 Years, in Millions) with Primary Open-Angle Glaucoma, Primary
Angle-Closure Glaucoma, and Glaucoma in 2013
World Region
POAG PACG Glaucoma (POAG and PACG Combined)
Prevalence Number Prevalence Number Prevalence Number
Asia 2.31 (1.44e3.44) 23.54 (18.32e29.73) 1.09 (0.43e2.32) 15.47 (6.26e32.41) 3.40 (2.26e5.02) 39.00 (27.78e55.80)
Africa 4.20 (2.08e7.35) 7.03 (4.25e10.60) 0.60 (0.16e1.48) 1.26 (0.34e3.30) 4.79 (2.63e8.03) 8.29 (5.16e12.30)
Europe 2.51 (1.54e3.89) 5.36 (3.99e7.11) 0.42 (0.13e0.98) 1.41 (0.43e3.37) 2.93 (1.85e4.40) 6.77 (4.94e9.24)
North America 3.29 (1.83e5.53) 2.97 (1.96e4.29) 0.26 (0.03e0.96) 0.39 (0.04e1.38) 3.55 (1.98e5.81) 3.36 (2.21e4.94)
Latin America and
the Caribbean
3.65 (1.90e6.54) 5.01 (2.70e8.88) 0.85 (0.14e3.00) 1.59 (0.31e5.24) 4.51 (2.44e7.90) 6.59 (3.61e11.95)
Oceania 2.63 (1.16e4.83) 0.20 (0.10e0.33) 0.35 (0.05e1.15) 0.05 (0.01e0.16) 2.97 (1.38e5.23) 0.25 (0.13e0.42)
Worldwide 3.05 (1.69e5.27) 44.11 (31.32e60.94) 0.50 (0.11e1.36) 20.17 (7.39e45.86) 3.54 (2.09e5.82) 64.26 (43.83e94.65)
Data in parentheses are 95% CrIs.
PACG ¼primary angle-closure glaucoma; POAG ¼primary open-angle glaucoma.
Number of people (aged 40e80 years) in 2013 was estimated on the basis of World Population Prospects: The 2012 Revision from Department of Economic
and Social Affairs, United Nations. Worldwide population number (aged 40e80 years) in 2013 was 2.33 billion.
Ophthalmology Volume -, Number -, Month 2014
4
a mild increment in POAG and PACG cases in the regions of
Europe, north America, and Oceania from 2013 to 2040.
Discussion
Our analysis provides comprehensive, up-to-date estima-
tions on the current worldwide glaucoma prevalence and
future projections on the number of people with glaucoma.
We estimated the global prevalence of glaucoma to be
3.54%, with the highest prevalence in Africa. The number of
people with glaucoma worldwide (aged 40e80 years) will
increase from 64.3 million in 2013 to 111.8 million in 2040,
disproportionally affecting people residing in Asia and
Africa.
Estimates of Current Global Primary Open-Angle
Glaucoma and Primary Angle-Closure Glaucoma
Prevalence
The pooled global prevalence of POAG was estimated to be
3.05% and that of PACG was 0.50%. In comparison,
Quigley and Broman
2
previously estimated global POAG
prevalence to be 1.96% and PACG prevalence to be
0.69% (overall glaucoma prevalence: 2.65%) for 2010.
They similarly reported Africa as the region with the
highest glaucoma prevalence. The previous estimates were
generally lower than our estimates. Nevertheless, since the
publication of the previous review in 2006, there has been
a rapid emergence of more than 20 population-based
studies, particularly from Asia.
7e11,16e31,46
With the inclu-
sion of these recent studies in our analysis, our current re-
view may provide more up-to-date estimates on the global
burden of glaucoma. In addition, in the previous review,
PACG prevalence estimates in Europe were used to
extrapolate rates in African and Latin American regions
because of the lack of available data in those regions. In
comparison, our current analysis included actual PACG data
from recent studies in African and Latin American
regions.
51,53,72
Trends of Primary Open-Angle Glaucoma and
Primary Angle-Closure Glaucoma Prevalence by
Ethnicity
Across ethnicity, we reported that the prevalence of POAG
was distinctively higher in people of African ancestry,
similar to an earlier POAG report.
14
However, the
prevalence of PACG was highest in Asians. This finding
provides evidence consistent with previous PACG
reviews,
2,75
indicating that greater emphasis on the devel-
opment of methods to identify and treat PACG would be
particularly needed in Asia.
Effects of Gender and Habitation Area on Primary
Open-Angle Glaucoma Prevalence
We found that men were 36% more likely to have POAG
than women. With a total of 37 pooled studies, our regres-
sion model was sufficiently powered to detect a difference
between the sexes. Thus, our finding provides substantial
evidence that men are more likely to develop POAG.
We also found that people living in urban areas were
58% more likely to have POAG than people in rural areas.
This may be explained in part by the higher prevalence of
myopia in urban areas.
76
It is also interesting to speculate
Figure 3. Pooled prevalence estimates of primary open-angle glaucoma
(POAG), primary angle-closure glaucoma (PACG), and glaucoma by
ethnic groups.
Table 3. Demographic Factors Associated with Primary Open-
Angle Glaucoma
Odds Ratio (95% CrI)*
Age and Gender Adjusted Multiple Adjusted
y
Age, per decade increase 1.75 (1.65e1.84) 1.73 (1.63e1.82)
Gender
Women 1.0 [Reference] 1.0 [Reference]
Men 1.36 (1.23e1.51) 1.36 (1.23e1.52)
Geographic region
Asia 1.0 [Reference] 1.0 [Reference]
Africa 2.39 (1.17e4.53) 1.97 (0.92e3.72)
Europe 0.87 (0.56e1.32) 0.69 (0.35e1.18)
North America 1.36 (0.66e2.56) 1.23 (0.53e2.50)
Latin America and the
Caribbean
2.21 (0.96e4.56) 1.53 (0.52e3.41)
Oceania 0.98 (0.41e1.97) 0.83 (0.30e1.92)
Urban/rural
Rural 1.0 [Reference] 1.0 [Reference]
Urban 1.51 (1.17e1.90) 1.58 (1.19e2.04)
Mixed 2.18 (0.55e5.77) 1.90 (0.47e5.44)
Ethnicity
European ancestry 1.0 [Reference] 1.0 [Reference]
African ancestry 2.88 (1.97e4.10) 2.80 (1.83e4.06)
Hispanic 1.28 (0.44e3.14) 2.00 (0.57e5.15)
Asian 1.12 (0.77e1.55) 1.43 (0.82e2.34)
Response rate 6.03 (0.17e32.25) 10.85 (0.15e65.61)
Year of study conducted 1.00 (0.97e1.03) 1.00 (0.97e1.03)
CrI ¼credible interval.
*Calculated on the basis of Bayesian meta-regression model.
y
Adjusted for age, gender, habitation type, response rate, and year of study
conducted accordingly.
Tham et al Global Prevalence and Projections of Glaucoma
5
that other potential differences between a rural and an urban
lifestyle might contribute to differences in glaucoma
prevalence; these include differences in stress, pollution,
diet, physical activity, and comorbid disease. Further
studies are needed to elucidate the mechanisms underlying
the prevalence difference by habitation area.
Future Projection of Global Number of People with
Glaucoma
By 2020, Asia will have the largest number of persons
affected by POAG and PACG worldwide. In part, this is
because Asia is the most populous continent, accounting for
more than 60% of the world population. Thus, although the
estimated prevalence of POAG and glaucoma in Asia is
lower than in other regions, the sheer number of those in
affected age groups leads to large absolute numbers of
glaucoma cases. Our estimates of glaucoma burden can be
compared directly with Quigley and Broman’s previous
report,
2
in which they estimated that 79.6 million people
will have glaucoma worldwide in 2020 (POAG: 58.6
million; PACG: 21 million). Our analysis projected a
similar number of PACG cases (23.4 million), but a
slightly lower number of POAG cases (52.7 million) and
total glaucoma cases (76 million) for the year 2020.
Nevertheless, as discussed earlier, our analysis consisted
of a more extensive and recent evidence base from Asia,
particularly from India and China.
7e11,16e31
Thus, our
new estimates are likely to represent more up-to-date
projections.
We estimated that the global number of people with
glaucoma will increase by 74% from 2013 to 2040. This
mainly results from the expected change in the number of
older persons, which affects some regions more than others.
Although the number of elderly persons is likely to increase
only slowly in Europe and North America, it is expected to
increase more dramatically in Asia and Africa because of
increased life expectancy in these regions.
40
These findings
Age
Prevalence (%)
Asia
Africa
Europe
North America
Latin America & the Caribbean
Oceania
Total
40 50 60 70 80
0 5 10 15
A
Age
Prevalence (%)
European Ancestry
African Ancestry
Hispanic
Asian
Total
40 50 60 70 80
0510
15
B
Figure 5. Age-specific prevalence of primary open-angle glaucoma (POAG) by (A) world regions and (B) ethnic groups.
Table 5. Projection of the Number of People (Aged 40e80 Years, in Millions) with Primary Open-Angle Glaucoma, Primary Angle-
Closure Glaucoma, and Glaucoma in 2020 and 2040
World Region
POAG PACG
Glaucoma (POAG
and PACG Combined)
2020 2040 2020 2040 2020 2040
Asia 28.29 (21.99e35.75) 42.32 (33.03e53.34) 17.96 (7.27e37.63) 24.50 (9.93e51.35) 46.24 (33.08e65.91) 66.83 (48.39e93.77)
Africa 8.73 (5.28e13.17) 16.26 (9.86e24.59) 1.57 (0.42e4.10) 2.88 (0.77e7.51) 10.31 (6.41e15.28) 19.14 (11.89e28.30)
Europe 5.67 (4.21e7.51) 6.39 (4.79e8.42) 1.46 (0.45e3.49) 1.46 (0.45e3.50) 7.12 (5.20e9.68) 7.85 (5.76e10.55)
North America 3.52 (2.31e5.08) 4.24 (2.80e6.10) 0.42 (0.05e1.48) 0.47 (0.05e1.65) 3.94 (2.61e5.72) 4.72 (3.13e6.75)
Latin America and
the Caribbean
6.22 (3.36e11.01) 10.20 (5.52e17.97) 1.89 (0.37e6.23) 2.66 (0.52e8.78) 8.11 (4.46e14.62) 12.86 (7.12e22.85)
Oceania 0.25 (0.12e0.40) 0.35 (0.18e0.58) 0.06 (0.01e0.19) 0.07 (0.01e0.24) 0.30 (0.16e0.50) 0.42 (0.22e0.69)
Worldwide 52.68 (37.27e72.92) 79.76 (56.18e111.0) 23.36 (8.57e53.12) 32.04 (11.73e73.03) 76.02 (51.92e111.7) 111.82 (76.50e162.9)
PACG ¼primary angle-closure glaucoma; POAG ¼primary open-angle glaucoma.
Number of people (aged 40e80 years) in 2013 was estimated on the basis of World Population Prospects: The 2012 Revision from Department of Economic and
Social Affairs, United Nations. Worldwide population numbers (aged 40e80 years) are 2.33 billion for 2013, 2.67 billion for 2020, and 3.61 billion for 2040.
Ophthalmology Volume -, Number -, Month 2014
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may further underscore the need for improvements in case
identification and glaucoma care services in Asia and Africa.
Study Strengths and Limitations
The strengths of our meta-analysis include critical appraisal
of study quality, strict application of inclusion and exclusion
criteria, and up-to-date estimates using HB modeling ap-
proaches. Of note, only studies with a participation rate of
70% were included. Furthermore, there was reasonable
coverage of evidence for large world regions, such as Asia,
Europe, and north America; these regions were well repre-
sented by a sufficient number of studies with large sample
sizes. In addition, the adopted HB approach took into ac-
count heterogeneity across different study populations. This
approach was also able to borrow information across other
regions or ethnic groups, which was especially useful for
regions with few data. Taken together, the HB approach
allowed more studies to be included in the final analysis,
thus potentially providing a more precise estimate of glau-
coma prevalence.
This review has a few limitations. First, in large conti-
nental regions such as Africa and Latin America and the
Caribbean, there were insufficient studies to entirely repre-
sent the regions. For instance, the prevalence estimate of
Latin America and the Caribbean region was derived only
from Barbados and Brazil. Second, we excluded non-
English publications in this review. Nevertheless, most of
the non-English publications did not meet our inclusion
criteria (i.e., hospital, clinic-based studies). Thus, exclusion
of non-English publications is unlikely to result in signifi-
cant publication bias in our analysis. Third, only 37 articles
with age groupestratified data were included for the
Bayesian meta-regression analysis for POAG prevalence.
Thus, the findings in this particular analysis may be sub-
jected to ecological fallacy because of the exclusion of 11
articles that did not provide age-stratified data. Fourth, in
our projection of glaucoma numbers, age-specific preva-
lence was assumed to remain constant over time. Never-
theless, change of prevalence over time is difficult to
quantify because it also depends on changes of risk expo-
sures and other environmental factors, such as public
awareness and screening modalities of the disease, all of
which may modify the development of the disease. How-
ever, it is interesting to note that in our Bayesian meta-
regression analysis, year of study conducted had no
significant effect on POAG prevalence (OR, 1.00; 95% CrI,
0.97e1.03), indicating a constant trend of prevalence from
1984 to 2010 in our reviewed literature data.
In conclusion, our study provides contemporary esti-
mates that reflect the significant present and future burden of
glaucoma globally. The current number of people (aged
40e80 years) with glaucoma worldwide is 64.3 million and
is expected to increase to 76.0 million in 2020 and 111.8
million in 2040. Asia accounts for the largest number of
glaucoma cases worldwide despite having a lower glaucoma
prevalence. The findings of the study will be useful for the
design of glaucoma screening, treatment, rehabilitation, and
related public health strategies.
Acknowledgments. The authors thank Harry Quigley (Proyecto
Eye Study), David Friedman (Salisbury Eye Evaluation Study),
Radoslaw Kaczmarek (The Wroclaw Epidemiological Study), Hua
Zhong and Yuansheng Yuan (The Yunnan Minority Eye Study),
Robert Casson (Kandy Eye Study), Fotis Topouzis (The Thessaloniki
Eye Study), Paul Mitchell(Blue Mountains Eye Study), and Lisandro
Sakata (Projecto Glaucoma) for providing raw data for age- and
gender-specific POAG prevalence rates from their respective studies.
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Footnotes and Financial Disclosures
Originally received: October 3, 2013.
Final revision: March 11, 2014.
Accepted: May 15, 2014.
Available online: ---. Manuscript no. 2013-1669.
1
Singapore Eye Research Institute, Singapore National Eye Centre,
Singapore.
2
Department of Ophthalmology, Yong Loo Lin School of Medicine,
National University of Singapore and National University Health System,
Singapore.
3
Department of Statistics and Applied Probability, National University of
Singapore, Singapore.
Tham et al Global Prevalence and Projections of Glaucoma
9
4
Glaucoma Service and Dana Center for Preventive Ophthalmology,
Wilmer Ophthalmological Institute, Johns Hopkins School of Medicine,
Baltimore, Maryland.
5
Saw Swee Hock School of Public Health, National University of
Singapore and National University Health System, Singapore.
6
Duke-NUS Graduate Medical School, Singapore.
*Y-C.T. and X.L. contributed equally to the manuscript.
Financial Disclosure(s):
The author(s) have made the following disclosure(s):
T.Y.W.: Member of the board of and a Consultant dAbbott, Novartis,
Pfizer, Allergan, Bayer.
H.A.Q.: Consultant to and has received payment for lectures, including
service on speakers bureauseZeiss; Expert testimonyeAllergan; Receives
book royalties; Stock/stock optionseGraybug.
T.A.: Member of the boardeAlcon, Allergan, MSD, Bausch & Lomb;
ConsultanteAlcon, Allergan, MSD, Bausch & Lomb, Quark; Grants
pendingeAlcon, Carl Zeiss Meditec, Allegan, Santen, Ellex, Ocular
Therapeutics, Aquesys; Payment for lectures, including service on speakers
bureauseAlcon, Allergan, Santen, Carl Zeiss Meditec, Ellex, Pfizer.
C-Y.C.: SupporteNational Medical Research Council, Singapore (CSA/
033/2012). The funding organization had no role in the design or conduct of
this research.
Abbreviations and Acronyms:
CrI ¼credible interval; HB ¼Hierarchical Bayesian; OR ¼odds ratio;
PACG ¼primary angle-closure glaucoma; POAG ¼primary open-angle
glaucoma.
Correspondence:
Ching-Yu Cheng, MD, PhD, Department of Ophthalmology, National
University Health System, 1E Kent Ridge Road, NUHS Tower Block Level
7, Singapore 119228. E-mail: ching-yu_cheng@nuhs.edu.sg.
Ophthalmology Volume -, Number -, Month 2014
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