Physical activity and myopia in Danish children-The CHAMPS Eye Study

Myopia prevalence, refractive status and uncorrected myopia among primary and secondary school students in Germany

Introduction

The increasing prevalence of myopia worldwide is problematic because myopia can result in severe secondary pathologies, and is associated with considerable financial burden. With plenty of prevalence data available for some regions, current data for Europe remain sparse. Yet, information on myopia prevalence and associations is essential for monitoring, preventive and interventive purposes. Likewise, uncorrected refractive errors are also critical, as they can, e.g., affect educational outcomes, making information on uncorrected myopia valuable for diagnostics and health education.

Methods

We performed non-cycloplegic autorefraction on two samples in Germany. The younger sample included 489 primary school students (grades 3-4, mean age: 9.30 ± 0.78 years), the older sample 1,032 secondary school students (grades 8-10, mean age 14.99 ± 1.12 years). These samples mark the limits of the age range during which school myopia usually emerges.

Results

Myopia (spherical equivalent ≤ -0.75D) prevalence was 8.4% in the younger sample and 19.5% in the older sample. The prevalence was generally higher in higher grade levels, with the most notable difference between grades 8 and 9. Females were more myopic than males in all grades except grade 3, with the largest gender difference in grade 10. The older sample also exhibited a more myopic spherical equivalent than the younger sample. In the older sample, spherical equivalent was more myopic in females than in males, and in grade 9 and 10 participants more than in grade 8 participants. Rates of uncorrected myopia were extremely high: 51.2% in the younger sample and 43.3% in the older sample.

Discussion

The obtained myopia prevalence rates are generally consistent with other European studies, as is the higher prevalence in female than male adolescents, accelerating with age. The high rates of uncorrected myopia warrant further investigation and should inform public health policies, including the implementation of regular refractive screenings.

Factors associated with myopia in the Portuguese child population: An epidemiological study

PURPOSE

Myopia, a leading cause of correctable visual impairment, is projected to affect nearly 50% of the global population by 2050, posing a significant public health challenge. Understanding its prevalence and associated factors, particularly in children, is crucial for devising prevention and intervention strategies. This study aims to determine the proportion of myopia in school-aged children in Portugal and to examine the correlation between myopia occurrence and various environmental and genetic factors.

METHODS

A cross-sectional epidemiological study was conducted on children aged from 5 to 17 years from nine schools in Lisbon, Portugal, between September 2020 and May 2021. It included optometric assessments to evaluate refractive status and binocular vision, as well as questionnaires about their lifestyles and parental myopia.

RESULTS

Out of 1992 participants enrolled, 12.7% of the children were found to be myopic. The proportion of myopia increased with age and was higher in girls. A significant association was observed between myopia and parental history, with the likelihood being higher if one or both parents were myopic. Engaging in outdoor activities was associated with a lower likelihood of myopia.

CONCLUSIONS

The study found that 12.7% of the children in the study sample, aged 5-17 years, were myopic, indicating a significant association with familial history and limited outdoor activities. These insights highlight the need for targeted myopia screening and prevention strategies in the paediatric population.

Objective Refraction Status before and after Cycloplegia: From Childhood to Young Adulthood

This study aimed to evaluate the clinical information revealed after cycloplegia and assess how age and non-cycloplegic refractive status influence the classification of types of refractive error, as well as the relationship between age and cycloplegia-induced changes in the power of refractive errors. We analysed the records of 472 non-population-based ophthalmology practice patients aged 3-28 years (mean ± SD: 9.1 ± 4.6). Cycloplegia was induced with one drop of cyclopentolate 1% in each eye, and eye refraction was measured 30 ± 5 min later using an objective autorefractometer. Cycloplegia induced a clinically significant (≥0.50 D) hyperopic shift in the spherical equivalent of 60.2% of participants and a myopic shift in 1%, resulting in a 34.1% increase in the frequency of participants with hyperopia, while the frequency of those with myopia and emmetropia decreased by 5.5% and 23.3%, respectively. The average spherical equivalent difference (mean ± SD) induced by cycloplegia was 0.72 ± 0.73 D, with the highest difference observed in the 3-5 years age group (1.18 ± 0.85 D). The differences in astigmatism power (p = 0.84) and astigmatism axis (p = 0.97) between non-cycloplegic and cycloplegic conditions were not statistically significant.

Causal relationships between height, screen time, physical activity, sleep and myopia: univariable and multivariable Mendelian randomization

Background

This study aims to investigate the independent causal relation between height, screen time, physical activity, sleep and myopia.

Methods

Instrumental variables (IVs) for exposures and outcome were obtained from the largest publicly available genome-wide association studies (GWAS) databases. First, we performed a bidirectional univariate MR analysis using primarily the inverse variance weighted method (IVW) with height, screen time, physical activity and sleep as the exposure and myopia as the outcome to investigate the causal relationship between exposures and myopia. Sensitivity analysis was used to demonstrate its robustness. Then the multivariable MR (MVMR) and MR-based mediation approach was further used to estimate the mediating effect of potential confounders (education and time outdoors) on causality.

Results

The results of univariate MR analysis showed that taller height (OR = 1.009, 95% CI = 1.005-1.012, p = 3.71 × 10-7), longer time on computer (OR = 1.048, 95% CI = 1.029-1.047, p = 3.87 × 10-7) and less moderate physical activity (OR = 0.976, 95% CI = 0.96-0.991 p = 2.37 × 10-3) had a total effect on the increased risk of developing myopia. Meanwhile our results did not have sufficient evidence to support the causal relationship between chronotype (p = 0.637), sleep duration (p = 0.952) and myopia. After adjusting for education, only taller height remains an independent risk factor for myopia. After adjusting for education, the causal relationship between height, screen and myopia still had statistical significance. A reverse causal relationship was not found in our study. Most of the sensitivity analyses showed consistent results with those of the IVW method.

Conclusion

Our MR study revealed that genetically predicted taller height, longer time on computer, less moderate physical activity increased the risk of myopia. After full adjustment for confounders, only height remained independently associated with myopia. As a complement to observational studies, the results of our analysis provide strong evidence for the improvement of myopia risk factors and provide a theoretical basis for future measures to prevent and control myopia in adolescents.

Myopia Prevalence in Latin American Children and Adolescents: A Systematic Review and Meta-Analysis

Although myopia is a growing global concern, comprehensive studies on its prevalence among Latin American (LATAM) children and adolescents are still lacking. Thus, we conducted a systematic review and meta-analysis to determine the prevalence of myopia in LATAM children and adolescents aged three to 20. The study conducted a thorough literature search from January 1, 1975, to February 28, 2023, identifying 24 studies on the prevalence of myopia in LATAM that met the inclusion criteria. Quality assessment and standardized data collection were performed. The meta-analysis used a random-effects model due to heterogeneity and calculated prevalence rates. Finally, the analysis of data from 24 eligible studies revealed a myopia prevalence of 8.61% (range 0.80-47.36%, 95% confidence interval (CI): 5.22-13.87%, p < 0.05) among 165,721 LATAM children and adolescents. No significant age-based associations or temporal trends were observed in this study. Studies with non-cycloplegic or objective assessment exhibited a numerically higher, although statistically non-significant, myopia prevalence (10.62%, 95% CI: 4.9-21.6%) compared to studies using cycloplegia (7.17%, 95% CI: 3.40-14.50%). In conclusion, myopia affects approximately one in 11 LATAM children and adolescents. Given the increasing exposure of LATAM youth to known myopia risk factors, such as extensive near-work, online learning, and limited outdoor activities, it is crucial to monitor myopia trends in this region. Further research is imperative to address and prevent myopia in LATAM.

Development and validation of a smartwatch algorithm for differentiating physical activity intensity in health monitoring

To develop and validate a machine learning based algorithm to estimate physical activity (PA) intensity using the smartwatch with the capacity to record PA and determine outdoor state. Two groups of participants, including 24 adults (13 males) and 18 children (9 boys), completed a sequential activity trial. During each trial, participants wore a smartwatch, and energy expenditure was measured using indirect calorimetry as gold standard. The support vector machine algorithm and the least squares regression model were applied for the metabolic equivalent (MET) estimation using raw data derived from the smartwatch. Exercise intensity was categorized based on MET values into sedentary activity (SED), light activity (LPA), moderate activity (MPA), and vigorous activity (VPA). The classification accuracy was evaluated using area under the ROC curve (AUC). The METs estimation accuracy were assessed via the mean absolute error (MAE), the correlation coefficient, Bland-Altman plots, and intraclass correlation (ICC). A total of 24 adults aged 21-34 years and 18 children aged 9-13 years participated in the study, yielding 1790 and 1246 data points for adults and children respectively for model building and validation. For adults, the AUC for classifying SED, MVPA, and VPA were 0.96, 0.88, and 0.86, respectively. The MAE between true METs and estimated METs was 0.75 METs. The correlation coefficient and ICC were 0.87 (p < 0.001) and 0.89, respectively. For children, comparable levels of accuracy were demonstrated, with the AUC for SED, MVPA, and VPA being 0.98, 0.89, and 0.85, respectively. The MAE between true METs and estimated METs was 0.80 METs. The correlation coefficient and ICC were 0.79 (p < 0.001) and 0.84, respectively. The developed model successfully estimated PA intensity with high accuracy in both adults and children. The application of this model enables independent investigation of PA intensity, facilitating research in health monitoring and potentially in areas such as myopia prevention and control.

Two-Year Results of 0.01% Atropine Eye Drops and 0.1% Loading Dose for Myopia Progression Reduction in Danish Children: A Placebo-Controlled, Randomized Clinical Trial

We investigated the two-year safety and efficacy of 0.1% loading dose and 0.01% low-dose atropine eye drops in Danish children for reduction in myopia progression in an investigator-initiated, placebo-controlled, double-masked, randomized clinical trial. Ninety-seven six- to twelve-year old myopic participants were randomized to 0.1% loading dose for six months and then 0.01% for eighteen months (loading dose group, N = 33), 0.01% for two years (0.01% group, N = 32) or placebo for two years (placebo, N = 32). Axial length (AL) and spherical equivalent refraction (SER) were primary outcomes. Secondary outcomes included adverse events and reactions, choroidal thickness, and other ocular biometrical measures. Outcomes were measured from baseline and at six-month intervals. Individual eyes nested by participant ID were analyzed with linear-mixed model analysis. Data were analyzed with intention-to-treat. Mean AL was 0.08 mm less (95% confidence interval (CI): -0.01; 0.17, p-value = 0.08) in the 0.1% loading dose and 0.10 mm less (95% CI: 0.01; 0.19, p-value = 0.02) in the 0.01% group after two years of treatment compared to placebo. Mean SER progression was 0.12 D (95% CI: -0.10; 0.33) less in the loading dose and 0.26 D (95% CI: 0.04; 0.48) less in the 0.01% groups after two years of treatment compared to placebo (p-value = 0.30 and 0.02, respectively). In total, 17 adverse events were reported in the second-year follow-up, and all were rated as mild. Adjusting for iris color did not affect treatment effect estimates. Intra-ocular pressure increased over two years comparably between all groups but remained within normal limits. Two-year treatment with 0.01% low-dose atropine eye drops is a safe and moderately efficacious intervention in Danish children for reducing myopia progression.

The influence of the environment and lifestyle on myopia

BACKGROUND

Myopia, commonly known as near-sightedness, has emerged as a global epidemic, impacting almost one in three individuals across the world. The increasing prevalence of myopia during early childhood has heightened the risk of developing high myopia and related sight-threatening eye conditions in adulthood. This surge in myopia rates, occurring within a relatively stable genetic framework, underscores the profound influence of environmental and lifestyle factors on this condition. In this comprehensive narrative review, we shed light on both established and potential environmental and lifestyle contributors that affect the development and progression of myopia.

MAIN BODY

Epidemiological and interventional research has consistently revealed a compelling connection between increased outdoor time and a decreased risk of myopia in children. This protective effect may primarily be attributed to exposure to the characteristics of natural light (i.e., sunlight) and the release of retinal dopamine. Conversely, irrespective of outdoor time, excessive engagement in near work can further worsen the onset of myopia. While the exact mechanisms behind this exacerbation are not fully comprehended, it appears to involve shifts in relative peripheral refraction, the overstimulation of accommodation, or a complex interplay of these factors, leading to issues like retinal image defocus, blur, and chromatic aberration. Other potential factors like the spatial frequency of the visual environment, circadian rhythm, sleep, nutrition, smoking, socio-economic status, and education have debatable independent influences on myopia development.

CONCLUSION

The environment exerts a significant influence on the development and progression of myopia. Improving the modifiable key environmental predictors like time spent outdoors and engagement in near work can prevent or slow the progression of myopia. The intricate connections between lifestyle and environmental factors often obscure research findings, making it challenging to disentangle their individual effects. This complexity underscores the necessity for prospective studies that employ objective assessments, such as quantifying light exposure and near work, among others. These studies are crucial for gaining a more comprehensive understanding of how various environmental factors can be modified to prevent or slow the progression of myopia.

Associations of school physical activity environment with comorbid obesity and myopia in children and adolescents: Findings from a Chinese national follow-up study

BACKGROUND

Overweight and obesity (OWOB) and myopia have become two of the most important issues affecting the health of children and adolescents worldwide. Despite the recognition that the school physical activity (PA) environment is a critical factor for preventing and controlling overweight, obesity (OWOB), and myopia in children and adolescents, research on OWOB and myopia as a comorbidity remains unexplored, with evidence for effective strategies still being inconclusive. Hence, this study aimed to assess the prevalence and progression of comorbid OWOB/myopia and each condition alone, and to explore the association with school PA environment.

METHODS

A total of 9814 children and adolescents aged 6-18 years were included from the Chinese National Survey on Students' Constitution and Health follow-up survey conducted from November 2019 to November 2020 in China. Anthropometric measurements, unaided distance vision acuity and non-cycloplegic refraction data were collected to assess OWOB and myopia, while eight indicators from questionnaires for children and adolescents aged 9-18 years were investigated to assess school PA environment. We calculated the one-year incidence and progression rates of comorbid OWOB/myopia, OWOB alone, and myopia alone. Mixed effect logistic regression was evaluated the association between school PA environment and incidence and progression of comorbid OWOB/myopia, OWOB, and myopia.

RESULTS

The prevalence of comorbid OWOB/myopia increased from 11.1% in 2019 to 17.9% in 2020, and the incidence of comorbid OWOB/myopia was 10.9%. Children and adolescents experiencing an unfavorable school PA environment had a higher risk of the incidence of comorbid OWOB/myopia compared to a favorable school environment (OR = 1.85, 95% CI: 1.42-2.42). Similar findings were seen in the incidence of obesity (OR = 1.86, 95% CI: 1.26-2.75). Children and adolescents in an unfavorable school PA environment had a higher risk of myopia progression (OR = 1.29, 95% CI: 1.01-1.65).

CONCLUSIONS

Obesity and myopia and their comorbidity have been serious among children and adolescents in China. A favorable school PA environment might mitigate the risk of comorbid OWOB/myopia, OWOB, and myopia progression.

An empirical study on the effect of outdoor illumination and exercise intervention on Children's vision

Objective

To explore the relationship between outdoor lighting and sports and the development of myopia, and to analyze the effects of outdoor lighting and exercise on the diopter of children with normal vision and myopia, so as to provide guidance for the prevention and treatment of myopia in children and adolescents in the future.

Methods

A total of 201 children were divided into two groups according to myopia or not. Each group was randomly divided into 4 groups: outdoor exercise group, outdoor control group, indoor exercise group and indoor control group. Among them, the outdoor exercise group and indoor exercise group received moderate and high intensity aerobic exercise 3 times a week for 60 min each time for 12 months, while the outdoor control group and indoor control group had normal study and life during the corresponding period of time. No additional exercise intervention. At the end of the experiment, the diopter of each group was compared.

Results

The diopter of all groups with normal vision and myopia decreased significantly after the experiment (p < 0.01). There were significant differences in diopter between outdoor exercise group and indoor control group (p < 0.01), between outdoor exercise group and indoor control group (p < 0.05), and between indoor exercise group and indoor control group (p < 0.01). There were significant differences in diopter between indoor exercise group and indoor control group (p < 0.01). The differences among myopic children after the experiment showed that there was significant difference in diopter between outdoor exercise group and indoor exercise group (p < 0.05), between outdoor exercise group and indoor control group (p < 0.01), and between outdoor control group and indoor control group (p < 0.05). There were significant differences in the changes of diopter between the outdoor control group and the indoor exercise group with normal vision and myopia before and after the experiment (p < 0.05).

Conclusion

Outdoor light and exercise intervention can have a beneficial effect on children's vision, but because of whether children are myopic or not, the effect is different, outdoor light and exercise have a better effect on reducing the diopter of children with normal vision.

Associations between meeting 24-hour movement guidelines and myopia among school-aged children: A cross-sectional study

BACKGROUND

The Canadian 24-hour movement behavior (24-HMB) guidelines recommend an adequate level of physical activity (PA), a limited amount of screen time (ST), and a sufficient sleep duration (SLP) to promote the healthy development of children. Although the positive effects of adhering to the 24-HMB guidelines have been established for several health parameters, less is known about how adherence to the 24-HMB guidelines relates to the myopia risk (i.e., inability to see distant objects properly). Thus, this study investigated associations between meeting 24-HMB guidelines and myopia risk in school-aged children.

METHOD

Using a questionnaire survey, this cross-sectional study was conducted among parents of school-aged children (5-13 years) in China from 15th September to 15th October 2022, with a total of 1423 respondents with complete data for analysis. Parents reported their child's time spent in moderate-to-vigorous-intensity physical activity (MVPA), SLP, and ST. Multiple logistic regression analyses were performed to examine the associations between measures of PA, ST, and SLP alone and in combination, and the occurrence of myopia.

RESULTS

A relatively low percentage of the children being included in the current study (4.92%) met all 24-HMB guidelines, while 32.46% had myopia. Girls had a significantly higher risk of myopia compared to boys (OR = 1.3, 1.002 to 1.68, p = 0.049). Children of parents without myopia had a lower risk of myopia (OR = 0.45, 0.34-0.59, p < 0.001). Children who lived in urban areas (OR = 1.83, 95% CI 1.33 to 2.52, p < 0.001) or towns (OR = 1.60, 1.03 to 2.47, p = 0.04) had a significantly higher risk of myopia compared to those living in rural areas. Meeting SLP guidelines (OR = 0.50, 95% CI 0.31 to 0.82, p < 0.01), meeting ST + SLP guidelines (OR = 0.47, 95% CI 0.32-0.69, <0.001), and meeting all three guidelines were associated with significantly lower risk of myopia (OR = 0.40, 95% CI 0.20-0.82, p = 0.01). Meeting more 24-HMB guidelines was associated with a reduced risk of myopia.

CONCLUSIONS

Our data suggest that adhering to SLP, ST + SLP, and ST + SLP + PA guidelines is associated with the risk of myopia. Future research investigating dose-response associations, and potential mechanisms, is necessary to achieve a more nuanced understanding of the observed associations.

Safety and efficacy of 0.01% and 0.1% low-dose atropine eye drop regimens for reduction of myopia progression in Danish children: a randomized clinical trial examining one-year effect and safety

BACKGROUND

To investigate the efficacy and safety of 0.1% and 0.01% low-dose atropine eye drops in reducing myopia progression in Danish children.

METHODS

Investigator-initiated, placebo-controlled, double-masked, randomized clinical trial. Ninety-seven six- to twelve-year old myopic participants were randomized to 0.1% loading dose for six months followed by 0.01% for six months (loading dose group, Number (N) = 33), 0.01% for twelve months (0.01% group, N = 32) or vehicle for twelve months (placebo, N = 32). Primary outcomes were axial length and spherical equivalent refraction. Secondary outcomes included adverse events and reactions, choroidal thickness and ocular biometry. Outcomes were measured at baseline and three-month intervals. Data was analyzed with linear-mixed model analysis according to intention-to-treat.

RESULTS

Mean axial elongation was 0.10 mm less (95% confidence interval (CI): 0.17; 0.02, adjusted-p = 0.06) in the 0.1% loading dose and 0.07 mm less (95% CI: 0.15; 0.00, adjusted-p = 0.16) in the 0.01% group at twelve months compared to placebo. Mean spherical equivalent refraction progression was 0.24 D (95% CI: 0.05; 0.42) less in the loading dose and 0.19 D (95% CI: 0.00; 0.38) less in the 0.01% groups at twelve months, compared to placebo (adjusted-p = 0.06 and 0.14, respectively). A total of 108 adverse events were reported during the initial six-month loading dose period, primarily in the loading dose group, and 14 were reported in the six months following dose switching, all deemed mild except two serious adverse events, unrelated to the intervention.

CONCLUSIONS

Low-dose atropine eye drops are safe over twelve months in otherwise healthy children. There may be a modest but clinically relevant reduction in myopia progression in Danish children after twelve months treatment, but the effect was statistically non-significant after multiple comparisons adjustment. After dose-switching at six months the loading dose group approached the 0.01% group, potentially indicating an early "rebound-effect".

TRIAL REGISTRATION

this study was registered in the European Clinical Trials Database (EudraCT, number: 2018-001286-16) 05/11/2018 and first posted at www.

CLINICALTRIALS

gov (NCT03911271) 11/04/2019, prior to initiation.

Myopia Control with Low-Dose Atropine in European Children: Six-Month Results from a Randomized, Double-Masked, Placebo-Controlled, Multicenter Study

The effect and safety of low-dose atropine in myopia control have not been studied in randomized, placebo-controlled trials outside Asia. We investigated the efficacy and safety of 0.1% atropine loading dose and 0.01% atropine compared with a placebo in a European population. Investigator-initiated, randomized, double-masked, placebo-controlled, equal-allocation, multicenter study comparing 0.1% atropine loading dose (six months) followed by 0.01% atropine (18 months), 0.01% atropine (24 months), and placebo (24 months). Participants were monitored for a 12-months washout period. Outcome measures were axial length (AL), cycloplegic spherical equivalent (SE), photopic and mesopic pupil size, accommodation amplitude, visual acuity, intraocular pressure (IOP), and adverse reactions and events. We randomized 97 participants (mean [standard deviation] age, 9.4 [1.7] years; 55 girls (57%) and 42 boys (43%)). After six months, AL was 0.13 mm shorter (95% confidence interval [CI], -0.18 to -0.07 [adjusted p < 0.001]) with 0.1% atropine loading dose and 0.06 mm shorter (95% CI, -0.11 to -0.01 [adjusted p = 0.06]) with 0.01% atropine than in the placebo group. We observed similar dose-dependent changes in SE, pupil size, accommodation amplitude, and adverse reactions. No significant differences in visual acuity or IOP were found between groups, and no serious adverse reactions were reported. We found a dose-dependent effect of low-dose atropine in European children without adverse reactions requiring photochromatic or progressive spectacles. Our results are comparable to those observed in East Asia, indicating that results on myopia control with low-dose atropine are generalizable across populations with different racial backgrounds.

Interventions recommended for myopia prevention and control among children and adolescents in China: a systematic review

In 2018, a consortium of government bodies in China led by the Ministry of Education released the Comprehensive Plan to Prevent Nearsightedness among Children and Teenagers (CPPNCT), aiming to reduce the incidence of myopia and control myopic progression in China. Recommendations span from home-based to school-based interventions, including time outdoors, physical activity, light exposure, near-work activity, screen time, Chinese eye exercises, diet and sleep. To date, the levels of evidence for this suite of interventions have not been thoroughly investigated. This review has summarised the evidence of the interventions recommended by the CPPNCT in myopia prevention and control. Thus, the following statements are supposed by the evidence: (1) Increasing time outdoors and reducing near-work time are effective in lowering incident myopia in school-aged children. (2) All interventions have a limited effect on myopia progression. Ongoing research may lead to a better understanding of the underlying mechanisms of myopia development, the interaction of different interventions and recommendations, confounding variables and their true effect on myopia prevention, and the identification of those most likely to respond to specific interventions. This field may also benefit from longer-term studies of the various interventions or strategies covered within this review article, to better understand the persistence of treatment effects over time and explore more novel approaches to myopia control.

A Review of the Role of the School Spatial Environment in Promoting the Visual Health of Minors

Rising childhood myopia rate has detrimental health consequences that pose a considerable challenge to health systems. The school spatial environment, which is where students are for the longest period of time, has a high health value for myopia systematic intervention. While research has demonstrated associations between physical daylight environments, medical gene and visual health, the literature currently lacks a synthesis of evidence that will act as a spatially-organized resource for school designers. This study is based on literature from the period 2000-2022 and has been taken from the Web of Science, scopus, Medline and CNKI core collection database. Collaboration, literature co-citation and quantitative and qualitative analysis, in addition to keyword co-occurrence are adopted to conduct a visual health research review. The results indicate that intensive near work activity (as a risk factor) and longer time spent outdoors (as a protective factor), are involved in visual health factors. Two main research themes are obtained and relate to: (1) The environment of visual work behavior (especially the near work learning environment) and adaptable multimedia learning environment; and (2) the environment of outdoor exposure behavior. Furthermore, with the variation of educational demands, models and concepts, there are different demands for near work behavior, and this study makes an important contribution by pointing to two future research directions, including the accurate and controllable environment of near work behavior, which operate in accordance with various educational mode requirements and the active design of the environment of outdoor exposure behavior. In referring to differences between regions and countries, as well as the development of the educational environment, it provides insight into how these demands can be controlled.

Relatively Stable Prevalence of Myopia among Swedish Children Aged 4 to 7 Years between 2015 and 2020

SIGNIFICANCE

The global increase of myopia has caused a lot of debate the last years. Previous research of myopia in the Nordic population has shown diverse results, and only a few Swedish studies have been published in the subject the last two decades.

PURPOSE

This study aimed to analyze trends in the prevalence of myopia in a population of Swedish children.

METHODS

A retrospective analysis of medical records for children between 4 and 7 years of age in a region in Sweden was performed. The inclusion criterion was a first glasses prescription for myopia between 2012 and 2020. Children with other eye diseases or syndromes affecting the eye and vision were excluded. Age, sex, uncorrected visual acuity, and cycloplegic refractive values were extracted. The number of myopic children was compared with population data to calculate incidence and estimate prevalence.

RESULTS

During the study period, 427 children between 4 and 7 years old in an average population of 17,200 children were prescribed glasses for myopia. The incidence for myopia increased from 0.11% in 2012 to 0.39% in 2020 ( P < .05). In 2015 to 2020, the prevalence of myopia for the same age group increased from 0.5 to 1.2% ( P < .05). Linear regression of the prevalence of myopia showed a significant increase in the age group of 7 years ( β = 0.2%, R2 = 0.82, P ≤ .05).

CONCLUSIONS

This study found a relatively stable prevalence of myopia among Swedish children aged 4 to 7 years between 2015 and 2020. The prevalence of 1.6% among 7-year-old children is not higher than in previous Scandinavian studies.

Prevalence of myopia and epidemiological factors contributing to its development

Myopia, which is the most common disorder of refraction, in case of progression causes a variety of dangerous and severe complications, which can eventually lead to a significant decrease in the quality of life and disability in young and working age people. The growing trend of myopia prevalence is due to a significant increase in visual work and psychological stress, which, in their turn, are explained by rapid scientific and technological progress and extensive urbanization. The genetic, ethnic and age factors, as well as the presence of chronic diseases and general lifestyle, also play an important role in the onset of myopia.

Effects of physical activity and use of digital devices on visual acuity in children and adolescents during the COVID-19 pandemic: A cross-sectional study

Purpose

To determine the association between poor visual acuity, the use of digital devices and physical activity (PA) during the COVID-19 pandemic.

Methods

A total of 327,646 Chinese children and adolescents were included in the analysis using a cluster random sampling method; this is a case-control study, of those 144,708 children and adolescents with poor visual acuity were included in the case group, while 182,938 who did not have poor visual acuity were included in the control group. A logistic regression model was used to assess the contribution of PA and the use of digital devices to poor visual acuity.

Results

A total of 144,708 children and adolescents experienced poor visual acuity during the COVID-19 pandemic; 54.8% were male, and 55.2% live in rural areas. Compared to controls, children and adolescents with poor visual acuity exhibited more time for the use of digital devices (4.51 ± 2.44 vs. 3.79 ± 2.34 for cases and controls, respectively; P < 0.001) and PA (3.07 ± 0.92 vs. 2.85 ± 1.00 for cases and controls, respectively; P < 0.001). During the COVID-19 pandemic, risk factors related to poor visual acuity among children and adolescents included the use of digital devices (OR 1.135; 95% CI 1.132-1.139), and PA (OR 1.269; 95%CI 1.259-1.278). The results of interaction analysis show that for children and adolescents aged 12 to 17, the positive association between the use of digital devices and poor visual acuity decreased. The interaction effect between PA and digital devices is 0.987.

Conclusions

Children and adolescents were at risk of poor visual acuity during the COVID-19 pandemic. Extended use of the digital devices increased the risk of poor visual acuity, especially for children aged 6-11 years. But the risk of poor visual acuity among children and adolescents decreases as the time spent on PA increases.

Does Physical Activity Moderate the Relationship between Myopia and Functional Status in Children 9-11 Years of Age?

Although previous studies have reported an association between physical activity (PA) and myopia in school-aged children, little is known about the link between myopia and children’s functional status. The purpose of this study was to investigate dynamic balance control in relation to the daily PA levels of myopic schoolchildren aged 9−11 years (n = 52) versus a non-myopic control group (n = 53). A single leg stance test performed on the instability platform of the Biodex Balance System was used to assess balance control. The overall stability index (OSI), anterior-posterior stability index (APSI) and medial-lateral stability index (MLSI) were analyzed. PA levels were calculated using the World Health Organization European Childhood Obesity Surveillance Initiative family record form. Myopes and non-myopes were separated into three subgroups based on PA level (low, moderate and high). Myopia significantly affected OSI (F = 40.46, p < 0.001), APSI (F = 33.93, p < 0.001) and MLSI (F = 49.51, p < 0.001). There were significant differences (p < 0.001) between myopic and non-myopic children with low and moderate levels of PA, whilst there were no differences between compared children with high levels of PA. High PA levels had a positive impact on balance control in myopes. Our results showed that PA levels moderate the relationship between myopia and children’s functional status.

Objective measures of viewing behaviour in children during near tasks

CLINICAL RELEVANCE

Objective assessment of near viewing behaviours performed in a laboratory setting showed that children demonstrate differing viewing distances and angles based on the type of task. Findings will contribute to our understanding of how near work influences myopia.

BACKGROUND

Evidence suggests that near working distance and viewing breaks are associated with myopia. The purpose of this study was to use an objective, continuously measuring range finding device to examine these viewing behaviours in children.

METHODS

Viewing distance, number of breaks, and head and eye angles were assessed in 16 non-myopic and 19 myopic children (ages 13.38 ± 4.14 years) using the Clouclip, an objective rangefinder, during five 15-minute near tasks, including (a) passive reading and (b) active writing on printed material, (c) passive viewing and (d) active engagement on an iPad, and (e) active engagement on a cell phone. Height and Harmon distance were measured. Viewing behaviours were analysed by task, refractive error group, and gender.

RESULTS

Mean viewing distances significantly differed by task (P < 0.001) and were highly correlated with children's Harmon distance and height for all near tasks (P < 0.05), except for the active printed task (P > 0.05). Viewing distances did not differ by gender or refractive error group. During each task, mean number of viewing breaks was 2.6 ± 4.1 and did not vary between task (P = 0.92) or refractive error group (P = 0.65). Head declination and total viewing angle varied by type of near task (P < 0.001 for both).

CONCLUSION

Children demonstrated differing viewing distances and viewing angles based on the type of near task they were performing. Viewing behaviours did not vary between myopic and non-myopic children. Findings will contribute to a better understanding of how near viewing behaviours can be quantified objectively and relationships with myopia.

Prevalence of refractive errors in Hungary reveals three-fold increase in myopia

AIM

To examine the prevalence and composition of refractive errors in Hungary.

METHODS

Nationwide cross-sectional data collected between 2014 and 2019 were analysed from the Comprehensive Health Screening Program of Hungary, which provided spectacle dioptric power and autorefractometry data for 68 227 people (35 850 women and 32 377 men). Their age distribution, 18-99y, was similar to the national demographic distributions.

RESULTS

Of the total population, 16.50% of the refractive errors exhibited hyperopia, 40.05% emmetropia, and 43.45% myopia. Myopia was 3 times more frequent (58.7%) in younger ages (18-35y of age) compared to older age groups (19.4% of those 56-70y of age; P<0.001). High myopia showed a low prevalence (0.21%), and an increase parallel with ageing (r=0.716; P=0.009).

CONCLUSION

Myopia is the most frequent refractive error in Hungary. The prevalence of myopia is especially increased, up to 2-3 times, in the younger age groups. Nationwide actions need to be taken to reduce the onset of myopia and its associated consequences.

Functional Analysis of an Intronic FBN1 Pathogenic Gene Variant in a Family With Marfan Syndrome

Marfan syndrome (MFS) is an autosomal dominant connective tissue disorder that canonically affects the ocular, skeletal, and cardiovascular system, in which aortic tear and rupture is the leading cause of death for MFS patients. Genetically, MFS is primarily associated with fibrillin-1 (FBN1) pathogenic variants. However, the disease-causing variant in approximately 10% of patients cannot be identified, partly due to some cryptic mutations that may be missed using routine exonic sequencing, such as non-coding intronic variants that affects the RNA splicing process. We present a 32-year female with typical MFS systemic presentation that reached to a clinical diagnosis according to the revised Ghent nosology. We performed whole-exome sequencing (WES) but the report failed to identify known causal variants when analyzing the exonic sequence. However, further investigation on the exon/intron boundaries of the WES report revealed a candidate intronic variant of the fibrillin 1 (FBN1) gene (c.248-3 C>G) that predicted to affect the RNA splicing process. We conducted minigene splicing analyses and demonstrated that the c.248-3 C>G variant abolished the canonical splicing site of intron 3, leading to activation of two cryptic splicing sites and causing insertion (c.248-1_248-2insAG and c.248-1_248-282ins). Our study not only characterizes an intronic variant to the mutational spectrum of the FBN1 gene in MFS and its aberrant effect on splicing, but highlights the importance to not neglect the exon/intron boundaries when reporting and assessing WES results. We point out the need of conducting functional analysis to verify the pathogenicity of intronic mutation, and the opportunity to re-consider the standard diagnostic approaches in cases of clinically diagnosed MFS with normal or variant of unknown significance genetic results.

Systematic review and meta-analysis of myopia prevalence in African school children

Purpose

Increased prevalence of myopia is a major public health challenge worldwide, including in Africa. While previous studies have shown an increasing prevalence in Africa, there is no collective review of evidence on the magnitude of myopia in African school children. Hence, this study reviews the evidence and provides a meta-analysis of the prevalence of myopia in African school children.

Methods

This review was conducted using the 2020 Preferred Reporting Items for Systematic reviews and Meta-Analyses (PRISMA) guidelines. Five computerized bibliographic databases, PUBMED, Scopus, Web of Science, ProQuest, and Africa Index Medicus were searched for published studies on the prevalence of myopia in Africa from 1 January 2000 to 18 August 2021. Studies were assessed for methodological quality. Data were gathered by gender, age and refraction technique and standardized to the definition of myopia as refractive error ≥ 0.50 diopter. A meta-analysis was conducted to estimate the prevalence. Significant heterogeneity was detected among the various studies (I² >50%), hence a random effect model was used, and sensitivity analysis was performed to examine the effects of outliers.

Results

We included data from 24 quality assessed studies, covering 36,395 African children. The overall crude prevalence of myopia over the last two decades is 4.7% (95% CI, 3.9–5.7) in African children. Although the prevalence of myopia was slightly higher in females (5.3%, 95%CI: 4.1, 6.5) than in males (3.7%, 95% CI, 2.6–4.7; p = 0.297) and higher in older [12–18 years 5.1% (95% CI, 3.8–6.3) than younger children (aged 5–11 years, 3.4%, 95% CI, 2.5–4.4; p = 0.091), the differences were not significant. There was a significantly lower prevalence of myopia with cycloplegic compared with non-cycloplegic refraction [4.2%, 95%CI: 3.3, 5.1 versus 6.4%, 95%CI: 4.4, 8.4; p = 0.046].

Conclusions

Our results showed that myopia affects about one in twenty African schoolchildren, and it is overestimated in non-cycloplegic refraction. Clinical interventions to reduce the prevalence of myopia in the region should target females, and school children who are aged 12–18 years.

Association Between Color Vision Deficiency and Myopia in Chinese Children Over a Five-Year Period

Purpose

To explore the relationship of color vision deficiency with myopia progression and axial elongation in Chinese primary school children during a five-year cohort study.

Methods

A total of 2849 grade 1 students (aged 7.1 ± 0.4 years) from 11 primary schools were enrolled and followed up for five years. Cycloplegic autorefraction and axial length were measured annually. Color vision testing was performed using Ishihara's test and the City University color vision test.

Results

The prevalence of color vision deficiency was 1.68%, with 2.81% in boys and 0.16% in girls. Color-deficient cases consisted of 91.6% deutan and 8.3% protan. Over the five years, the cumulative incidence of myopia was 35.4% (17/48) in the color-vision deficiency group, which was lower than the 56.7% (1017/1794) in the color normal group (P = 0.004). Over the five-year study period, the change in spherical equivalent refraction in the color vision–deficiency group (−1.81 D) was also significantly lower than that in the color normal group (−2.41 D) (P = 0.002).

Conclusions

The lower incidence and slower progression of myopia in children with color-vision deficiency over the five-year follow-up period suggest that color-deficient individuals are less susceptible to myopia onset and development.

Objective and Subjective Behavioral Measures in Myopic and Non-Myopic Children During the COVID-19 Pandemic

Purpose

The coronavirus disease 2019 (COVID-19) pandemic required a shift to electronic devices for education and entertainment, with children more confined to home, which may affect eye growth and myopia. Our goal was to assess behaviors during COVID-19 in myopic and non-myopic children.

Methods

Parents completed a questionnaire for their children (ages 8.3 ± 2.4 years, n = 53) regarding visual activity in summer 2020, during the COVID-19 pandemic, as well as during school time and the summer before COVID-19. Children also wore an Actiwatch for 10 days in summer 2020 for objective measures of light exposure, activity, and sleep. Data were analyzed with repeated-measures analysis of variance.

Results

Subjective measures showed that during COVID-19, children exhibited increased electronic device use and decreased activity and time outdoors (P < 0.05 for all), while time spent doing near work was not different than during a typical school or summer session before COVID-19 (P > 0.05). Objective measures during COVID-19 showed that myopic children exhibited lower daily light exposure (P = 0.04) and less activity (P = 0.04) than non-myopic children.

Conclusions

Children demonstrated increased electronic device use and decreased activity and time outdoors during COVID-19, with myopic children exhibiting lower light exposure and activity than non-myopes. Long-term follow-up is needed to understand if these behavioral changes ultimately contribute to myopia progression.

Translational Relevance

Children's behaviors changed during the COVID-19 pandemic, which may have implications in eye growth and myopia.

Refractive errors and visual impairment among children and adolescents in southernmost China

Background

Refractive errors and visual impairment in southernmost China have not been reported previously. We aim to investigate and determine the age-specific prevalence of myopia, hyperopia, astigmatism, and visual impairment based on a large population cross-sectional study in Hainan area of southernmost tropical province in China.

Methods

A population-based sample of 31,524 children aged 615years from Hainan was assessed. Non-cycloplegic autorefraction and visual acuity (VA) analyses were performed on all participants and a subgroup of participants undergoing cycloplegia.

Results

Of all participants, 23.0% presented uncorrected VA (UCVA) was worse than 20/40 in worse eye, 6.0% presented mild presenting visual acuity impairment (PVAI), 7.0% presented moderate PVAI, 0.2% presented severe PVAI in the better eye, and 46.9% presented abnormal UCVA [worse than 20/25 (6,<8years old) and worse than 20/20 (8years and older)] at least in one eye. The overall prevalence of myopia [spherical equivalent (SE)0.50 D] and high myopia (SE6.00 D) were 46.0%, 1.0% respectively. Hyperopia [SE+1.00 D (7years old) and SE+2.00 D (6,<7years old)] and significant hyperopia (SE+3.00 D) were 4.2 and 0.6%, respectively. Astigmatism [cylinder1.00 D (7years old) and1.75 D (6,<7years old)] was found in 31.9%.

Conclusions

Myopia was the most common refractive error in southernmost province in China (Hainan). Its prevalence increased with age, while hyperopia prevalence showed a decreasing trend. However, myopia, especially high myopia prevalence was much lower than in other urban regions across China.

Characterization of Brain Microstructural Abnormalities in High Myopia Patients: A Preliminary Diffusion Kurtosis Imaging Study

Objective

To evaluate microstructural damage in high myopia (HM) patients using 3T diffusion kurtosis imaging (DKI).

Materials and Methods

This prospective study included 30 HM patients and 33 age- and sex-matched healthy controls (HCs) with DKI. Kurtosis parameters including kurtosis fractional anisotropy (FA), mean kurtosis (MK), axial kurtosis (AK), and radial kurtosis (RK) as well as diffusion metrics including FA, mean diffusivity, axial diffusivity (AD), and radial diffusivity derived from DKI were obtained. Group differences in these metrics were compared using tract-based spatial statistics. Partial correlation analysis was used to evaluate correlations between microstructural changes and disease duration.

Results

Compared to HCs, HM patients showed significantly reduced AK, RK, MK, and FA and significantly increased AD, predominately in the bilateral corticospinal tract, right inferior longitudinal fasciculus, superior longitudinal fasciculus, inferior fronto-occipital fasciculus, and left thalamus (all p < 0.05, threshold-free cluster enhancement corrected). In addition, DKI-derived kurtosis parameters (AK, RK, and MK) had negative correlations (r = −0.448 to −0.376, all p < 0.05) and diffusion parameter (AD) had positive correlations (r = 0.372 to 0.409, all p < 0.05) with disease duration.

Conclusion

HM patients showed microstructural alterations in the brain regions responsible for motor conduction and vision-related functions. DKI is useful for detecting white matter abnormalities in HM patients, which might be helpful for exploring and monitoring the pathogenesis of the disease.

Update and guidance on management of myopia. European Society of Ophthalmology in cooperation with International Myopia Institute

The prevalence of myopia is increasing extensively worldwide. The number of people with myopia in 2020 is predicted to be 2.6 billion globally, which is expected to rise up to 4.9 billion by 2050, unless preventive actions and interventions are taken. The number of individuals with high myopia is also increasing substantially and pathological myopia is predicted to become the most common cause of irreversible vision impairment and blindness worldwide and also in Europe. These prevalence estimates indicate the importance of reducing the burden of myopia by means of myopia control interventions to prevent myopia onset and to slow down myopia progression. Due to the urgency of the situation, the European Society of Ophthalmology decided to publish this update of the current information and guidance on management of myopia. The pathogenesis and genetics of myopia are also summarized and epidemiology, risk factors, preventive and treatment options are discussed in details.

IMI Risk Factors for Myopia

Risk factor analysis provides an important basis for developing interventions for any condition. In the case of myopia, evidence for a large number of risk factors has been presented, but they have not been systematically tested for confounding. To be useful for designing preventive interventions, risk factor analysis ideally needs to be carried through to demonstration of a causal connection, with a defined mechanism. Statistical analysis is often complicated by covariation of variables, and demonstration of a causal relationship between a factor and myopia using Mendelian randomization or in a randomized clinical trial should be aimed for. When strict analysis of this kind is applied, associations between various measures of educational pressure and myopia are consistently observed. However, associations between more nearwork and more myopia are generally weak and inconsistent, but have been supported by meta-analysis. Associations between time outdoors and less myopia are stronger and more consistently observed, including by meta-analysis. Measurement of nearwork and time outdoors has traditionally been performed with questionnaires, but is increasingly being pursued with wearable objective devices. A causal link between increased years of education and more myopia has been confirmed by Mendelian randomization, whereas the protective effect of increased time outdoors from the development of myopia has been confirmed in randomized clinical trials. Other proposed risk factors need to be tested to see if they modulate these variables. The evidence linking increased screen time to myopia is weak and inconsistent, although limitations on screen time are increasingly under consideration as interventions to control the epidemic of myopia.

Myopia prevalence in Denmark - a review of 140 years of myopia research

PURPOSE

To evaluate potential changes in myopia prevalence in Denmark by revising more than 100 years of myopia research.

METHODS

A systematic literature search was performed in the PubMed, Embase and Cochrane Library databases. Only studies reporting a myopia prevalence in Denmark were included. Myopia was defined using the definition in individual references. We did not restrict inclusion of studies to specific methods of measuring or evaluating refraction. As refraction changes throughout life, information from available studies was divided in relevant age groups. Chi-squared test was used when analysing the effect of sex and education on myopia prevalence except when the expected values were beneath 5, where Fisher's exact test was used. To further compare the effect of sex, we calculated the odds ratio of being myopic for females compared to males.

RESULTS

We identified 29 Danish studies reporting on prevalence of myopia. The studies were performed between year 1882 and 2018. We found no strong evidence of an increase in myopia prevalence in Denmark. Increasing age was associated with an increased myopia prevalence up to the age of 60 years where after the prevalence decreased. Longer education and more intensive educational load were associated with myopia. Fourteen studies compared the prevalence of myopia between males and females and two of these studies found a significant higher prevalence in females.

CONCLUSION

We evaluated nearly 140 years of myopia research in Denmark and did not find a convincing change in prevalence of myopia which is in contrast to the high prevalence of myopia reported in some parts of the world and the expected rise in myopia as predicted by WHO.

Intra- and Inter-Model Variability of Light Detection Using a Commercially Available Light Sensor

The veracity of claims made by researchers and clinicians when reporting the impact of lighting on vision and other biological mechanisms is, in part, reliant on accurate and valid measurement devices. We aim to quantify the intra- and inter-watch variability of a commercially available light sensor device which has been widely used in vision and other photobiological research. Intra- and inter-watch differences were investigated between four Actiwatch Spectrum Pro devices. The devices were used to obtain measurements on two separate occasions, under three different controlled light conditions; the Gretag Macbeth Judge II lightbox was used to produce Simulated Daylight (D65), Illuminant A (A) and Cool White Fluorescent (CWF) lighting. Significant inter-watch differences were noted when considering tricolour (red, green, blue) and the white sensor outputs under each of the three illuminants (p < 0.01). A significant interaction was also found between tricolour sensor and watch used (p < 0.01). Intra-watch differences were noted for the tricolour and for the white sensor outputs under the three illuminants (≤0.05), for all but one watch which showed no significant intra-watch difference for the white 'sensor output' under the D65 illuminant. Use of spectral sensitivity devices is an evolving field. Before drawing causal relationships between light and other biological processes, researchers should acknowledge the limitations of the instruments used, their validation, and the resultant data. The outcomes of the study indicate caution must be exercised in longitudinal data collection and the mixing of watches amongst study participants should be avoided.

Low physical activity and higher use of screen devices are associated with myopia at the age of 16-17 years in the CCC2000 Eye Study

PURPOSE

To determine the myopia prevalence in a Danish cohort aged 16-17 years and its relation to physical activity and use of screen-based electronic devices.

METHODS

The Copenhagen Child Cohort 2000 Eye Study is a prospective, population-based, observational study. Information about use of screen devices and physical activity was obtained using questionnaires. Myopia was defined as non-cycloplegic subjective spherical equivalent refraction ≤-0.50 D in right eye.

RESULTS

We included 1443 participants (45% boys) with a median age (±IQR) of 16.6 years (±0.3). The prevalence of myopia was 25% (CI95% 23-28, n = 360) with no differences between sexes (p = 0.10). The odds ratio (OR) for myopia was 0.57 (CI95% 0.42-0.76, p = 0.0002) in participants physically active 3-6 hr/week (n = 502) and 0.56 (CI95% 0.42-0.76, p = 0.0002) if active >6 hr/week (n = 506), both compared with participants physically active <3 hr/week (n = 396). The use of screen devices >6 hr/day was associated with increased OR for myopia compared with screen device use <2 hr/day in both weekdays (OR = 1.95, CI95% 1.16-3.30, p = 0.012) and weekends (OR = 2.10, CI95% 1.17-3.77, p = 0.013).

CONCLUSION

In this cohort of healthy 16-17-year olds, lower physical activity and more use of screen devices contributed significantly to the observed 25% prevalence of myopia with a roughly doubled risk of having myopia if physically active <3 hr/week or if using screen devices >6 hr/day. Our results support physical activity being a protective factor and near work a risk factor for myopia in adolescents.

Thirty-five-year trend in the prevalence of refractive error in Austrian conscripts based on 1.5 million participants

Background

To quantify the current burden of myopia and hyperopia in Austrian young men and the time trend of myopia in the past 35 years by individual and social correlates.

Method

We included data on all Austrian military conscripts from 1983 to 2017 (n=1 507 063) from six medical investigation stations. Young men provided data on education, weight and height for calculating body mass index, blood pressure and resting heart rate. Non-cycloplegic refractions were measured by an autorefractometer. Spherical equivalent was calculated by standard formula (sphere+cylinder/2, unit dioptres (D)). Myopic refractive error was defined as <−0.5 D). Hyperopic refractive error was defined as >0.5 D.

Results

The largest burden of refractive error in Austria is myopia, which rose from 13.8% to 24.4% over 35 years, with less than 5% hyperopic population. Over time, the prevalence of myopia was constantly lower yet increased more rapidly among those with low education levels (11.4%–21.7%) compared with those with higher education (24.5%–29.6%) in all medical investigation stations. We found consistent associations of some unfavourable health indicators (underweight: ORs 1.1–1.4, higher resting heart rate: all p trend <0.001) with higher myopia prevalence, which point towards lifestyle factors playing an important role in the development of myopia.

Conclusion

Primary preventive measures are needed to curb the observed trend in myopia among Austrian young men. Future research should investigate the impact of modifiable factors on myopia development and progression, particularly lifestyle factors that are dramatically shifting.

A review on the epidemiology of myopia in school children worldwide

Background

Due to high prevalence myopia has gained importance in epidemiological studies. Children with early onset are at particular risk of complications associated with myopia, as progression over time might result in high myopia and myopic macular degeneration. Both genetic and environmental factors play a role in the increasing prevalence of myopia. The aim of this study is to review the current literature on epidemiology and risk factors for myopia in school children (aged 6–19 years) around the world.

Main body

PubMed and Medline were searched for the following keywords: prevalence, incidence, myopia, refractive error, risk factors, children and visual impairment. English language articles published between Jan 2013 and Mar 2019 were included in the study. Studies were critically reviewed for study methodology and robustness of data. Eighty studies were included in this literature review.

Myopia prevalence remains higher in Asia (60%) compared with Europe (40%) using cycloplegic refraction examinations. Studies reporting on non-cycloplegic measurements show exceptionally high myopia prevalence rates in school children in East Asia (73%), and high rates in North America (42%). Low prevalence under 10% was described in African and South American children. In recent studies, risk factors for myopia in schoolchildren included low outdoor time and near work, dim light exposure, the use of LED lamps for homework, low sleeping hours, reading distance less than 25 cm and living in an urban environment.

Conclusion

Low levels of outdoor activity and near work are well-established risk factors for myopia; this review provides evidence on additional environmental risk factors. New epidemiological studies should be carried out on implementation of public health strategies to tackle and avoid myopia. As the myopia prevalence rates in non-cycloplegic studies are overestimated, we recommend considering only cycloplegic measurements.

How does spending time outdoors protect against myopia? A review

Myopia is an increasingly common condition that is associated with significant costs to individuals and society. Moreover, myopia is associated with increased risk of glaucoma, retinal detachment and myopic maculopathy, which in turn can lead to blindness. It is now well established that spending more time outdoors during childhood lowers the risk of developing myopia and may delay progression of myopia. There has been great interest in further exploring this relationship and exploiting it as a public health intervention aimed at preventing myopia in children. However, spending more time outdoors can have detrimental effects, such as increased risk of melanoma, cataract and pterygium. Understanding how spending more time outdoors prevents myopia could advance development of more targeted interventions for myopia. We reviewed the evidence for and against eight facets of spending time outdoors that may protect against myopia: brighter light, reduced peripheral defocus, higher vitamin D levels, differing chromatic spectrum of light, higher physical activity, entrained circadian rhythms, less near work and greater high spatial frequency (SF) energies. There is solid evidence that exposure to brighter light can reduce risk of myopia. Peripheral defocus is able to regulate eye growth but whether spending time outdoors substantially changes peripheral defocus patterns and how this could affect myopia risk is unclear. Spectrum of light, circadian rhythms and SF characteristics are plausible factors, but there is a lack of solid evidence from human studies. Vitamin D, physical activity and near work appear unlikely to mediate the relationship between time spent outdoors and myopia.

Risk factors for high myopia: a 22-year follow-up study from childhood to adulthood

PURPOSE

To determine the effect of the definition of high myopia on its prevalence and risk factors for high myopia.

METHODS

A total of 240 myopic schoolchildren (119 boys and 121 girls) at the mean age of 10.9 years (range 8.8-12.8 years) were recruited to a randomized clinical trial of myopia treatment among children from 3rd- and 5th grades of school referred for an eye examination due to poor distant vision and having no previous spectacles. Clinical follow-ups, including refraction with cycloplegia, were conducted annually at 3 years [third follow-up here = clinical follow-up 1, (n = 237)], and thereafter twice at approximately 10-year intervals [clinical follow-ups 2 (n = 179) and 3, (n = 134)]. Additional refraction values between follow-ups 2 and 3 were received from ophthalmologists and opticians' prescriptions and records. The most recent adulthood refraction measure available was taken as the final refraction value for 204 (85%) of the original cohort [mean follow-up time (±standard deviation) 22.1 (±3.9) years]. Parental myopia, time spent on reading and close work, watching TV and outdoor activities were assessed with a questionnaire at the clinical follow-ups. The influence of different definitions of high myopia on its prevalence was analysed. The associations of different factors with high myopia were investigated.

RESULTS

Mean spherical equivalent (SE) at baseline was -1.43 (±0.60) D, ranging from -0.38 D to -3.00 D. At follow-up end, mean SE of the more myopic eye was -5.29 (±1.95) D, ranging from -1.00 D to -11.25 D. High myopia prevalence with the definitions SE < -6.00 D in the right eye and SE ≤ -6.00 D or ≤-5.00 D in either eye was 24%, 32% and 52%, respectively. In this study, high myopia was defined as spherical equivalent (SE) ≤ -6.00 D in either eye. If both parents were myopic, the odds ratio (OR) of having high myopia was 3.9 (95% CI: 1.5-10.4). Younger age at baseline predicted higher prevalence of high myopia; baseline ages between 8.8 and 9.7 and between 11.9 and 12.8 years gave prevalences 65% and 7%. Higher myopia at baseline, higher myopic progression between the first follow-ups and more time spent on reading and close work as compared with time spent outdoors were associated with high myopia.

CONCLUSION

About 32% of the children receiving first spectacles for myopia between ages of 8.8-12.8 years had high myopia (SE ≤ -6.00 D in either eye) in adulthood. Different definitions of high myopia ranging between -5 D and -6 D lead to large differences in prevalence. A generally accepted definition of high myopia is thus needed. Parental myopia, age at baseline, myopic progression during the first post onset year, and more time spent on reading and close work and less on outdoor activities in childhood were associated with adulthood high myopia.

Physical activity and eye diseases. The Beijing Eye Study

PURPOSE

To assess associations between the amount of physical activity and the prevalence of ocular diseases.

METHODS

The participants of the population-based Beijing Eye Study underwent a detailed ophthalmological examination and an interview. Physical activity was assessed in a standardized questionnaire.

RESULTS

Out of 3468 study participants, information on their physical activity was available for 3031 (87.4%) individuals (age: 64.6 ± 9.7 years; range: 50-93 years). In multivariate analysis (regression coefficient r: 0.41), higher physical activity was associated with a lower prevalence of diabetic retinopathy [p = 0.009; standardized regression coefficient beta: -0.05; non-standardized regression coefficient B: -15.7; 95% confidence interval (CI): -27.6, -3.90] after adjusting for younger age, rural region of habitation, lower level of education, lower blood concentrations of triglycerides and low-density lipoproteins and higher blood concentrations of high-density lipoproteins, higher systolic blood pressure, lower body mass index and lower depression score. Other major ocular diseases such as open-angle glaucoma (p = 0.25), angle-closure glaucoma (p = 0.59), nuclear cataract (p = 0.78), cortical cataract (p = 0.54), posterior subcapsular cataract (p = 0.96), retinal vein occlusions (p = 0.93) and central serous choroidopathy (p = 0.39) were not statistically associated with physical activity in that model. The association between higher physical activity and prevalence of age-related macular degeneration (p = 0.04; β: 0.04; B: 4.87; 95% CI: 0.25, 9.50) was marginally significant.

CONCLUSIONS

Higher physical activity and less sedentary lifestyle were associated with a lower prevalence of diabetic retinopathy, while the occurrence of other major ocular diseases such as any type of cataract and of glaucoma, retinal vein occlusions and central serous choroidopathy was statistically independent of physical activity or a more sedentary lifestyle.

Influence of seasons upon personal light exposure and longitudinal axial length changes in young adults

PURPOSE

To investigate the association between objectively measured ambient light exposure and longitudinal axial length changes (and their seasonal variations) over a period of 12 months in young adults.

METHODS

This prospective longitudinal observational study included 43 healthy young adult university students (21 emmetropes and 22 myopes) aged between 18 and 30 years. Three axial length measurements were collected at 6-month intervals (i.e. at baseline, 6 and 12 months), in summer and winter to determine the axial eye growth. Personal ambient light exposure data were measured in winter and summer months with wearable sensors, from which the mean daily time exposed to bright (outdoor) light levels (>1000 lux) was derived.

RESULTS

Greater daily bright light exposure was associated with less axial eye growth (β = -0.002, p = 0.006) over 12 months. In summer, myopes exhibited significantly greater changes in axial length (mean change 0.04 ± 0.05 mm) compared to emmetropes (-0.01 ± 0.05 mm) (p = 0.001), but there was no significant difference between refractive groups in winter. Emmetropes also spent significantly greater time in outdoor light levels in summer compared to winter (p < 0.0001), while myopes spent similar time outdoors during both seasons (p = 0.12). Differences in light exposure between summer and winter were also associated with seasonal differences in axial eye growth (p = 0.026).

CONCLUSION

In young adults, greater time spent in bright light was associated with slower longitudinal axial eye growth. Seasonal light exposure and axial length changes were dependent on refractive error in this population and also exhibited an inverse relationship.

Retinal vascular diameters in relation to physical activity in Danish children - The CHAMPS Eye Study

Our objective was to determine associations between retinal vascular caliber and physical activity (PA) in a school-based child cohort. In a prospective study, we created a childhood cumulative average PA-index using objectively measured PA (accelerometry) assessed at four periods between 2009 and 2015. Cumulative exposure to PA intensities was estimated. Cross-sectional examinations on biomarkers, anthropometry, and ophthalmological data including retinal fundus photographs were performed in 2015. Semi-automated measurements of retinal vascular diameters were performed and summarized into central retinal arteriolar and venular equivalents (CRAE, CRVE). We included 307 participants. Mean age in 2015 was 15.4 years (0.7). The mean CRAE and CRVE were 156.5 μm (2.8) and 217.6 μm (7.7), respectively. After adjusting for age, gender, and axial length, more time in PA was independently related to thinner retinal venules (β-coefficient = -1.25 μm/%, 95% confidence interval = -2.20, -0.30, P < .01). Sedentary time was associated with wider venules (P < .01). Furthermore, birthweight (β-coefficient = 0.56 μm/%, 95% confidence interval = 0.18, 0.95, P < .01) was associated with CRVE. Blood pressure was associated with thinner retinal arterioles (β-coefficient = -0.19 μm/mmHg, 95% confidence interval = -0.36, -0.01, P = .04). We concluded that children with higher PA in childhood had thinner retinal venular caliber. Our results suggest that PA during childhood positively impacts the retinal microcirculation and that retinal vascular analysis may be a possible assessment to detect microvascular impairments in children with an increased risk of future cardiovascular disease.