In 2020, the population of the Asia-Pacific (AP) region has reached about 4.3 billion,1 accounting for about 60% of the world population. Meeting the eye care needs of the people in the region is essential to improving patients’ quality of life by ensuring better educational outcomes and increased work productivity, and can lessen the social burden and promote productivity.2 Since the launch of the VISION 2020: The Right to Sight initiative in 1999 by the World Health Organization (WHO) and the International Agency for the Prevention of Blindness (IAPB), which aimed to eliminate avoidable blindness in the world by 2020, over 20 countries in the AP region have provided de facto or formal declarations of support for such initiative.3 Indeed, over the past 2 decades, major progress against the objectives of the initiative has been witnessed in the AP region. The demands, demographics, and disease spectrums in ophthalmic services in the region are nonetheless highly variable. For instance, the major ocular diseases that impose a threat to vision differ across countries and subregions, with cataracts being the major blinding disease in developing countries, whilst glaucoma and diabetic retinopathy are priority diseases in high-income countries. Therefore, it is of great importance to identify the major challenges faced by the region, and develop strategies to bring together ophthalmologists in the region to work together to improve the eye care delivery in the region whereas addressing the individual needs of all countries and subregions.
A Large and Rapidly Ageing Population
From a global perspective, the changing demographics of the world's population have been taking a toll in the fight against avoidable visual impairment.4 Flaxman et al revealed that despite a reduction in the prevalence of many major causes of blindness worldwide, there was a rise in the absolute number of patients who suffered from blindness and visual impairment due to population growth and aging.4 Eye diseases are commonly seen in elderly patients5 and the older population has been on the rise. According to the United Nations World Population Prospects 2019: Highlights,6 the population aged over 65 would nearly double from 2019, from 1 in 11 to 1 in 6. In addition, the total population aged over 80 will triple from 143 million in 2019 to 426 million in 2050. From 1990 to 2015, there was a 17.9% increase in the total number of blind patients and a 35.5% increase of patients suffering from moderate to severe visual impairment (MSVI). Population growth and aging contribute to over 30% of such rise in patients living with clinically significant vision loss globally.7
The AP region is home to more than half of the world's population, which per se would translate into a great demand for eye care services. As of 2015, most blind people or people with MSVI resided in South Asia, East Asia, and Southeast Asia.7 In these three subregions alone, the number of people with MSVI accounted for 62% of the estimated 216.6 million of people with MSVI worldwide: South Asia (61.2 million); East Asia (52.9 million); and Southeast Asia (20.8 million), whereas the number of blind people in these three subregions accounted for about 60% of the total (36 million).7
The AP region also has a rapidly aging population.8 In 2019, it was estimated that 60.1% of the world's older population aged above 60 resided in the AP region, and was projected to rise from an estimate of 548 million in 2019 to 1.3 billion by 2050 (Fig. 1).9
Old age is a major risk factor for sight-threatening diseases,11 and the increased number of patients suffering from significant visual impairment due to aging would create a huge burden for the healthcare system and society in this region.12 As reported by Flaxman et al, the age-standardized all-age prevalence of blindness caused by cataract, uncorrected refractive error, and glaucoma (top 3 leading causes of global blindness) were 0.17%, 0.1%, and 0.04% respectively, whereas such figures for populations aged 50 and above reached as high as 0.67%, 0.38%, and 0.16% respectively.4 Furthermore, in terms of number, populations aged 50 or above also constitute a majority of the visually impaired: 86% of the blind people (31/36 million), 80% of people with moderate and severe vision impairment (172.3/216.6 million), and 74% of people with mild vision impairment (140.3/188.5 million).7 With the forecast of a huge rise in old age population, the AP region would be faced with great challenges in catering for the eye care needs of such in the decades to come.
A Wide Disease Spectrum
The AP region represents a highly dynamic community with huge differences and discrepancies in economic development, population demographics, and social and cultural advancement. There would therefore be no surprise that specific needs in eye care services would differ between countries in the region (eFigure 1; https://links.lww.com/APJO/A110).13,14
Traditionally, cataract is a leading cause of blindness in the less developed countries in the region. Although prodigious improvements have been witnessed in both the volume and quality of cataract surgery over the past decades, the cataract surgery rate remained subpar for some less privileged countries in the region.15 Furthermore, new challenges also emerge as myopia and diabetic retinopathy become priority diseases in the region owing to lifestyle changes and social development.3 Contrary to cataract, which is a reversible cause of blindness, these emerging diseases could cause long-term complications and irreversible vision loss, and necessitate long-term care.15 The AP region should be prepared to continue tackling traditional challenges whilst advocating for the prevention and care of emerging diseases to aim for a holistic ophthalmic care for the population.
Myopia has emerged as a major health issue in the region. It was reported that high-income countries of the AP region have the highest overall prevalence of myopia, reaching 53.4%, with East Asia having the second-highest overall prevalence (51.6%).16 In addition, it was reported that in East Asia, the prevalence of myopia has now reached 80% to 90% in children who completed high school, and about 10% to 20% of them could develop high myopia, a sight-threatening condition.17 Morgan et al predicted that by 2100, China will have 700- to 800-million myopic population, and 100- to 200-million with high myopia.18 Myopia does not only represent a refractive error, but also a sight-threatening illness with the many associated complications leading to irreversible blindness. Of particular note, the productivity loss due to uncorrected myopia in Asia was reported to be more than twice that of other regions, and equivalent to more than 1% of gross domestic product.19
With the rapid urbanization of the AP region and the advent of sedentary and western lifestyle, the incidence of diabetes mellitus has an exponential rise.20 For instance, the prevalence of type 2 diabetes mellitus in South Asia is expected to rise by 150% from 2000 to 2035. This would without doubt lead to an enormous surge in diabetic retinopathy cases in the region. Currently the age-standardized all-age prevalence of MSVI caused by diabetic retinopathy is 0.06% in high-income countries of the AP region, which already doubles the global prevalence (0.03%).4 Furthermore, in China, the number of adult diabetic patients has reached 92.4 million, and the prevalence of diabetic retinopathy was 24.7% to 43.1% among diabetic patients,21 which could result in a heavy burden of blindness and vision impairment. The AP region will face the challenge of an incessant need for ophthalmologists and ally healthcare workers to provide for the specialized eye care needs of this region's population in the coming century, and will require effective policies, public health intervention, and patient education to mitigate and resolve such challenge (Fig. 2).
The AP region faces high prevalence of various blinding eye diseases. Not only the economically less developed subregions are suffering from a high prevalence of blindness and MSVI caused by cataract, uncorrected refractive error, and glaucoma, but high-income countries in the region also have a high prevalence of blindness and MSVI caused by age-related macular degeneration and diabetic retinopathy, indicating that the region needs to tackle both traditional challenges in preventing blindness, such as cataracts, and emerging causes of blindness, like diabetic retinopathy and myopia.
Imbalanced Distribution of Resources
The affordability and accessibility of eye care services are usually the lowest in low-income countries due to inadequate resource allocation, lack of national eye health policies or ineffective execution, and lack of human resources.22 The gross domestic product (GDP) per capita (US dollars, $) of the world is $11,526.7 in 2018. After excluding the high-income countries in the region, the figure for East Asia and the Pacific was $8,222, which was significantly below the global average.23 In addition, the GDP per capita in South Asia was only $1,959.9.23 Such discrepancy in financial status between countries in the AP region and developed countries could in turn lead to a discrepancy in quality and standard of the ophthalmic services, and hinder the prevention and eradication of blindness in the region.
It was reported that in 2015, there were about 232,866 ophthalmologists globally. However, the majority (two-thirds) of the global ophthalmologist population were located in 13 countries; among them, 10 are outside the AP region despite the aforementioned enormous demand for ophthalmic services.24 Resnikoff et al further revealed that the average number of ophthalmologists per million in population was much lower in low-income countries (9 per million) than that in high-income countries (79 per million).25 Within the AP region, the density of ophthalmologists also varies significantly between countries with different economic conditions. In 2015, Japan has reached over 114 ophthalmologists per million population25, which exceeded the goal set for Asian countries in the VISION 2020 initiative.26 However, a survey conducted in the Southeast Asia showed that only 4 out of 10 countries reached the target ophthalmologist-population ratio (1:100,000), and the urban-rural distribution is highly disproportionate with most ophthalmologists located in urban areas.27 Furthermore, assessment between 2014 and 2016 showed that 59% of low-income or low- to middle-income countries lacked a government plan for equitable geographical distribution of eye health workers.28 All in all, although the AP region is highly populous and an enormous need for eye care providers exists for such a population, this remains a currently unmet demand owing to socioeconomic factors. The suboptimal ophthalmologist-population ratio in many AP countries would hinder the AP region in achieving the VISION 2020 initiative and is a challenge to preventing blindness in the area (eFigure 2; https://links.lww.com/APJO/A111).25
COUNTERMEASURES AND STRATEGIES
It was reported that global blindness was responsible for about $27-billion loss of GDP in 2020, whereas financial loss caused by visual impairment was about $3 trillion.22 The latest report revealed that over 90% of vision impairment could have been prevented or can be treated.29 Given the serious challenges in the region, it appears crucial and cost-effective to take urgent and effective actions to halt further progression of the existing problems and to prevent the emergence of expected challenges. This could be achieved through various countermeasures and strategies, such as human resources building, appropriate distribution of eye care health workers (especially, the eye care needs of the underserved areas should be addressed), and collaboration among the countries within the regions.
It is reported that one of the major barriers to effective eye care delivery is the lack of human resources, in particular in Southeast Asia.30 As the saying goes, “Give a man fish and you feed him for a day. Teach a man to fish and you feed him for a lifetime.”. The ultimate solution to inadequate eye care services in the underserved areas is to upgrade the ophthalmic education and training instead of sending temporary medical teams to provide ophthalmic services.31 In addition, it has been reported that the number of the people aged 60 and above doubles the need for ophthalmologists in the region. Therefore, there is a great necessity to improve ophthalmic education and training to cope with expected increase in eye care needs even in regions currently with sufficient ophthalmologists.25 To achieve this goal, effective actions should be taken by both the government and the academic institutions to ensure that all parties could exercise their roles in improving the nurturing of the next generation of ophthalmologists. In addition, it is essential to establish regional collaborations to maximize the impact to this end.
Issues like scarcity of human resources need to be addressed at the national level with the involvement of the government. The policymakers should factor in the economy, disease burden, spectrum of blinding eye diseases, and the most cost-effective interventions, so that the national plans for human resources development could be effectively implemented.27 By identifying the gap between the needs of the people and available eye care resources, the government would be able to develop a national plan for eye care capacity building to narrow the gap and ensure appropriate distribution so that the services could be equally accessed, especially by the underprivileged, such as the females, the elderly, and minority ethnic groups.24,27
Introduction of advanced technologies and experience from developed countries could be one of the fastest ways to help promote the eye care services capacity in the developing and underdeveloped countries. Ophthalmologists from developing and underdeveloped countries should be properly exposed to training opportunities in developed countries, which will allow them to learn about the practice in developed countries, and bring back to their own countries more advanced techniques and establish cooperation between their own facilities and institutes in developed countries. As reported by Taraprasad Das et al, in their study on the eye care service delivery profile in Southeast Asia, cataract has been a severe challenge for years and effective interventions have been taken in many countries. Thus, the prevention and treatment of other emerging causes of blindness, such as glaucoma and diabetic retinopathy, should be prioritized, and the training of the ophthalmologists should also be aligned with that goal.27
Moreover, scholars from developed countries in the region should visit training facilities in developing and underdeveloped countries, so that they understand the equipment and human resources available, thereby adapting the curricula and design training courses according to local reality. In this regard, the involvement of the academic institutions plays a unique and irreplaceable role in identifying cost-effective training models (for not only the ophthalmologists but also the other eye caregivers including ophthalmic nurses, optometrists, and other allied eye care personal) and best practices in different settings, and in creating training and educational opportunities.32 Apart from the traditional ways, online education is now becoming a popular alternative, which maximizes the reach of the audience and minimizes the cost of learning. Currently most international, regional, and national ophthalmology congresses put online the lectures from the meeting for educational purposes. In addition, large ophthalmic organizations put other educational resources, such as guidelines for clinical practices, and share challenging cases on their websites. Apart from the training of academics, these organizations also provide various leadership development programs, visiting scholar programs, and mentorship programs to build up leadership and boost collaborations.33
Allocation and Integration of Resources
The disproportionate urban-rural distribution of eye care personnel is identified as a major barrier to the effective eye care delivery. Therefore, a key approach to universal eye health is to make both preventive and curative eye health services more accessible through an extensive national eye care network.30 For instance, in China, apart from the national-provincial-municipal three-tier eye care network, the county-township-village three-tier eye care network is also established to ensure the accessibility of eye care at grassroot level. By 2016, it was estimated that 90% of county-level hospitals had a separate ophthalmology department with 90% of them qualified to perform cataract surgery.34 Additionally, teleophthalmology is another approach that should be promoted given it ensures easier access to high-quality medical services in the less developed and underserved areas. Meanwhile, since patients will not have to travel to large cities, the cost of time, energy, and expense could be greatly reduced.
A previous study has reported that the burden of vision loss is related to national health expenditure metrics, indicating the planning, development, and implementation of the strategies at the national level is crucial to reducing the disease burden at a population level.22 Thus, an effective and feasible social welfare system including medical insurance system and national eye care programs that provide subsidies should be in place to improve the affordability of eye care services.30 From 1997 to 2007, the first and second phases of “SightFirst China Action”, a program led by the Chinese government and sponsored by Lions Clubs International, completed 5.03 million of cataract surgeries.35 In 2009, the Chinese government initiated the “Free Cataract Surgeries for A Million Poor Patients” project, in which, the government subsidized RMB800 for each surgery, and by 2013, 1.75 million cases were performed.36,37 Through these efforts, the cataract surgery rate in China has increased from 610 in 2007 to 2205 in 2017.36,37 In fact, previous studies already suggested that the government health expenditure from domestic sources should be about 5% of its GDP.22 In addition, although the training of local medical staff is the ultimate solution to the scarcity of medical resources in the underserved areas, these trained eye care personnel would still need the necessary infrastructure and support to carry out the work. Therefore, regular funding and support from the government or non-governmental organizations would be indispensable.38
Given the region faces both current and emerging causes of blindness,27 two sets of strategies should be adopted to address the issues. For traditional challenges in low-income and low-to-medium income countries, low-cost and accessible devices and practice patterns should be developed for surgically reversible eye diseases such as cataract, and for eye diseases that could be well controlled by medication. The research and development of generic drugs should be prioritized to make the medication more affordable and reduce the financial burden of the patients. In addition, the guidelines and policies adapted to fit the setting in these countries should be developed and advocated at national or regional meetings and symposiums. The regional and national academic organizations have played an important role in this. For instance, the Asia-Pacific Glaucoma Society developed the Asia-Pacific Glaucoma Guidelines and translated the Guidelines into several languages for its promotion in the region.
As for the emerging challenges with high potential for research and advancements, regional collaborations should be promoted to yield the most impacts, such as through multicenter genetic research on high myopia, which could also serve as an opportunity to develop research capacity in low-income countries and low- and middle-income countries. In addition, the establishment of consortiums, such as the Asian Eye Epidemiology Consortium, which collected data from more than 35 population-based studies originating from at least 10 different Asian countries,39 will allow researchers to collect sufficient data. The data could be used to characterize eye diseases in the region and deepen the understanding of the epidemiology of eye diseases (prevalence, distribution, incidence, and risk factors of both leading and less common conditions) to develop targeted strategies and take cause-targeted actions, which provide the most optimal treatments for patients. The large data could be used for machine learning, contributing to optimization of artificial intelligence model algorithm, which could be then applied to improve the efficiency of screening of fundus eye diseases and even formulation of follow-up plans (eFigure 3; https://links.lww.com/APJO/A112).39–46
Eye Health Literacy
A study by Haddad et al revealed improved awareness would lead to increased possibility of early detection and diagnosis, thereby avoiding preventable blindness and visual impairment.47 Meanwhile, it is crucial to realize that misconception about disease is just as, if not more, dangerous as the lack of awareness, as it deters people from seeking proper care even when they are aware of the conditions. For instance, previous studies showed that many parents believed that wearing spectacles will accelerate the progression of myopia, which has been a major reason for parents to be reluctant to get their children a pair of glasses.48 Since eye health literacy plays an essential role in eye health outcomes, given its influences on one's ability to take initiative and make informed decisions in health-seeking,49,50 targeted efforts to improve eye health literacy should be adopted to enable and empower patients to sustainably manage their eye health.
Though the importance of health education is well-recognized and both in print and online materials are widely available, the readers are often discouraged by the high complexity and low readability, hence, education materials must be developed to be easy to understand and fun to read.51 Improving the eye health literacy among children and adolescents might be more feasible than among adults, as health education is usually part of the school curricula, which would be an efficient way to instill such knowledge into the school-aged population.52 However, at a time of exploding information, it would be crucial to ensure that only the right message is delivered to the targeted audience. Social media has become the main information channel for most people. The press media and the ophthalmic communities should make joint efforts to ensure that wrong information that often goes viral online receives proper clarifications to avoid misinformation and myths being circulated among the laypeople. In addition, correct information ought to be disseminated in a way that fits the new ecology of the social platform, which favors vivid, interesting, and informal presentation over hard facts and lectures. Therefore, the new social media platforms and current hot topics should be utilized to attract more audience. Apart from health education for the general public, patient education is also an indispensable component of improving health literacy.53 Pamphlets and videos that convey clear and specific information should be always available at the waiting area of the clinic and in the wards, which could be the fastest way to help patients and their families understand what to expect and how to cooperate for better health outcomes.
Given the large and rapidly aging population, a high prevalence of blindness and visual impairment, and the wide disease spectrums in this socially and economically diverse region, the AP region is expected to face a multitude of challenges in the delivery of optimal ophthalmic services to satisfy the great demands of the population. To that end, countries within the region need to collaborate and identify strategies that ensure accessible and affordable quality eye care services and improve eye health literacy to maximize the impacts of the concerted efforts and guarantee that our patients receive the optimal care.
1. United Nations Population Fund. Population Trends. 2020. https://asiapacific.unfpa.org/en/node/15207
. Accessed November 18, 2020.
2. Burton MJ, Faal HB, Ramke J, et al. Announcing the lancet global health commission on global eye health. Lancet Glob Health
3. Pizzarello L, Abiose A, Ffytche T, et al. VISION 2020: The Right to Sight: a global initiative to eliminate avoidable blindness. Arch Ophthalmol
4. Flaxman SR, Bourne R, Resnikoff S, et al. Global causes of blindness and distance vision impairment 1990-2020: a systematic review and meta-analysis. Lancet Global Health
5. Hashemi H, Khabazkhoob M, Nabovati P, et al. The prevalence of age-related eye disease in an elderly population. Ophthalmic Epidemiol
6. United Nations, Department of Economic and Social Affairs, Population Division (2019). World Population Prospects 2019: Highlights. ST/ESA/SER.A/423. https://population.un.org/wpp/Publications/Files/WPP2019_10KeyFindings.pdf
. Accessed March 4, 2021.
7. Rra B, Flaxman SR, 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
8. United Nations Development Program. Asia-Pacific Human Development Report 2016: shaping the future - how changing demographics can power human development. https://www.undp.org/content/dam/rbap/docs/RHDR2016/RHDR2016-overview.pdf
. Accessed March 4, 2021.
9. United Nations Economics and Social Commission for Asia and the Pacific. Ageing Societies, 2019. Thailand: United Nations Economics and Social Commission for Asia and the Pacific. https://staging-legacy.unescap.org/our-work/social-development/ageing/about
. Accessed March 4, 2021.
10. United Nations, Department of Economic and Social Affairs, Population Division (2019). World Population Prospects 2019: Highlights
. Accessed March 4, 2021.
11. Resnikoff S, Pascolini D, Etya’Ale D, et al. Global data on visual impairment in the year 2002. Bull World Health Organ
12. Wang B, Congdon N, Bourne R, et al. Burden of vision loss associated with eye disease in China 1990-2020: findings from the Global Burden of Disease Study. Br J Ophthalmol
13. Zheng Y, Cheng CY, Lamoureux EL, et al. How much eye care services do Asian populations need? Projection from the Singapore Epidemiology of Eye Disease (SEED) study. Invest Ophthalmol Vis Sci
14. Taylor HR. Global Blindness: The progress we are making and still need to make. Asia Pac J Ophthalmol (Phila)
15. Wu PC, Huang HM, Yu HJ, et al. Epidemiology of myopia. Asia Pac J Ophthalmol (Phila)
16. Holden BA, Fricke TR, Wilson DA, et al. Global prevalence of myopia and high myopia and temporal trends from 2000 through. Ophthalmology
17. Morgan IG, Ohno-Matsui K, Saw S-M. Myopia. Lancet
18. Morgan IG. What public policies should be developed to deal with the epidemic of myopia? Optom Vis Sci
19. Naidoo KS, Fricke TR, Frick KD, et al. Potential lost productivity resulting from the global burden of myopia: systematic review, meta-analysis and modelling. Ophthalmology
20. Wong TY, Zheng Y, Jonas JB, et al. Prevalence and causes of vision loss in East Asia: 1990–2010. Br J Ophthalmol
21. Chinese National Committee for the Prevention of Blindness. Guidelines for the Prevention and Treatment of Diabetic Retinopathy in China (for Primary Medical Institutions). Beijing: People's Medical Publishing House; 2017.
22. Wang W, Yan W, Müller A, et al. Association of socioeconomics with prevalence of visual impairment and blindness. JAMA Ophthalmol
23. World Bank Open Data. World Bank Group. Source: World Bank national accounts data, and OECD National Accounts data files. License Type: CC BY-4.0. https://data.worldbank.org
. Accessed March 26, 2020.
24. Resnikoff S, Lansingh VC, Washburn L, et al. Estimated number of ophthalmologists worldwide (International Council of Ophthalmology update): will we meet the needs? Br J Ophthalmol
25. Resnikoff S, Felch W, Gauthier TM, et al. The number of ophthalmologists in practice and training worldwide: a growing gap despite more than 200 000 practitioners. Br J Ophthalmol
26. Thylefors B. A global initiative for the elimination of avoidable blindness. Community Eye Health
27. Das T, Ackland P, Correia M, et al. Is the 2015 eye care service delivery profile in Southeast Asia closer to universal eye health need!. Int Ophthalmol
28. World Health Organisation. World Report on Vision. Geneva: World Health Organization; 2019. Licence: CC BY-NC-SA 3.0 IGO. 2021. https://apps.who.int/iris/rest/bitstreams/1257940/retrieve
. World Report on Vision.
29. Burton MJ, Ramke J, Marques AP, et al. The Lancet Global Health Commission on Global Eye Health: vision beyond. Lancet Glob Health
. Accessed April 6, 2020.
30. Das T. Blindness and visual impairment profile and rapid assessment of avoidable blindness in South East Asia: Analysis of New Data. 2017 APAO Holmes Lecture. Asia Pac J Ophthalmol (Phila)
31. Lam DS, Martin FJ, Tham CC. APAO's commitment to ophthalmic education. Asia Pac J Ophthalmol (Philadelphia, Pa)
32. Golnik K, Mayorga E, Spivey B, et al. International Council of Ophthalmology: Refocusing Ophthalmic Education in the Asia-Pacific Region and Beyond. Asia Pac J Ophthalmol (Phila)
33. Asia-Pacific Academy of Ophthalmology. Asia-Pacific Academy of Ophthalmology. https://www.apaophth.org
. Accessed June 2, 2020.
34. National Health Commission of the People's Republic of China. Notice of the Release of 13th Five-Year National Plan on Eye Health by National Health Commission. Bureau of Medical Administration of National Health Commission of the People's Republic of China. 2016. http://www.nhc.gov.cn/cms-search/xxgk/getManuscriptXxgk.htm?id=1513ba075e1842e993337d0cee6dab0b
. Accessed March 4, 2021.
35. Guan HJ. Present status and development of prevention of blindness and ophthalmic epidemiologic studies in China. Zhonghua Yan Ke Za Zhi
36. Zhao JL. Review and outlook of the eye health in China. Zhonghua Yan Ke Za Zhi
2018; 54:561–564. Chinese.
37. He X, Zhang R, Li Y, et al. Review and future direction of eliminating cataract blindness in China. Chin J Ophthalmol
38. Taylor HR. Latest developments and advances in the prevention of blindness, a global perspective. J Curr Ophthalmol
39. Rim TH, Ryo K, Tham YC, et al. Prevalence and pattern of geographic atrophy in asia: The Asian Eye Epidemiology Consortium. Ophthalmology
40. Mitchell P, Cumming RG, Attebo K, et al. Prevalence of cataract in Australia: the Blue Mountains eye study. Ophthalmology
41. Shah SP, Jadoon MZ, Dineen B, et al. Refractive errors in the adult pakistani population: the national blindness and visual impairment survey. Ophthalmic Epidemiol
42. Kang MT, Li SM, Li H, et al. Peripapillary retinal nerve fibre layer thickness and its association with refractive error in Chinese children: the Anyang Childhood Eye Study. Clin Exp Ophthalmol
43. Zhu D, Wang Y, Zheng YF, et al. Choroidal thickness in school children: the gobi desert children eye study. PLoS One
2017; 12:e0179579doi: 10.1371/journal.pone.0179579.
44. Foreman J, Keel S, Xie J, et al. Adherence to diabetic eye examination guidelines in Australia: the National Eye Health Survey. Med J Aust
45. Sherwin JC, Hewitt AW, Kearns LS, et al. Distribution of conjunctival ultraviolet autofluorescence in a population-based study: the Norfolk Island Eye Study. Eye (Lond)
46. Wang L, Zhao Y, Han X, et al. Five-year visual outcome among people with correctable visual impairment: the Liwan Eye Study. Clin Exp Ophthalmol
47. Haddad MF, Bakkar MM, Abdo N. Public awareness of common eye diseases in Jordan. BMC Ophthalmol
2017; 17:177doi: 10.1186/s12886-017-0575-3.
48. Li L, Lam J, Lu Y, et al. Attitudes of students, parents and teachers toward glasses use in rural China. Arch Ophthalmol
49. Warren M, DeCarlo DK, Dreer LE. Health literacy in older adults with and without low vision. Am J Occup Ther
2016; 70:7003270010p1-7doi: 10.5014/ajot.2016.017400.
50. Sorensen K, Van den Broucke S, Fullam J, et al. Health literacy and public health: a systematic review and integration of definitions and models. BMC Public Health
2012; 12:80doi: 10.1186/1471-2458-12-80.
51. Williams AM, Muir KW, Rosdahl JA. Readability of patient education materials in ophthalmology: a single-institution study and systematic review. BMC Ophthalmol
2016; 16:133doi: 10.1186/s12886-016-0315-0.
52. Burnett AM, Yashadhana A, Lee L, et al. Interventions to improve school-based eye-care services in low- and middle-income countries: a systematic review. Bull World Health Organ
53. Jandorf S, Krogh Nielsen M, Sorensen K, et al. Low health literacy levels in patients with chronic retinal disease. BMC Ophthalmol
2019; 19:174doi: 10.1186/s12886-019-1191-1.