September 2008
Volume 49, Issue 9
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Clinical and Epidemiologic Research  |   September 2008
The Prevalence and Types of Glaucoma in Malay People: The Singapore Malay Eye Study
Author Affiliations
  • Sunny Y. Shen
    From the Singapore National Eye Centre, Singapore; the
    Singapore Eye Research Institute, Singapore; the
  • Tien Y. Wong
    From the Singapore National Eye Centre, Singapore; the
    Singapore Eye Research Institute, Singapore; the
    Departments of Ophthalmology and
    Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia; the
  • Paul J. Foster
    Institute of Ophthalmology, University College, London, United Kingdom; the
    Glaucoma Research Unit, Moorfields Eye Hospital, London, United Kingdom; and the
  • Jing-Liang Loo
    From the Singapore National Eye Centre, Singapore; the
    Singapore Eye Research Institute, Singapore; the
  • Mohamad Rosman
    From the Singapore National Eye Centre, Singapore; the
    Singapore Eye Research Institute, Singapore; the
  • Seng-Chee Loon
    Department of Ophthalmology, National University Hospital, Singapore.
  • Wan Ling Wong
    Singapore Eye Research Institute, Singapore; the
  • Seang-Mei Saw
    Singapore Eye Research Institute, Singapore; the
    Community, Occupational, and Family Medicine, Yong Loo Lin School of Medicine, National University of Singapore, Singapore; the
  • Tin Aung
    From the Singapore National Eye Centre, Singapore; the
    Singapore Eye Research Institute, Singapore; the
    Departments of Ophthalmology and
Investigative Ophthalmology & Visual Science September 2008, Vol.49, 3846-3851. doi:10.1167/iovs.08-1759
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      Sunny Y. Shen, Tien Y. Wong, Paul J. Foster, Jing-Liang Loo, Mohamad Rosman, Seng-Chee Loon, Wan Ling Wong, Seang-Mei Saw, Tin Aung; The Prevalence and Types of Glaucoma in Malay People: The Singapore Malay Eye Study. Invest. Ophthalmol. Vis. Sci. 2008;49(9):3846-3851. doi: 10.1167/iovs.08-1759.

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      © ARVO (1962-2015); The Authors (2016-present)

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Abstract

purpose. To assess the prevalence and types of glaucoma in an Asian Malay population.

methods. The Singapore Malay Eye Study is a population-based, cross-sectional survey that examined 3280 (78.7% response) persons aged 40 to 80 years. Participants underwent a standardized clinical examination including slit-lamp biomicroscopy, Goldmann applanation tonometry, and dilated optic disc assessment. Participants who were suspected to have glaucoma also underwent visual field examination (24-2 SITA standard, Humphrey Visual Field Analyzer II), gonioscopy, and repeat applanation tonometry. Glaucoma was defined according to International Society for Geographical and Epidemiologic Ophthalmology criteria.

results. Of the 3280 participants, 150 (4.6%) had diagnosed glaucoma, giving an age- and sex-standardized prevalence of 3.4% (95% confidence interval [CI], 3.3%–3.5%). The age- and sex-standardized prevalence of primary open-angle glaucoma was 2.5% (95% CI, 2.4%–2.6%), primary angle-closure glaucoma 0.12% (95% CI, 0.10%–0.14%), and secondary glaucoma 0.61% (95% CI, 0.59%–0.63%). Of the 150 glaucoma cases, only 12 (8%) had a previous known history of glaucoma. Twenty-seven (18%) eyes had low vision (based on best corrected visual acuity logarithm of the minimal angle of resolution [logMAR] >0.30 to <1.00 in the eye with glaucoma for unilateral cases; and based on the better eye for bilateral cases) and 15 (10%) were blind (logMAR, ≥1.00).

conclusions. The prevalence of glaucoma among Malay persons 40 years of age and older in Singapore is 3.4%, comparable to ethnic Chinese people in Singapore and other racial/ethnic groups in Asia. As in Chinese, Caucasians, and African people, primary open-angle glaucoma was the main form of glaucoma in this population. More than 90% of glaucoma cases were previously undetected.

Glaucoma is the second leading cause of blindness worldwide, with Asians accounting for approximately half of the world’s glaucoma cases. 1 2 3 In recent years, several population-based studies in Asia have reported on the prevalence of glaucoma among different racial/ethnic groups, including studies in Chinese, 4 5 Indian, 6 7 8 9 10 and other Asian populations. 11 In general, these studies show that the prevalence of glaucoma ranges from 2.4% to 5%. With the possible exception of Mongolia 11 and Myanmar, 12 in which primary angle-closure glaucoma (PACG) was reportedly more common, these data indicate most of the glaucoma cases were primary open-angle glaucoma (POAG). In the Tanjong Pagar Survey in Singapore, which examined ethnic Chinese persons, we have reported that 3.2% Chinese people 40 to 80 years of age have glaucoma; 50% are cases of POAG and 30% of PACG. 4 5  
Malays comprise the third largest racial/ethnic group in Asia, accounting for 5% of the world population. 13 There are approximately 300 to 400 million Malays living in South-East Asia. However, there has not been any previous population-based study on the epidemiology of glaucoma in Malay persons. In this population-based study, we describe the prevalence, type, and impact of glaucoma in Malay persons 40 to 80 years in Singapore. 
Methods
Study Design
The Singapore Malay Eye Study was a population-based, cross-sectional epidemiologic study of vision and major eye diseases in 3280 Malay adults aged 40 to 80 years in Singapore, conducted from August 2004 to June 2006. The study population and methodology have been described in previous reports. 14 15 In brief, the Singapore Ministry of Home Affairs provided a list of names of 16,069 Malay persons living in 15 residential districts across the southwestern part of Singapore. An age-stratified, random sampling procedure was used to select a list of 5600 names for the study (1400 residents from each decade of 40–49, 50–59, 60–69, and 70–79 years). A person was considered ineligible if he/she had moved from the residential address, had not lived there in the past 6 months, or was deceased or terminally ill. Of the selected names, 4168 (74.4%) individuals were determined to be eligible to participate. Among eligible individuals, 831 (19.9%) declined to participate, and 57 (1.4%) could not be contacted, leaving 3280 (78.7% of 4168) who participated in the study. Nonparticipants were older but did not differ in sex from the participants. 
Ethics approval was obtained from the Institutional Review Board of the Singapore Eye Research Institute, and the study was conducted in accordance with the World Medical Association’s Declaration of Helsinki. Informed written consent was obtained from all participants. 
Glaucoma Assessment
At the Singapore Eye Research Institute, all participants had a comprehensive interview and ocular examination, described in detail elsewhere. 14 The standardized protocol was based on that from the Tanjong Pagar Survey and the Blue Mountains Eye Study. Relevant parts of the examination for glaucoma diagnosis have been described 16 17 and are included herein. 
Glaucoma was diagnosed based on prespecified criteria in the International Society of Geographical and Epidemiologic Ophthalmology (ISGEO) scheme. 18  
Slit lamp biomicroscopy (model BQ-900; Haag-Streit, Köniz, Switzerland) was performed to identify abnormalities of the anterior segment, including evidence of secondary glaucoma, ischemic sequelae of previous acute primary angle closure and signs of previous surgery before pupil dilatation. Peripheral anterior chamber depth was determined by using the Van Herick technique, with the temporal peripheral anterior chamber examined under optical section at ×15 magnification. 
Intraocular pressure (IOP) was measured with a Goldmann applanation tonometer (Haag-Streit) before pupil dilation. Topical anesthesia (amethocaine hydrochloride 0.5%) was instilled into the inferior conjunctival sac, and a dry strip of fluorescein was used to stain the cornea. Care was taken to ensure that just enough fluorescein was used to make the tonometry prism visible. One reading was taken from each eye. If the IOP reading was greater than 21 mm Hg, a repeat reading was taken and the second reading was used for analysis. 
Gonioscopy was performed with a Goldmann two-mirror gonioscope (model 903; Haag-Streit) under standard low ambient illumination in three groups of participants: those suspected to have glaucoma (definition provided later), all participants with shallow peripheral anterior chamber (Van Herick grade 2 or less), and one in five randomly selected participants who did not meet the first two criteria. A narrow vertical beam of 1 mm in length was offset vertically for superior and inferior quadrants, horizontally for nasal and temporal quadrants. Care was taken to avoid light falling on the pupil. Small angle movement was allowed for visualizing the drainage angle but larger movements were avoided to reduce the possibility of inadvertent indentation. Dynamic indentation gonioscopy with a four-mirror Sussman gonioscope (Ocular Instruments, Inc., Bellevue, WA) was used to establish if peripheral anterior synechiae were present when angles appeared closed with standard gonioscopy. Angle width, iris angle insertion, iris profile, and presence of peripheral anterior synechiae were documented according to classification systems by Spaeth 19 and Scheie. 20  
After pupil dilation, the optic disc was evaluated with a +78-D lens, at ×16 magnification, with measuring graticule (Haag-Streit) during dilated funduscopy. Vertical disc diameter was measured excluding parapapillary atrophy and the scleral ring of Elschnig. The margins of the optic cup were defined stereoscopically as the point of maximal inflection of vessels crossing the neuroretinal rim (NRR). The vertical cup diameter was measured as the vertical distance between the points of maximum centrifugal extension of the cup between 11 and 1 o’clock and 5 and 7 o’clock. The vertical cup-to-disc ratio (VCDR) was then calculated. For small optic discs with no visible cup, the measurement was taken as the diameter of the emerging retinal vessels. Disc hemorrhage, notching of the NRR, and thinning of retinal nerve fiber layer were documented. 
Finally, automated perimetry (SITA 24-2; Humphrey Visual Field Analyzer II; Carl Zeiss Meditec, Inc., Oberkochen, Germany) was performed with near refractive correction by trained study technicians on 1 in 10 participants before examination by study ophthalmologists and all participants suspected to have glaucoma (definition in the next section). The visual field test was repeated if the test reliability was not satisfactory (fixation loss, >20%; false positive, >33%; and/or false negative >33%) or if there was a glaucomatous visual field defect. Data from participants with normal perimetry in the former group were used to define normative values for the population. 
Diagnostic Definitions
“Glaucoma suspects” were defined as those participants fulfilling any of the following criteria: (1) IOP greater than 21 mm Hg, (2) VCDR > 0.6 or VCDR asymmetry > 0.2, (3) abnormal anterior segment deposit consistent with pseudoexfoliation or pigment dispersion syndrome, (4) occludable or closed anterior chamber angle (defined in the next section), (5) peripheral anterior synechiae or other findings consistent with secondary glaucoma, and (6) known history of glaucoma. 14 As indicated, these participants underwent gonioscopy, visual field test, and a second IOP measurement, usually on another day. 
“Glaucoma cases” were defined according to the ISGEO criteria based on three categories 18 : Category 1 cases were defined as optic disc abnormality (VCDR/VCDR asymmetry ≥ 97.5 percentile or NRR width between 11 and 1 o’clock or 5 and 7 o’clock <0.1 VCDR), with a corresponding glaucomatous visual field defect. Category 2 cases were defined as having a severely damaged optic disc (VCDR or VCDR asymmetry ≥ 99.5th percentile) in the absence of adequate performance in a visual field test. In diagnosing category 1 or 2 glaucoma, it was required that there be no other explanation for the VCDR finding (dysplastic disc or marked anisometropia) or visual field defect (retinal vascular disease, macular degeneration, or cerebrovascular diseases). Category 3 cases were defined as subjects without visual field or optic disc data who were blind (corrected visual acuity, <3/60) and who had previous glaucoma surgery or have IOP > 99.5 percentile. 
To determine normative values for optic disc parameters (VCDR and VCDR asymmetry) and IOP, we used data from the 1 in 10 participants who underwent perimetry and had normal findings in visual field examinations in both eyes on two separate occasions. 
A glaucomatous visual field defect was considered to be present if the following were found: (1) glaucoma hemifield test (GHT) result outside normal limits, and (2) a cluster of three or more nonedge, contiguous points, not crossing the horizontal meridian, with a probability of <5% of the age-matched normal on the pattern deviation plot on two separate occasions. A narrow anterior chamber angle was diagnosed if the posterior trabecular meshwork was seen for 180° or less of the angle circumference during static gonioscopy. 21 PACG was defined as an eye with an occludable anterior chamber angle, features of trabecular obstruction by peripheral iris (PAS [peripheral anterior synechiae], elevated IOP, iris whirling, “glaukomflecken” lens opacities, or excessive pigment deposition on the trabecular surface), and evidence of glaucoma as defined herein. Final identification, adjudication, and classification of glaucoma cases were reviewed by the senior author (TA). 
Other Variables
An interviewer-administered questionnaire was used to collect demographic data, socioeconomic information, lifestyle factors, general medical history, and family history. The presenting visual acuity with habitual correction and best corrected visual acuity with subjective refraction were measured by trained study optometrists using an Early Treatment Diabetic Retinopathy Study (EDTRS) logarithm of the minimal angle of resolution (logMAR) number chart (Lighthouse International, New York, NY) at a distance of 4 m. 14 15 22 Low vision was defined as best corrected visual acuity logMAR >0.30 (Snellen 20/40) to <1.00 (20/200), and blindness was defined as logMAR ≥ 1.00 (20/200). 15 We also used an alternative definition from the World Health Organization (WHO): low vision as logMAR >0.48 (20/60) to ≤1.30 (20/400) and blindness as logMAR > 1.30 (20/400). 15 Visual acuity was based on the eye with glaucoma in unilateral cases and on the better eye in bilateral cases. 
Statistical Analysis
Statistical analysis was performed with commercial software (SPSS; ver. 13, SPSS Inc., Chicago, IL). Prevalence estimate of glaucoma was performed for the whole cohort and in age- and sex-stratified groups. Prevalence rates were standardized to the population distribution from the 2000 Singapore Census, using the direct method of adjustment. Logistic regression was used to assess the correlation of age and sex. 
Results
From the sample of 1 in 10 participants with perimetry tested before ophthalmic assessment, 254 (77.4%; 150 males and 104 females) had bilateral normal visual field examination on two separate occasions. The mean VCDR asymmetry (absolute value of right VCDR minus left VCDR) was 0.05, with 97.5 and 99.5 percentiles of 0.20 and 0.23, respectively. The mean IOP was 15.5 mm Hg, with 97.5 and 99.5 percentiles of 21.5 and 26.5 mm Hg, respectively. 
Of the 3280 participants, 430 (13.1%) were classified as “glaucoma suspects” and completed gonioscopy, visual field examination, and a second Goldmann tonometry measurement. Of these, 150 had glaucoma, of which 104 (69.3%) had POAG and only 8 (5.3%) had PACG. There were an additional 30 (20.0%) who had secondary glaucoma (21 pseudophakic glaucoma, 6 pseudoexfoliative glaucoma, 2 developmental glaucoma, and 1 neovascular glaucoma) and another 8 in whom glaucoma was unclassifiable. Ninety-one (2.9%) subjects had ocular hypertension. 
Table 1shows the overall crude and age- and sex-standardized prevalence of glaucoma, POAG, and PACG. The crude prevalence of glaucoma in the population was 4.6%, with an age- and sex-standardized prevalence rate of 3.4% (95% confidence interval [CI], 3.3–3.5). The age and sex-adjusted standardized prevalence of POAG was 2.5% and PACG was 0.12%. The prevalence increased with age and was 4-fold higher in participants aged 70 to 79 years (odds ratio [OR], 4.2; 95% CI, 2.5–7.2; P < 0.001) and 2.5-fold higher among those aged 60 to 69 years (OR, 2.4; 95% CI, 1.4–4.2; P = 0.003) compared with those aged 40 to 49 years. There was no significant difference in sex. The standardized prevalence of secondary glaucoma was 0.61% (95% CI, 0.59%–0.63%; data not shown). 
Table 2shows the characteristics of subjects with glaucoma by categories and types of glaucoma. The majority were category 1 and 2 cases, with only 1 classified as category 3. Overall, 12 (8%) of the 150 had a previous known history of glaucoma; thus, 92% had never received a diagnosis of glaucoma. More participants gave a known history of PACG (25%) than of POAG (2.9%). There were no marked sex differences in types of glaucoma with the exception of pseudoexfoliation glaucoma, in which males outnumbered females by five to one. 
A large proportion of glaucoma cases had IOP ≤ 97.5 percentile for IOP (21.5 mm Hg) on two separate tonometry measurements. Of the 104 participants with POAG, 88 (84.6%) had IOP ≤ 21.5 mm Hg and were classified as having normal-tension glaucoma. Five (62.5%) of the 8 participants with PACG and 22 (73.3%) of the 30 participants with secondary glaucoma also had IOP ≤ 21.5 mm Hg. 
Table 3shows the distribution of visual acuity among the 150 participants with glaucoma. Of the 150 glaucoma cases, 27 (18%) had low-vision (logMAR, >0.30 to <1.00) and 15 (10%) were blind (logMAR, ≥1.00), according to the primary definition. The proportion of people with blindness caused by glaucoma was higher in males than females (12.2% vs. 7.4%) and in PACG than POAG (25% vs. 5.8%). According to the alternative WHO definition, 13 (8.7%) had low vision (logMAR, >0.48 to ≤1.30) and 14 (9.3%) were blind (logMAR, >1.30; data not shown). 
Discussion
In this population-based study among Asian Malay people 40 to 80 years of age in Singapore, we report that 3.4% of the population had glaucoma—nearly identical with the 3.2% glaucoma prevalence among Chinese people aged 40 to 80 years from the Tanjong Pagar Survey in Singapore. 4 POAG accounted for more than 75% of the glaucoma cases, whereas PACG accounted for less than 10%. More than 90% of participants with glaucoma did not have a known history of glaucoma, and 10% were blind. 
Table 4shows the prevalence of glaucoma in selected Asian population-based studies. The Aravind Comprehensive Eye Study, 7 the West Bengal Glaucoma Study, 8 the Chennai Glaucoma Study 9 25 and the Andhra Pradesh Eye Study 8 have examined glaucoma prevalence in India, whereas other studies have described the prevalence of glaucoma in Mongolia, Thailand, Bangladesh, Japan, and Myanmar. 6 11 12 23 24 26 In general, the prevalence of glaucoma in Southeast Asia appears higher than in the Caucasian populations, but lower than in the populations of African decent. 3 24 27 In Myanmar and Thailand, higher rates of glaucoma (4.9% and 3.8%, respectively) were reported, but in these populations, there was a mixture of people of different races and ethnicities. 12 26 In addition, the Thai population were older (≥50 years). A small survey of rural villages in central Sumatra, Indonesia, provided data on visual impairment and blindness for Malays but did not examine glaucoma specifically. 28  
In our present study, POAG accounted for 69.3% of glaucoma cases and PACG accounted for only 5.3% cases. The finding of a lower prevalence of PACG in Malays compared with Chinese people in Singapore from the Tanjong Pagar Study (POAG:PACG; 50%:30%) 4 is consistent with hospital data showing that Malays had a rate of acute, symptomatic angle-closure that was half that of the Chinese population. 29 Nonetheless, a PACG prevalence of 0.12% in Malay people in this study is considerably lower than one would expect, considering the results in other studies. A study performed on the Cape people of South Africa of predominantly Southeast Asian origin (many of whom originated from Malaysia and Indonesia) found a higher rate of PACG compared with POAG (2.3% vs. 1.5%), although the definition of PACG used in this study included subjects with previous acute or intermittent symptoms of angle closure. 30 The relative proportions of glaucoma attributable to POAG and PACG found in our study were comparable to that in the Japanese 23 24 and Irish populations 31 but differed significantly with rates in the other Asian data and may not be entirely applicable to the Malay population living outside Singapore (Table 4) . It is possible that the lower prevalence of PACG is an underestimate due to the limited amount of gonioscopy performed in our study and the Tajimi study. 23 24 In both studies, the van Herick technique was used to screen for participants with a shallow peripheral anterior chamber who then proceeded to undergo gonioscopy. Although the van Herick technique has been sensitive in screening for occludable angles, 21 cases of occludable angles and PACG can still be missed. In this study, we used a less stringent definition for occludable angles (posterior trabecular meshwork seen for <180° of the angle circumference) in contrast to the ISGEO definition (posterior trabecular meshwork seen for <90° of the angle circumference) that was used in Mongolia, Singapore, and Guangzhou. 5 25 32 A recent study has suggested that the latter definition may be too strict and cause an underestimate of angle closure, as eyes with lesser extent of closure may still have PAS. 33 Besides our study, the Chennai Glaucoma study also used the 180° definition. 9 25 Regardless, further analysis on variations in ocular dimensions, axial length, and anterior chamber depth is needed to explore reasons for the low prevalence of PACG in Malays. 
It was noteworthy that 86.4% of POAG (and 62.5% of PACG) cases had IOP equal to or less than the 97.5 percentile (21.5 mm Hg) on two separate settings. We should take into consideration that all tonometry measurements were taken during office hours, and we may have missed peak diurnal IOP levels. However, the high prevalence of normal-tension glaucoma is similar to that observed in the Tajimi Eye Study, in which the investigators used a fixed cutoff value instead of the 97.5 percentile of normal IOP. 23 24 The findings raise the possibility that non–IOP-dependent mechanisms may be significant in Malays with glaucomatous optic neuropathy. 
In comparison with other Asian data, we found a relatively high rate of pseudophakic glaucoma. Analysis of causal factors (surgical complications, intraocular lens status, etc.), however, was limited by the heterogeneity of the condition, the lack of access to previous surgical notes and the small sample size. Nevertheless, it is of importance because a high proportion (35%) of the Malay population has visually significant cataract. Similar to other studies in the region, 4 5 8 12 26 subjects with secondary glaucoma and PACG had a higher rate of blindness than did those with POAG. 
From a public health perspective, more than 90% of persons with glaucoma did not have a known history of glaucoma, suggesting that many cases were undiagnosed. Not unexpectedly, more than 97% of POAG was undiagnosed, compared with PACG and secondary glaucoma cases, where only 75% were undiagnosed. First, this difference is consistent with PACG’s being more likely to be symptomatic than POAG. Second, it may be due to the significant portion of pseudophakic glaucoma in the secondary glaucoma group. Because this later group of participants had access to the healthcare system, glaucoma was more likely to be detected. Besides the low rate of previously diagnosed glaucoma, an additional cause for concern is that most subjects with glaucoma had IOP within the normal range, suggesting that screening for glaucoma based on IOP measurements may not be effective. 
As in other studies, we found that the prevalence of glaucoma increased with age in Malay people. With increasing longevity in Asia, glaucoma morbidity can be expected to increase. If we calculate the burden of glaucoma based on our estimated levels, in Southeast Asia alone, Malays would account for approximately 5 million glaucoma cases, which is not far from the 4.25 million estimate of Quigley and Broman. 2 Our study also shows that 4.5 million persons have undiagnosed glaucoma, and 0.5 million may be blind in at least one eye. These data emphasize the importance of increasing awareness of the problem of glaucoma in the Malay population in this region. 
Strengths of our study include a large sample size, high response rate (79% response), and the use of standardized protocols based on that from the Tanjong Pagar Survey and the Blue Mountains Eye Study. However, our study has some limitations. First, we did not perform visual field testing on all participants, and it is possible we underestimated the prevalence of glaucoma among the participants who were not considered glaucoma suspects. Second, for the entire cohort, we measured IOP only once in each eye. This is less sensitive than having multiple IOP measurements. The possibility of selection bias as a result of inclusion of participants from only the southwest region of Singapore cannot be excluded, although according to the 2000 Singapore Census, these residents were a fair representation of the Singapore population in terms of age distribution, housing type, and socioeconomic status. 
We did not have objective documentation of the optic nerve head (e.g., stereoscopic optic disc photography) for our participants. This lack of imaging made it difficult to assess intergrader or intragrader reproducibility for VCDR assessment. With the use of ISGEO criteria, the impact of optic disc size in determining the presence of structural damage was not analyzed. 34 Finally, because we repeated the measurement of IOP if the initial measurement was more than 21 mm Hg, this may result in regression to the mean for IOP readings, and may explain the relatively low prevalence of reported IOP more than 21 mm Hg in our glaucoma cases. 
In summary, in our study prevalence of glaucoma in an urban Malay population was 3.4%, which is comparable with that in other Asian populations. The most common type of glaucoma was POAG, and the prevalence of PACG was much lower than those reported in Chinese in the same urban setting. More than 90% of persons with glaucoma did not have a known history of glaucoma, suggesting the need for public health measures and research into appropriate and cost-effective screening strategies to detect this major cause of blindness. 
 
Table 1.
 
Prevalence of Glaucoma by Age and Sex
Table 1.
 
Prevalence of Glaucoma by Age and Sex
Age All Persons Males Females
N n (%) N n (%) N n (%)
All glaucoma (y)
 40–49 814 18 (2.2) 379 5 (1.3) 435 13 (3.0)
 50–59 957 28 (2.9) 429 14 (3.3) 528 14 (2.7)
 60–69 780 40 (5.1) 377 27 (7.2) 403 13 (3.2)
 70–80 729 64 (8.8) 391 36 (9.2) 338 28 (8.3)
P for trend P < 0.001 P < 0.001 P < 0.001
Crude 3280 150 (4.6) 1576 82 (5.2) 1704 68 (4.0)
Adjusted 3.4 (3.3–3.5)* 3.4 (3.3–3.6), † 3.4 (3.3–3.6), †
Primary open-angle glaucoma
 40–49 y 814 14 (1.7) 379 3 (0.8) 435 11 (2.5)
 50–59 y 957 24 (2.5) 429 13 (3.0) 528 11 (2.1)
 60–69 y 780 28 (3.6) 377 20 (5.3) 403 8 (2.0)
 70–80 y 729 38 (5.2) 391 23 (5.9) 338 15 (4.4)
P for trend P < 0.001 P < 0.001 P < 0.158
Crude 3280 104 (3.2) 1576 59 (3.7) 1704 45 (2.6)
Adjusted 2.5 (2.4–2.6)* 2.5 (2.4–2.6), † 2.5 (2.4–2.6), †
Primary angle-closure glaucoma
 40–49 y 814 0 (0.0) 379 0 (0.0) 435 0 (0.0)
 50–59 y 957 1 (0.1) 429 0 (0.0) 528 1 (0.2)
 60–69 y 780 1 (0.1) 377 1 (0.3) 403 0 (0.0)
 70–80 y 729 6 (0.8) 391 3 (0.8) 338 3 (0.9)
P for trend P = 0.002 P = 0.023 P = 0.036
Crude 3280 8 (0.2) 1576 4 (0.3) 1704 4 (0.2)
Adjusted 0.12 (0.10–0.14)* 0.12 (0.09–0.14), † 0.12 (0.10–0.15), †
Table 2.
 
Characteristics of Cases of Glaucoma
Table 2.
 
Characteristics of Cases of Glaucoma
All (n = 150) n (%)* Median age (y) Males (n = 82) n (%)* Females (n = 68) n (%)* M:F Ratio
Any glaucoma
 Category 1 112 (74.7) 66.0 61 (74.4) 51 (75.0) 1.20
 Category 2 37 (24.7) 69.0 21 (25.6) 16 (23.5) 1.31
 Category 3 1 (0.7) 62.0 0 (0.0) 1 (1.5)
Types of glaucoma
 POAG 104 (69.3) 66.0 59 (72.0) 45 (66.2) 1.31
 PACG 8 (5.3) 72.0 4 (4.9) 4 (5.9) 1.00
 Pseudophakic 21 (14.0) 72.0 11 (13.4) 10 (14.7) 1.10
 Pseudoexfoliation 6 (4.0) 69.5 5 (6.1) 1 (1.5) 5.00
 Developmental 2 (1.3) 56.5 1 (1.2) 1 (1.5) 1.00
 Rubeotic 1 (0.7) 62.0 0 (0.0) 1 (1.5)
 Others/unspecified 8 (5.3) 63.5 2 (2.4) 6 (8.8) 0.33
Table 3.
 
Visual Acuity of Glaucoma Cases
Table 3.
 
Visual Acuity of Glaucoma Cases
N Visual Acuity*
Normal Vision n (%) Low Vision n (%) Blind n (%)
Any glaucoma 150 108 (72.0) 27 (18.0) 15 (10.0)
Age group
 40–49 y 18 17 (94.4) 0 (0.0) 1 (5.6)
 50–59 y 28 26 (92.9) 1 (3.6) 1 (3.6)
 60–69 y 40 29 (72.5) 6 (15.0) 5 (12.5)
 70–80 y 64 36 (56.3) 20 (31.3) 8 (12.5)
Sex
 Men 82 57 (69.5) 15 (18.3) 10 (12.2)
 Women 68 51 (75.0) 12 (17.6) 5 (7.4)
Types of glaucoma
 POAG 104 81 (77.9) 17 (16.3) 6 (5.8)
 PACG 8 4 (50.0) 2 (25.0) 2 (25.0)
 Pseudophakic 21 12 (57.1) 6 (28.6) 3 (14.3)
 Pseudo-exfoliation 6 5 (83.3) 0 (0.0) 1 (16.7)
 Developmental 2 0 (0.0) 1 (50.0) 1 (50.0)
 Rubeotic 1 0 (0.0) 0 (0.0) 1 (100.0)
 Others/unspecified 8 6 (75.0) 1 (12.5) 1 (12.5)
Table 4.
 
Prevalence of Glaucoma in Selected Population-based Studies in Asia
Table 4.
 
Prevalence of Glaucoma in Selected Population-based Studies in Asia
Study Population Age (y) Prevalence, % Ratio of POAG to PACG
All POAG PACG
East Asian (Chinese/Japanese)
 Hovsgol, Mongolia 11 40+ 1.2 0.4 0.8 0.5
 Tajimi, Japan 23 24 40+ 5.0 3.9 0.6 6.5
 Liwan, China 5 50+ 2.7 1.8 1.3 1.4
 Tanjong Pagar, Singapore 4 40+ 3.2 2.4 0.8 3.0
South Asian
 Dhaka, Bangladesh 6 40+ 3.1 2.5 0.4 6.3
 West Bengal, East India 8 50+ 3.3 3.1 0.2 10.0
 Aravind, South India 7 40+ 2.6 1.2 0.5 2.4
 Andhra Pradesh, South India 10 40+ 2.6 1.1 2.4
 Chennai, South India 9 25 40+ 1.6 0.9 1.8
South-East Asian
 Meiktila, Myanmar 12 40+ 4.9 2.0 2.5 0.8
 Rom Klao, Thailand 26 50+ 3.8 2.3 0.9 2.6
 Singapore Malay Eye Study 40+ 3.4 2.5 0.12 20.8
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Table 1.
 
Prevalence of Glaucoma by Age and Sex
Table 1.
 
Prevalence of Glaucoma by Age and Sex
Age All Persons Males Females
N n (%) N n (%) N n (%)
All glaucoma (y)
 40–49 814 18 (2.2) 379 5 (1.3) 435 13 (3.0)
 50–59 957 28 (2.9) 429 14 (3.3) 528 14 (2.7)
 60–69 780 40 (5.1) 377 27 (7.2) 403 13 (3.2)
 70–80 729 64 (8.8) 391 36 (9.2) 338 28 (8.3)
P for trend P < 0.001 P < 0.001 P < 0.001
Crude 3280 150 (4.6) 1576 82 (5.2) 1704 68 (4.0)
Adjusted 3.4 (3.3–3.5)* 3.4 (3.3–3.6), † 3.4 (3.3–3.6), †
Primary open-angle glaucoma
 40–49 y 814 14 (1.7) 379 3 (0.8) 435 11 (2.5)
 50–59 y 957 24 (2.5) 429 13 (3.0) 528 11 (2.1)
 60–69 y 780 28 (3.6) 377 20 (5.3) 403 8 (2.0)
 70–80 y 729 38 (5.2) 391 23 (5.9) 338 15 (4.4)
P for trend P < 0.001 P < 0.001 P < 0.158
Crude 3280 104 (3.2) 1576 59 (3.7) 1704 45 (2.6)
Adjusted 2.5 (2.4–2.6)* 2.5 (2.4–2.6), † 2.5 (2.4–2.6), †
Primary angle-closure glaucoma
 40–49 y 814 0 (0.0) 379 0 (0.0) 435 0 (0.0)
 50–59 y 957 1 (0.1) 429 0 (0.0) 528 1 (0.2)
 60–69 y 780 1 (0.1) 377 1 (0.3) 403 0 (0.0)
 70–80 y 729 6 (0.8) 391 3 (0.8) 338 3 (0.9)
P for trend P = 0.002 P = 0.023 P = 0.036
Crude 3280 8 (0.2) 1576 4 (0.3) 1704 4 (0.2)
Adjusted 0.12 (0.10–0.14)* 0.12 (0.09–0.14), † 0.12 (0.10–0.15), †
Table 2.
 
Characteristics of Cases of Glaucoma
Table 2.
 
Characteristics of Cases of Glaucoma
All (n = 150) n (%)* Median age (y) Males (n = 82) n (%)* Females (n = 68) n (%)* M:F Ratio
Any glaucoma
 Category 1 112 (74.7) 66.0 61 (74.4) 51 (75.0) 1.20
 Category 2 37 (24.7) 69.0 21 (25.6) 16 (23.5) 1.31
 Category 3 1 (0.7) 62.0 0 (0.0) 1 (1.5)
Types of glaucoma
 POAG 104 (69.3) 66.0 59 (72.0) 45 (66.2) 1.31
 PACG 8 (5.3) 72.0 4 (4.9) 4 (5.9) 1.00
 Pseudophakic 21 (14.0) 72.0 11 (13.4) 10 (14.7) 1.10
 Pseudoexfoliation 6 (4.0) 69.5 5 (6.1) 1 (1.5) 5.00
 Developmental 2 (1.3) 56.5 1 (1.2) 1 (1.5) 1.00
 Rubeotic 1 (0.7) 62.0 0 (0.0) 1 (1.5)
 Others/unspecified 8 (5.3) 63.5 2 (2.4) 6 (8.8) 0.33
Table 3.
 
Visual Acuity of Glaucoma Cases
Table 3.
 
Visual Acuity of Glaucoma Cases
N Visual Acuity*
Normal Vision n (%) Low Vision n (%) Blind n (%)
Any glaucoma 150 108 (72.0) 27 (18.0) 15 (10.0)
Age group
 40–49 y 18 17 (94.4) 0 (0.0) 1 (5.6)
 50–59 y 28 26 (92.9) 1 (3.6) 1 (3.6)
 60–69 y 40 29 (72.5) 6 (15.0) 5 (12.5)
 70–80 y 64 36 (56.3) 20 (31.3) 8 (12.5)
Sex
 Men 82 57 (69.5) 15 (18.3) 10 (12.2)
 Women 68 51 (75.0) 12 (17.6) 5 (7.4)
Types of glaucoma
 POAG 104 81 (77.9) 17 (16.3) 6 (5.8)
 PACG 8 4 (50.0) 2 (25.0) 2 (25.0)
 Pseudophakic 21 12 (57.1) 6 (28.6) 3 (14.3)
 Pseudo-exfoliation 6 5 (83.3) 0 (0.0) 1 (16.7)
 Developmental 2 0 (0.0) 1 (50.0) 1 (50.0)
 Rubeotic 1 0 (0.0) 0 (0.0) 1 (100.0)
 Others/unspecified 8 6 (75.0) 1 (12.5) 1 (12.5)
Table 4.
 
Prevalence of Glaucoma in Selected Population-based Studies in Asia
Table 4.
 
Prevalence of Glaucoma in Selected Population-based Studies in Asia
Study Population Age (y) Prevalence, % Ratio of POAG to PACG
All POAG PACG
East Asian (Chinese/Japanese)
 Hovsgol, Mongolia 11 40+ 1.2 0.4 0.8 0.5
 Tajimi, Japan 23 24 40+ 5.0 3.9 0.6 6.5
 Liwan, China 5 50+ 2.7 1.8 1.3 1.4
 Tanjong Pagar, Singapore 4 40+ 3.2 2.4 0.8 3.0
South Asian
 Dhaka, Bangladesh 6 40+ 3.1 2.5 0.4 6.3
 West Bengal, East India 8 50+ 3.3 3.1 0.2 10.0
 Aravind, South India 7 40+ 2.6 1.2 0.5 2.4
 Andhra Pradesh, South India 10 40+ 2.6 1.1 2.4
 Chennai, South India 9 25 40+ 1.6 0.9 1.8
South-East Asian
 Meiktila, Myanmar 12 40+ 4.9 2.0 2.5 0.8
 Rom Klao, Thailand 26 50+ 3.8 2.3 0.9 2.6
 Singapore Malay Eye Study 40+ 3.4 2.5 0.12 20.8
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