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BACKGROUND: Myopia is a pervasive global public health concern, particularly among the younger population. However, the escalating prevalence of myopia remains uncertain. Hence, our research aims to ascertain the global and regional prevalence of myopia, along with its occurrence within specific demographic groups. METHODS: An exhaustive literature search was performed on several databases covering the period from their inception to 27 June 2023. The global prevalence of myopia was determined by employing pooled estimates with a 95% CI, and further analysis was conducted to assess variations in prevalence estimates across different subgroups. Additionally, a time series model was utilised to forecast and fit accurately the future prevalence of myopia for the next three decades. RESULTS: This study encompasses a comprehensive analysis of 276 studies, involving a total of 5 410 945 participants from 50 countries across all six continents. The findings revealed a gradual increase in pooled prevalence of myopia, ranging from 24.32% (95% CI 15.23% to 33.40%) to 35.81% (95% CI 31.70% to 39.91%), observed from 1990 to 2023, and projections indicate that this prevalence is expected to reach 36.59% in 2040 and 39.80% in 2050. Notably, individuals residing in East Asia (35.22%) or in urban areas (28.55%), female gender (33.57%), adolescents (47.00%), and high school students (45.71%) exhibit a higher proportion of myopia prevalence. CONCLUSION: The global prevalence of childhood myopia is substantial, affecting approximately one-third of children and adolescents, with notable variations in prevalence across different demographic groups. It is anticipated that the global incidence of myopia will exceed 740 million cases by 2050.
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Background: The 24-Hour Movement Guidelines (24-HMG) recommend a balanced combination of physical activity (PA), sedentary behavior (SB) and sleep (SLP) for optimal health. However, there is limited understanding of how well U.S. adolescents adhere to these guidelines. This study aims to analyze the prevalence trends of meeting the 24-HMG among a nationally representative sample of U.S. general adolescents. Methods: The study included 2,273 adolescents (55.3% boys) aged 16-19 who participated in the National Health and Nutrition Examination Surveys (NHANES) from 2007 to 2016. The researchers categorized the adolescents based on whether they met various PA, SB, and SLP recommendations, as well as different combinations of these recommendations, separately for boys and girls. The prevalence rate, weighted by survey data, was calculated along with a 95% confidence interval (CI) to assess the changes in meeting the 24-HMG among U.S. adolescents across different survey years and sociodemographic subgroups. Results: In the 2015-2016 cycle, approximately 6.3% of adolescents did not meet any of the three recommendations, while only 19.2% of adolescents achieved all three guidelines. Compliance with PA and SB recommendations among adolescents has decreased over time, from 72.5% (65.9% to 79.2%) to 64.2% (57.4% to 70.9%) for PA, and from 59.0% (49.6% to 68.4%) to 46.6% (37.8% to 55.5%) for SB, respectively, from 2007-2008 cycle to 2015-2016 cycle. Boys exhibited more favorable patterns in meeting different sets of recommendations compared to girls (p-value <0.001). This includes meeting both PA and SB guidelines (15.5% for boys and 11.1% for girls) and meeting both PA and SLP guidelines (19.5% for boys and 15.7% for girls). The level of parental education was found to have effect on meeting all three guidelines (Ptrend < 0.05). Conclusion: We analyzed ten consecutive years of representative NHANES data to evaluate the prevalence meeting 24-HMG and found that the proportion of adolescents aged 16-19 in the U.S. who adhered to all three movement guidelines simultaneously has consistently remained low throughout each survey cycle. Notably, there has been a significant decline in the proportion of adolescents meeting the SB guideline.