You are here

Article Text

Article menu

Download PDFPDF

Clinical science
Prevalence and causes of vision loss in East Asia in 2015: magnitude, temporal trends and projections
  1. Ching-Yu Cheng1,2,
  2. Ningli Wang3,4,
  3. Tien Y Wong1,2,
  4. Nathan Congdon5,6,
  5. Mingguang He7,
  6. Ya Xing Wang8,
  7. Tasanee Braithwaite9,10,
  8. Robert J Casson11,
  9. Maria Vittoria Cicinelli12,
  10. Aditi Das13,
  11. Seth R Flaxman14,
  12. Jost B Jonas15,
  13. Jill Elizabeth Keeffe16,
  14. John H Kempen17,
  15. Janet Leasher18,
  16. Hans Limburg19,
  17. Kovin Naidoo20,
  18. Konrad Pesudovs21,
  19. Serge Resnikoff22,
  20. Alexander J Silvester23,
  21. Nina Tahhan22,
  22. Hugh R Taylor24,
  23. Rupert R A Bourne9
  24. on behalf of the Vision Loss Expert Group of the Global Burden of Disease Study
    1. 1 Singapore Eye Research Institute, Singapore National Eye Centre, Singapore
    2. 2 Ophthalmology & Visual Sciences Academic Clinical Program (Eye ACP), Duke-NUS Medical School, Singapore
    3. 3 Beijing Tongren Eye Center, Beijing Tongren Hospital, Capital Medical University, Beijing Ophthalmology & Visual Science Key Lab, Beijing, China
    4. 4 Beijing Institute of Ophthalmology, Capital Medical University, Beijing, China
    5. 5 Preventive Ophthalmology, Zhongshan Ophthalmic Center, Guangdong, China
    6. 6 Centre for Public Health, Queen's University Belfast School of Medicine Dentistry and Biomedical Sciences, Belfast, UK
    7. 7 Ophthalmology Eye and Ear Hospital, University of Melbourne, Melbourne, Victoria, Australia
    8. 8 Beijing Institute of Ophthalmology, Beijing Tongren Hospital, Capital University of Medical Science, Beijing, China
    9. 9 School of Medicine, Vision and Eye Research Unit (VERU), Anglia Ruskin University, Chelmsford, UK
    10. 10 Moorfields Eye Hospital NHS Foundation Trust, London, UK
    11. 11 Ophthalmology, Royal Adelaide Hospital, Adelaide, South Australia, Australia
    12. 12 Department of Ophthalmology, University Vita-Salute, San Raffaele Hospital, Milan, Italy
    13. 13 Ophthalmic Public Health, Leeds Teaching Hospital NHS Trust, London, UK
    14. 14 Department of Mathematics and Data Science Institute, Imperial College, London, UK
    15. 15 Department of Ophthalmology, Ruprecht-Karls-University Heidelberg, Seegartenklinik Heidelberg, Mannheim, Germany
    16. 16 L V Prasad Eye Institute, Hyderabad, India
    17. 17 Ophthalmology and Epidemiology, University of Pennsylvania, Philadelphia, Pennsylvania, USA
    18. 18 HPD/College of Optometry, Nova Southeastern University, Davie, Florida, USA
    19. 19 Health Information Services, Grootebroek, The Netherlands
    20. 20 African Vision Research Institute, Durban, South Africa
    21. 21 Pesudovs, GLENELG, South Australia, Australia
    22. 22 Brien Holden Vision Institute, Sydney, New South Wales, Australia
    23. 23 Ophthalmology, Royal Liverpool University Hospital, Liverpool, UK
    24. 24 Melbourne School of Population Health, The University of Melbourne, Carlton, Victoria, Australia
    1. Correspondence to Professor Rupert R A Bourne, School of Medicine, Vision and Eye Research Unit (VERU), Cambridge CB1 1PT, UK; rb{at}rupertbourne.co.uk

    Abstract

    Background To determine the prevalence and causes of blindness and vision impairment (VI) in East Asia in 2015 and to forecast the trend to 2020.

    Methods Through a systematic literature review and meta-analysis, we estimated prevalence of blindness (presenting visual acuity <3/60 in the better eye), moderate-to-severe vision impairment (MSVI; 3/60≤presenting visual acuity <6/18), mild vision impairment (mild VI: 6/18≤presenting visual acuity <6/12) and uncorrected presbyopia for 1990, 2010, 2015 and 2020. A total of 44 population-based studies were included.

    Results In 2015, age-standardised prevalence of blindness, MSVI, mild VI and uncorrected presbyopia was 0.37% (80% uncertainty interval (UI) 0.12%–0.68%), 3.06% (80% UI 1.35%–5.16%) and 2.65% (80% UI 0.92%–4.91%), 32.91% (80% UI 18.72%–48.47%), respectively, in East Asia. Cataract was the leading cause of blindness (43.6%), followed by uncorrected refractive error (12.9%), glaucoma, age-related macular degeneration, corneal diseases, trachoma and diabetic retinopathy (DR). The leading cause for MSVI was uncorrected refractive error, followed by cataract, age-related macular degeneration, glaucoma, corneal disease, trachoma and DR. The burden of VI due to uncorrected refractive error, cataracts, glaucoma and DR has continued to rise over the decades reported.

    Conclusions Addressing the public healthcare barriers for cataract and uncorrected refractive error can help eliminate almost 57% of all blindness cases in this region. Therefore, public healthcare efforts should be focused on effective screening and effective patient education, with access to high-quality healthcare.

    • global burden of disease study
    • vision loss expert group
    • vision loss
    • blindness
    • vision impairment
    • refractive error
    • cataract
    • glaucoma
    • macular degeneration, epidemiology

    https://doi.org/10.1136/bjophthalmol-2018-313308

    Statistics from Altmetric.com

      Request Permissions

      If you wish to reuse any or all of this article please use the link below which will take you to the Copyright Clearance Center’s RightsLink service. You will be able to get a quick price and instant permission to reuse the content in many different ways.

      Introduction

      Approximately one-fifth of the world’s 7.6 billion people reside in East Asia. From 2015 onwards, it is estimated that East Asia’s elderly population (aged 65 years or older) will grow by 22% every 5 years for the next 20 years.1 With this increase in growth of the elderly population that is unparalleled in human history, we expect to see a dramatic increase in major age-related eye diseases and vision impairment (VI) in this region. Vision loss is among the top three most common impairments in terms of years lived with disability (YLD),2 and has a clinically meaningful impact on overall mobility and independence in populations in the region.3 Furthermore, VI decreases quality of life among affected people, and therefore poses a large and growing public health concern for East Asia.

      Several studies have investigated the prevalence of VI in East Asian countries,4–6 but there are few reports summarising epidemiological data and establishing specific causes for vision loss across the region. Notably, the Vision Loss Expert Group of the Global Burden of Disease Study was the first to summarise causes of vision loss from 1990 to 2010 in East Asia.7 We demonstrated that those with moderate-to-severe vision impairment (MSVI) in 2010 numbered 33.3 million and those with blindness numbered 5.2 million.7 We also reported that the major causes of blindness and MSVI were cataract (28.1%; 13.3%) and uncorrected refractive error (13.7%; 46.1%), respectively. With an increasing elderly population and changing lifestyles and socioeconomic conditions in East Asia, and newly published studies, an updated report on vision loss is needed to improve systematic allocation of healthcare resources for the coming years. The current report aims to update these epidemiological data by analysing the prevalence and causes of vision loss in East Asia for 2015, providing projections for 2020 and comparing these findings globally.

      Methods

      The methodology used for the preparation of prevalence estimates for VI and blindness, which includes a Preferred Reporting Items for Systematic Reviews and Meta-Analyses (PRISMA) checklist, PRISMA flow sheet and a detailed account of the statistical models used, have been published in full elsewhere.8–10 A brief overview is given as follows. Using data from the Global Vision Database,11 we estimated 1990–2015 trends in VI prevalence and their uncertainties, by age and gender, for 188 countries in the 21 Global Burden of Disease regions. For this report targeting East Asia, we included data from a total of 44 studies from the Chinese mainland (n=41 studies) and Taiwan (n=3 studies). South Korea and Japan were not included in this report, as data from these two countries were included in the report addressing the high-income Asia Pacific region.12

      Eligible studies were identified through a systematic review, including reports published between 1980 and 2014 and unpublished data identified by members of the Vision Loss Expert Group convened for the 2010 Global Burden of Disease Study. Using the same search terms as a previously published systematic review published previously,13 we extended the review to include more recently published studies up to July 2014.

      Using WHO definitions and an analytical framework similar to our earlier report,14 we estimated the prevalence of two of the core categories of VI: (1) blindness (presenting visual acuity <3/60 in the better eye) and (2) a combined MSVI (3/60≤presenting visual acuity <6/18). These definitions were used to standardise all prevalence following the strategy of Stevens et al 14 Four regressions were used to convert two commonly used definitions of blindness (visual acuity worse than 6/60 and visual acuity of 6/60 or worse) to our definition of blindness; and two commonly reported definitions of VI (visual acuity worse than 6/18 but not worse than 3/60 and visual acuity worse than 6/12 but not worse than 3/60) to our definition of MSVI.

      We fitted two hierarchical Bayesian logistic regressions (one for the prevalence of blindness and one for MSVI) to estimate VI prevalence over time, by age group, gender and country. Using fully Bayesian statistical inference,15 our posterior estimates of VI were able to flexibly borrow strength such that country-specific estimates were informed by study data from the same country, and by study data from other countries in the same region or the same year. We modelled hierarchical linear trends over time to estimate region-specific trends in prevalence of VI. Prevalence estimates are reported as posterior means along with 80% posterior uncertainty intervals (UI).

      In order to estimate the prevalence of near VI due to uncorrected presbyopia (functional presbyopia), we included studies where presbyopia was defined as presenting near vision worse than N6 or N8 at 40 cm regardless of distance refractive status. We only included people whose best-corrected distance visual acuity was 6/12 (20/40) or better, so as to avoid double counting those with both distance and near VI associated with non-refractive causes. We developed a similar model to the main model used for blindness and MSVI for uncorrected presbyopia.

      We applied our model to forecast future estimates of the prevalence of blindness and MSVI. Our model relies on health status and education as covariates. Since it is impossible to predict how these will evolve into the future, we extrapolated these covariates to the year 2020. We used the United Nations Population Division’s forecasts to derive crude numbers and to provide the WHO reference population, which was used to age-standardise estimates of prevalence.16

      Using Bayesian hierarchical logistic regression models, we estimated the proportions of overall VI attributable to uncorrected refractive error, cataract, glaucoma, age-related macular degeneration (AMD), diabetic retinopathy (DR), corneal diseases, trachoma and other causes in 1990–2015 by geographical region and year.10

      Results

      A total of 44 studies met the inclusion criteria for the Global Burden of Disease Study super-region of East Asia and were included for analysis. The majority of studies (30/44) included only adults, while six involved the entire age range. Seventeen were conducted in both rural and urban regions while 13 were conducted only in urban areas and 14 only in rural areas.

      In 2015, the age-standardised prevalence of blindness (all ages) was 0.37% (80% UI 0.12%–0.68%) in East Asia, while the prevalence of MSVI was 3.06% (80% UI 1.35%–5.16%) and the prevalence of mild VI was 2.65% (80% UI 0.92%–4.91%) (table 1). The age-standardised prevalence of uncorrected presbyopia was 32.91% (80% UI 18.72%–48.47%) (table 1).

      View this table:
      Table 1

      Crude and age-standardised prevalence (%) of blindness and MSVI, mild VI and near VI due to uncorrected presbyopia in 2015 in East Asia

      A comparison between the world and East Asia for the age-standardised prevalence of vision loss by gender and age group for 2015 can be found in table 2. In the group aged 50 years and older in East Asia, both genders demonstrated a slightly higher prevalence of MSVI and mild VI, compared with the world population. This trend also was observed for all ages. On the contrary, the global prevalence of blindness for all ages was higher than the prevalence in East Asia for both genders. In general, compared with males, females demonstrated a higher prevalence of blindness, MSVI and mild VI when considering either the entire population (table 1), or the subpopulation aged 50 years or older (table 2). In addition, the same pattern of higher prevalence in females was observed across the different countries in East Asia (figures 1 and 2).

      Figure 1
      Figure 1

      Ladder plot showing the age-standardised prevalence of blindness for males and females aged 50 years or older in 2015.

      Figure 2
      Figure 2

      Ladder plot showing the age-standardised prevalence of moderate-to-severe vision impairment for males and females aged 50 years or older in 2015.

      View this table:
      Table 2

      Age-standardised prevalence of blindness, MSVI and mild VI, by sex and region comparing adults 50 years and older with all ages for 2015 in East Asia and world

      In 2015, the total number of people blind was estimated at 6.19 million in East Asia (table 3), and China alone had 6.02 million blind people. The total number of blind individuals residing in East Asia was projected to increase by 8.2%–6.70 million in 2020. In addition, 52.88 million people had MSVI and 46.42 million more had mild VI, in 2015. The number of individuals with MSVI and mild VI is projected to increase by 10.6% and 9.9%, respectively by 2020. There were 265.34 million additional people with near VI due to uncorrected presbyopia and the number was projected to increase to 289.84 million by 2020.

      View this table:
      Table 3

      Estimated number of people (millions) affected by blindness and MSVI, mild VI and near VI due to uncorrected presbyopia in East Asia in 2015 and projections to 2020

      Cataract has been the leading cause of blindness in East Asia since first studied in 1990, accounting for >42% of blindness, and was estimated to continue being the leading cause in 2020 (table 4). In 2015, the second largest cause of blindness was uncorrected refractive error (12.90%, 80% UI 11.15%–14.61%), followed by glaucoma (7.06%, 80% UI 2.79%–12.53%), AMD (5.33%, 80% UI 1.34%–10.95%), corneal disease (4.26%, 80% UI 0.71%–9.41%), trachoma (1.81%, 80% UI 1.25%–2.36%) and lastly DR (0.51%, 80% UI 0.09%–1.08%). This trend was projected to remain the same for 2020 except that trachoma will have a much lower impact on total blindness compared with other causes. The percentage of blindness due to DR globally in 2015 (1.06%) was more than double, compared with East Asia (0.51%). Conversely, the percentage of blindness due to cataract (43.58%) and trachoma (1.81%) in East Asia in 2015 was much higher than the global prevalence of blindness due to these diseases in 2015. Notably, the percentage of blindness owing to uncorrected refractive error was lower in East Asia (12.90%), compared with the world (20.28%).

      View this table:
      Table 4

      Percentage of total blindness by cause for all ages

      The percentage of total MSVI by cause for all ages is presented in table 5. The leading cause for MSVI globally and for East Asia has been uncorrected refractive error since first reported in 1990, and was projected to continue being the leading cause for 2020. Interestingly, the prevalence of uncorrected refractive error for East Asia was lower than the prevalence globally throughout these years, although this should be interpreted with caution due to the relatively wide uncertainty intervals. Cataract was the second most common cause of MSVI accounting for 32.54% (80% UI 24.96%–40.48%) of total MSVI in 2015. Conversely to uncorrected refractive error, the prevalence of cataract-induced MSVI in East Asia was higher than the global prevalence for all years. The third most common cause of MSVI in 2015 was AMD, followed by glaucoma, corneal disease, trachoma and lastly DR. The specific cause rankings for MSVI for 2020 were projected to remain fairly constant, except for a slight decrease in the percentage of MSVI due to trachoma (0.14%, 80% UI 0.00–0.64). Generally for causes of MSVI in East Asia, there has been an increase in the percentages prevalence for uncorrected refractive error, cataract, glaucoma and DR from 1990 to 2015, whereas there has been a decrease for corneal disease and trachoma.

      View this table:
      Table 5

      Percentage of total moderate-to-severe vision impairment by cause for all ages

      Discussion

      In 2010, the Global Burden of Disease Study group estimated the prevalence and major causes of blindness and MSVI for different global regions including East Asia.7 As the East Asian population rapidly ages, we expected an increase in number of people with blindness and MSVI and near VI due to uncorrected presbyopia in this region in the next decade. This report provided an updated meta-analysis (adding a further 16 studies from this region) of the prevalence and major causes of blindness and MSVI for 2015 in East Asia and projected these findings to 2020 using data from 41 studies conducted in this region.

      East Asia alone accounted for 17.2%, 24.4% and 24.2% of the world’s blind, MSVI and uncorrected presbyopia populations, respectively (table 3). Additionally, the age standardised prevalence of MSVI and mild VI was higher in East Asia compared with the global prevalence for all ages. The most common cause of blindness, namely cataract and uncorrected refractive error, together accounted for almost 57% and 80% of all blindness and MSVI cases, respectively in the region. The increased burden of disease from these few avoidable conditions reflects the dire need for increased awareness of avoidable MSVI and blindness. For this region, simply providing suitable custom or ready-made glasses is a non-surgical approach that can greatly reduce the number of people with MSVI and blindness.17–19 Recently, eight Commissions and Ministries of China have jointly issued a comprehensive plan to prevent myopia among children and adolescents, which is expected to lead to a decrease in the prevalence of uncorrected refractive error in the future.20 In addition to making cataract surgery more accessible and affordable in the region,21 the benefit and safety of cataract surgery also needs to be communicated more effectively to the population.22 Therefore, healthcare efforts should be focused on vision screenings and patient education to increase cataract surgery uptake and reduce the burden of vision loss in East Asia. Indeed, since China’s medical reform in 1998 that led to 95% medical insurance coverage of the Chinese population,23 there has been an increased cataract surgical rate (number of cataract operations per million population per year) in China, from 370 in 2000 to 2205 in 2017 and an estimated 3000 by the end of 2018.24 Increasing capability and capacity for eye care in the rural population is also a major focus of China’s new National Eye Health Plan through development of the county-level hospitals.25

      After refractive error and cataract, glaucoma was the next major cause for blindness in East Asia and also was projected to increase. The number of glaucoma cases in Asia was projected to increase from 39 million in 2013 to 111.8 million in 2040, and Asia accounts for the largest number of cases worldwide.26 The contribution of the largest number of glaucoma cases of any region is not surprising given that East Asia has a population size of 1.65 billion and has been ageing rapidly. In addition, there is a higher risk for primary angle-closure glaucoma in East Asians and a higher risk for primary open-angle glaucoma for people living in urban areas.26 27 As glaucoma continues as a major threat to blindness in this region and is expected to worsen as China moves towards urbanisation, public health strategies should aim to increase efforts for improvements in both glaucoma screening models and better access to eye care service to reduce blindness due to glaucoma.

      Unlike AMD, DR prevalence has been steadily increasing from 1990 to 2015 as an increasing cause of blindness, but it still contributes a notably lower proportion of all blindness in the East Asia region than globally. A recent review on DR also noted a similar trend where the prevalence of DR-related VI in Asian countries was lower than in Western countries28 and in Africa.29 This observation could be due to a shorter life expectancy of people with diabetes in East Asia,29 especially in rural parts of China due to limited access to medical care.30 In contrast, the decrease in blindness due to AMD may be due to increased clinical therapies for choroidal neovascularisation through intravitreal injections of antivascular endothelial growth factor antibodies.31 32 Public healthcare efforts to reduce blindness and VI from retinal diseases therefore should try to focus on promoting the importance of both eye screenings in people with diabetes and early detection and treatment of vision-threatening DR. According to recent surveys, myopic macular degeneration has become a major cause of vision loss in East Asia.31–35 Although we extracted data on prevalence of VI due to myopic macular degeneration from studies where this was reported, the data were so sparse that an analysis of prevalence would have been meaningless. Yet it is presumed that this cause of VI constitutes a proportion of the ‘other’ causal category.

      In East Asia, the prevalence of trachoma as a cause for blindness and MSVI has significantly decreased throughout the study period. Long-running trachoma control policies such as the implementation of the Chinese National Programme and National Blindness Prevention and Treatment Programme, were instituted by the central Chinese government to eliminate trachoma by the end of 2015.36 Therefore, active trachoma is a declining threat to vision in East Asia.

      There are some limitations to our studies. First, data from Rapid Assessment of Avoidable Blindness surveys were included in this meta-analysis, but these surveys only contributed data to presenting visual acuity and in some cases best-corrected visual acuity data were usually measured through a pin hole. Consequently, these studies were only statistically analysed for cataract and uncorrected refractive error as causes for vision loss, potentially biasing upward the proportion of blindness attributed to these entities. Second, a significant percentage of vision loss causes were only categorised under ‘other causes’ accounting for about 25% of blindness and 12% of MSVI in 2015; what these causes are needs further definition beyond what is available in our data sources. Third, studies used different disease definitions, especially for glaucoma.37 Fourth, participants with VI may have multiple ocular diseases contributing to their vision loss which make it difficult to decipher the disease with the greatest impact. Moreover, there were few population-based studies on near VI as most studies focused on the causes of distance VI. Lastly, the projections for 2020 should be taken with caution as these projections assumed that access to healthcare and literacy remained unchanged after 2015.

      In conclusion, blindness and VI remain a significant public health concern in East Asia. While there is a decreasing trend for the prevalence of VI due to trachoma and AMD, the burden of VI due to uncorrected refractive error, cataracts, glaucoma and DR continues to rise. Identifying the barriers to eliminate uncorrected refractive error and cataract as the leading causes for vision loss should become priority as these two causes are avoidable with relatively limited resources. Identifying other diseases causing an important share of VI also is needed, as the burden of some of these in causing VI might now exceed that of some entities studied directly (eg, trachoma). Furthermore, routine DR screening should be implemented and better glaucoma VI prevention models should be developed as these two diseases are forecasted to become the next major causes for vision loss in East Asia.

      References

      1. ↵
        2. Bank TW
        . Rapid aging in East Asia and Pacific will shrink workforce and increase public spending, 2015. Available: http://www.worldbank.org/en/region/eap/brief/rapid-aging-in-east-asia-and-pacific-will-shrink-workforce-increase-public-spending
      2. ↵
        1. GBD 2015 Disease and Injury Incidence and Prevalence Collaborators
        . Global, regional, and national incidence, prevalence, and years lived with disability for 310 diseases and injuries, 1990-2015: a systematic analysis for the global burden of disease study 2015. Lancet 2016;388:1545–602.doi:10.1016/S0140-6736(16)31678-6
        OpenUrlCrossRefPubMed
      3. ↵
        2. Fenwick EK ,
        3. Ong PG ,
        4. Man REK , et al
        . Association of vision impairment and major eye diseases with mobility and independence in a Chinese population. JAMA Ophthalmol 2016;134:1087–93.doi:10.1001/jamaophthalmol.2016.2394
        OpenUrl
      4. ↵
        2. Hsu W-M ,
        3. Cheng C-Y ,
        4. Liu J-H , et al
        . Prevalence and causes of visual impairment in an elderly Chinese population in Taiwan: the Shihpai eye study. Ophthalmology 2004;111:62–9.doi:10.1016/j.ophtha.2003.05.011
        OpenUrlCrossRefPubMedWeb of Science
      5. ↵
        2. Liang YB ,
        3. Friedman DS ,
        4. Wong TY , et al
        . Prevalence and causes of low vision and blindness in a rural Chinese adult population: the Handan eye study. Ophthalmology 2008;115:1965–72.doi:10.1016/j.ophtha.2008.05.030
        OpenUrlCrossRefPubMedWeb of Science
      6. ↵
        2. Yang W-Y ,
        3. Li J ,
        4. Zhao C-H , et al
        . Population-Based assessment of visual impairment among ethnic DAI adults in a rural community in China. Sci Rep 2016;6:22590.doi:10.1038/srep22590
      7. ↵
        2. Wong TY ,
        3. Zheng Y ,
        4. Jonas JB , et al
        . Prevalence and causes of vision loss in East Asia: 1990-2010. Br J Ophthalmol 2014;98:599–604.doi:10.1136/bjophthalmol-2013-304047
        OpenUrlAbstract/FREE Full Text
      8. ↵
        2. Bourne RRA ,
        3. Stevens GA ,
        4. White RA , et al
        . Causes of vision loss worldwide, 1990-2010: a systematic analysis. Lancet Glob Health 2013;1:e339–49.doi:10.1016/S2214-109X(13)70113-X
        OpenUrl
      9. ↵
        2. Bourne RRA ,
        3. Flaxman SR ,
        4. Braithwaite T , et al
        . Magnitude, temporal trends, and projections of the global prevalence of blindness and distance and near vision impairment: a systematic review and meta-analysis. Lancet Glob Health 2017;5:e888–97.doi:10.1016/S2214-109X(17)30293-0
        OpenUrl
      10. ↵
        2. Flaxman SR ,
        3. Bourne RRA ,
        4. Resnikoff S , et al
        . Global causes of blindness and distance vision impairment 1990-2020: a systematic review and meta-analysis. Lancet Glob Health 2017;5:e1221–34.doi:10.1016/S2214-109X(17)30393-5
        OpenUrl
      11. ↵
        1. Global Vision Database
        , 2017. Available: http://www.globalvisiondata.org
      12. ↵
        2. Bourne RRA ,
        3. Jonas JB ,
        4. Bron AM , et al
        . Prevalence and causes of vision loss in high-income countries and in eastern and central Europe in 2015: magnitude, temporal trends and projections. Br J Ophthalmol 2018;102:575–85.doi:10.1136/bjophthalmol-2017-311258
        OpenUrlAbstract/FREE Full Text
      13. ↵
        2. Bourne R ,
        3. Price H ,
        4. Taylor H , et al
        . New systematic review methodology for visual impairment and blindness for the 2010 global burden of disease study. Ophthalmic Epidemiol 2013;20:33–9.doi:10.3109/09286586.2012.741279
        OpenUrlCrossRefPubMedWeb of Science
      14. ↵
        2. Stevens GA ,
        3. White RA ,
        4. Flaxman SR , et al
        . Global prevalence of vision impairment and blindness: magnitude and temporal trends, 1990-2010. Ophthalmology 2013;120:2377–84.doi:10.1016/j.ophtha.2013.05.025
        OpenUrlCrossRefPubMedWeb of Science
      15. ↵
        2. Gelman A ,
        3. Carlin J ,
        4. Stern H , et al
        . Bayesian data analysis. 3rd ed. London: Chapman & Hall/CRC Press, 2013.
      16. ↵
        1. Department of Economic and Social Affairs
        . Population division 2015.
      17. ↵
        2. Ma X ,
        3. Zhou Z ,
        4. Yi H , et al
        . Effect of providing free glasses on children's educational outcomes in China: cluster randomized controlled trial. BMJ 2014;349:g5740.doi:10.1136/bmj.g5740
      18. ↵
        2. Evans JR ,
        3. Morjaria P ,
        4. Powell C , et al
        . Vision screening for correctable visual acuity deficits in school-age children and adolescents. Cochrane Database Syst Rev 2018;118.doi:10.1002/14651858.CD005023.pub3
      19. ↵
        2. Yi H ,
        3. Zhang H ,
        4. Ma X , et al
        . Impact of free glasses and a teacher incentive on children's use of eyeglasses: a cluster-randomized controlled trial. Am J Ophthalmol 2015;160:889–96.doi:10.1016/j.ajo.2015.08.006
        OpenUrl
      20. ↵
        2. Zhang M ,
        3. Wu X ,
        4. Li L , et al
        . Understanding barriers to cataract surgery among older persons in rural China through focus groups. Ophthalmic Epidemiol 2011;18:179–86.doi:10.3109/09286586.2011.580884
        OpenUrlCrossRefPubMedWeb of Science
      21. ↵
        1. Ministry of Education of the People’s Republic of China
        . National plan for the comprehensive prevention and control of myopia in children and adolescents, 2018. Available: http://www.moe.gov.cn/jyb_xwfb/gzdt_gzdt/s5987/201808/t20180830_346673.html [Accessed 30 Aug 2018].
      22. ↵
        2. Ren X-tao ,
        3. Snellingen T ,
        4. Gu H , et al
        . Use of cataract surgery in urban Beijing: a post screening follow-up of the elderly with visual impairment due to age-related cataract. Chin Med Sci J 2015;30:1–6.doi:10.1016/S1001-9294(15)30001-8
        OpenUrl
      23. ↵
        1. National Bureau of Statistics of China
        . Statistics for basic medical insurance system for urban and rural Chinese people. Available: http://data.stats.gov.cn/easyquery.htm?cn=C01 [Accessed 30 Aug 2018].
      24. ↵
        2. Zhao JL
        . [Review and outlook of the eye health in China]. Zhonghua Yan Ke Za Zhi 2018;54:561–4.doi:10.3760/cma.j.issn.0412-4081.2018.08.001
        OpenUrl
      25. ↵
        1. General Office of the State Council
        . Opinions of the general office of the state Council on the comprehensive reform of County level hospitals, 2015. Available: http://www.gov.cn/zhengce/content/2015-05/08/content_9710.htm [Accessed 20 Sep 2018].
      26. ↵
        2. Tham Y-C ,
        3. Li X ,
        4. Wong TY , et al
        . Global prevalence of glaucoma and projections of glaucoma burden through 2040: a systematic review and meta-analysis. Ophthalmology 2014;121:2081–90.doi:10.1016/j.ophtha.2014.05.013
        OpenUrlCrossRefPubMedWeb of Science
      27. ↵
        2. Chan Errol Wei'en ,
        3. Li X ,
        4. Tham Y-C , et al
        . Glaucoma in Asia: regional prevalence variations and future projections. Br J Ophthalmol 2016;100:78–85.doi:10.1136/bjophthalmol-2014-306102
        OpenUrlAbstract/FREE Full Text
      28. ↵
        2. Lee R ,
        3. Wong TY ,
        4. Sabanayagam C
        . Epidemiology of diabetic retinopathy, diabetic macular edema and related vision loss. Eye Vis 2015;2.doi:10.1186/s40662-015-0026-2
      29. ↵
        2. Leasher JL ,
        3. Bourne RRA ,
        4. Flaxman SR , et al
        . Global estimates on the number of people blind or visually impaired by diabetic retinopathy: a meta-analysis from 1990 to 2010. Diabetes Care 2016;39:1643–9.doi:10.2337/dc15-2171
        OpenUrlAbstract/FREE Full Text
      30. ↵
        2. Sabanayagam C ,
        3. Yip W ,
        4. Ting DSW , et al
        . Ten emerging trends in the epidemiology of diabetic retinopathy. Ophthalmic Epidemiol 2016;23:209–22.doi:10.1080/09286586.2016.1193618
        OpenUrl
      31. ↵
        2. Rosenfeld PJ ,
        3. Brown DM ,
        4. Heier JS , et al
        . Ranibizumab for neovascular age-related macular degeneration. N Engl J Med 2006;355:1419–31.doi:10.1056/NEJMoa054481
        OpenUrlCrossRefPubMedWeb of Science
      32. ↵
        2. Brown DM ,
        3. Kaiser PK ,
        4. Michels M , et al
        . Ranibizumab versus verteporfin for neovascular age-related macular degeneration. N Engl J Med 2006;355:1432–44.doi:10.1056/NEJMoa062655
        OpenUrlCrossRefPubMedWeb of Science
      33. ↵
        2. Wu L ,
        3. Sun X ,
        4. Zhou X , et al
        . Causes and 3-year-incidence of blindness in Jing-An district, Shanghai, China 2001-2009. BMC Ophthalmol 2011;11:10.doi:10.1186/1471-2415-11-10
      34. ↵
        2. Wong TY ,
        3. Ferreira A ,
        4. Hughes R , et al
        . Epidemiology and disease burden of pathologic myopia and myopic choroidal neovascularization: an evidence-based systematic review. Am J Ophthalmol 2014;157:9–25.doi:10.1016/j.ajo.2013.08.010
        OpenUrlCrossRefPubMed
      35. ↵
        2. Xu L ,
        3. Wang Y ,
        4. Li Y , et al
        . Causes of blindness and visual impairment in urban and rural areas in Beijing. Ophthalmology 2006;113:1134.e1–1134.e11.doi:10.1016/j.ophtha.2006.01.035
        OpenUrlCrossRefPubMedWeb of Science
      36. ↵
        2. Yang G-J ,
        3. Liu L ,
        4. Zhu H-R , et al
        . China's sustained drive to eliminate neglected tropical diseases. Lancet Infect Dis 2014;14:881–92.doi:10.1016/S1473-3099(14)70727-3
        OpenUrlCrossRefPubMed
      37. ↵
        2. Wolfs RC ,
        3. Borger PH ,
        4. Ramrattan RS , et al
        . Changing views on open-angle glaucoma: definitions and prevalences--the Rotterdam study. Invest Ophthalmol Vis Sci 2000;41:3309–21.
        OpenUrlAbstract/FREE Full Text

      Footnotes

      • C-YC, NW and TYW are joint first authors.

      • C-YC, NW and TYW contributed equally.

      • Collaborators Rupert Bourne (Anglia Ruskin University, Cambridge, UK); Peter Ackland (International Agency for Prevention of Blindness, London, UK); Aries Arditi (Visibility Metrics LLC, New York, USA); Yaniv Barkana (Assaf Harofe Medical Center, Zerifin, Israel); Banu Bozkurt (Department of Ophthalmology, Meram Medical Faculty, Selcuk University, Konya, Turkey); Tasanee Braithwaite (Moorfields Eye Hospital, London); Alain Bron (Service d'Ophtalmologie CHU Dijon, France); Donald Budenz (University of Miami, Miami, USA); Feng Cai (Green-Valley Group, Freedom, California, USA); Robert Casson (University of Adelaide, Adelaide, Australia); Usha Chakravarthy (The Queen's University of Belfast, Belfast, Northern Ireland); Jaewan Choi (Hangil Eye Hospital, Incheon, South Korea); Maria Vittoria Cicinelli (San Raffaele Scientific Institute, Milan, Italy); Nathan Congdon (The Queen's University of Belfast, Belfast, Northern Ireland); Reza Dana (Massachussets Eye & Ear Infirmary, Harvard Medical School, Boston, USA); Rakhi Dandona (George Institute for International Health, Sydney, Australia); Lalit Dandona (Institute for Health Metrics and Evaluation, University of Washington, Seattle, WA, USA); Aditi Das (St James’s University Hospital, Leeds, UK); Iva Dekaris (Eye Clinic Svjetlost, Zagreb, Croatia); Monte Del Monte (University of Michigan, Ann Arbor, USA); Jenny Deva (Universiti Tunku Abdul Rahman, Dept of Surgery (Ophthalmology)); Mohamed Dirani (Singapore Eye Research Institute, Singapore); Laura Dreer (University of Alabama, Birmingham, USA); Leon Ellwein (National Eye Institute, Bethesda, USA); Marcela Frazier (University of Alabama at Birmingham); Kevin Frick (Johns Hopkins Bloomberg School of Public Health, Baltimore, USA); David Friedman (Johns Hopkins Bloomberg School of Public Health, Baltimore, USA); Joao Furtado (University of São Paulo, São Paulo, Brazil); Hua Gao (Henry Ford Medical Center, Dept of Ophthalmology); Andrew Gazzard (Institute of Ophthalmology, London); Ronnie George (Medical Research Foundation, Chennai, India); Stephen Gichuhi (University of Nairobi, Nairobi, Kenya); Victor Gonzalez (Valley Retina Institute, Texas, USA); Billy Hammond (University of Georgia, Athens, USA); Mary Elizabeth Hartnett (University of Utah, Salt Lake City, USA); Minguang He (University of Melbourne, Melbourne, USA); James Hejtmancik (National Eye Institute, Bethesda, USA); Flavio Hirai (Federal University of Sao Paulo, Brazil); John Huang (Yale University School of Medicine, Connecticut, USA); April Ingram (Alberta Children's Hospital, Calgary, Canada); Jonathan Javitt (Johns Hopkins University School of Medicine, Baltimore, USA); Jost Jonas (Department of Ophthalmology, Medical Faculty Mannheim, Heidelberg University, Mannheim, Germany); Charlotte Joslin (University of Illinois, Chicago, USA); Jill Keeffe (L V Prasad Eye Institute, Hyderabad, India); John Kempen (University of Pennsylvania Perelman School of Medicine, Philadelphia, USA); Moncef Khairallah (University Hospital Monastir,Tunisia); Rohit Khanna (L V Prasad Eye Institute, Hyderabad, India); Judy Kim (Medical College of Wisconsin, Milwaukee, USA); George Lambrou (Novartis, Basel, Switzerland); Van Charles Lansingh (HelpMeSee, Inc. New York, USA); Paolo Lanzetta (Department of Ophthalmology, University of Udine. Udine, Italy); Janet Leasher (Nova Southeastern University, Florida, USA); Jennifer Lim (University of Illinois, Urbana, USA); Hans Limburg (Health Information Services, Grootebroek, Netherlands); Kaweh Mansouri (Clinique De Montchoisi, Lausanne, Switzerland); Anu Mathew (Royal Children's Hospital, Melbourne, Australia); Alan Morse (Jewish Guild Healthcare, New York, USA); Beatriz Munoz (Wilmer Eye Institute John Hopkins University, Baltimore, USA); David Musch (University of Michigan, Ann Arbor, USA); Kovin Naidoo (University of KwaZulu-Natal, Durban, South Africa); Vinay Nangia (Suraj Eye Institute, Nagpur, India); Maria Palaiou (Massachusetts Eye and Ear Institute, Boston, USA); Maurizio Battaglia Parodi (University Vita Salute, Ospedale San Raffaele, Milan, Italy); Fernando Yaacov Pena (Fundacion Vision, Asuncion, Paraguay); Konrad Pesudovs (Adelaide, Australia); Tunde Peto (The Queen's University of Belfast, Belfast, Northern Ireland); Harry Quigley (Wilmer Eye Institute John Hopkins University, Baltimore, USA); Murugesan Raju (University of Missouri, Columbia, USA); Pradeep Ramulu (Wilmer Eye Institute John Hopkins University, Baltimore, USA); Serge Resnikoff (Brien Holden Vision Institute, Sydney, Australia); Dana Reza (Schepens Eye Research Inst./Mass Eye and Ear, Harvard Medical School, Boston, USA); Alan Robin (Johns Hopkins University, Baltimore, USA); Luca Rossetti (University of Milan, Milan, Italy); Jinan Saaddine (National Center for Chronic Disease Prevention and Health Promotion, Centers for Disease Control and Prevention, Atlanta, USA); Mya Sandar (Singapore Eye Research Institute, Singapore); Janet Serle (Mt Sinai School of Medicine, New York, USA); Tueng Shen (University of Washington, Seattle, USA); Rajesh Shetty (Mayo Clinic, Minnesota, USA); Pamela Sieving (National Institutes of Health, Bethesda, USA); Juan Carlos Silva (Pan-American Health Organization, Columbia); Alex Silvester (St Paul's Eye Unit, Royal Liverpool University Hospital.Liverpool, UK); Rita S Sitorus (Department of Ophthalmology, Faculty of Medicine University of Indonesia, Depok, Indonesia); Dwight Stambolian (University of Pennsylvania, Philadelphia, USA); Gretchen Stevens (World Health Organization, Geneva, Switzerland); Hugh Taylor (Centre for Eye Research Australia, University of Melbourne, Melbourne, Australia); Jaime Tejedor (Hospital Raman y Cajal, Madrid, Spain); James Tielsch (Johns Hopkins Bloomberg School of Public Health, Baltimore, USA); Fotis Topouzis (University of Thessaloniki, Greece); Miltiadis Tsilimbaris (University of Crete Medical School. Crete); Jan van Meurs (The Rotterdam Eye Hospital and Erasmus University, Rotterdam, Netherlands); Rohit Varma (Department of Ophthalmology for Keck School of Medicine, University of Southern California, USA); Gianni Virgili (Department of Ophthalmology, University of Florence, Italy); Jimmy Volmink (Faculty of Health Sciences, Stellenbosch University, South Africa); Ya Xing Wang (Capital Medical University, Beijing, China); Ning-Li Wang (Eye Centre of Beijing Tongren Hospital, Beijing, China); Sheila West (Johns Hopkins Hospital, Baltimore, USA); Peter Wiedemann (Leipzig University, Leipzig, Germany); Tien Wong (University of Melbourne, Melbourne, Australia); Richard Wormald (Moorfields Eye Hospital, London); Yingfeng Zheng (Singapore Eye Research Institute, Singapore).

      • Contributors RRAB, MVC, AD, AJS, NT and TB prepared the vision impairment survey data. SRF and RRAB analysed the data. C-YC and TYW wrote the first draft of the report. RRAB oversaw the research.

      • Funding This study was funded by the Brien Holden Vision Institute. The results in this paper are prepared independently of the final estimates of the Global Burden of Diseases, Injuries and Risk Factors study. NC is supported by the Ulverscroft Foundation (UK), JK is supported by an institutional Research to Prevent Blindness Grant and Sight for Souls.

      • Competing interests JBJ: Consultant for Mundipharma Co. (Cambridge, UK); Patent holder with Biocompatibles UK Ltd. (Farnham, Surrey, UK) (Title: Treatment of eye diseases using encapsulated cells encoding and secreting neuroprotective factor and/or anti-angiogenic factor; Patent number: 20120263794), and Patent application with University of Heidelberg (Heidelberg, Germany) (Title: Agents for use in the therapeutic or prophylactic treatment of myopia or hyperopia; Europäische Patentanmeldung 15 000 771.4). JHK: consultant for Gilead (DSMC Chair), Santen (protocol design). SR: consultant for Brien Holden Vision Institute.

      • Patient consent for publication Not required.

      • Provenance and peer review Not commissioned; externally peer reviewed.

      • Data availability statement Data may be obtained from a third party and are not publicly available.