1. Prevalence of angle-closure disease in a Korean population: The Namil Study Report 2
EVIDENCE LEVEL III
CONFIRMATORY
Joo Hwa Lee 1 , Yong Yeon Kim 2 and The Korean Glaucoma Society
Department of Ophthalmology, Inje University Sanggye Paik Hospital1, Korea University College of Medicine 2, Seoul, Korea.
DISCUSSION
PURPOSE
This study was performed to estimate the prevalence of primary angle-closure suspect (PACS), primary angle-closure (PAC), and primary angle-closure glaucoma (PACG) in a Korean population as a part of the Namil Study.
<Definitions of angle closure disease>
Definition
Characteistics
Primary angle-closure suspect (PACS)
posterior trabecular meshwork not visible by gonioscopy in ≥ 3 quarters of the angle circumference
Primary angle closure (PAC)
PACS plus elevated IOP, peripheral anterior synechiae, iris distortion, and/or glaukomflecken
Primary angle-closure glaucoma (PACG)
PAC plus optic nerve/visual field damage
Population (year)
Prevalence
Myanmar > 40 yrs (2007)
2.5%
China > 50 yrs (2006)
1.5%
Mongolia > 40 yrs (1996)
1.4% 
Singapore (Chinese) > 40yrs (2000)
1.0%
Thailand > 50 yrs (2003)
0.9%
India > 40 yrs (2000)
1.08%
India > 40 yrs (2008)
0.88%
Japan > 40 yrs (2005)
0.6%
Japan > 40 yrs (1991)
0.34%
Korea (Namil Study) > 40 yrs
0.65%
INTRODUCTION
Glaucoma is one of the common causes of world blindness, and the majo-ity of those blinded reside in Asia.
It has become recognized that angle-closure glaucoma is more common in people of Asian origin than those with European or African ethnicity.
Prevalence of primary angle-closure glaucoma (PACG) varies according to the study populations.
The published prevalence rates of PACG are highest for the Eskimo popul-ation and lowest for the white population. In between these come the Mong-ol, Chinese, Indian, Thai, and Japanese populations. However, there has been a paucity of population-based epidemiological study of PACG in Korea.
RESULTS
Gender
Total
Male
(total = 643)
Female
(total = 889)
PACS 8 21 29
PAC 1 6 7
PACG 4 10
Table 4. Prevalence of PACG in Asians
PATIENTS AND METHODS
The representatives of rural Korean population in Namil-myon, Chung-cheongnamdo were selected in this population-based epidemiologic study. This study included 1,532 people (80.3% participation rate) of 1909 eligible residents aged 40 years or older.
Each subject underwent full screening tests for the detection of glaucoma including an interview, Goldmann applanation tonometry, slit-lamp biomicroscopy, refraction, a van Herick test, fundus photography, corneal thickness measurement with ultrasound pachymetry, a visual field test using frequency-doubling technology, gonioscopy, and ocular biometry using IOL master. If the findings were suspicious or equivocal, visual field tests with Humphrey field analyzer as well as optical coherence tomography and scanning laser polarimetry were performed for confirmation of the diagnosis.
* Indications of additional examinations
(1) FDT VF abnormality
- any abnormal area,1% in FDT VF
- poor reliability with repeated FDT examinations
(2) GAT > 21 mmHg
(3) Optic disc abnormality
- Cup/disc (C/D) ratio > 0.6 or C/D difference > 0.2 between the 2 eyes
- Against the ISN’T rule
- Disc hemorrhage or retinal nerve fiber layer defect
Population (year)
Prevalence
Mongolia > 40 yrs (1996)
PACS: 6.4% / PACG: 1.4%
India – APEDS > 40 yrs (2000)
PACS 2.21% / PACG 1.08%
India – Chennai Glaucoma Study > 40 yrs (2008)
PACS: 7.24% / PAC: 2.75% /
PACG: 0.88%
Japan - Tajimi Study > 40 yrs (2005)
PAC: 0.5% / PACG: 0.6%
Korea – Namil Study > 40 yrs
PACS: 1.89% / PAC: 0.46% / PACG: 0.65%
Table 1. Distribution of primary angle-closure disease (PACS + PAC + PACG) by gender
Age (years)
Total
40-49
50-59
60-69
70-79
80-
PACS 11 12 7 29
PAC 1 3 2
PACG 10
Table 5. Prevalence of angle-closure disease in Asians
CONCLUSION
Prevalence of PACG in this population was 0.65%.
Primary angle-closure disease was associated with female gender, older age, shallower anterior chamber depth, shorter axial length, and hyperopia.
Table 2. Distribution of primary angle-closure disease (PACS + PAC + PACG) by age
Normal
Angle-closure disease
P value
Central ACD (mm)
3.07 ± 0.41
2.47 ± 0.33
0.000
AL (mm)
23.32 ± 1.01
22.64 ± 0.68
SE (diopter)
0.19 ± 1.65
0.66 ± 1.33
0.020
IOP (mmHg)
13.48 ± 4.22
13.92 ± 3.20
0.476
Corneal thickness (㎛)
± 32.37
± 32.66
0.965
REFERENCES
Dandona L, Dandona R, Mandal P, et al. Angle-closure glaucoma in an urban population in southern India: the Andhra Pradesh Eye Disease Study. Ophthalmology 2000;107:1710–6
Bourne RR, Sukudom P, Foster PJ, et al. Prevalence of glaucoma in Thailand: a population based survey in Rom Klao district, Bangkok. Br J Ophthalmol 2003;87:1069 –74.
Yamamoto T, Iwase A, Araie M, et al. The Tajimi Study report 2. Prevalence of primary angle closure and secondary glaucoma in a Japanese population. Ophthalmology 2005;112:1661–9.
Table 3. Comparison of ocular parameters: normal vs primary angle-closure disease (PACS + PAC + PACG)
(ACD = anterior chamber depth; AL = axial length; SE = spherical equivalent; IOP = intraocul-ar pressure)