J Huazhong Univ Sci Technol [Med Sci] 34(1):137-141,2014 DOI 10.1007/s11596-014-1245-9 J Huazhong Univ Sci Technol［Med Sci］ 34(1):2014
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Prevalence of Open-angle Glaucoma in Southwestern China: the Yongchuan Glaucoma Study* Hua LI (李 华)1, Yong-ye ZHANG (张永烨)1, Shi-chun LIU (刘世纯)1, Xiang-ge HE (贺翔鸽)2, Chong-jin LI (李崇金)1, Chun-hua LI (李春华)1, Ge LI (李 革)3, Ji XU (徐 霁)1, Yu-fei WU (邬羽飞)1, Sheng-fang SONG (宋胜仿)1# 1 Department of Ophthalmology, Yongchuan Hospital, Chongqing Medical University, Chongqing 402160, China 2 Department of Ophthalmology, Daping Hospital, the Third Military Medical University, Chongqing 400042, China 3 Chongqing Medical University, Chongqing 400016, China © Huazhong University of Science and Technology and Springer-Verlag Berlin Heidelberg 2014
Summary: This study examined the prevalence of primary open-angle glaucoma (POAG) among residents aged ≥50 years living in Yongchuan district of Chongqing. Stratified cluster sampling was employed in random selection to estimate the prevalence of glaucoma from April to June, 2005. Twenty-nine villages or neighborhood communities were randomly selected in urban area (Zhongshan Road), suburban area (Shanjiao Town) and exurban area (Zhutuo Town) of this district. All the respondents underwent detailed ophthalmic examinations. The examinations included questionnaire investigation, visual acuity test, naked-eye examination, measurement of peripheral anterior chamber depth (Van Herrick’s technique), detection of intraocluar pressure (IOP) with a Perkins hand-held applanation tonometer (HA-2) and examination of the optic disc by using a 78 diopters (D) lens (including the cup-disc ratio, cup/disc ratio asymmetries, horizontal and vertical diameter, notching and optic disc hemorrhages). A total of 5938 residents were actually examined, and the response rate was 85.19%. The crude prevalence of POAG was 0.86% (n=51/5938, 95% CI 0.64%–1.11%). There were 24 males and 27 females in the glaucoma group. The glaucoma prevalence was not significant different in case number between the male and female subjects (P=0.4900). Furthermore, no association between age or schooling and POAG was noted (P=0.8030, 0.0734). Out of 51 subjects with POAG, unilateral glaucoma-related blindness occurred in 38 subjects (74.5%) and bilateral glaucoma-related blindness was found in 7 subjects (13.7%). This study exhibited that the prevalence of POAG was 0.86% among residents aged ≥50 years living in Yongchuan District of Chongqing. The vision loss caused by POAG in this population was obviously higher than that previously reported in other studies. Glaucoma management, detection of affected persons and handling of the burden of glaucoma should be the priorities of the agenda of local health authorities of Western China. Key words: primary open-angle glaucoma; prevalence, blindness
Glaucoma is the second leading cause of blindness after cataract and is estimated to affect approximately 60 million people worldwide. About 8.4 million people have developed blindness as the result of glaucoma[1]. A recent study predicted that approximately 79.6 million people will suffer from open-angle glaucoma (OAG) and angle closure glaucoma (ACG) in 2020, and Asians will account for 47% of these glaucoma populations[2]. A number of glaucoma prevalence surveys have been conducted in various racial groups, and the prevalence of glaucoma varies with different regions and races[3–9]. It Hua LI, E-mail: [email protected] # Corresponding author, E-mail: [email protected] * This work was supported by the Medical Research Foundation of Chongqing Municipal Health Bureau (No. 2005-02-248).
was found that primary open-angle glaucoma (POAG) is more common in Africans than thatin Europeans or Asians, and the age-adjusted prevalence of POAG in African Americans is 4 to 5 times higher than that in European Americans in the United States[1]. It was once believed that POAG was less common than PACG among Chinese people[10, 11]. But the Liwan study showed that POAG was more common than PACG in this population[12]. More recently, the Kailu study showed that the prevalence rate of PACG was approximately equal to that of POAG in the population[13]. Due to the different conditions under which the studies were undertaken and different diagnostic criteria used, the results were not amenable to comparison. Data from the World Health Organization from 2002 suggested that countries, especially densely-populated ones, should conduct population-based surveys on regular basis and more attention should be paid to glau-
138 coma[14]. Accurate burden estimation of diseases, such as glaucoma, is essential to public health planning and reasonable allocation of resources. China, with a population of 1.3 billion people, has the largest population in the world. Although Western China accounts for two thirds of the land area of China, the per capita GDP is only two thirds of the country’s average. Compared with other regions, this region is sparsely populated and less developed. Currently, there are no scientifically representative data available in Southwest China regarding the prevalence of POAG except for the results of the Yunnan Minority Eye Study[15]. To determine the prevalence of POAG in this region, we performed a population-based study in the representative city (the Yongchuan District of Chongqing Municipality) of Southwest China. 1 SUBJECTS AND METHODS 1.1 Study Population Examination of subjects was performed between April and June in 2005 in Yongchuan District of Chongqing Municipality. Chongqing is a major city in Southwest China and an economic and cultural hub of Western China. According to the China Fifth National Population Census (2000), the municipality of Chongqing has a population of 30.51 million. Yongchuan District is 1 of 40 administrative districts in Chongqing Municipality, has a relatively stable, old population, and a socioeconomic profile, which makes it a representative area of Western China. We sought to determine the prevalence of POAG among residents aged ≥50 years living in the Yongchuan District. Stratified cluster sampling was used in random selection to estimate the prevalence of glaucoma from April to June, 2005. A sample size of 6843 was determined as necessary to estimate the prevalence of glaucoma with a 95% confidence interval (CI) of ±0.5%, assuming an 85% response rate, design effect as high as 2.0 for an assumed 2.07% population prevalence of glaucoma from a previous survey in Shunyi[16]. All persons aged≥50 years who had resided in the selected villages or neighborhood committees (Juming Weiyuanhui, a grassroot administrative unit in China) for at least 6 months were eligible for inclusion. At the end of 2004, when the study was planned, the population of the area based on the registry of the township office was 1 082 348, with 300 027 residents aged≥50 years. The sampling frame was constructed by using geographically defined clusters based on registration data of villages or neighborhood committees. There were 29 villages or neighborhood committees, which were randomly selected in urban area (Zhongshan Road), rurban area (Shanjiao Town) and exurban area (Zhutuo Town ) of this district, providing a total sample population of 6970 people. 1.2 Clinical Examination All participants were interviewed regarding their medical history, including past systemic illness and ocular disease. A single survey team conducted the entire
J Huazhong Univ Sci Technol［Med Sci］ 34(1):2014
study, each team member receiving additional training in the procedures and being assigned specific tasks. Two trained glaucoma specialists were involved in clinical evaluation. All equipment and personnel were transported to each village, and the data collection was performed on site. All the responding participants underwent detailed ophthalmic examinations. The examination included visual acuity, questionnaire investigation, anterior segment examination with a slit lamp, intraocular pressure (IOP), optic disc and retinal examination. Slit lamp biomicroscopy (SL-D7; Topcon, Tokyo, Japan) was performed to identify abnormalities of the anterior segment, and peripheral anterior chamber depth was graded according to the Van Herrick’s technique. IOP was measured 3 times with a Perkins hand-held applanation tonometer (HA-2; Kowa Xinghe, Japan), and the mean value was adopted. Gonioscopy was done 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. Optic disc and retinal examinations were conducted by two experienced glaucoma specialists (SSF and ZYY) by using a 78 diopters (D) lens and reference to standard disc images. The vertical cup-to-disc ratio (VCDR) was used as the key index of glaucomatous change, and the presence of focal enlargement of cup (notching) and disc hemorrhage were recorded. The agreement between two ophthalmologists (SSF and ZYY) was good for grading the occludability and determining the CDR in pilot study. Those subjects with the following signs were identified as glaucoma suspects[3, 16]: IOP ≥24 mmHg, VCDR ≥0.6 in either eye, VCDR asymmetry ≥0.2, or a neuroretinal rim width reduced to
137
Prevalence of Open-angle Glaucoma in Southwestern China: the Yongchuan Glaucoma Study* Hua LI (李 华)1, Yong-ye ZHANG (张永烨)1, Shi-chun LIU (刘世纯)1, Xiang-ge HE (贺翔鸽)2, Chong-jin LI (李崇金)1, Chun-hua LI (李春华)1, Ge LI (李 革)3, Ji XU (徐 霁)1, Yu-fei WU (邬羽飞)1, Sheng-fang SONG (宋胜仿)1# 1 Department of Ophthalmology, Yongchuan Hospital, Chongqing Medical University, Chongqing 402160, China 2 Department of Ophthalmology, Daping Hospital, the Third Military Medical University, Chongqing 400042, China 3 Chongqing Medical University, Chongqing 400016, China © Huazhong University of Science and Technology and Springer-Verlag Berlin Heidelberg 2014
Summary: This study examined the prevalence of primary open-angle glaucoma (POAG) among residents aged ≥50 years living in Yongchuan district of Chongqing. Stratified cluster sampling was employed in random selection to estimate the prevalence of glaucoma from April to June, 2005. Twenty-nine villages or neighborhood communities were randomly selected in urban area (Zhongshan Road), suburban area (Shanjiao Town) and exurban area (Zhutuo Town) of this district. All the respondents underwent detailed ophthalmic examinations. The examinations included questionnaire investigation, visual acuity test, naked-eye examination, measurement of peripheral anterior chamber depth (Van Herrick’s technique), detection of intraocluar pressure (IOP) with a Perkins hand-held applanation tonometer (HA-2) and examination of the optic disc by using a 78 diopters (D) lens (including the cup-disc ratio, cup/disc ratio asymmetries, horizontal and vertical diameter, notching and optic disc hemorrhages). A total of 5938 residents were actually examined, and the response rate was 85.19%. The crude prevalence of POAG was 0.86% (n=51/5938, 95% CI 0.64%–1.11%). There were 24 males and 27 females in the glaucoma group. The glaucoma prevalence was not significant different in case number between the male and female subjects (P=0.4900). Furthermore, no association between age or schooling and POAG was noted (P=0.8030, 0.0734). Out of 51 subjects with POAG, unilateral glaucoma-related blindness occurred in 38 subjects (74.5%) and bilateral glaucoma-related blindness was found in 7 subjects (13.7%). This study exhibited that the prevalence of POAG was 0.86% among residents aged ≥50 years living in Yongchuan District of Chongqing. The vision loss caused by POAG in this population was obviously higher than that previously reported in other studies. Glaucoma management, detection of affected persons and handling of the burden of glaucoma should be the priorities of the agenda of local health authorities of Western China. Key words: primary open-angle glaucoma; prevalence, blindness
Glaucoma is the second leading cause of blindness after cataract and is estimated to affect approximately 60 million people worldwide. About 8.4 million people have developed blindness as the result of glaucoma[1]. A recent study predicted that approximately 79.6 million people will suffer from open-angle glaucoma (OAG) and angle closure glaucoma (ACG) in 2020, and Asians will account for 47% of these glaucoma populations[2]. A number of glaucoma prevalence surveys have been conducted in various racial groups, and the prevalence of glaucoma varies with different regions and races[3–9]. It Hua LI, E-mail: [email protected] # Corresponding author, E-mail: [email protected] * This work was supported by the Medical Research Foundation of Chongqing Municipal Health Bureau (No. 2005-02-248).
was found that primary open-angle glaucoma (POAG) is more common in Africans than thatin Europeans or Asians, and the age-adjusted prevalence of POAG in African Americans is 4 to 5 times higher than that in European Americans in the United States[1]. It was once believed that POAG was less common than PACG among Chinese people[10, 11]. But the Liwan study showed that POAG was more common than PACG in this population[12]. More recently, the Kailu study showed that the prevalence rate of PACG was approximately equal to that of POAG in the population[13]. Due to the different conditions under which the studies were undertaken and different diagnostic criteria used, the results were not amenable to comparison. Data from the World Health Organization from 2002 suggested that countries, especially densely-populated ones, should conduct population-based surveys on regular basis and more attention should be paid to glau-
138 coma[14]. Accurate burden estimation of diseases, such as glaucoma, is essential to public health planning and reasonable allocation of resources. China, with a population of 1.3 billion people, has the largest population in the world. Although Western China accounts for two thirds of the land area of China, the per capita GDP is only two thirds of the country’s average. Compared with other regions, this region is sparsely populated and less developed. Currently, there are no scientifically representative data available in Southwest China regarding the prevalence of POAG except for the results of the Yunnan Minority Eye Study[15]. To determine the prevalence of POAG in this region, we performed a population-based study in the representative city (the Yongchuan District of Chongqing Municipality) of Southwest China. 1 SUBJECTS AND METHODS 1.1 Study Population Examination of subjects was performed between April and June in 2005 in Yongchuan District of Chongqing Municipality. Chongqing is a major city in Southwest China and an economic and cultural hub of Western China. According to the China Fifth National Population Census (2000), the municipality of Chongqing has a population of 30.51 million. Yongchuan District is 1 of 40 administrative districts in Chongqing Municipality, has a relatively stable, old population, and a socioeconomic profile, which makes it a representative area of Western China. We sought to determine the prevalence of POAG among residents aged ≥50 years living in the Yongchuan District. Stratified cluster sampling was used in random selection to estimate the prevalence of glaucoma from April to June, 2005. A sample size of 6843 was determined as necessary to estimate the prevalence of glaucoma with a 95% confidence interval (CI) of ±0.5%, assuming an 85% response rate, design effect as high as 2.0 for an assumed 2.07% population prevalence of glaucoma from a previous survey in Shunyi[16]. All persons aged≥50 years who had resided in the selected villages or neighborhood committees (Juming Weiyuanhui, a grassroot administrative unit in China) for at least 6 months were eligible for inclusion. At the end of 2004, when the study was planned, the population of the area based on the registry of the township office was 1 082 348, with 300 027 residents aged≥50 years. The sampling frame was constructed by using geographically defined clusters based on registration data of villages or neighborhood committees. There were 29 villages or neighborhood committees, which were randomly selected in urban area (Zhongshan Road), rurban area (Shanjiao Town) and exurban area (Zhutuo Town ) of this district, providing a total sample population of 6970 people. 1.2 Clinical Examination All participants were interviewed regarding their medical history, including past systemic illness and ocular disease. A single survey team conducted the entire
J Huazhong Univ Sci Technol［Med Sci］ 34(1):2014
study, each team member receiving additional training in the procedures and being assigned specific tasks. Two trained glaucoma specialists were involved in clinical evaluation. All equipment and personnel were transported to each village, and the data collection was performed on site. All the responding participants underwent detailed ophthalmic examinations. The examination included visual acuity, questionnaire investigation, anterior segment examination with a slit lamp, intraocular pressure (IOP), optic disc and retinal examination. Slit lamp biomicroscopy (SL-D7; Topcon, Tokyo, Japan) was performed to identify abnormalities of the anterior segment, and peripheral anterior chamber depth was graded according to the Van Herrick’s technique. IOP was measured 3 times with a Perkins hand-held applanation tonometer (HA-2; Kowa Xinghe, Japan), and the mean value was adopted. Gonioscopy was done 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. Optic disc and retinal examinations were conducted by two experienced glaucoma specialists (SSF and ZYY) by using a 78 diopters (D) lens and reference to standard disc images. The vertical cup-to-disc ratio (VCDR) was used as the key index of glaucomatous change, and the presence of focal enlargement of cup (notching) and disc hemorrhage were recorded. The agreement between two ophthalmologists (SSF and ZYY) was good for grading the occludability and determining the CDR in pilot study. Those subjects with the following signs were identified as glaucoma suspects[3, 16]: IOP ≥24 mmHg, VCDR ≥0.6 in either eye, VCDR asymmetry ≥0.2, or a neuroretinal rim width reduced to
