A worrying upward trend in myopia cases that leads to even more than 50% global prevalence?
The latest research on the prevalence of myopia in children and adolescents reveals that global myopia rates are projected to affect around 40% of young people by 2050, with nearly 740 million cases expected. This aligns closely with the 2016 WHO report led by Holden, which predicted that 50% of the global population would be myopic by 2050, potentially reaching nearly 5 billion people.
The study by Liang J, et al (1)., considers children and adolescents in this prediction. The WHO study (2) suggested that 50% of the whole population would by myopic by 2050. Does that mean, with a growing population, that there could be more than 50% of people with myopia by 2050?
We know that birth rates are, in general, falling(3), though this will vary from region to region. Sub-Saharan Africa is likely to see large rises in population for decades to come. Currently, around 660 million people are over 60 around the world, but this is likely to rise to over 2 billion by 2050 (4, 5).
India’s population is likely to grow above China’s and may reach 1.7 billion people by 2050 (6). What proportion of those older people will be myopic?
We know that Asia will see population growth, despite reducing birth rates (7). We also know that the highest prevalence of myopia occurs in East and Southeast Asia (8), but rates are growing in India too (9).
However, rates in Africa are expected to be much lower, even in 2050 (10).
Could the proportional shift of demographics, despite the high prevalence of myopia in the hugely populated areas of Asia, balance the global prevalence of myopia? The overall proportion of the global population is changing, and Africa will make up an increasing proportion of the whole figure (Fig. 1). It’s also likely that Africa’s myopia prevalence will be much lower than Asian figures.
But some parts of South-East Asia have myopic prevalences over 80% now. Many of these people will be over 60 by 2050. Will their children and grandchildren have even higher rates of myopia?
Will Africa ‘balance’ this effect and lower the overall global prevalence? Does it matter?
Ultimately, probably not, but it does raise interesting questions about how the growing population will live. Increasingly, more and more people will live in overcrowded cities. Children will, inevitably, spend less time outdoors or in green spaces (11). This is the risk. If the growing African and Indian populations see effects like those in Southeast Asia (but without the same genetic predisposition to myopia), could that start to create a worrying upward trend in myopia cases that leads to even more than 50% global prevalence?
If that is the case, it poses important questions for the World’s health authorities, as it could suggest more people are at risk of sight-threatening conditions secondary to high myopia.
References
Liang J, Pu Y, Chen J, et al. Br J Ophthalmol Epub ahead of print: 22/10/2024 doi:10.1136/bjo-2024-325427.
Brien A. Holden, Timothy R. Fricke, David A. Wilson, Monica Jong, Kovin S. Naidoo, Padmaja Sankaridurg, Tien Y. Wong, Thomas J. Naduvilath, Serge Resnikoff, Global Prevalence of Myopia and High Myopia and Temporal Trends from 2000 through 2050, Ophthalmology, Volume 123, Issue 5, 2016, Pages 1036-1042.
Martin, J., Hamilton, B., Osterman, M., & Driscoll, A. (2021). Births: Final Data for 2019. National vital statistics reports: from the Centres for Disease Control and Prevention, National Centre for Health Statistics, National Vital Statistics System, 70 2, 1-51.
Rich, P. (2005). The World in 2050. Review of Policy Research, 22, 753-753. https://doi.org/10.1111/J.1541-1338.2005.00173.X.
Lee, R. (2011). The Outlook for Population Growth. Science, 333, 569 - 573. https://doi.org/10.1126/science.1208859.
Liu, H., Fang, C., Miao, Y., Ma, H., Zhang, Q., & Zhou, Q. (2018). Spatio-temporal evolution of population and urbanization in the countries along the Belt and Road 1950–2050. Journal of Geographical Sciences, 28, 919-936. https://doi.org/10.1007/s11442-018-1513-x.
Zhang, W. (2008). A forecast analysis on world population and urbanization process. Environment, Development and Sustainability, 10, 717-730. https://doi.org/10.1007/S10668-007-9081-8.
Dong, L., Kang, Y., Li, Y., Wei, W., & Jonas, J. (2020). PREVALENCE AND TIME TRENDS OF MYOPIA IN CHILDREN AND ADOLESCENTS IN CHINA: A Systemic Review and Meta-Analysis. Retina. https://doi.org/10.1097/IAE.0000000000002590.
Agarwal, D., Saxena, R., Gupta, V., Mani, K., Dhiman, R., Bhardawaj, A., & Vashist, P. (2020). Prevalence of myopia in Indian school children: Meta-analysis of last four decades. PLoS ONE, 15. https://doi.org/10.1371/journal.pone.0240750.
Ovenseri-Ogbomo, G., Osuagwu, U., Ekpenyong, B., Agho, K., Ekure, E., Ndep, A., Ocansey, S., Mashige, K., Naidoo, K., & Ogbuehi, K. (2022). Systematic review and meta-analysis of myopia prevalence in African school children. PLoS ONE, 17. https://doi.org/10.1371/journal.pone.0263335.
Peng BA, Naduvilath T, Flitcroft DI, Jong M. Is myopia prevalence related to outdoor green space? Ophthalmic Physiol Opt. 2021; 41: 1371–1381. https://doi.org/10.1111/opo.12896.
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