A pooled data analysis of the available evidence, published online in the British Journal of Ophthalmology, estimates that around one in three children and teenagers around the world is myopic, with the global prevalence of myopia set to top 740 million cases by 2050 in this age group (age five to 19 years).
The findings also indicated that female sex, East Asian or urban area residence, and educational level were key factors influencing prevalence.
To obtain an up-to-date picture, with a view to informing healthcare policy and preventive efforts, the researchers drew on relevant research and government reports published up to June 2023. A total of 276 studies, involving 5,410,945 children and teenagers and 1,969,090 cases of myopia, from 50 countries in Asia, Europe, Africa, Oceania, North and Latin America were included. Geographical, temporal and other variables were considered.
Their analysis revealed that overall prevalence rose from 24 per cent in 1990-2000 to 25 per cent in 2001-10, to 30 per cent in 2011-19, and to 36 per cent in 2020-23.
While the prevalence among teenagers surpassed that of children, peaking at 54 per cent during 2020-23, the increase among children from 1990 to 2023 was nearly twice that of teenagers.
Prevalence was found to be significantly higher in low to middle income countries than in high income countries, and was highest in Japan and lowest in Paraguay between 1990 and 2023.
Certain factors were associated with a higher prevalence, notably residence in East Asia (35 per cent) or in urban areas (29 per cent), female sex (34 per cent), adolescence (47 per cent), and high (secondary) school education (46 per cent).
Based on the figures and trends up to 2023, the researchers estimated that overall global myopia prevalence would reach around 40 per cent by 2050, exceeding 740 million cases, up from 600 million in 2030.
It is expected to be higher among girls and young women than among boys and young men: 33 vs 31 per cent in 2030; 40 vs 35.5 per cent in 2040; and 42 vs 37.5 per cent, respectively, in 2050.
And it is expected to be significantly higher among 13 to 19-year-olds than among six to 12-year-olds, with projected rates of 43 vs 21 per cent in 2030, 49 vs 24 per cent in 2040, and 52.5 vs 27.5 per cent, respectively, in 2050.
Asia is expected to have the highest prevalence of all, with rates of 52 per cent in 2030, 62 per cent in 2040, and 69 per cent in 2050.
The Covid-19 pandemic may have had a role in the sharp increase after 2020 the researchers suggested, stating: “Emerging evidence suggests a potential association between the pandemic and accelerated vision deterioration among young adults.”
By way of an explanation for the geographical differences, they posited that people in East and South Asia had experienced rapid economic development along with the steepest rise in myopia prevalence.
“The elevated incidence of myopia observed in the Asian population, particularly among younger children, as compared with other regions, could potentially account for the observed ethnic disparity,” they wrote. “Moreover, a correlation between the duration of education and the occurrence of myopia has been observed, suggesting that the early implementation of formal education in certain East Asian nations could potentially serve as a contributing element.
“Conversely, African populations exhibit a lower prevalence of myopia, likely attributed to lower literacy rates and delayed initiation of formal education, typically occurring between the ages of six to eight years for most children,” they explained.
The researchers acknowledged various limitations to their findings, including the variable quality and considerable differences in the design and methodology of the studies included in their pooled data analysis. The definitions and assessments of myopia also varied widely.
They stated: “Despite these known limitations, given the large sample size included, our estimates of the prevalence of myopia are considered to be close to the precise number. It is crucial to recognise that myopia may become a global health burden in the future.”